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Animal Science Journal (2015) 86, 707–715
doi: 10.1111/asj.12342
ORIGINAL ARTICLE Effect of fat content on sensory characteristics of marbled beef from Japanese Black steers Fumiko IIDA,1 Kaoru SAITOU,2 Tadashi KAWAMURA,2 Shizuko YAMAGUCHI3 and Toshihide NISHIMURA4 1
Department of Food and Nutrition, Japan Women’s University, 3Taste and Food Preference Laboratory, Department of Food Science and Technology, Nippon Veterinary and Life Science University, Tokyo and 2National Livestock Breeding Center, Fukushima, Japan 4
ABSTRACT To analyze the sensory characteristics of meat samples with a crude fat content between 23.8% and 48.6% taken from 34 Japanese Black steers, we grilled the meat and subjected it to analytical sensory evaluation. We also measured the amounts of moisture, protein, nucleic acid and glutamic acid. An increase in crude fat content increased the tenderness, juiciness, and fattiness in the meat quality evaluation. An increase in crude fat content reduced the crude protein and moisture contents; it also slightly reduced the nucleic acid and glutamic acid contents, although when the reductions in these umami components were assessed relative to the moisture content they changed little. Increasing the fat content up to a certain point greatly enhanced the umami intensity and beef flavor intensity in the meat quality evaluation and raised the overall evaluation score; the peak of the appropriate crude fat content for these purposes was about 36%.
Key words: appropriate fat content, beef flavor, marbled beef, sensory characteristics, umami.
INTRODUCTION The Japanese preference for beef differs from that in many countries and has developed as part of the unique Japanese food culture. Whereas lean meat is strongly preferred in other countries (Richardson et al. 1993; Grunert 1997; Verbeke & Viaene 1999; Holm & Mohl 2000; Lea & Worsley 2001; Killinger et al. 2004), marbled beef is the absolute preference in Japan. Japanese Black beef is known for its very large amount of marbling and has distinctive textural, flavor and taste characteristics. Even when this meat is cooked, the beef remains tender and is characterized by a smooth texture, pleasant oiliness and rich umami (the fifth taste) (Yamaguchi 2011), as well as the unique and pleasant aroma of wagyu (Okitani 1993; Matsuishi et al. 2004). Marbled beef has been studied overseas, as well as in Japan. In a review by Blumer (1963) of earlier studies (Blumer & Fleming 1959; Blumer et al. 1962) performed by his research group, he described the taste characteristics of marbled beef. The crude fat content of the cattle that his group examined for marbling ranged from 0.87% to 14.82%, and the amount of intramuscular fat was related to the amounts of tenderness, flavor and juiciness. Recent studies have examined the relationships among marbling, the length of the fattening period © 2014 Japanese Society of Animal Science
and meat characteristics at the time of slaughter. May et al. (1992) reported that marbling grade was more closely correlated with juiciness and flavor intensity than was backfat thickness in fattened cattle late in the fattening period. Shackelford et al. (1994) similarly reported that marbling grade was more closely correlated with tenderness than was backfat thickness. There have recently been reports that even Americans, who traditionally have favored lean meat, are gradually beginning to acquire a taste for marbled meat (Platter et al. 2003; Killinger et al. 2004). Nevertheless, the fat content of the beef examined in the above reports were extremely low (less than about 10%) compared with that of marbled beef in Japan. In Japan, the crude fat content of A5 grade beef (the highest grade of beef graded by the Japan Meat Grading Association) recently exceeded 40%. In addition, beef with more marbling tends to be given a higher rating in the Beef Marbling Standard (BMS numbers range from 1 to 12) because of consumers’ strong appreciation of fine marbling and an increasing
Correspondence: Fumiko Iida, Department of Food and Nutrition, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo, Tokyo 112-8681, Japan. (Email: [email protected]) Received 6 March 2014; accepted for publication 11 September 2014.
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trend in the amount of marbling in Japanese beef (Ozutsumi et al. 1985; Ozutsumi 1989; Cameron et al. 1994; Inoue et al. 2002; Ueda et al. 2007). In contrast, Okita et al. (1999) and Yamaguchi (2011) reported that consumers do not necessarily favor excessive marbling. According to one of our own surveys, the crude fat content of the highest grade (A5) of wagyu sirloin beef sold at high-class department stores was 69%; sensory evaluation by customers revealed that this beef was clearly not favored (Yamaguchi et al. 2009; Yamaguchi 2011). Beef is regarded as a protein food, and if it has too much fat it is not considered suitable as a major source of the proteins needed to sustain life. For this reason, it is very important that we identify the ideal fat content of beef in terms of sensory characteristics. To clarify the relationship between the fat content of marbled beef from Japanese Black steers and its effect on taste characteristics, we conducted a sensory evaluation of the beef from 34 Japanese Black steers that had been raised under strictly managed breeding conditions. The beef had a crude fat content of between 23.8% and 48.6% (BMS numbers from 3 to 9 and grades from B2 to A5). The chemical components of the beef were also measured and taken into consideration.
METHODS Samples The 34 cattle used were common Japanese Black steers raised since age 6 months at the National Livestock Breeding Center in Fukushima Prefecture by using the same fattening method and slaughtered and processed by the same method at ages 21 to 30 months. The portion from the seventh to the 11th thoracic vertebrae was used for the chemical analysis; this portion is closest to the sixth and seventh thoracic vertebrae used for grading beef in Japan. The portion from the 13th thoracic vertebra to the first lumbar vertebra was used for the sensory evaluation. After the cattle had been slaughtered, the dressed carcasses were aged at 2°C for 14 days and then frozen at −30°C. Beginning 2 days before the sensory evaluation, the samples were thawed at 2°C for 24 h and then cut into 1-cm-thick slices. The slices were then sent by refrigerated delivery service from Fukushima Prefecture to the Japan Women’s University in Tokyo. They were immediately stored at 2°C in a thermostatic chamber. They were cooked and evaluated the following day.
Sensory evaluation of beef The experiment was conducted between December 2003 and December 2006. The sensory evaluation was conducted as part of a research project conducted by Japan’s National Livestock Breeding Center. In line © 2014 Japanese Society of Animal Science
with the overall plan of the experiment, the 34 cattle used in the experiment were slaughtered in groups of three and the samples taken from them were simultaneously evaluated. The evaluation was performed on sliced beef that was grilled after the meat had been taken out of the refrigerator and returned to room temperature. The sliced beef was cut parallel to the muscle (Longissimus thoracis) fiber orientation to a size of 3 × 4 × 1 cm. The three beef samples compared each time were grilled side by side on a hotplate (Zojirushi Corporation, Osaka, Japan) preheated to 200°C. One side of the meat was grilled for 1 min and the other side was grilled for around 1.5 min, so that the internal temperature reached 60°C. Although this condition for grilling was decided in our previous paper (Iida et al. 2014), the internal temperature of marbled beef after grilling was not necessarily 60°C because of the differences in fat content. So, the slight changes in heating time for meat samples were performed using an infrared thermometer (refractive index 0.95). Concretely, a meat was cut at its center after grilling described above, and then the temperature at the center spot of the cross section of cooked meat was measured with an infrared thermometer, and the 60°C at the center of meat was confirmed. The cooked beef without salt was left to rest for 10 min, cut in half, and subjected to sensory evaluation without addition of salt at room temperature. The following six items were evaluated: tenderness, juiciness, fattiness, intensity of the pleasant beef flavor (aroma perceived through the mouth), umami intensity and overall evaluation (based not on subjective likes and dislikes but on whether or not the sample represented good or bad beef). The items were evaluated on an 8-point scale without a median value. The highest score of 8 was given to very tender on a scale ranging from very tender to very tough; similarly, the highest scores were given to very juicy on the very juicy to dry scale, to very fatty on the very fatty to lean scale, to strongly flavored on the strongly flavored to weakly flavored scale, to strongly umami intensity on the strongly umami intensity to weakly umami intensity scale, and to good on the good to bad scale. From a pool composed of 15 undergraduate and graduate students of the Laboratory of Cookery Science and three faculty members (all female), between 14 and 18 people became the evaluation panel. The composition of the panel varied from time to time. All panel members had basic knowledge of sensory evaluation, as obtained through lectures, exercises and frequent experience as panel members for judging various foods, including beef. However, before the experiment started, so that they could learn and remember the characteristics of beef, the panel members tasted various grades of commercially available beef that fully covered the range of experimental samples. Animal Science Journal (2015) 86, 707–715
BEEF FAT CONTENT AND SENSORY CHARACTERISTICS
Chemical analysis General composition analysis (moisture, crude protein and crude fat content) The moisture content of the Longissimus thoracis muscle was calculated by weighing the minced muscle before and after it had been heated at 105°C for 24 h. After moisture content measurement, the crude protein content of the dried sample was measured by using the Kjeldahl method. The nitrogen content was measured by using the Soxhlet extraction method, and the crude fat content was measured by using the Official Methods of Analysis of the Association of Official Analytical Chemists (1990). The values shown here were all converted to raw meat values. Free amino acids The method reported by Nishimura et al. (1988, 1999) was used in the following experiment. Ten grams of raw meat was homogenized with 25 mL of distilled water for 1 min. The homogenate was centrifuged at 11 500 × g for 10 min at 4°C and the supernatant was collected. The supernatant was then percolated through a filter paper (Advantec 5B; Toyo, Tokyo, Japan). After the proteins had been removed from this filtrate by adding trichloroacetic acid (5% final concentration) and the filtrate centrifuged as described above, the supernatant was passed through a membrane filter (0.45 μm, Advantec; Toyo, Tokyo, Japan) and analyzed for free amino acids with an amino acid analyzer (Jasco LC-NET II/ADC Analyzer; Jasco, Tokyo, Japan).
supernatant was then passed through a membrane filter (0.45 μm, Advantec, Toyo, Japan) and diluted tenfold with distilled water to determine the 5′-IMP content by employing high-performance liquid chromatography (HPLC) (Shimadzu SPD-10AV: UV-VIS, Detector LC-10AD, Kyoto, Japan), with a column (Senshu Pak Pegasil-B ODS 4.6 φ × 250 mm, Tokyo, Japan) equilibrated with 20 mmol/L phosphoric acid and 22 mmol/L diethyl amino ethanol. The flow rate was 1.0 mL/min and the 5′-IMP was detected at a wavelength of 250 nm.
Statistical analysis Regression analysis was conducted with analysis tool of Excel 2010 for Windows (Microsoft Corp., Redmond, WA, USA) and JUSE-StatWorks V5 (JusePackage Software Products, Tokyo, Japan).
RESULTS AND DISCUSSION Sensory evaluation Among the evaluation items tenderness, juiciness and fattiness, increased fattiness was associated with perceptions of increased tenderness and increased juiciness, and increased tenderness was associated with increased juiciness (Fig. 1). Pearson’s correlation coefficient (r) between fattiness and juiciness was especially high at 0.966. Among the evaluation items beef flavor intensity, umami intensity, and overall evaluation, a strong beef flavor was associated with strong umami and high overall evaluation (Fig. 2). Although a general linear relationship was observed between beef flavor intensity and overall evaluation and between umami intensity and overall evaluation, the data were widely scattered. The reason for this could have been because other factors, such as tenderness, were included in the overall evaluation. Although the data were widely scattered, a convex curve relationship was observed between fattiness and beef flavor intensity, umami intensity, or overall evaluation (Fig. 3). One reason for this is that there is an optimum level of perceived fattiness; another reason is that there is a
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Figure 1 Relationships between fattiness and tenderness, fattiness and juiciness, and tenderness and juiciness.
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Figure 2 Relationships between beef flavor intensity and umami intensity, beef flavor intensity and umami intensity, and overall evaluation.
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Relationships of fattiness with beef flavor intensity, umami intensity and overall judgment.
limit imposed by the composition of the meat. The protein and fat in red meat both contribute to beef flavor, and because an increase in the content of one component leads to a decrease in the other, within a fixed total amount there is an optimum mixing ratio of these components that gives optimum beef flavor intensity. In terms of umami intensity, although fat itself does not have any particular taste, its presence brings out a mellow and rich flavor similar to that of umami; to some extent, this effect is likely to be the reason for the relationship between increased umami intensity and increased fat content (Yamaguchi 2008; Nishimura & Egusa 2012; Yamamoto 2012). As shown in Figure 3, the fattiness score that was associated with the highest scores for beef flavor intensity, umami intensity and overall evaluation was greater than 4.5 – that is, neither too strong nor too weak. This score implied that a fairly strong degree of fattiness enhanced the scores of these evaluation items. However, when the amount of fat exceeded a certain limit, the umami components in the protein decreased, causing the fattiness to stand out and disrupting the balance between taste and flavor. The relationship between fat and umami components will be described in detail in the later discussion. Graphs similar to the top panels in Figure 2 were obtained when juiciness, which had a strong linear relationship with fattiness, was used on the horizontal axis (data not shown). However, this relationship is probably not an indication that juiciness directly affects flavor and umami intensity; instead, it is likely © 2014 Japanese Society of Animal Science
to reflect the insubstantial relationship with fattiness. When tenderness was used on the horizontal axis (Fig. 4), increased tenderness was expected to help the beef flavor and umami intensity to fill the mouth and thus result in higher overall evaluation. However, when the score for tenderness became higher than the median score, the associated excessive fattiness caused the convex curves seen in the panels for beef flavor intensity, umami intensity and overall evaluation to plateau out.
Relationship between crude fat content and sensory evaluation characteristics We examined the relationship between crude fat content and fattiness, tenderness or juiciness (Fig. 5). Comparison of these panels with those in Figure 3 (the sensory evaluation with fattiness on the horizontal axis) revealed a basically monotonous increase, although a minor convex curve was seen when the amount of fat was low. One reason for this is because the horizontal axis indicates not the amount of fat identified via the senses but the actual physical quantity. Another possible reason, especially when the crude fat content is low, is the influence of factors other than the crude fat content – for example, the thickness of the muscle fibers or the amount of connective tissue in the red meat portion of the beef (Nishimura et al. 1999). We also examined the relationship between crude fat content and beef flavor intensity, umami intensity or overall evaluation score (Fig. 6). Animal Science Journal (2015) 86, 707–715
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Figure 4 Relationships of tenderness with beef flavor intensity, umami intensity and overall judgment.
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Figure 6 Relationships of crude fat content and beef flavor intensity, umami intensity, and overall evaluation.
Comparison of these panels with those obtained when fattiness was placed on the horizontal axis (see Fig. 3) reveals that although the data in Figure 6 are more widely scattered, the convex curves are similar. We performed a least-squares fit of a quadratic equation using crude fat content (x) as a variable to calculate the crude fat content that yielded the largest sensory score (y) in each evaluation item. The quadratic equations are shown in each panel of Figure 6. The standard error of the coefficient and the results of a one-tailed t-test on the null hypothesis (the assumption that coefficients of the quadratic equation were zero) against the alternative hypothesis (the assumption that they were positive or negative) are shown in Table 1. In all cases, the first-degree coefficients were positive and the second-degree coefficients were negative; all were statistically significant. These statistical results indicated that the evaluation score in each item increased with the crude fat content. And, when fat Animal Science Journal (2015) 86, 707–715
Table 1 Estimated value of parameters of quadratic equation between crude fat content and beef flavor intensity, umami intensity, and overall evaluation
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Beef flavor intensity x 0.2698 0.1313 2.054 0.0241 −0.003809 0.00185 −2.060 0.0238 x2 Umami intensity x 0.2545 0.1205 2.113 0.0213 −0.003371 0.00170 −1.987 0.0277 x2 Overall judgement x 0.3483 0.1368 2.545 0.0080 −0.004932 0.00193 −2.560 0.0077 x2
content exceeded a certain level, the evaluation score steeply dropped. The crude fat content that yielded the maximum score in each item was calculated from each equation. About 36% was estimated as the appropriate crude fat content in marbled beef based on the © 2014 Japanese Society of Animal Science
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Figure 7 Relationships between fat content and marbling score (BMS no.). For beef with BMS numbers from 3 to 9, fat content increased linearly from 23.8% to 48.6%.
evaluation in each item: 35.4% for beef flavor intensity, 37.7% for umami intensity and 35.3% for overall evaluation. The values did not change greatly even when the horizontal axis was plotted on a logarithmic scale. However, samples with less than half the crude fat content frequently gave scores above the convex curve; this was especially apparent for overall evaluation. This suggested that meat qualities other than fat content contributed to these evaluation item scores when the crude fat content was low. It also suggests that the computed optimum fat content can be further reduced if meat qualities other than fat content are improved in future.
Relationship between general composition and sensory evaluation characteristics We examined the relationship between the BMS numbers and crude fat content of the meat from the 34 Japanese Black cattle used in our experiment conducted between 2003 and 2006 (Fig. 7). The highest possible BMS number is 12, but even the sample with a BMS number of 9 (the highest in this experiment) had about 50% crude fat content. In a report by Ozutsumi et al. (1985), the crude fat content of the highest-grade Japanese Black steers (BMS numbers 11 and 12) was 31.7%. Ueda et al. (2007) reported that the meat from 21 Japanese Black steers studied in 1998 had a crude fat content of between 4.8% and 39.0% and BMS numbers between 2 and 10. Comparison of the results of these two reports with those in Figure 6 reveals that crude fat content for the same BMS number has increased over a short period of time. Horii et al. (2009) also pointed this out. We examined the relationship between crude fat content and the moisture or crude protein content of the samples. An increase in crude fat content linearly decreased the percentage moisture and crude protein contents: © 2014 Japanese Society of Animal Science
when the crude fat content was doubled from 23.8% to 48.6%, the moisture content decreased from 58.4% to 39.6% (to 0.68 of the original value) and the crude protein content decreased from 17.9% to 11.6% (to 0.69) (data not shown). The rates of reduction were thus about the same. In the above-mentioned report by Ueda et al. (2007), when the crude fat content was no more than 23% the protein content stayed steady at 18%, even if the fat content increased because of a reduction in moisture content, but when the fat content surpassed this amount the protein content rapidly declined. Horii et al. (2009), in a study conducted between 1996 and 2004 on 195 wagyu cattle (aged 28 months and the progeny of 15 bulls), found that meat protein content decreased linearly with increasing fat content from 5.6% to 50.4%. Their results thus agreed with those of Horii et al. (2009). Even when the fat content increased, the ratio of protein to moisture did not greatly change. Although taste is said to be produced when substances dissolved in water react with the taste receptors, even when the quantities of water-soluble umami components and taste components such as amino acids from proteins are reduced, their water-soluble concentrations can be thought to remain about the same.
Relationships between amount of umami components and sensory evaluation characteristics We examined the relationships between crude fat content and the amount of umami components, namely inosinic acid and glutamic acid, in the samples (Fig. 8). Although the data were widely scattered, the calculated correlation coefficients were −0.30 (P = 0.084) and −0.34 (P = 0.092), respectively; there was thus a negative correlation trend. When the contents of these umami components as a ratio of the moisture content were plotted against crude fat content, both ratios remained constant when the fat content was increased. On the other hand, in the sensory evaluation, a certain degree of increase in fat content clearly intensified umami intensity (Fig. 6). This indicates that fat enhances the human sense of umami. Explanations for this might be that fat directly enhances umami, fat adds characteristics similar to those of umami, or fat and umami combine to intensify the taste sensation. We conducted a simple model experiment to find out whether or not fat enhanced umami intensity. A umami solution containing molar concentrations of monosodium inosinate and monosodium glutamate equivalent to the average chemical analysis values (1 mmol/L of inosine-5′-monophshate disodium hydrate and 0.6 mmol/L of sodium hydrogen L(+)glutamate monohydrate) was mixed with rapeseed oil Animal Science Journal (2015) 86, 707–715
BEEF FAT CONTENT AND SENSORY CHARACTERISTICS
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Figure 8 Relationship between 5′-inosine monophosphate (5′-IMP) (left panel) or glutamic acid (right panel) and crude fat content.
Figure 9 Intensity of umami in a solution with 10% to 50% rapeseed oil emulsion.
such that the concentration of rapeseed oil was exactly 10%, 20%, 30%, 40% or 50%. To prevent separation, 0.1% sucrose ester stearate was added to these samples to create an emulsion. Nine panelists took one sip of each sample (5 mL). After the entire tongue had been covered, the panelist spat out the sample and evaluated the intensity of the umami components remaining deep in the surface of the tongue. The temperature of the samples was 30°C, and the mouth was rinsed twice with water at 40°C. Figure 9 shows the results for the sample solutions, scored over an umami intensity range of −3 to +3; a score of 0 was assumed for the sample with 10% fat content. The solution with 50% fat content tended to have a lower umami intensity than that with 10% fat (P < 0.01) and 20% fat (P < 0.05). In this experiment, the amount of umami solution in the mouth decreased when the amount of fat was increased, but if the amount of sample solution was more than 2.5 mL this decrease was considered to have little effect on taste intensity (Maruyama & Yamaguchi 1994, 1996; Yamaguchi 1998). Thus if the Animal Science Journal (2015) 86, 707–715
fat content exceeded a certain value it seemed to prevent the umami solution from interacting with the taste receptors. On the other hand, the following factors may have contributed to the increased intensity of umami. Marbled beef from Japanese Black cattle is characterized by umami (mainly in the red meat), the feel of the fat and aroma. Umami substances are not by themselves pleasant, but when they are in harmony with the tastes of other food components, such as amino acids, they are identified as a beef taste. Yamaguchi (1998) profiled the effects of umami and reported that it brings richness, thickness, mellowness, depth, complexity and lastingness. Fat by itself does not have any particular taste and is not particularly pleasant, but its smooth texture brings richness, depth, complexity and lastingness to the taste of food, and has effects similar to those of umami. Its association with the Maillard reaction contributes to the pleasant beef aroma (Hong et al. 2012). When the crude fat content is increased, the aroma of fat, as well as the sweet smell, is increased. In addition, Kunieda (2006) reported that, depending on the combination, aroma can increase the intensity of taste. Moreover, Yamaguchi (1987) showed that aroma can dramatically change whether or not umami intensity is liked or disliked. Overall, it can be said that an appropriate amount of fat not only intensifies umami intensity but also gives richness, smoothness and other characteristics similar to those of umami, and contributes to the Maillard reaction. Fat thus intensifies aroma and umami, all at once. This could explain the high level of correlation between the beef flavor and umami. As evident in many reports, including those of Cover et al. (1956), Blumer (1963), Berry and Leddy (1990), Morgan et al. (1991), Shackelford et al. (1994), Garmyn et al. (2011) and Sasaki et al. (2012), it is generally understood that tender beef is favored by consumers all over the world. Our experiment has revealed that if the amount of marbling alone is increased to make meat tender, then excessive marbling can decrease the important taste characteristics © 2014 Japanese Society of Animal Science
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of beef, such as flavor and umami intensity, and result in lower overall evaluation scores. In summary, the role of fat in marbled beef from Japanese Black cattle is to intensify the sensations of fattiness, tenderness, juiciness, beef flavor intensity and umami intensity, thus leading to high overall evaluation. However, there is an optimum level for the amount of fat in terms of sensory characteristics; we determined this level to be about 36%. Here, we approached the problem from the perspective of fat content – a basic component of meat. However, to improve meat quality, other factors such as the quality of the red meat and fat, the fineness of marbling, the fattening method (Nishimura et al. 1999) and aging (Nishimura et al. 1988) are equally important. Through further investigation into these factors it may be possible to further reduce the appropriate fat content.
Conclusions To analyze the sensory characteristics of beef with different fat contents from Japanese Black cattle, samples from 34 Japanese Black steers (meat crude fat content 23.8% to 48.6%) raised under the same conditions were subjected to analytical sensory evaluation as well as measurement of chemical components. An increase in the crude fat content increased tenderness, juiciness and fattiness in the meat quality evaluation. Whereas an increase in the crude fat content reduced the protein and moisture contents and the contents of components associated with umami intensity, the protein content and content of umami components remained constant when assessed relative to the moisture content. An increase in crude fat content up to a certain point intensified both the umami and the beef flavor intensity and increased the overall evaluation score of the meat; the appropriate fat content in this regard was around 36%.
ACKNOWLEDGMENTS This study was subsidized by a Japanese Ministry of Agriculture, Forestry, and Fisheries grant (No. 1674; chief: Masakazu Irie) (2004–2008).
REFERENCES Association of Official Analytical Chemists. 1990. Official Methods of Analysis, 15th edn. AOAC, Washington, DC. Berry BW, Leddy KF. 1990. Comparison of restaurant vs research-type broiling with beef loin steaks differing in marbling. Journal of Animal Science 68, 666–672. Blumer TN. 1963. Relationship of marbling to the palatability of beef. Journal of Animal Science 22, 771–778. Blumer TN, Craig HB, Pierce EA, Smart WWG Jr, Wise MB. 1962. Nature and variability of marbling deposits in longissimus dorsi muscle of beef carcasses. Journal of Animal Science 21, 935–942.
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Blumer TN, Fleming HP. 1959. A method for the quantitative estimation of marbling in the beef rib eye muscle. Journal of Animal Science 18, 959–963. Cameron PJ, Zembayashi M, Lunt DK, Mitsuhashi T, Mitsumoto M, Ozawa S, Smith SB. 1994. Relationship between Japanese beef marbling standard and intramuscular lipid in the M. longissimus thoracis of Japanese Black and American Wagyu cattle. Meat Science 38, 361–364. Cover S, Butler OD, Cartwright TC. 1956. The relationship of fatness in yearling steers to juiciness and tenderness of broiled and braised steaks. Journal of Animal Science 15, 464–472. Garmyn AJ, Hilton GG, Mateescu RG, Morgan JB, Reecy JM, Tait RG Jr, et al. 2011. Estimation of relationships between mineral concentration and fatty acid composition of longissimus muscle and beef palatability traits. Journal of Animal Science 89, 2849–2858. Grunert KG. 1997. What’s in a steak? A cross-cultural study on the quality perception of beef. Food Quality and Preference 8, 157–174. Holm L, Mohl M. 2000. The role of meat in everyday food culture: an analysis of an interview study in Copenhagen. Appetite 34, 277–283. Hong JH, Kwon KY, Kim KO. 2012. Sensory characteristics and consumer acceptability of beef stock containing the glutathione -xylose Maillard reaction product and/or monosodium glutamate. Journal of Food Science 77, S233– S239. Horii M, Sakurai Y, Kanbe Y, Kasai K, Ono K, Asada T, et al. 2009. Relationship between Japanese Beef Marbling Standard numbers and intramuscular lipid in M. longissimus thoracis of Japanese Black steers from 1996 to 2004. Nihon Chikusan Gakkaiho 80, 55–61. (In Japanese) Iida F, Horie K, Nishimura T. 2014. Taste and texture characteristics of beef cooked by different methods. Journal of Home Economics of Japan 65, 3–12. Inoue K, Hirabara S, Nade T, Fujita K, Yamauchi K. 2002. Effects of sire on ether extract and fatty acid composition of the M. longissimus dorsi in crossbred between Japanese Black bulls and Holstein cows. Nihon Chikusan Gakkaiho 73, 381–387. (In Japanese) Killinger KM, Calkins CR, Umberger WJ, Feuz DM, Eskridge KM. 2004. Consumer sensory acceptance and value for beef steaks of similar tenderness, but differing on marbling level. Journal of Animal Science 82, 3294–3301. Kunieda S. 2006. With the flavor & fragrance – the interactions between the olfactory sensibility and the other senses. Japanese Journal of Sensory Evaluation 10, 19–24. (In Japanese) Lea E, Worsley A. 2001. Influences on meat consumption in Australia. Appetite 36, 127–136. Maruyama I, Yamaguchi S. 1994. Proceedings of the 24th Symposium on Sensory Evaluation. pp.181–186. Japanese Union of Scientists and Engineers, Tokyo. (In Japanese) Maruyama I, Yamaguchi S. 1996. Sigekiryou ga umami no kanjyusei ni oyobosu eikyou. Japanese Journal of Taste and Smell Research 3, 632–635. (In Japanese) Matsuishi M, Kume J, Itou Y, Takahashi M, Arai M, Nagatomi H, et al. 2004. Aroma components of Wagyu Beef and imported beef. Japanese Journal of Zootechnical Science 75, 409–415. (In Japanese) May SG, Dolezal HG, Gill DR, Ray FK, Buchanan DS. 1992. Effects of days fed, carcass grade traits, and subcutaneous fat removal on postmortem muscle characteristics and beef palatability. Journal of Animal Science 70, 444–453.
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Morgan JB, Savell JW, Hale DS, Miller RK, Griffin DB, Cross HR, Shackelford SD. 1991. National beef tenderness survey. Journal of Animal Science 69, 3274–3283. Nishimura T, Egusa A. 2012. Classification of compounds enhancing ‘koku’ to foods and the discovery of a novel ‘koku’-inducing compound. Japanese Journal of Taste and Smell Research 19, 167–176. (In Japanese) Nishimura T, Hattori A, Takahashi K. 1999. Structural changes in intramuscular connective tissue during the fattening of Japanese Black cattle: effect of marbling on beef tenderization. Journal of Animal Science 77, 93–104. Nishimura T, Rhue MR, Okitani A, Kato H. 1988. Components contributing to the improvement of meat taste during storage. Agricultural and Biological Chemistry 52, 2323–2330. Okita M, Iwamori H, Akuzawa S, Swayama S, Yamaguchi S, Iida F. 1999. Factors affecting the palatability of beef. Union of Japanese Scientists and Engineering Sensory Evaluation Symposium 29, 113–122. (In Japanese) Okitani A. 1993. Influence of aging conditions on flavor of beef. Nippon Shokuhin Kogyo Gakkaishi 40, 535–541. (In Japanese) Ozutsumi K. 1989. Gyuniku no hinnsituhyouka ni kansuru kenkyu. Nippon Shokuhin Kogyo Gakkaishi 36, 857–866. (In Japanese) Ozutsumi K, Ando S, Ikeda T, Nakai H, Chikuni K. 1985. Shijou gyuniku no kakuzuketoukyu to rikagakutekitokusei ni tsuite. Japanese Journal of Zootechnical Science 56, 1–6. (In Japanese) Platter WJ, Tatum JD, Belk KE, Chapman PL, Scanga JA, Smith GC. 2003. Relationships of consumer sensory ratings, marbling score, and shear force value to consumer acceptance of beef strip loin steaks. Journal of Animal Science 81, 2741–2750. Richardson N, Shepherd R, Elliman N. 1993. Current attitudes and future influences on meat consumption in the UK. Appetite 21, 41–51. Sasaki K, Motoyama M, Narita T. 2012. Increased intramuscular fat improves both ‘chewiness’ and ‘hardness’ as
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defined in ISO5492:1992 of beef Longissimus muscle of Holstein × Japanese Black F1 steers. Animal Science Journal 83, 338–343. Shackelford SD, Koohmaraie M, Wheeler TL. 1994. The efficacy of adding a minimum adjusted fat thickness requirement to the USDA Beef Quality Grading Standards for select grade beef. Journal of Animal Science 72, 1502– 1507. Suzuki A, Homma N, Fukuda A, Hirao K, Uryuu T, Ikeuchi Y. 1994. Effect of high pressure treatment on the flavourrelated components in meat. Meat Science 37, 369– 379. Ueda Y, Watanabe A, Higuchi M, Shingu H, Kushibiki S, Shinoda M. 2007. Effect of intramuscular fat deposition on the beef traits of Japanese Black steers (Wagyu). Animal Science Journal 78, 189–194. Verbeke W, Viaene J. 1999. Beliefs, attitude and behavior towards fresh meat consumption in Belgium: empirical evidence from a consumer survey. Food Quality and Preference 10, 437–445. Yamaguchi S. 1987. Fundamental properties of umami in human taste sensation. In: Kawamura Y, Kare M (eds), Umami: A Basic Taste, pp. 48–73. Marcel Dekker Inc., New York and Basel. Yamaguchi S. 1998. Basic properties of umami and its effects on food flavor. Food Reviews International 14, 139–176. Yamaguchi S. 2008. Basic properties of umami and its contribution to the pleasantness of food. Japanese Journal of Taste and Smell Research 15, 145–158. (In Japanese) Yamaguchi S. 2011. Sensory evaluation of palatability of highly expensive Wagyu beeves. Japanese Journal of Taste and Smell Research 18, 409–412. (In Japanese) Yamaguchi S, Maruyama S, Tsuneishi E. 2009. Effects of maturation on the palatability of Wagyu beef containing different levels of marbled fat. Japanese Journal of Taste and Smell Research 16, 441–444. (In Japanese) Yamamoto T. 2012. Concept of koku and its scientific background. Japanese Journal of Taste and Smell Research 19, 189–195. (In Japanese)
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doi: 10.1111/asj.12342
ORIGINAL ARTICLE Effect of fat content on sensory characteristics of marbled beef from Japanese Black steers Fumiko IIDA,1 Kaoru SAITOU,2 Tadashi KAWAMURA,2 Shizuko YAMAGUCHI3 and Toshihide NISHIMURA4 1
Department of Food and Nutrition, Japan Women’s University, 3Taste and Food Preference Laboratory, Department of Food Science and Technology, Nippon Veterinary and Life Science University, Tokyo and 2National Livestock Breeding Center, Fukushima, Japan 4
ABSTRACT To analyze the sensory characteristics of meat samples with a crude fat content between 23.8% and 48.6% taken from 34 Japanese Black steers, we grilled the meat and subjected it to analytical sensory evaluation. We also measured the amounts of moisture, protein, nucleic acid and glutamic acid. An increase in crude fat content increased the tenderness, juiciness, and fattiness in the meat quality evaluation. An increase in crude fat content reduced the crude protein and moisture contents; it also slightly reduced the nucleic acid and glutamic acid contents, although when the reductions in these umami components were assessed relative to the moisture content they changed little. Increasing the fat content up to a certain point greatly enhanced the umami intensity and beef flavor intensity in the meat quality evaluation and raised the overall evaluation score; the peak of the appropriate crude fat content for these purposes was about 36%.
Key words: appropriate fat content, beef flavor, marbled beef, sensory characteristics, umami.
INTRODUCTION The Japanese preference for beef differs from that in many countries and has developed as part of the unique Japanese food culture. Whereas lean meat is strongly preferred in other countries (Richardson et al. 1993; Grunert 1997; Verbeke & Viaene 1999; Holm & Mohl 2000; Lea & Worsley 2001; Killinger et al. 2004), marbled beef is the absolute preference in Japan. Japanese Black beef is known for its very large amount of marbling and has distinctive textural, flavor and taste characteristics. Even when this meat is cooked, the beef remains tender and is characterized by a smooth texture, pleasant oiliness and rich umami (the fifth taste) (Yamaguchi 2011), as well as the unique and pleasant aroma of wagyu (Okitani 1993; Matsuishi et al. 2004). Marbled beef has been studied overseas, as well as in Japan. In a review by Blumer (1963) of earlier studies (Blumer & Fleming 1959; Blumer et al. 1962) performed by his research group, he described the taste characteristics of marbled beef. The crude fat content of the cattle that his group examined for marbling ranged from 0.87% to 14.82%, and the amount of intramuscular fat was related to the amounts of tenderness, flavor and juiciness. Recent studies have examined the relationships among marbling, the length of the fattening period © 2014 Japanese Society of Animal Science
and meat characteristics at the time of slaughter. May et al. (1992) reported that marbling grade was more closely correlated with juiciness and flavor intensity than was backfat thickness in fattened cattle late in the fattening period. Shackelford et al. (1994) similarly reported that marbling grade was more closely correlated with tenderness than was backfat thickness. There have recently been reports that even Americans, who traditionally have favored lean meat, are gradually beginning to acquire a taste for marbled meat (Platter et al. 2003; Killinger et al. 2004). Nevertheless, the fat content of the beef examined in the above reports were extremely low (less than about 10%) compared with that of marbled beef in Japan. In Japan, the crude fat content of A5 grade beef (the highest grade of beef graded by the Japan Meat Grading Association) recently exceeded 40%. In addition, beef with more marbling tends to be given a higher rating in the Beef Marbling Standard (BMS numbers range from 1 to 12) because of consumers’ strong appreciation of fine marbling and an increasing
Correspondence: Fumiko Iida, Department of Food and Nutrition, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo, Tokyo 112-8681, Japan. (Email: [email protected]) Received 6 March 2014; accepted for publication 11 September 2014.
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trend in the amount of marbling in Japanese beef (Ozutsumi et al. 1985; Ozutsumi 1989; Cameron et al. 1994; Inoue et al. 2002; Ueda et al. 2007). In contrast, Okita et al. (1999) and Yamaguchi (2011) reported that consumers do not necessarily favor excessive marbling. According to one of our own surveys, the crude fat content of the highest grade (A5) of wagyu sirloin beef sold at high-class department stores was 69%; sensory evaluation by customers revealed that this beef was clearly not favored (Yamaguchi et al. 2009; Yamaguchi 2011). Beef is regarded as a protein food, and if it has too much fat it is not considered suitable as a major source of the proteins needed to sustain life. For this reason, it is very important that we identify the ideal fat content of beef in terms of sensory characteristics. To clarify the relationship between the fat content of marbled beef from Japanese Black steers and its effect on taste characteristics, we conducted a sensory evaluation of the beef from 34 Japanese Black steers that had been raised under strictly managed breeding conditions. The beef had a crude fat content of between 23.8% and 48.6% (BMS numbers from 3 to 9 and grades from B2 to A5). The chemical components of the beef were also measured and taken into consideration.
METHODS Samples The 34 cattle used were common Japanese Black steers raised since age 6 months at the National Livestock Breeding Center in Fukushima Prefecture by using the same fattening method and slaughtered and processed by the same method at ages 21 to 30 months. The portion from the seventh to the 11th thoracic vertebrae was used for the chemical analysis; this portion is closest to the sixth and seventh thoracic vertebrae used for grading beef in Japan. The portion from the 13th thoracic vertebra to the first lumbar vertebra was used for the sensory evaluation. After the cattle had been slaughtered, the dressed carcasses were aged at 2°C for 14 days and then frozen at −30°C. Beginning 2 days before the sensory evaluation, the samples were thawed at 2°C for 24 h and then cut into 1-cm-thick slices. The slices were then sent by refrigerated delivery service from Fukushima Prefecture to the Japan Women’s University in Tokyo. They were immediately stored at 2°C in a thermostatic chamber. They were cooked and evaluated the following day.
Sensory evaluation of beef The experiment was conducted between December 2003 and December 2006. The sensory evaluation was conducted as part of a research project conducted by Japan’s National Livestock Breeding Center. In line © 2014 Japanese Society of Animal Science
with the overall plan of the experiment, the 34 cattle used in the experiment were slaughtered in groups of three and the samples taken from them were simultaneously evaluated. The evaluation was performed on sliced beef that was grilled after the meat had been taken out of the refrigerator and returned to room temperature. The sliced beef was cut parallel to the muscle (Longissimus thoracis) fiber orientation to a size of 3 × 4 × 1 cm. The three beef samples compared each time were grilled side by side on a hotplate (Zojirushi Corporation, Osaka, Japan) preheated to 200°C. One side of the meat was grilled for 1 min and the other side was grilled for around 1.5 min, so that the internal temperature reached 60°C. Although this condition for grilling was decided in our previous paper (Iida et al. 2014), the internal temperature of marbled beef after grilling was not necessarily 60°C because of the differences in fat content. So, the slight changes in heating time for meat samples were performed using an infrared thermometer (refractive index 0.95). Concretely, a meat was cut at its center after grilling described above, and then the temperature at the center spot of the cross section of cooked meat was measured with an infrared thermometer, and the 60°C at the center of meat was confirmed. The cooked beef without salt was left to rest for 10 min, cut in half, and subjected to sensory evaluation without addition of salt at room temperature. The following six items were evaluated: tenderness, juiciness, fattiness, intensity of the pleasant beef flavor (aroma perceived through the mouth), umami intensity and overall evaluation (based not on subjective likes and dislikes but on whether or not the sample represented good or bad beef). The items were evaluated on an 8-point scale without a median value. The highest score of 8 was given to very tender on a scale ranging from very tender to very tough; similarly, the highest scores were given to very juicy on the very juicy to dry scale, to very fatty on the very fatty to lean scale, to strongly flavored on the strongly flavored to weakly flavored scale, to strongly umami intensity on the strongly umami intensity to weakly umami intensity scale, and to good on the good to bad scale. From a pool composed of 15 undergraduate and graduate students of the Laboratory of Cookery Science and three faculty members (all female), between 14 and 18 people became the evaluation panel. The composition of the panel varied from time to time. All panel members had basic knowledge of sensory evaluation, as obtained through lectures, exercises and frequent experience as panel members for judging various foods, including beef. However, before the experiment started, so that they could learn and remember the characteristics of beef, the panel members tasted various grades of commercially available beef that fully covered the range of experimental samples. Animal Science Journal (2015) 86, 707–715
BEEF FAT CONTENT AND SENSORY CHARACTERISTICS
Chemical analysis General composition analysis (moisture, crude protein and crude fat content) The moisture content of the Longissimus thoracis muscle was calculated by weighing the minced muscle before and after it had been heated at 105°C for 24 h. After moisture content measurement, the crude protein content of the dried sample was measured by using the Kjeldahl method. The nitrogen content was measured by using the Soxhlet extraction method, and the crude fat content was measured by using the Official Methods of Analysis of the Association of Official Analytical Chemists (1990). The values shown here were all converted to raw meat values. Free amino acids The method reported by Nishimura et al. (1988, 1999) was used in the following experiment. Ten grams of raw meat was homogenized with 25 mL of distilled water for 1 min. The homogenate was centrifuged at 11 500 × g for 10 min at 4°C and the supernatant was collected. The supernatant was then percolated through a filter paper (Advantec 5B; Toyo, Tokyo, Japan). After the proteins had been removed from this filtrate by adding trichloroacetic acid (5% final concentration) and the filtrate centrifuged as described above, the supernatant was passed through a membrane filter (0.45 μm, Advantec; Toyo, Tokyo, Japan) and analyzed for free amino acids with an amino acid analyzer (Jasco LC-NET II/ADC Analyzer; Jasco, Tokyo, Japan).
supernatant was then passed through a membrane filter (0.45 μm, Advantec, Toyo, Japan) and diluted tenfold with distilled water to determine the 5′-IMP content by employing high-performance liquid chromatography (HPLC) (Shimadzu SPD-10AV: UV-VIS, Detector LC-10AD, Kyoto, Japan), with a column (Senshu Pak Pegasil-B ODS 4.6 φ × 250 mm, Tokyo, Japan) equilibrated with 20 mmol/L phosphoric acid and 22 mmol/L diethyl amino ethanol. The flow rate was 1.0 mL/min and the 5′-IMP was detected at a wavelength of 250 nm.
Statistical analysis Regression analysis was conducted with analysis tool of Excel 2010 for Windows (Microsoft Corp., Redmond, WA, USA) and JUSE-StatWorks V5 (JusePackage Software Products, Tokyo, Japan).
RESULTS AND DISCUSSION Sensory evaluation Among the evaluation items tenderness, juiciness and fattiness, increased fattiness was associated with perceptions of increased tenderness and increased juiciness, and increased tenderness was associated with increased juiciness (Fig. 1). Pearson’s correlation coefficient (r) between fattiness and juiciness was especially high at 0.966. Among the evaluation items beef flavor intensity, umami intensity, and overall evaluation, a strong beef flavor was associated with strong umami and high overall evaluation (Fig. 2). Although a general linear relationship was observed between beef flavor intensity and overall evaluation and between umami intensity and overall evaluation, the data were widely scattered. The reason for this could have been because other factors, such as tenderness, were included in the overall evaluation. Although the data were widely scattered, a convex curve relationship was observed between fattiness and beef flavor intensity, umami intensity, or overall evaluation (Fig. 3). One reason for this is that there is an optimum level of perceived fattiness; another reason is that there is a
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Figure 1 Relationships between fattiness and tenderness, fattiness and juiciness, and tenderness and juiciness.
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limit imposed by the composition of the meat. The protein and fat in red meat both contribute to beef flavor, and because an increase in the content of one component leads to a decrease in the other, within a fixed total amount there is an optimum mixing ratio of these components that gives optimum beef flavor intensity. In terms of umami intensity, although fat itself does not have any particular taste, its presence brings out a mellow and rich flavor similar to that of umami; to some extent, this effect is likely to be the reason for the relationship between increased umami intensity and increased fat content (Yamaguchi 2008; Nishimura & Egusa 2012; Yamamoto 2012). As shown in Figure 3, the fattiness score that was associated with the highest scores for beef flavor intensity, umami intensity and overall evaluation was greater than 4.5 – that is, neither too strong nor too weak. This score implied that a fairly strong degree of fattiness enhanced the scores of these evaluation items. However, when the amount of fat exceeded a certain limit, the umami components in the protein decreased, causing the fattiness to stand out and disrupting the balance between taste and flavor. The relationship between fat and umami components will be described in detail in the later discussion. Graphs similar to the top panels in Figure 2 were obtained when juiciness, which had a strong linear relationship with fattiness, was used on the horizontal axis (data not shown). However, this relationship is probably not an indication that juiciness directly affects flavor and umami intensity; instead, it is likely © 2014 Japanese Society of Animal Science
to reflect the insubstantial relationship with fattiness. When tenderness was used on the horizontal axis (Fig. 4), increased tenderness was expected to help the beef flavor and umami intensity to fill the mouth and thus result in higher overall evaluation. However, when the score for tenderness became higher than the median score, the associated excessive fattiness caused the convex curves seen in the panels for beef flavor intensity, umami intensity and overall evaluation to plateau out.
Relationship between crude fat content and sensory evaluation characteristics We examined the relationship between crude fat content and fattiness, tenderness or juiciness (Fig. 5). Comparison of these panels with those in Figure 3 (the sensory evaluation with fattiness on the horizontal axis) revealed a basically monotonous increase, although a minor convex curve was seen when the amount of fat was low. One reason for this is because the horizontal axis indicates not the amount of fat identified via the senses but the actual physical quantity. Another possible reason, especially when the crude fat content is low, is the influence of factors other than the crude fat content – for example, the thickness of the muscle fibers or the amount of connective tissue in the red meat portion of the beef (Nishimura et al. 1999). We also examined the relationship between crude fat content and beef flavor intensity, umami intensity or overall evaluation score (Fig. 6). Animal Science Journal (2015) 86, 707–715
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Figure 6 Relationships of crude fat content and beef flavor intensity, umami intensity, and overall evaluation.
Comparison of these panels with those obtained when fattiness was placed on the horizontal axis (see Fig. 3) reveals that although the data in Figure 6 are more widely scattered, the convex curves are similar. We performed a least-squares fit of a quadratic equation using crude fat content (x) as a variable to calculate the crude fat content that yielded the largest sensory score (y) in each evaluation item. The quadratic equations are shown in each panel of Figure 6. The standard error of the coefficient and the results of a one-tailed t-test on the null hypothesis (the assumption that coefficients of the quadratic equation were zero) against the alternative hypothesis (the assumption that they were positive or negative) are shown in Table 1. In all cases, the first-degree coefficients were positive and the second-degree coefficients were negative; all were statistically significant. These statistical results indicated that the evaluation score in each item increased with the crude fat content. And, when fat Animal Science Journal (2015) 86, 707–715
Table 1 Estimated value of parameters of quadratic equation between crude fat content and beef flavor intensity, umami intensity, and overall evaluation
Term
Parameter S.E.
t-value P-value
Beef flavor intensity x 0.2698 0.1313 2.054 0.0241 −0.003809 0.00185 −2.060 0.0238 x2 Umami intensity x 0.2545 0.1205 2.113 0.0213 −0.003371 0.00170 −1.987 0.0277 x2 Overall judgement x 0.3483 0.1368 2.545 0.0080 −0.004932 0.00193 −2.560 0.0077 x2
content exceeded a certain level, the evaluation score steeply dropped. The crude fat content that yielded the maximum score in each item was calculated from each equation. About 36% was estimated as the appropriate crude fat content in marbled beef based on the © 2014 Japanese Society of Animal Science
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Figure 7 Relationships between fat content and marbling score (BMS no.). For beef with BMS numbers from 3 to 9, fat content increased linearly from 23.8% to 48.6%.
evaluation in each item: 35.4% for beef flavor intensity, 37.7% for umami intensity and 35.3% for overall evaluation. The values did not change greatly even when the horizontal axis was plotted on a logarithmic scale. However, samples with less than half the crude fat content frequently gave scores above the convex curve; this was especially apparent for overall evaluation. This suggested that meat qualities other than fat content contributed to these evaluation item scores when the crude fat content was low. It also suggests that the computed optimum fat content can be further reduced if meat qualities other than fat content are improved in future.
Relationship between general composition and sensory evaluation characteristics We examined the relationship between the BMS numbers and crude fat content of the meat from the 34 Japanese Black cattle used in our experiment conducted between 2003 and 2006 (Fig. 7). The highest possible BMS number is 12, but even the sample with a BMS number of 9 (the highest in this experiment) had about 50% crude fat content. In a report by Ozutsumi et al. (1985), the crude fat content of the highest-grade Japanese Black steers (BMS numbers 11 and 12) was 31.7%. Ueda et al. (2007) reported that the meat from 21 Japanese Black steers studied in 1998 had a crude fat content of between 4.8% and 39.0% and BMS numbers between 2 and 10. Comparison of the results of these two reports with those in Figure 6 reveals that crude fat content for the same BMS number has increased over a short period of time. Horii et al. (2009) also pointed this out. We examined the relationship between crude fat content and the moisture or crude protein content of the samples. An increase in crude fat content linearly decreased the percentage moisture and crude protein contents: © 2014 Japanese Society of Animal Science
when the crude fat content was doubled from 23.8% to 48.6%, the moisture content decreased from 58.4% to 39.6% (to 0.68 of the original value) and the crude protein content decreased from 17.9% to 11.6% (to 0.69) (data not shown). The rates of reduction were thus about the same. In the above-mentioned report by Ueda et al. (2007), when the crude fat content was no more than 23% the protein content stayed steady at 18%, even if the fat content increased because of a reduction in moisture content, but when the fat content surpassed this amount the protein content rapidly declined. Horii et al. (2009), in a study conducted between 1996 and 2004 on 195 wagyu cattle (aged 28 months and the progeny of 15 bulls), found that meat protein content decreased linearly with increasing fat content from 5.6% to 50.4%. Their results thus agreed with those of Horii et al. (2009). Even when the fat content increased, the ratio of protein to moisture did not greatly change. Although taste is said to be produced when substances dissolved in water react with the taste receptors, even when the quantities of water-soluble umami components and taste components such as amino acids from proteins are reduced, their water-soluble concentrations can be thought to remain about the same.
Relationships between amount of umami components and sensory evaluation characteristics We examined the relationships between crude fat content and the amount of umami components, namely inosinic acid and glutamic acid, in the samples (Fig. 8). Although the data were widely scattered, the calculated correlation coefficients were −0.30 (P = 0.084) and −0.34 (P = 0.092), respectively; there was thus a negative correlation trend. When the contents of these umami components as a ratio of the moisture content were plotted against crude fat content, both ratios remained constant when the fat content was increased. On the other hand, in the sensory evaluation, a certain degree of increase in fat content clearly intensified umami intensity (Fig. 6). This indicates that fat enhances the human sense of umami. Explanations for this might be that fat directly enhances umami, fat adds characteristics similar to those of umami, or fat and umami combine to intensify the taste sensation. We conducted a simple model experiment to find out whether or not fat enhanced umami intensity. A umami solution containing molar concentrations of monosodium inosinate and monosodium glutamate equivalent to the average chemical analysis values (1 mmol/L of inosine-5′-monophshate disodium hydrate and 0.6 mmol/L of sodium hydrogen L(+)glutamate monohydrate) was mixed with rapeseed oil Animal Science Journal (2015) 86, 707–715
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20
4 Glutamic acid (%)
5'-IMP (%)
15 10 5 0
713
20
30
40 Crude fat (%)
50
3 2 1 0
20
30
40 Crude fat (%)
50
Figure 8 Relationship between 5′-inosine monophosphate (5′-IMP) (left panel) or glutamic acid (right panel) and crude fat content.
Figure 9 Intensity of umami in a solution with 10% to 50% rapeseed oil emulsion.
such that the concentration of rapeseed oil was exactly 10%, 20%, 30%, 40% or 50%. To prevent separation, 0.1% sucrose ester stearate was added to these samples to create an emulsion. Nine panelists took one sip of each sample (5 mL). After the entire tongue had been covered, the panelist spat out the sample and evaluated the intensity of the umami components remaining deep in the surface of the tongue. The temperature of the samples was 30°C, and the mouth was rinsed twice with water at 40°C. Figure 9 shows the results for the sample solutions, scored over an umami intensity range of −3 to +3; a score of 0 was assumed for the sample with 10% fat content. The solution with 50% fat content tended to have a lower umami intensity than that with 10% fat (P < 0.01) and 20% fat (P < 0.05). In this experiment, the amount of umami solution in the mouth decreased when the amount of fat was increased, but if the amount of sample solution was more than 2.5 mL this decrease was considered to have little effect on taste intensity (Maruyama & Yamaguchi 1994, 1996; Yamaguchi 1998). Thus if the Animal Science Journal (2015) 86, 707–715
fat content exceeded a certain value it seemed to prevent the umami solution from interacting with the taste receptors. On the other hand, the following factors may have contributed to the increased intensity of umami. Marbled beef from Japanese Black cattle is characterized by umami (mainly in the red meat), the feel of the fat and aroma. Umami substances are not by themselves pleasant, but when they are in harmony with the tastes of other food components, such as amino acids, they are identified as a beef taste. Yamaguchi (1998) profiled the effects of umami and reported that it brings richness, thickness, mellowness, depth, complexity and lastingness. Fat by itself does not have any particular taste and is not particularly pleasant, but its smooth texture brings richness, depth, complexity and lastingness to the taste of food, and has effects similar to those of umami. Its association with the Maillard reaction contributes to the pleasant beef aroma (Hong et al. 2012). When the crude fat content is increased, the aroma of fat, as well as the sweet smell, is increased. In addition, Kunieda (2006) reported that, depending on the combination, aroma can increase the intensity of taste. Moreover, Yamaguchi (1987) showed that aroma can dramatically change whether or not umami intensity is liked or disliked. Overall, it can be said that an appropriate amount of fat not only intensifies umami intensity but also gives richness, smoothness and other characteristics similar to those of umami, and contributes to the Maillard reaction. Fat thus intensifies aroma and umami, all at once. This could explain the high level of correlation between the beef flavor and umami. As evident in many reports, including those of Cover et al. (1956), Blumer (1963), Berry and Leddy (1990), Morgan et al. (1991), Shackelford et al. (1994), Garmyn et al. (2011) and Sasaki et al. (2012), it is generally understood that tender beef is favored by consumers all over the world. Our experiment has revealed that if the amount of marbling alone is increased to make meat tender, then excessive marbling can decrease the important taste characteristics © 2014 Japanese Society of Animal Science
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of beef, such as flavor and umami intensity, and result in lower overall evaluation scores. In summary, the role of fat in marbled beef from Japanese Black cattle is to intensify the sensations of fattiness, tenderness, juiciness, beef flavor intensity and umami intensity, thus leading to high overall evaluation. However, there is an optimum level for the amount of fat in terms of sensory characteristics; we determined this level to be about 36%. Here, we approached the problem from the perspective of fat content – a basic component of meat. However, to improve meat quality, other factors such as the quality of the red meat and fat, the fineness of marbling, the fattening method (Nishimura et al. 1999) and aging (Nishimura et al. 1988) are equally important. Through further investigation into these factors it may be possible to further reduce the appropriate fat content.
Conclusions To analyze the sensory characteristics of beef with different fat contents from Japanese Black cattle, samples from 34 Japanese Black steers (meat crude fat content 23.8% to 48.6%) raised under the same conditions were subjected to analytical sensory evaluation as well as measurement of chemical components. An increase in the crude fat content increased tenderness, juiciness and fattiness in the meat quality evaluation. Whereas an increase in the crude fat content reduced the protein and moisture contents and the contents of components associated with umami intensity, the protein content and content of umami components remained constant when assessed relative to the moisture content. An increase in crude fat content up to a certain point intensified both the umami and the beef flavor intensity and increased the overall evaluation score of the meat; the appropriate fat content in this regard was around 36%.
ACKNOWLEDGMENTS This study was subsidized by a Japanese Ministry of Agriculture, Forestry, and Fisheries grant (No. 1674; chief: Masakazu Irie) (2004–2008).
REFERENCES Association of Official Analytical Chemists. 1990. Official Methods of Analysis, 15th edn. AOAC, Washington, DC. Berry BW, Leddy KF. 1990. Comparison of restaurant vs research-type broiling with beef loin steaks differing in marbling. Journal of Animal Science 68, 666–672. Blumer TN. 1963. Relationship of marbling to the palatability of beef. Journal of Animal Science 22, 771–778. Blumer TN, Craig HB, Pierce EA, Smart WWG Jr, Wise MB. 1962. Nature and variability of marbling deposits in longissimus dorsi muscle of beef carcasses. Journal of Animal Science 21, 935–942.
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Blumer TN, Fleming HP. 1959. A method for the quantitative estimation of marbling in the beef rib eye muscle. Journal of Animal Science 18, 959–963. Cameron PJ, Zembayashi M, Lunt DK, Mitsuhashi T, Mitsumoto M, Ozawa S, Smith SB. 1994. Relationship between Japanese beef marbling standard and intramuscular lipid in the M. longissimus thoracis of Japanese Black and American Wagyu cattle. Meat Science 38, 361–364. Cover S, Butler OD, Cartwright TC. 1956. The relationship of fatness in yearling steers to juiciness and tenderness of broiled and braised steaks. Journal of Animal Science 15, 464–472. Garmyn AJ, Hilton GG, Mateescu RG, Morgan JB, Reecy JM, Tait RG Jr, et al. 2011. Estimation of relationships between mineral concentration and fatty acid composition of longissimus muscle and beef palatability traits. Journal of Animal Science 89, 2849–2858. Grunert KG. 1997. What’s in a steak? A cross-cultural study on the quality perception of beef. Food Quality and Preference 8, 157–174. Holm L, Mohl M. 2000. The role of meat in everyday food culture: an analysis of an interview study in Copenhagen. Appetite 34, 277–283. Hong JH, Kwon KY, Kim KO. 2012. Sensory characteristics and consumer acceptability of beef stock containing the glutathione -xylose Maillard reaction product and/or monosodium glutamate. Journal of Food Science 77, S233– S239. Horii M, Sakurai Y, Kanbe Y, Kasai K, Ono K, Asada T, et al. 2009. Relationship between Japanese Beef Marbling Standard numbers and intramuscular lipid in M. longissimus thoracis of Japanese Black steers from 1996 to 2004. Nihon Chikusan Gakkaiho 80, 55–61. (In Japanese) Iida F, Horie K, Nishimura T. 2014. Taste and texture characteristics of beef cooked by different methods. Journal of Home Economics of Japan 65, 3–12. Inoue K, Hirabara S, Nade T, Fujita K, Yamauchi K. 2002. Effects of sire on ether extract and fatty acid composition of the M. longissimus dorsi in crossbred between Japanese Black bulls and Holstein cows. Nihon Chikusan Gakkaiho 73, 381–387. (In Japanese) Killinger KM, Calkins CR, Umberger WJ, Feuz DM, Eskridge KM. 2004. Consumer sensory acceptance and value for beef steaks of similar tenderness, but differing on marbling level. Journal of Animal Science 82, 3294–3301. Kunieda S. 2006. With the flavor & fragrance – the interactions between the olfactory sensibility and the other senses. Japanese Journal of Sensory Evaluation 10, 19–24. (In Japanese) Lea E, Worsley A. 2001. Influences on meat consumption in Australia. Appetite 36, 127–136. Maruyama I, Yamaguchi S. 1994. Proceedings of the 24th Symposium on Sensory Evaluation. pp.181–186. Japanese Union of Scientists and Engineers, Tokyo. (In Japanese) Maruyama I, Yamaguchi S. 1996. Sigekiryou ga umami no kanjyusei ni oyobosu eikyou. Japanese Journal of Taste and Smell Research 3, 632–635. (In Japanese) Matsuishi M, Kume J, Itou Y, Takahashi M, Arai M, Nagatomi H, et al. 2004. Aroma components of Wagyu Beef and imported beef. Japanese Journal of Zootechnical Science 75, 409–415. (In Japanese) May SG, Dolezal HG, Gill DR, Ray FK, Buchanan DS. 1992. Effects of days fed, carcass grade traits, and subcutaneous fat removal on postmortem muscle characteristics and beef palatability. Journal of Animal Science 70, 444–453.
Animal Science Journal (2015) 86, 707–715
BEEF FAT CONTENT AND SENSORY CHARACTERISTICS 715
Morgan JB, Savell JW, Hale DS, Miller RK, Griffin DB, Cross HR, Shackelford SD. 1991. National beef tenderness survey. Journal of Animal Science 69, 3274–3283. Nishimura T, Egusa A. 2012. Classification of compounds enhancing ‘koku’ to foods and the discovery of a novel ‘koku’-inducing compound. Japanese Journal of Taste and Smell Research 19, 167–176. (In Japanese) Nishimura T, Hattori A, Takahashi K. 1999. Structural changes in intramuscular connective tissue during the fattening of Japanese Black cattle: effect of marbling on beef tenderization. Journal of Animal Science 77, 93–104. Nishimura T, Rhue MR, Okitani A, Kato H. 1988. Components contributing to the improvement of meat taste during storage. Agricultural and Biological Chemistry 52, 2323–2330. Okita M, Iwamori H, Akuzawa S, Swayama S, Yamaguchi S, Iida F. 1999. Factors affecting the palatability of beef. Union of Japanese Scientists and Engineering Sensory Evaluation Symposium 29, 113–122. (In Japanese) Okitani A. 1993. Influence of aging conditions on flavor of beef. Nippon Shokuhin Kogyo Gakkaishi 40, 535–541. (In Japanese) Ozutsumi K. 1989. Gyuniku no hinnsituhyouka ni kansuru kenkyu. Nippon Shokuhin Kogyo Gakkaishi 36, 857–866. (In Japanese) Ozutsumi K, Ando S, Ikeda T, Nakai H, Chikuni K. 1985. Shijou gyuniku no kakuzuketoukyu to rikagakutekitokusei ni tsuite. Japanese Journal of Zootechnical Science 56, 1–6. (In Japanese) Platter WJ, Tatum JD, Belk KE, Chapman PL, Scanga JA, Smith GC. 2003. Relationships of consumer sensory ratings, marbling score, and shear force value to consumer acceptance of beef strip loin steaks. Journal of Animal Science 81, 2741–2750. Richardson N, Shepherd R, Elliman N. 1993. Current attitudes and future influences on meat consumption in the UK. Appetite 21, 41–51. Sasaki K, Motoyama M, Narita T. 2012. Increased intramuscular fat improves both ‘chewiness’ and ‘hardness’ as
Animal Science Journal (2015) 86, 707–715
defined in ISO5492:1992 of beef Longissimus muscle of Holstein × Japanese Black F1 steers. Animal Science Journal 83, 338–343. Shackelford SD, Koohmaraie M, Wheeler TL. 1994. The efficacy of adding a minimum adjusted fat thickness requirement to the USDA Beef Quality Grading Standards for select grade beef. Journal of Animal Science 72, 1502– 1507. Suzuki A, Homma N, Fukuda A, Hirao K, Uryuu T, Ikeuchi Y. 1994. Effect of high pressure treatment on the flavourrelated components in meat. Meat Science 37, 369– 379. Ueda Y, Watanabe A, Higuchi M, Shingu H, Kushibiki S, Shinoda M. 2007. Effect of intramuscular fat deposition on the beef traits of Japanese Black steers (Wagyu). Animal Science Journal 78, 189–194. Verbeke W, Viaene J. 1999. Beliefs, attitude and behavior towards fresh meat consumption in Belgium: empirical evidence from a consumer survey. Food Quality and Preference 10, 437–445. Yamaguchi S. 1987. Fundamental properties of umami in human taste sensation. In: Kawamura Y, Kare M (eds), Umami: A Basic Taste, pp. 48–73. Marcel Dekker Inc., New York and Basel. Yamaguchi S. 1998. Basic properties of umami and its effects on food flavor. Food Reviews International 14, 139–176. Yamaguchi S. 2008. Basic properties of umami and its contribution to the pleasantness of food. Japanese Journal of Taste and Smell Research 15, 145–158. (In Japanese) Yamaguchi S. 2011. Sensory evaluation of palatability of highly expensive Wagyu beeves. Japanese Journal of Taste and Smell Research 18, 409–412. (In Japanese) Yamaguchi S, Maruyama S, Tsuneishi E. 2009. Effects of maturation on the palatability of Wagyu beef containing different levels of marbled fat. Japanese Journal of Taste and Smell Research 16, 441–444. (In Japanese) Yamamoto T. 2012. Concept of koku and its scientific background. Japanese Journal of Taste and Smell Research 19, 189–195. (In Japanese)
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