Food Chemistry 179 (2015) 232–238
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Effects of waterlogging after pollination on the physicochemical properties of starch from waxy maize Dalei Lu a, Xuemei Cai a, Yaxing Shi b, Jiuran Zhao b, Weiping Lu a,⇑ a b
Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, PR China Maize Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, PR China
a r t i c l e
i n f o
Article history: Received 4 September 2014 Received in revised form 8 November 2014 Accepted 19 January 2015 Available online 24 January 2015 Keywords: Crystallinity Pasting Swelling Thermal Waterlogging Waxy maize starch
a b s t r a c t Waterlogging frequently occurs in Southern China in summer and significantly affects waxy maize growth. This study investigated the physicochemical properties of starch from six waxy maize varieties exposed to waterlogging for 1–7 days after pollination. Waterlogging decreased the starch granule size. Starch maximum absorption wavelength, iodine-binding capacity, crystallinity, and peak intensities in response to waterlogging depended on varieties. Swelling power and solubility in response to waterlogging increased in Wannuo5 and decreased in the other five varieties. Gelatinization and pasting temperatures were only slightly affected by waterlogging. Gelatinization enthalpy was unaffected in Nongkeyu301, increased in Guangbainuo5, and decreased in the other four varieties. Peak and breakdown viscosities decreased and retrogradation percentage increased when plants were subjected to waterlogging after pollination. In conclusion, waterlogging decreased starch granule size, crystallinity, swelling power, and solubility, resulting in deteriorated starch quality (i.e., low swelling, less sticky and easy to retrograde). Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Maize starch dominates nearly 80% of the global starch market (Jobling, 2004). Maize starch can be divided as waxy, normal, and high amylose based on amylose content (Singh, Sandhu, & Kaur, 2005). Among different maize types, waxy maize starch is composed of 100% amylopectin, which features high viscosity, easy digestion, good light transmittance, and low retrogrades (Lu & Lu, 2012). The physicochemical properties of maize starch change with a growing environment. Ji et al. (2004) observed that the thermal properties of maize starch vary in different growth environments. Lenihan, Pollak, and White (2005) found that maize starch harvested in a warm environment has high gelatinization onset temperature and enthalpy, as well as a narrow gelatinization range. Oktem (2008) observed that water deficit decreases some mineral element (Fe, Cu, and Zn) contents but increases the protein content in sweet maize grains. Liu et al. (2013) observed that maize starch granule size and viscosities decrease and gelatinization temperatures increase under low irrigation levels. Our previous studies showed that high temperature, weak light, and drought after pollination significantly deteriorated the quality of waxy maize starch ⇑ Corresponding author. Tel.: +86 514 87979377; fax: +86 514 87996817. E-mail address: [email protected] (W. Lu). http://dx.doi.org/10.1016/j.foodchem.2015.01.096 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved.
(Lu, Cai, Zhao, Shen, & Lu, 2015; Lu, Sun, Wang, Yan, & Lu, 2013; Lu et al., 2014). Several abiotic factors, including rainfall, sunlight, temperature, soil type, and growing conditions affecting the starch physicochemical properties of crops, may sometimes exhibit considerable influence than genotypic differences (Beckles & Thitisaksakul, 2014; Thitisaksakul, Jimenez, Abias, & Beckles, 2012; Wang & Frei, 2011). Waterlogging is one of the most important abiotic factors and occurs frequently. Over 18% of the total maize production areas in South Asia and Southeast Asia are frequently affected by flooding or waterlogging, causing production losses of 25–30% annually (Zaidi, Maniselvan, Srivastava, Yadav, & Singh, 2010). Cairns et al. (2012) reviewed that waterlogging influences maize growth and development. However, no research has focused on the effects of waterlogging on the physicochemical properties of maize starch. In the present paper, we reported the physicochemical properties of waxy maize starch under normal and waterlogging conditions after pollination. 2. Materials and methods 2.1. Plant materials and experimental design Six varieties of waxy maize, namely, Huainuo1, Nongkeyu301, Wannuo5, Meiyu16, YN525, and Guangbainuo5 were used in this
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study. These six varieties were provided by the Maize Regional Test Management Office of the China Ministry of Agriculture. The experiment was conducted at the Yangzhou University Farm in 2013. Seeds were sown on March 15 and transplanted to a cement pit (2 m depth) on March 28. Plant density was 60,000/ha and plot area was 12 m2. The plants were given a basal dressing of 500 kg/ha (commercial fertilizer, N:P2O5:K2O = 15%:15%:15%) during transplantation and a top dressing of 326 kg/ha (commercial urea, 46% N) during the jointing stage. The plants were grown under relative soil moisture content of approximately 75% before pollination. The plants were subjected to waterlogging (about 3 cm water above ground) after artificial pollination for 7 days. The soil moisture content of the control was 75–80%. The plants were covered with a transparent canopy that was 5 m high aboveground to avoid the effects of rainfall. 2.2. Starch isolation The grains (100 g) were steeped in 500 ml of distilled water containing 1 g/l sodium hydrogen sulfite (1 g/l SO2) for 48 h at room temperature. The starch was isolated according to a previously described method (Lu & Lu, 2012). The samples were rinsed with distilled water, and then ground using a blender for 2.5 min. The suspensions were passed through a 100-mesh sieve. The materials left on the screen were again homogenized for 1.5 min, and then passed through the same sieve. The starch–protein slurry was collected in a 1000 ml wide-neck flask and allowed to stand for 4 h. The supernatant was removed through suction and the settled starch layer was collected in 50 ml centrifuge tubes and centrifuged at 3000g for 10 min. The upper non-white layer was scooped. The white layer was resuspended in distilled water and stirred for 30 min before centrifugation. The isolation procedures were repeated three times. The starch was then collected and dried in an oven at 40 °C for 48 h. 2.3. Granule size distribution The particle sizes of the starch were analyzed using a laser diffraction particle size analyzer (Mastersizer 2000, Malvern, England). Instrument accuracy was verified using Malvern standard glass particles. The instrument was operated based on the principle of laser light scattering and could measure sizes between 0.1 and 2000 lm. The disperse phase was absolute ethyl alcohol. The size distribution was expressed in terms of the volume of equivalent spheres. The average granule size was defined as the volume weighted mean. 2.4. X-ray diffraction (XRD) pattern The XRD patterns of starch were obtained using an X-ray diffractometer (D8 Advance; Bruker-AXS, Germany). The diffractometer was operated at 200 mA and 40 kV. The scanning region of the diffraction angle (2h) ranged from 5° to 40° at a step size of 0.04° and a counting time of 0.6 s. Relative crystallinity (%) was calculated as the percentage of the total crystalline peak areas to that of the total diffractogram (total crystalline and amorphous peak areas) by using software (MDI Jade 6). 2.5. Iodine staining The maximum absorption wavelength (kmax) and iodine-binding capacity of starch were measured according to the method described by Fiedorowicz and Rebilas (2002), with minor modifications, as described by Lu et al. (2014). Starch (40 mg) was dispersed in 10 ml of DMSO containing 10% of 6 M urea. A 1.0 ml aliquot of each sample was placed in a 100 ml volumetric flash, to which
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95 ml of deionised water and 2 ml of an aqueous I2–KI solution was added. The latter solution was prepared with 200 mg of I2 and 2 g of KI in 100 ml of distilled water. The mixture was made up to 100 ml with deionised water and mixed immediate. Blank solutions that were prepared identically did not contain starch. Spectra ranging from 500 to 700 nm were obtained from all of the samples using a UV–Vis spectrophotometer. The blue value of the samples was defined as the absorbance at 635 nm, and the kmax was designated as the peak absorbance value over the range of wavelengths examined. The iodine-binding capacity of the starches was defined as the ratio of absorbance at 635 nm to that at 520 nm. 2.6. Swelling power and solubility The swelling power and solubility of the starches at 90 °C was studied according to a previously described method (Lu & Lu, 2012). Samples (0.1 g) were weighed in a centrifuge tube with coated screw cap to which 10 ml distilled water was added. The tube was heated at 90 °C in a shaking water bath for an hour. The tube was cooled to room temperature in an iced bath and centrifuged at 4000g for 20 min. The supernatant was discarded. The materials that adhered to the wall of the centrifuge tube were considered as sediments and weighed (W1) and the sediments were dried to constant weight (W2) in an air oven at 100 °C. The swell power and solubility were calculated as follows: swell power = W1/ W2 (g/g) and solubility (%) (0.1-W2)/0.1. 2.7. Pasting properties The starch pasting properties (28 g total weight; 7%, w/w, dry basis) were evaluated using a rapid viscosity analyzer (RVA, Model 3D; Newport Scientific, Australia) following a previously defined method (Lu & Lu, 2012). A sample suspension was equilibrated at 50 °C for 1 min, heated to 95 °C at 12 °C/min, maintained at 95 °C for 2.5 min, cooled to 50 °C at 12 °C/min, and then maintained at 50 °C for 1 min. The paddle speed was set at 960 rpm for the first 10 s and then decreased to 160 rpm for the rest of the analysis. 2.8. Thermal properties The thermal characteristics of the starch were studied using differential scanning calorimetry (Model 200 F3 Maia, NETZSCH, Germany) according to a previously utilized method (Lu & Lu, 2012). Each sample (5 mg, dry weight) was loaded into an aluminum pan (25/40 ml, D = 5 mm) and distilled water was added to achieve a starch–water suspension containing 66.7% water. Samples were hermetically sealed and allowed to stand for 24 h at 4 °C before heating in the DSC. The DSC analyzer was calibrated using an empty aluminum pan as a reference. Sample pans were heated at a rate of 10 °C/min from 20 to 100 °C. Thermal transitions of starch samples were defined as To (onset temperature), Tp (peak of gelatinization temperature) and Tc (conclusion temperature) and DHgel referred to the gelatinization enthalpy. Enthalpies were calculated on a starch dry weight basis. After conducting thermal analysis, the samples were stored at 4 °C for 7 days for retrogradation studies. The sample pans containing the starches were reheated at the rate of 10 °C/min from 20 to 100 °C to measure retrogradation. The retrogradation enthalpies (DHret) were evaluated automatically and retrogradation percentage (%R) was calculated as %R = 100 DHret/ DHgel. 2.9. Statistical analyses The data reported in all tables are expressed as the average of two repeated observations. These data were subjected to ANOVA,
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using the least significant difference test at a 5% probability level with a data processing system (DPS 7.05) (Tang & Feng, 2007). 3. Results and discussion 3.1. Starch granule distribution Waterlogging after pollination decreased the ratio of large granules and the average granule size of starch for all the test varieties except Nongkeyu301, which exhibited a similar average granule size in two conditions (Fig. 1). The small starch granule size under waterlogging conditions may be caused by waterlogging shortening the grain filling period and reducing the grain growth rates (Araki, Hamada, Hossain, & Takahashi, 2012; Hossain, Araki, & Takahashi, 2011); thus, starch granule development was suppressed and formed small granules. 3.2. Starch iodine staining The kmax and iodine-binding capacity in all samples present typical waxy character, as waxy maize starch is composed of 100% amylopectin (Fiedorowicz & Rebilas, 2002). The blue value, kmax, and iodine-binding capacity in YN525 were not influenced by
waterlogging treatment. Those three parameters increased in Meiyu16 and decreased in the other four varieties (Table 1), indicating that the proportion of long chains in amylopectin decreased (Fiedorowicz & Rebilas, 2002). The high proportion of long chains in amylopectin under controlled conditions was primarily due to the large starch granules containing high proportion of long chains in amylopectin than small ones (Lindeboom, Chang, & Tyler, 2004).
3.3. XRD and crystallinity Waterlogging after pollination did not change the XRD pattern. All the samples present typical ‘‘A’’-type diffraction pattern (Fig. 2). However, the peak intensities at different diffraction angles in response to waterlogging were dependent on varieties. The peak intensity was unaffected by waterlogging in YN525, decreased in Huanuo1, Wannuo5, and Guangbainuo5, and increased in Nongkeyu301 and Meiyu16. Waterlogging also changed the relative crystallinity, which increased in Nongkeyu301, remained unchanged in Guangbainuo5, and decreased in the other four varieties. The lower peak intensities and crystallinity under waterlogging was because of the small starch granules and low proportion of long chains in amylopectin, as large starch granules have sharper intensities than small ones (Tang, Ando, Watanabe, Takeda, &
Fig. 1. Starch granule distribution and average granule size under control and waterlogging conditions.
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D. Lu et al. / Food Chemistry 179 (2015) 232–238 Table 1 Starch iodine staining under control and waterlogging conditions. Variety
Treatment
Blue value
kmax (nm)
Iodine-binding capacity
Huanuo1
Waterlogging Control
0.161 cd 0.184 a
534.7 cd 536.4 a
0.534 abc 0.541 a
Nongkeyu301
Waterlogging Control
0.156 de 0.185 a
534.8 bcd 536.2 a
0.530 cd 0.540 ab
Wannuo5
Waterlogging Control
0.148 e 0.171 bc
535.8 abc 536.3 a
0.532 bc 0.538 ab
Meiyu16
Waterlogging Control
0.170 bc 0.147 e
536.0 ab 533.6 d
0.528 cd 0.515 f
YN525
Waterlogging Control
0.174 ab 0.171 bc
534.8 bcd 533.7 d
0.523 de 0.523 de
Guangbainuo5
Waterlogging Control
0.147 e 0.186 a
534.7 cd 536.1 a
0.517 ef 0.539 ab
Mean values in the same column followed by different letters are significantly different (p < 0.05).
Fig. 2. Starch X-ray diffraction pattern and crystallinity under control and waterlogging conditions.
Mitsunaga, 2000; Zeng, Li, Gao, & Ru, 2011), and waxy maize starch with high amount of long chains was responsible for high crystallinity (Singh, Inouchi, & Nishinari, 2006). 3.4. Swelling power and solubility Swelling power and solubility can be used to assess the extent of interaction between starch chains within the amor-
phous and crystalline domains of the starch granule (Sandhu & Singh, 2007). The swelling power and solubility for all the varieties were decreased by waterlogging treatments except for Wannuo5, which were increased (Fig. 3). The high swelling power and solubility under control conditions is primarily due to large starch granules (Sandhu, Singh, & Kaur, 2004) and high crystallinity (Singh et al., 2006). In addition, higher proportions of long chains in amylopectin contributed to increased starch
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swelling (Sasaki & Matsuki, 1998; Srichuwong, Sunarti, Mishima, Isono, & Hisamatsu, 2005). 3.5. Pasting properties The starch pasting properties were significantly affected by waterlogging after pollination (Table 2). The peak viscosity was unaffected in Huanuo1 and it was decreased by waterlogging treatments in the five other varieties. The high peak viscosities under control conditions may be due to the fact that larger starch granules increase the rate of swelling, which occupy more volume and enhance viscosity (Srichuwong et al., 2005). The breakdown viscosity in all the varieties decreased under waterlogging conditions. The low breakdown viscosities under waterlogging conditions indicated that the starch granules were harder to break down compared to the control conditions. Kim, Johnson, Graybosch, and Gaines (2003) observed that starch with high crystallinity exhibited high peak and breakdown viscosities. Noda et al. (2005) reported that smaller granules have lower peak and breakdown viscosities than larger granules in potato starch. A positive correlation between swelling power, solubility, as well as peak and breakdown viscosities was observed in normal maize starch (Sandhu & Singh, 2007). Trough and final viscosity increased in Huanuo1 and Meiyu16 and decreased in the four other varieties in response to waterlogging. The setback viscosity in all samples was lower than 9.3 RVU; this low value was because the amylopectin did not aggregate during cooling of the paste (Singh et al., 2005). The pasting temperature only increased in Meiyu16 and remained unaffected in the five other varieties. The difference was also negligible (coefficient of variation was 0.5).
3.6. Thermal properties Gelatinization temperature represents a measure of starch crystallite and gelatinization enthalpy (DHgel) the amount of crystalline structure (Ji et al., 2004). The gelatinization temperatures in response to waterlogging were dependent on the varieties. However, the variable coefficient values for To, Tp, and Tc were 1.0, 0.7, and 0.6, respectively, indicating that the difference was insignificant. Tang et al. (2000) observed that the waxy barley starch gelatinization temperatures were similar among the different granule fractions. DHgel in response to waterlogging was dependent on varieties. It was unchanged in Nongkeyu301, increased in Guangbainuo5, and decreased in the four other varieties (Table 3). A low value of DHgel was also observed for starch with low crystallinity and small granules in waxy barley starch (Tang et al., 2000). Also, positive correlations between swelling power and DHgel were observed in wheat starch (Sasaki & Matsuki, 1998). Retrogradation occurred in the gelatinized sample after storing at 4 °C for 1 week. The retrogradation properties of the starch gels are indirectly influenced by the structural arrangement of starch chains within the amorphous and crystalline regions of the granule, which in turn influences the extent of granule breakdown during gelatinization and the interaction that occurs between the starch chains during gel storage (Sandhu et al., 2004). Retrogradation enthalpy (DHret) increased in Nongkeyu301, Wannuo5, Meiyu16, and YN525, but remained unaffected in Huanuo1 and Guangbainuo5. A high DHret under waterlogging treatment results in a high retrogradation percentage (%R). The %R was unchanged in Guangbainuo5, but increased in the five other varieties under waterlogging conditions. This result indicates that the waterlogging after pollination aggravated the staling or aging
Fig. 3. Starch swelling power and solubility under control and waterlogging conditions.
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D. Lu et al. / Food Chemistry 179 (2015) 232–238 Table 2 Starch pasting properties under control and waterlogging conditions. Variety
Treatment
PV (RVU)
TV (RVU)
BD (RVU)
FV (RVU)
SB (RVU)
Ptemp (°C)
Huanuo1
Waterlogging Control
174.5 e 174.8 e
74.5 cd 71.4 ef
100.0 d 103.4 c
83.5 de 76.9 g
9.0 a 5.5 de
68.7 cd 68.4 d
Nongkeyu301
Waterlogging Control
182.3 c 184.5 b
81.7 a 81.0 a
100.6 d 103.5 c
86.2 bc 87.8 ab
4.5 e 6.8 bc
69.2 bcd 69.2 bcd
Wannuo5
Waterlogging Control
168.8 f 173.6 e
75.3 c 74.9 cd
93.5 e 98.7 d
81.1 ef 82.0 ef
5.8 cd 7.1 b
69.2 bcd 69.9 ab
Meiyu16
Waterlogging Control
173.3 e 180.6 d
78.7 b 69.8 f
94.6 e 110.8 a
85.3 cd 72.6 h
6.6 bcd 2.8 f
70.3 a 69.1 bcd
YN525
Waterlogging Control
168.5 f 192.1 a
78.7 b 80.7 ab
89.8 f 111.4 a
86.2 bc 90.0 a
7.5 b 9.3 a
69.2 bcd 69.2 bcd
Guangbainuo5
Waterlogging Control
167.5 f 184.0 b
73.0 de 76.0 c
94.5 e 108.0 b
80.6 f 83.3 de
7.6 b 7.3 b
69.2 bcd 69.3 bc
PV, peak viscosity; TV, trough viscosity; BD, breakdown viscosity; FV, final viscosity; SB, setback viscosity; Ptemp, pasting temperature. Mean values in the same column followed by different letters are significantly different (p < 0.05).
Table 3 Starch thermal properties under control and waterlogging conditions. Variety
Treatment
DHgel (J/g)
To (°C)
Tp (°C)
Tc (°C)
DHret (J/g)
%R (%)
Huanuo1
Waterlogging Control
12.2 de 14.5 a
64.6 d 63.7 e
69.8 d 69.8 d
78.1 cd 78.4 bc
6.9 bcd 7.2 bc
56.6 b 49.4 de
Nongkeyu301
Waterlogging Control
12.2 de 12.2 de
65.5 b 63.6 e
70.8 c 70.1 d
78.4 bc 78.4 bc
6.7 cde 5.4 h
55.0 bc 44.0 ef
Wannuo5
Waterlogging Control
12.2 de 13.3 bc
63.8 e 64.3 de
71.3 b 70.9 bc
79.1 ab 79.3 a
7.6 ab 6.8 cde
62.2 a 51.0 cd
Meiyu16
Waterlogging Control
12.1 de 13.8 ab
66.9 a 65.9 b
72.0 a 71.1 ab
79.4 a 78.4 bc
8.0 a 6.0 fgh
66.0 a 43.2 f
YN525
Waterlogging Control
12.5 cd 14.2 ab
65.3 bc 64.0 de
70.9 bc 70.8 c
78.6 bc 79.4 a
6.9 bcd 5.6 gh
55.3 bc 39.5 f
Guangbainuo5
Waterlogging Control
12.5 cd 11.4 e
65.4 bc 64.7 cd
70.2 d 70.7 c
77.6 d 78.1 cd
6.4 def 6.1 efg
51.2 bcd 53.9 bcd
DHgel = gelatinization enthalpy; To = onset temperature; Tp = peak gelatinization temperature; Tc = conclusion temperature; DHret = retrogradation enthalpy; and %R = retrogradation percentage. Mean values in the same column followed by different letters are significantly different (p < 0.05).
of starch. This may due to fact that the breakage of the starch granule under waterlogging conditions (present as low breakdown viscosities observed by RVA) was less than under control conditions, and those ungelatinized granules gelatinized during heating after refrigerated storage, which in turn, increased DHret and %R. 4. Conclusion Waterlogging changed the physicochemical properties of waxy maize starch. Starch granule size and crystallinity were decreased by waterlogging in all varieties except for Nongkeyu301. Iodinebinding capacity in response to waterlogging was dependent on varieties; it was unaffected in YN525, increased in Meiyu16, and decreased in the four other varieties. Starch swelling power and solubility increased in Wannuo5 and decreased in the five other varieties when the plants were exposed to waterlogging. Starch peak and breakdown viscosities were decreased by waterlogging, whereas trough and final viscosities in response to waterlogging were dependent on varieties. The low setback viscosities in all the varieties indicated that waxy maize starch paste was hard to aggregate during cooling. The pasting and gelatinization temperatures were only slightly affected by waterlogging. DHgel was unchanged in Nongkeyu301, increased in Guangbainuo5, and decreased in the four other varieties. Waterlogging increased the DHret value, resulting in the increment of %R. The low swelling power, peak and breakdown viscosities and high %R under water-
logging treatment may be helpful to select waxy maize starch with low swelling, less stickiness, increased resistance to breaking and a high tendency to retrograde. Significant differences in the physicochemical properties were also observed among the test varieties, which make the selection of varieties based on different purposes is possible. For example, under waterlogging condition, the starch of Nongkeyu301 was sticky and stable as it has high peak and breakdown viscosities, and the starch of Guangbainuo5 retrograded less than the others as it had lower %R than the other starches.
Acknowledgments This study was supported by the Chinese Natural Science Foundation (Grant Nos. 31271640 and 31471436), Jiangsu High School Natural Science Foundation (Grant No. 14KJA210004), Priority Academic Program Development of Jiangsu Higher Education Institutions, and New Century Talents Project of Yangzhou University.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.foodchem.2015. 01.096.
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References Araki, H., Hamada, A., Hossain, M. A., & Takahashi, T. (2012). Waterlogging at jointing and/or after anthesis in wheat induces early leaf senescence and impairs grain filling. Field Crops Research, 137, 27–36. Beckles, D. M., & Thitisaksakul, M. (2014). How environmental stress affects starch composition and functionality in cereal endosperm. Starch/Stärke, 66, 58–71. Cairns, J. E., Sonder, K., Zaidi, P. H., Verhulst, N., Mahuku, G., Babu, R., et al. (2012). Maize production in a changing climate: Impacts, adaptation, and mitigation strategies. In S. Donald (Ed.). Advances in agronomy (Vol. 114, pp. 1–58). Burlington: Academic Press. Fiedorowicz, M., & Rebilas, K. (2002). Physicochemical properties of waxy corn starch and corn amylopectin illuminated with linearly polarized visible light. Carbohydrate Polymers, 50, 315–319. Hossain, M. A., Araki, H., & Takahashi, T. (2011). Poor grain filling induced by waterlogging is similar to that in abnormal early ripening in wheat in Western Japan. Field Crops Research, 123, 100–108. Ji, Y., Pollak, L. M., Duvick, S., Seetharaman, K., Dixon, P. M., & White, P. J. (2004). Gelatinization properties of starches from three successive generations of six exotic corn lines grown in two locations. Cereal Chemistry, 81, 59–64. Jobling, S. (2004). Improving starch for food and industrial applications. Plant Biology, 7, 210–218. Kim, W., Johnson, J. W., Graybosch, R. A., & Gaines, C. S. (2003). Physicochemical properties and end-use quality of wheat starch as a function of waxy protein alleles. Journal of Cereal Science, 37, 195–204. Lenihan, E., Pollak, L., & White, P. (2005). Thermal properties of starch from exotic by adapted corn (Zea mays L.) lines grown in four environments. Cereal Chemistry, 82, 683–689. Lindeboom, N., Chang, P. R., & Tyler, R. T. (2004). Analytical, biochemical and physicochemical aspects of starch granule size, with emphasis on small granule starches: A review. Starch/Stärke, 56, 89–99. Liu, L., Klocke, N., Yan, S., Rogers, D., Schlegel, A., Lamm, F., et al. (2013). Impact of deficit irrigation on maize physical and chemical properties and ethanol yield. Cereal Chemistry, 90, 453–462. Lu, D., Cai, X., Zhao, J., Shen, X., & Lu, W. (2015). Effects of drought after pollination on grain yield and quality of fresh waxy maize. Journal of the Science of Food and Agriculture, 95, 210–215. Lu, D., & Lu, W. (2012). Effects of protein removal on the physico-chemical properties of waxy maize flours. Starch/Stärke, 64, 874–881. Lu, D., Shen, X., Cai, X., Yan, F., Lu, W., & Shi, Y.-C. (2014). Effects of heat stress during grain filling on the structure and thermal properties of waxy maize starch. Food Chemistry, 143, 313–318.
Lu, D., Sun, X., Wang, X., Yan, F., & Lu, W. (2013). Effect of shading during grain filling on the physicochemical properties of fresh waxy maize. Journal of Integrative Agriculture, 12, 1560–1567. Noda, T., Takigawa, S., Matsuura-Endo, C., Kim, S. J., Hashimoto, N., & Yamauchi, H. (2005). Physicochemical properties and amylopectin structures of large, small, and extremely small potato starch granules. Carbohydrate Polymers, 60, 245–251. Oktem, A. (2008). Effect of water shortage on yield, and protein and mineral compositions of drip-irrigated sweet corn in sustainable agricultural systems. Agricultural Water Management, 95, 1003–1010. Sandhu, K. S., & Singh, N. (2007). Some properties of corn starches II: Physicochemical, gelatinization, retrogradation, pasting and gel textural properties. Food Chemistry, 101, 1499–1507. Sandhu, K. S., Singh, N., & Kaur, M. (2004). Characteristics of the different corn types and their grain fractions: Physicochemical, thermal, morphological and rheological properties of starches. Journal of Food Engineering, 64, 119–127. Sasaki, T., & Matsuki, J. (1998). Effect of wheat starch structure on swelling power. Cereal Chemistry, 75, 525–529. Singh, N., Inouchi, N., & Nishinari, K. (2006). Structure, thermal and viscoelastic characteristics of starches separated from normal, sugary and waxy maize. Food Hydrocolloids, 20, 923–935. Singh, M., Sandhu, K. S., & Kaur, M. (2005). Physico-chemical properties including granular morphology, amylose content, swelling and solubility, thermal and pasting properties of starches from normal, waxy, high amylose and sugary corn. Progress in Food Biopolymer Research, 1, 43–54. Srichuwong, S., Sunarti, T. C., Mishima, T., Isono, N., & Hisamatsu, M. (2005). Starches from different botanical sources II: Contribution of starch structure to swelling and pasting properties. Carbohydrate Polymers, 62, 25–34. Tang, H., Ando, H., Watanabe, K., Takeda, Y., & Mitsunaga, T. (2000). Some physicochemical properties of small-, medium-, and large-granule starches in fractions of waxy barley grain. Cereal Chemistry, 77, 27–31. Tang, Q. Y., & Feng, M. G. (2007). Data processing system: Experimental design, statistical analysis and data mining. Beijing, China: Science Press. Thitisaksakul, M., Jimenez, R. C., Abias, M. C., & Beckles, D. M. (2012). Effects of environmental factors on cereal starch biosynthesis and composition. Journal of Cereal Science, 56, 67–80. Wang, Y., & Frei, M. (2011). Stressed food – The impact of abiotic environmental stresses on crop quality. Agriculture, Ecosystems & Environment, 141, 271–286. Zaidi, P. H., Maniselvan, P., Srivastava, A., Yadav, P., & Singh, R. P. (2010). Genetic analysis of water-logging tolerance in tropical maize (Zea Mays L.). Maydica, 55, 17–26. Zeng, J., Li, G., Gao, H., & Ru, Z. (2011). Comparison of A and B starch granules from three wheat varieties. Molecules, 16, 10570–10591.
Contents lists available at ScienceDirect
Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Effects of waterlogging after pollination on the physicochemical properties of starch from waxy maize Dalei Lu a, Xuemei Cai a, Yaxing Shi b, Jiuran Zhao b, Weiping Lu a,⇑ a b
Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, PR China Maize Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, PR China
a r t i c l e
i n f o
Article history: Received 4 September 2014 Received in revised form 8 November 2014 Accepted 19 January 2015 Available online 24 January 2015 Keywords: Crystallinity Pasting Swelling Thermal Waterlogging Waxy maize starch
a b s t r a c t Waterlogging frequently occurs in Southern China in summer and significantly affects waxy maize growth. This study investigated the physicochemical properties of starch from six waxy maize varieties exposed to waterlogging for 1–7 days after pollination. Waterlogging decreased the starch granule size. Starch maximum absorption wavelength, iodine-binding capacity, crystallinity, and peak intensities in response to waterlogging depended on varieties. Swelling power and solubility in response to waterlogging increased in Wannuo5 and decreased in the other five varieties. Gelatinization and pasting temperatures were only slightly affected by waterlogging. Gelatinization enthalpy was unaffected in Nongkeyu301, increased in Guangbainuo5, and decreased in the other four varieties. Peak and breakdown viscosities decreased and retrogradation percentage increased when plants were subjected to waterlogging after pollination. In conclusion, waterlogging decreased starch granule size, crystallinity, swelling power, and solubility, resulting in deteriorated starch quality (i.e., low swelling, less sticky and easy to retrograde). Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Maize starch dominates nearly 80% of the global starch market (Jobling, 2004). Maize starch can be divided as waxy, normal, and high amylose based on amylose content (Singh, Sandhu, & Kaur, 2005). Among different maize types, waxy maize starch is composed of 100% amylopectin, which features high viscosity, easy digestion, good light transmittance, and low retrogrades (Lu & Lu, 2012). The physicochemical properties of maize starch change with a growing environment. Ji et al. (2004) observed that the thermal properties of maize starch vary in different growth environments. Lenihan, Pollak, and White (2005) found that maize starch harvested in a warm environment has high gelatinization onset temperature and enthalpy, as well as a narrow gelatinization range. Oktem (2008) observed that water deficit decreases some mineral element (Fe, Cu, and Zn) contents but increases the protein content in sweet maize grains. Liu et al. (2013) observed that maize starch granule size and viscosities decrease and gelatinization temperatures increase under low irrigation levels. Our previous studies showed that high temperature, weak light, and drought after pollination significantly deteriorated the quality of waxy maize starch ⇑ Corresponding author. Tel.: +86 514 87979377; fax: +86 514 87996817. E-mail address: [email protected] (W. Lu). http://dx.doi.org/10.1016/j.foodchem.2015.01.096 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved.
(Lu, Cai, Zhao, Shen, & Lu, 2015; Lu, Sun, Wang, Yan, & Lu, 2013; Lu et al., 2014). Several abiotic factors, including rainfall, sunlight, temperature, soil type, and growing conditions affecting the starch physicochemical properties of crops, may sometimes exhibit considerable influence than genotypic differences (Beckles & Thitisaksakul, 2014; Thitisaksakul, Jimenez, Abias, & Beckles, 2012; Wang & Frei, 2011). Waterlogging is one of the most important abiotic factors and occurs frequently. Over 18% of the total maize production areas in South Asia and Southeast Asia are frequently affected by flooding or waterlogging, causing production losses of 25–30% annually (Zaidi, Maniselvan, Srivastava, Yadav, & Singh, 2010). Cairns et al. (2012) reviewed that waterlogging influences maize growth and development. However, no research has focused on the effects of waterlogging on the physicochemical properties of maize starch. In the present paper, we reported the physicochemical properties of waxy maize starch under normal and waterlogging conditions after pollination. 2. Materials and methods 2.1. Plant materials and experimental design Six varieties of waxy maize, namely, Huainuo1, Nongkeyu301, Wannuo5, Meiyu16, YN525, and Guangbainuo5 were used in this
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study. These six varieties were provided by the Maize Regional Test Management Office of the China Ministry of Agriculture. The experiment was conducted at the Yangzhou University Farm in 2013. Seeds were sown on March 15 and transplanted to a cement pit (2 m depth) on March 28. Plant density was 60,000/ha and plot area was 12 m2. The plants were given a basal dressing of 500 kg/ha (commercial fertilizer, N:P2O5:K2O = 15%:15%:15%) during transplantation and a top dressing of 326 kg/ha (commercial urea, 46% N) during the jointing stage. The plants were grown under relative soil moisture content of approximately 75% before pollination. The plants were subjected to waterlogging (about 3 cm water above ground) after artificial pollination for 7 days. The soil moisture content of the control was 75–80%. The plants were covered with a transparent canopy that was 5 m high aboveground to avoid the effects of rainfall. 2.2. Starch isolation The grains (100 g) were steeped in 500 ml of distilled water containing 1 g/l sodium hydrogen sulfite (1 g/l SO2) for 48 h at room temperature. The starch was isolated according to a previously described method (Lu & Lu, 2012). The samples were rinsed with distilled water, and then ground using a blender for 2.5 min. The suspensions were passed through a 100-mesh sieve. The materials left on the screen were again homogenized for 1.5 min, and then passed through the same sieve. The starch–protein slurry was collected in a 1000 ml wide-neck flask and allowed to stand for 4 h. The supernatant was removed through suction and the settled starch layer was collected in 50 ml centrifuge tubes and centrifuged at 3000g for 10 min. The upper non-white layer was scooped. The white layer was resuspended in distilled water and stirred for 30 min before centrifugation. The isolation procedures were repeated three times. The starch was then collected and dried in an oven at 40 °C for 48 h. 2.3. Granule size distribution The particle sizes of the starch were analyzed using a laser diffraction particle size analyzer (Mastersizer 2000, Malvern, England). Instrument accuracy was verified using Malvern standard glass particles. The instrument was operated based on the principle of laser light scattering and could measure sizes between 0.1 and 2000 lm. The disperse phase was absolute ethyl alcohol. The size distribution was expressed in terms of the volume of equivalent spheres. The average granule size was defined as the volume weighted mean. 2.4. X-ray diffraction (XRD) pattern The XRD patterns of starch were obtained using an X-ray diffractometer (D8 Advance; Bruker-AXS, Germany). The diffractometer was operated at 200 mA and 40 kV. The scanning region of the diffraction angle (2h) ranged from 5° to 40° at a step size of 0.04° and a counting time of 0.6 s. Relative crystallinity (%) was calculated as the percentage of the total crystalline peak areas to that of the total diffractogram (total crystalline and amorphous peak areas) by using software (MDI Jade 6). 2.5. Iodine staining The maximum absorption wavelength (kmax) and iodine-binding capacity of starch were measured according to the method described by Fiedorowicz and Rebilas (2002), with minor modifications, as described by Lu et al. (2014). Starch (40 mg) was dispersed in 10 ml of DMSO containing 10% of 6 M urea. A 1.0 ml aliquot of each sample was placed in a 100 ml volumetric flash, to which
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95 ml of deionised water and 2 ml of an aqueous I2–KI solution was added. The latter solution was prepared with 200 mg of I2 and 2 g of KI in 100 ml of distilled water. The mixture was made up to 100 ml with deionised water and mixed immediate. Blank solutions that were prepared identically did not contain starch. Spectra ranging from 500 to 700 nm were obtained from all of the samples using a UV–Vis spectrophotometer. The blue value of the samples was defined as the absorbance at 635 nm, and the kmax was designated as the peak absorbance value over the range of wavelengths examined. The iodine-binding capacity of the starches was defined as the ratio of absorbance at 635 nm to that at 520 nm. 2.6. Swelling power and solubility The swelling power and solubility of the starches at 90 °C was studied according to a previously described method (Lu & Lu, 2012). Samples (0.1 g) were weighed in a centrifuge tube with coated screw cap to which 10 ml distilled water was added. The tube was heated at 90 °C in a shaking water bath for an hour. The tube was cooled to room temperature in an iced bath and centrifuged at 4000g for 20 min. The supernatant was discarded. The materials that adhered to the wall of the centrifuge tube were considered as sediments and weighed (W1) and the sediments were dried to constant weight (W2) in an air oven at 100 °C. The swell power and solubility were calculated as follows: swell power = W1/ W2 (g/g) and solubility (%) (0.1-W2)/0.1. 2.7. Pasting properties The starch pasting properties (28 g total weight; 7%, w/w, dry basis) were evaluated using a rapid viscosity analyzer (RVA, Model 3D; Newport Scientific, Australia) following a previously defined method (Lu & Lu, 2012). A sample suspension was equilibrated at 50 °C for 1 min, heated to 95 °C at 12 °C/min, maintained at 95 °C for 2.5 min, cooled to 50 °C at 12 °C/min, and then maintained at 50 °C for 1 min. The paddle speed was set at 960 rpm for the first 10 s and then decreased to 160 rpm for the rest of the analysis. 2.8. Thermal properties The thermal characteristics of the starch were studied using differential scanning calorimetry (Model 200 F3 Maia, NETZSCH, Germany) according to a previously utilized method (Lu & Lu, 2012). Each sample (5 mg, dry weight) was loaded into an aluminum pan (25/40 ml, D = 5 mm) and distilled water was added to achieve a starch–water suspension containing 66.7% water. Samples were hermetically sealed and allowed to stand for 24 h at 4 °C before heating in the DSC. The DSC analyzer was calibrated using an empty aluminum pan as a reference. Sample pans were heated at a rate of 10 °C/min from 20 to 100 °C. Thermal transitions of starch samples were defined as To (onset temperature), Tp (peak of gelatinization temperature) and Tc (conclusion temperature) and DHgel referred to the gelatinization enthalpy. Enthalpies were calculated on a starch dry weight basis. After conducting thermal analysis, the samples were stored at 4 °C for 7 days for retrogradation studies. The sample pans containing the starches were reheated at the rate of 10 °C/min from 20 to 100 °C to measure retrogradation. The retrogradation enthalpies (DHret) were evaluated automatically and retrogradation percentage (%R) was calculated as %R = 100 DHret/ DHgel. 2.9. Statistical analyses The data reported in all tables are expressed as the average of two repeated observations. These data were subjected to ANOVA,
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using the least significant difference test at a 5% probability level with a data processing system (DPS 7.05) (Tang & Feng, 2007). 3. Results and discussion 3.1. Starch granule distribution Waterlogging after pollination decreased the ratio of large granules and the average granule size of starch for all the test varieties except Nongkeyu301, which exhibited a similar average granule size in two conditions (Fig. 1). The small starch granule size under waterlogging conditions may be caused by waterlogging shortening the grain filling period and reducing the grain growth rates (Araki, Hamada, Hossain, & Takahashi, 2012; Hossain, Araki, & Takahashi, 2011); thus, starch granule development was suppressed and formed small granules. 3.2. Starch iodine staining The kmax and iodine-binding capacity in all samples present typical waxy character, as waxy maize starch is composed of 100% amylopectin (Fiedorowicz & Rebilas, 2002). The blue value, kmax, and iodine-binding capacity in YN525 were not influenced by
waterlogging treatment. Those three parameters increased in Meiyu16 and decreased in the other four varieties (Table 1), indicating that the proportion of long chains in amylopectin decreased (Fiedorowicz & Rebilas, 2002). The high proportion of long chains in amylopectin under controlled conditions was primarily due to the large starch granules containing high proportion of long chains in amylopectin than small ones (Lindeboom, Chang, & Tyler, 2004).
3.3. XRD and crystallinity Waterlogging after pollination did not change the XRD pattern. All the samples present typical ‘‘A’’-type diffraction pattern (Fig. 2). However, the peak intensities at different diffraction angles in response to waterlogging were dependent on varieties. The peak intensity was unaffected by waterlogging in YN525, decreased in Huanuo1, Wannuo5, and Guangbainuo5, and increased in Nongkeyu301 and Meiyu16. Waterlogging also changed the relative crystallinity, which increased in Nongkeyu301, remained unchanged in Guangbainuo5, and decreased in the other four varieties. The lower peak intensities and crystallinity under waterlogging was because of the small starch granules and low proportion of long chains in amylopectin, as large starch granules have sharper intensities than small ones (Tang, Ando, Watanabe, Takeda, &
Fig. 1. Starch granule distribution and average granule size under control and waterlogging conditions.
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D. Lu et al. / Food Chemistry 179 (2015) 232–238 Table 1 Starch iodine staining under control and waterlogging conditions. Variety
Treatment
Blue value
kmax (nm)
Iodine-binding capacity
Huanuo1
Waterlogging Control
0.161 cd 0.184 a
534.7 cd 536.4 a
0.534 abc 0.541 a
Nongkeyu301
Waterlogging Control
0.156 de 0.185 a
534.8 bcd 536.2 a
0.530 cd 0.540 ab
Wannuo5
Waterlogging Control
0.148 e 0.171 bc
535.8 abc 536.3 a
0.532 bc 0.538 ab
Meiyu16
Waterlogging Control
0.170 bc 0.147 e
536.0 ab 533.6 d
0.528 cd 0.515 f
YN525
Waterlogging Control
0.174 ab 0.171 bc
534.8 bcd 533.7 d
0.523 de 0.523 de
Guangbainuo5
Waterlogging Control
0.147 e 0.186 a
534.7 cd 536.1 a
0.517 ef 0.539 ab
Mean values in the same column followed by different letters are significantly different (p < 0.05).
Fig. 2. Starch X-ray diffraction pattern and crystallinity under control and waterlogging conditions.
Mitsunaga, 2000; Zeng, Li, Gao, & Ru, 2011), and waxy maize starch with high amount of long chains was responsible for high crystallinity (Singh, Inouchi, & Nishinari, 2006). 3.4. Swelling power and solubility Swelling power and solubility can be used to assess the extent of interaction between starch chains within the amor-
phous and crystalline domains of the starch granule (Sandhu & Singh, 2007). The swelling power and solubility for all the varieties were decreased by waterlogging treatments except for Wannuo5, which were increased (Fig. 3). The high swelling power and solubility under control conditions is primarily due to large starch granules (Sandhu, Singh, & Kaur, 2004) and high crystallinity (Singh et al., 2006). In addition, higher proportions of long chains in amylopectin contributed to increased starch
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swelling (Sasaki & Matsuki, 1998; Srichuwong, Sunarti, Mishima, Isono, & Hisamatsu, 2005). 3.5. Pasting properties The starch pasting properties were significantly affected by waterlogging after pollination (Table 2). The peak viscosity was unaffected in Huanuo1 and it was decreased by waterlogging treatments in the five other varieties. The high peak viscosities under control conditions may be due to the fact that larger starch granules increase the rate of swelling, which occupy more volume and enhance viscosity (Srichuwong et al., 2005). The breakdown viscosity in all the varieties decreased under waterlogging conditions. The low breakdown viscosities under waterlogging conditions indicated that the starch granules were harder to break down compared to the control conditions. Kim, Johnson, Graybosch, and Gaines (2003) observed that starch with high crystallinity exhibited high peak and breakdown viscosities. Noda et al. (2005) reported that smaller granules have lower peak and breakdown viscosities than larger granules in potato starch. A positive correlation between swelling power, solubility, as well as peak and breakdown viscosities was observed in normal maize starch (Sandhu & Singh, 2007). Trough and final viscosity increased in Huanuo1 and Meiyu16 and decreased in the four other varieties in response to waterlogging. The setback viscosity in all samples was lower than 9.3 RVU; this low value was because the amylopectin did not aggregate during cooling of the paste (Singh et al., 2005). The pasting temperature only increased in Meiyu16 and remained unaffected in the five other varieties. The difference was also negligible (coefficient of variation was 0.5).
3.6. Thermal properties Gelatinization temperature represents a measure of starch crystallite and gelatinization enthalpy (DHgel) the amount of crystalline structure (Ji et al., 2004). The gelatinization temperatures in response to waterlogging were dependent on the varieties. However, the variable coefficient values for To, Tp, and Tc were 1.0, 0.7, and 0.6, respectively, indicating that the difference was insignificant. Tang et al. (2000) observed that the waxy barley starch gelatinization temperatures were similar among the different granule fractions. DHgel in response to waterlogging was dependent on varieties. It was unchanged in Nongkeyu301, increased in Guangbainuo5, and decreased in the four other varieties (Table 3). A low value of DHgel was also observed for starch with low crystallinity and small granules in waxy barley starch (Tang et al., 2000). Also, positive correlations between swelling power and DHgel were observed in wheat starch (Sasaki & Matsuki, 1998). Retrogradation occurred in the gelatinized sample after storing at 4 °C for 1 week. The retrogradation properties of the starch gels are indirectly influenced by the structural arrangement of starch chains within the amorphous and crystalline regions of the granule, which in turn influences the extent of granule breakdown during gelatinization and the interaction that occurs between the starch chains during gel storage (Sandhu et al., 2004). Retrogradation enthalpy (DHret) increased in Nongkeyu301, Wannuo5, Meiyu16, and YN525, but remained unaffected in Huanuo1 and Guangbainuo5. A high DHret under waterlogging treatment results in a high retrogradation percentage (%R). The %R was unchanged in Guangbainuo5, but increased in the five other varieties under waterlogging conditions. This result indicates that the waterlogging after pollination aggravated the staling or aging
Fig. 3. Starch swelling power and solubility under control and waterlogging conditions.
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D. Lu et al. / Food Chemistry 179 (2015) 232–238 Table 2 Starch pasting properties under control and waterlogging conditions. Variety
Treatment
PV (RVU)
TV (RVU)
BD (RVU)
FV (RVU)
SB (RVU)
Ptemp (°C)
Huanuo1
Waterlogging Control
174.5 e 174.8 e
74.5 cd 71.4 ef
100.0 d 103.4 c
83.5 de 76.9 g
9.0 a 5.5 de
68.7 cd 68.4 d
Nongkeyu301
Waterlogging Control
182.3 c 184.5 b
81.7 a 81.0 a
100.6 d 103.5 c
86.2 bc 87.8 ab
4.5 e 6.8 bc
69.2 bcd 69.2 bcd
Wannuo5
Waterlogging Control
168.8 f 173.6 e
75.3 c 74.9 cd
93.5 e 98.7 d
81.1 ef 82.0 ef
5.8 cd 7.1 b
69.2 bcd 69.9 ab
Meiyu16
Waterlogging Control
173.3 e 180.6 d
78.7 b 69.8 f
94.6 e 110.8 a
85.3 cd 72.6 h
6.6 bcd 2.8 f
70.3 a 69.1 bcd
YN525
Waterlogging Control
168.5 f 192.1 a
78.7 b 80.7 ab
89.8 f 111.4 a
86.2 bc 90.0 a
7.5 b 9.3 a
69.2 bcd 69.2 bcd
Guangbainuo5
Waterlogging Control
167.5 f 184.0 b
73.0 de 76.0 c
94.5 e 108.0 b
80.6 f 83.3 de
7.6 b 7.3 b
69.2 bcd 69.3 bc
PV, peak viscosity; TV, trough viscosity; BD, breakdown viscosity; FV, final viscosity; SB, setback viscosity; Ptemp, pasting temperature. Mean values in the same column followed by different letters are significantly different (p < 0.05).
Table 3 Starch thermal properties under control and waterlogging conditions. Variety
Treatment
DHgel (J/g)
To (°C)
Tp (°C)
Tc (°C)
DHret (J/g)
%R (%)
Huanuo1
Waterlogging Control
12.2 de 14.5 a
64.6 d 63.7 e
69.8 d 69.8 d
78.1 cd 78.4 bc
6.9 bcd 7.2 bc
56.6 b 49.4 de
Nongkeyu301
Waterlogging Control
12.2 de 12.2 de
65.5 b 63.6 e
70.8 c 70.1 d
78.4 bc 78.4 bc
6.7 cde 5.4 h
55.0 bc 44.0 ef
Wannuo5
Waterlogging Control
12.2 de 13.3 bc
63.8 e 64.3 de
71.3 b 70.9 bc
79.1 ab 79.3 a
7.6 ab 6.8 cde
62.2 a 51.0 cd
Meiyu16
Waterlogging Control
12.1 de 13.8 ab
66.9 a 65.9 b
72.0 a 71.1 ab
79.4 a 78.4 bc
8.0 a 6.0 fgh
66.0 a 43.2 f
YN525
Waterlogging Control
12.5 cd 14.2 ab
65.3 bc 64.0 de
70.9 bc 70.8 c
78.6 bc 79.4 a
6.9 bcd 5.6 gh
55.3 bc 39.5 f
Guangbainuo5
Waterlogging Control
12.5 cd 11.4 e
65.4 bc 64.7 cd
70.2 d 70.7 c
77.6 d 78.1 cd
6.4 def 6.1 efg
51.2 bcd 53.9 bcd
DHgel = gelatinization enthalpy; To = onset temperature; Tp = peak gelatinization temperature; Tc = conclusion temperature; DHret = retrogradation enthalpy; and %R = retrogradation percentage. Mean values in the same column followed by different letters are significantly different (p < 0.05).
of starch. This may due to fact that the breakage of the starch granule under waterlogging conditions (present as low breakdown viscosities observed by RVA) was less than under control conditions, and those ungelatinized granules gelatinized during heating after refrigerated storage, which in turn, increased DHret and %R. 4. Conclusion Waterlogging changed the physicochemical properties of waxy maize starch. Starch granule size and crystallinity were decreased by waterlogging in all varieties except for Nongkeyu301. Iodinebinding capacity in response to waterlogging was dependent on varieties; it was unaffected in YN525, increased in Meiyu16, and decreased in the four other varieties. Starch swelling power and solubility increased in Wannuo5 and decreased in the five other varieties when the plants were exposed to waterlogging. Starch peak and breakdown viscosities were decreased by waterlogging, whereas trough and final viscosities in response to waterlogging were dependent on varieties. The low setback viscosities in all the varieties indicated that waxy maize starch paste was hard to aggregate during cooling. The pasting and gelatinization temperatures were only slightly affected by waterlogging. DHgel was unchanged in Nongkeyu301, increased in Guangbainuo5, and decreased in the four other varieties. Waterlogging increased the DHret value, resulting in the increment of %R. The low swelling power, peak and breakdown viscosities and high %R under water-
logging treatment may be helpful to select waxy maize starch with low swelling, less stickiness, increased resistance to breaking and a high tendency to retrograde. Significant differences in the physicochemical properties were also observed among the test varieties, which make the selection of varieties based on different purposes is possible. For example, under waterlogging condition, the starch of Nongkeyu301 was sticky and stable as it has high peak and breakdown viscosities, and the starch of Guangbainuo5 retrograded less than the others as it had lower %R than the other starches.
Acknowledgments This study was supported by the Chinese Natural Science Foundation (Grant Nos. 31271640 and 31471436), Jiangsu High School Natural Science Foundation (Grant No. 14KJA210004), Priority Academic Program Development of Jiangsu Higher Education Institutions, and New Century Talents Project of Yangzhou University.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.foodchem.2015. 01.096.
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References Araki, H., Hamada, A., Hossain, M. A., & Takahashi, T. (2012). Waterlogging at jointing and/or after anthesis in wheat induces early leaf senescence and impairs grain filling. Field Crops Research, 137, 27–36. Beckles, D. M., & Thitisaksakul, M. (2014). How environmental stress affects starch composition and functionality in cereal endosperm. Starch/Stärke, 66, 58–71. Cairns, J. E., Sonder, K., Zaidi, P. H., Verhulst, N., Mahuku, G., Babu, R., et al. (2012). Maize production in a changing climate: Impacts, adaptation, and mitigation strategies. In S. Donald (Ed.). Advances in agronomy (Vol. 114, pp. 1–58). Burlington: Academic Press. Fiedorowicz, M., & Rebilas, K. (2002). Physicochemical properties of waxy corn starch and corn amylopectin illuminated with linearly polarized visible light. Carbohydrate Polymers, 50, 315–319. Hossain, M. A., Araki, H., & Takahashi, T. (2011). Poor grain filling induced by waterlogging is similar to that in abnormal early ripening in wheat in Western Japan. Field Crops Research, 123, 100–108. Ji, Y., Pollak, L. M., Duvick, S., Seetharaman, K., Dixon, P. M., & White, P. J. (2004). Gelatinization properties of starches from three successive generations of six exotic corn lines grown in two locations. Cereal Chemistry, 81, 59–64. Jobling, S. (2004). Improving starch for food and industrial applications. Plant Biology, 7, 210–218. Kim, W., Johnson, J. W., Graybosch, R. A., & Gaines, C. S. (2003). Physicochemical properties and end-use quality of wheat starch as a function of waxy protein alleles. Journal of Cereal Science, 37, 195–204. Lenihan, E., Pollak, L., & White, P. (2005). Thermal properties of starch from exotic by adapted corn (Zea mays L.) lines grown in four environments. Cereal Chemistry, 82, 683–689. Lindeboom, N., Chang, P. R., & Tyler, R. T. (2004). Analytical, biochemical and physicochemical aspects of starch granule size, with emphasis on small granule starches: A review. Starch/Stärke, 56, 89–99. Liu, L., Klocke, N., Yan, S., Rogers, D., Schlegel, A., Lamm, F., et al. (2013). Impact of deficit irrigation on maize physical and chemical properties and ethanol yield. Cereal Chemistry, 90, 453–462. Lu, D., Cai, X., Zhao, J., Shen, X., & Lu, W. (2015). Effects of drought after pollination on grain yield and quality of fresh waxy maize. Journal of the Science of Food and Agriculture, 95, 210–215. Lu, D., & Lu, W. (2012). Effects of protein removal on the physico-chemical properties of waxy maize flours. Starch/Stärke, 64, 874–881. Lu, D., Shen, X., Cai, X., Yan, F., Lu, W., & Shi, Y.-C. (2014). Effects of heat stress during grain filling on the structure and thermal properties of waxy maize starch. Food Chemistry, 143, 313–318.
Lu, D., Sun, X., Wang, X., Yan, F., & Lu, W. (2013). Effect of shading during grain filling on the physicochemical properties of fresh waxy maize. Journal of Integrative Agriculture, 12, 1560–1567. Noda, T., Takigawa, S., Matsuura-Endo, C., Kim, S. J., Hashimoto, N., & Yamauchi, H. (2005). Physicochemical properties and amylopectin structures of large, small, and extremely small potato starch granules. Carbohydrate Polymers, 60, 245–251. Oktem, A. (2008). Effect of water shortage on yield, and protein and mineral compositions of drip-irrigated sweet corn in sustainable agricultural systems. Agricultural Water Management, 95, 1003–1010. Sandhu, K. S., & Singh, N. (2007). Some properties of corn starches II: Physicochemical, gelatinization, retrogradation, pasting and gel textural properties. Food Chemistry, 101, 1499–1507. Sandhu, K. S., Singh, N., & Kaur, M. (2004). Characteristics of the different corn types and their grain fractions: Physicochemical, thermal, morphological and rheological properties of starches. Journal of Food Engineering, 64, 119–127. Sasaki, T., & Matsuki, J. (1998). Effect of wheat starch structure on swelling power. Cereal Chemistry, 75, 525–529. Singh, N., Inouchi, N., & Nishinari, K. (2006). Structure, thermal and viscoelastic characteristics of starches separated from normal, sugary and waxy maize. Food Hydrocolloids, 20, 923–935. Singh, M., Sandhu, K. S., & Kaur, M. (2005). Physico-chemical properties including granular morphology, amylose content, swelling and solubility, thermal and pasting properties of starches from normal, waxy, high amylose and sugary corn. Progress in Food Biopolymer Research, 1, 43–54. Srichuwong, S., Sunarti, T. C., Mishima, T., Isono, N., & Hisamatsu, M. (2005). Starches from different botanical sources II: Contribution of starch structure to swelling and pasting properties. Carbohydrate Polymers, 62, 25–34. Tang, H., Ando, H., Watanabe, K., Takeda, Y., & Mitsunaga, T. (2000). Some physicochemical properties of small-, medium-, and large-granule starches in fractions of waxy barley grain. Cereal Chemistry, 77, 27–31. Tang, Q. Y., & Feng, M. G. (2007). Data processing system: Experimental design, statistical analysis and data mining. Beijing, China: Science Press. Thitisaksakul, M., Jimenez, R. C., Abias, M. C., & Beckles, D. M. (2012). Effects of environmental factors on cereal starch biosynthesis and composition. Journal of Cereal Science, 56, 67–80. Wang, Y., & Frei, M. (2011). Stressed food – The impact of abiotic environmental stresses on crop quality. Agriculture, Ecosystems & Environment, 141, 271–286. Zaidi, P. H., Maniselvan, P., Srivastava, A., Yadav, P., & Singh, R. P. (2010). Genetic analysis of water-logging tolerance in tropical maize (Zea Mays L.). Maydica, 55, 17–26. Zeng, J., Li, G., Gao, H., & Ru, Z. (2011). Comparison of A and B starch granules from three wheat varieties. Molecules, 16, 10570–10591.
