J. Nutr.
Cooking
Losses
of Thiamin
Nutritional
Mieko KIMURA, Yoshinori
Sci.
in Food
Vitaminol.,
and
36, S17-S24,
1990
Its
Significance
ITOKAWA, and Motonori
FUJIWARA
Department of Hygiene, Faculty of Medicine, Kyoto University, Sakyoku, Kyoto 606, Japan
Summary To clarify the discrepancy between values of thiamin intake reported in national nutrition survey in Japan and judgment which was concluded by medical and biochemical examination in our field survey, thiamin of various daily foods were analyzed pre and post cooking in the various cooking methods, the following results were obtained. (1) The thiamin contents in cooked daily meals were 50-60 percent of the cal culated values on an average. (2) The cooking losses of thiamin were particularly large in rice and green vegetables. (3) The loss of thiamin largest in boiling, followed by baking, parching and frying. (4) High temperature, pH, and chlorine on the public water acclerated thiamin losses. (5) The decrease of thiamin in cooked foods is caused by both of getting away of thiamin from foods and cleavage of thiamin of foods. Key Words thiamin, cooking loss, temperature, pH, chlorine
Large cooking loss of thiamin, a water soluble vitamin, has been known widely (1-4). Recently, it has been reported by the Japan Nutritional survey that thiamin intake of Japanese is enough, and there is 1.4 times high of recommended value (5). However, we reported that there is a great discrepancy between the value of thiamin intake reported in Japan nutritional survey and thiamin status in Japanese judged by medical and biochemical examination in our field survey (6, 7). To elucidate this discrepancy authors have studied both of field survey and experimental studies. MATERIALS AND METHODS Field survey. Daily meals of 21 persons living in Simane and Kyoto prefec tures were collected. Each one day's meals were homogenized and made the volume to 1,000ml with distilled water. A part of the homogenate (25-50ml) was deproteinized by trichrolic acid and thiamin concentrations were determined by thiochrome method (determined value) (8). Thiamin contents of these menu were also calculated using a personal computer program prepared by ourselves based on S17
Table
1.
Cooking
methods
of spinach
and pork
at fundamental
experiment.J. Nutr. Sci. Vitaminol.
COOKING
LOSS
OF THIAMIN
S19
a Japanese standard food table (calculated value) (9). From this two data, cooking losses of thiamin calculated. Experimental studies. (a) Thiamin contents in various foods cooked by various methods were determined and at the sametimes thiamin values of these foods were calculated. (b) To make clear the decrease of thiamin of cooking in detail, various experimental cooking studies have made with pork and spinach as shown in Table 1. (c) Effects of pH and temperature on cleavage of thiamin were studied. (d) Effect of chlorine in tap water on cleavage of thiamin was investigated with rice. RESULTS
Field
Table
Vol.
survey.
2.
36, Suppl.
Analyzed
I, 1990
Table
2 shows
and calculated
AND
METHODS
determined
values
and calculated
of thiamin
of daily
values
meals
of thiamin
of 21 persons.
in
S20
M. KIMURA
et al.
daily meals of 21 persons (energy intakes of their daily meals were 1,381kcal to 3,840kcal). Thiamin intakes in calculated values were 0.67mg to 4.53mg and those of determined values were 0.32mg to 3.54mg. Consequently, the range of values of percentage of analyzed to calculated were 34 to 78%, showing the fact that approximately 45% of thiamin in foods has been lost in the process of cooking. Experimental studies. (a) Figure 1 shows the percentage of analyzed values to the calculated values of various foods in various cooking methods. Although almost of the materials showed the loss of thiamin by cooking. (b) Figure 2 shows thiamin contents of spinach before and after cooking by various methods. Cooking loss was largest in long time boiling, followed by short time boiling, microwave heating, steaming and parching. Thiamin was found in
Fig.
1.
Cooking
determined / calculated
losses
of thiamin
in various
foods.
value value •~100
J. Nutr.
Sci.
Vitaminol.
COOKING
LOSS
OF THIAMIN
S21
Fig. 2. Changes of thiamin content in spinach cooked by various methods. * thiamin content of raw material showed as 100% .
soup
of
squeezing
Thiamin shown
in
time
7.0 (d)
of
steaming, of
at
100•Ž
Effect
pork
of
before
loss
was
pH
and
and
high
in
heating,
temperature by
after
largest
microwave
is cleaved
processes tap
boiling.
Cooking
Thiamin
cooking
Vol.
3.
Effects
4.
above
with
Fig.
boiling, (c)
Fig.
or contents
on
cooking
long
parching of
above
various
boiling,
and
cleavage
temperature
by
time
methods
followed
are
by
short
frying.
thiamin 140•Ž,
standard high
pH
solution above
8.0
in and
temperature. chlorine is shown
(0.2ppm) in
Table
in 3.
tap
Thiamin
water
on
content
thiamin of
rice
content
of
decreased
by
rice
in
boiling
water.
Cleavage
of
36, Suppl.
I, 1990
thiamin
by
chlorine
depended
upon
temperature,
pH
and
con
S22
M. KIMURA
et al.
Fig. 3. Changes of thiamin content in pork cooked by various methods. * thiamin content of raw material showed as 100% .
centration of chlorine. Thiamin cleaved by chlorine results in hydroxymethyl pyrimidine and 4-methyl-5-hydroxyethylthiazole (3). The measures to prevent cooking loss of thiamin are; (a) eating the boiled foods with the soup, (b) using previously boiled tap water for cooking, to wash away chlorine, (c) avoiding heating for long time and high pH condition, (d) selection of a cooking method causing less thiamin loss (raw, stewing, parching or frying). It is clear that; (1) cooking losses are about 40% in thiamin on an average of daily meals, (2) the decrease of mineral content in cooked foods is mainly caused by getting away of minerals from foods. On the other hand, the decrease of thiamin in cooked foods is caused by getting away of thiamin from foods and cleavage of thiamin in foods, (3) accordingly, in conclusion, there is question in the quantity of J. Nutr.
Sci.
Vitaminol.
COOKING
Fig.
Table 3.
thiamin
4.
Effects
LOSS
OF
of pH and temperature
THIAMIN
S23
on the cleavage
of thiamin.
Cooking loss of thiamin in rice by tap water. (percentage of loss)
intakes
of the people
reported
by the national
servey.
REFERENCES
1) 2) 3) 4) 5) b) Vol.
Somogyi, J. C. (1945): Versuche uber Wirkstoffe, die den Ascorbinsaureabbau hemmen. Z. Vitaminforsch., 16, 134-168. Kimura, M., Saito, N., and Itokawa, Y. (1982): Cooking loss of vitamin B1 in foods and its nutritional significance. Vitamins (J. Vitamin Soc. Jpn.), 56, 415-423. Yagi, N., and Itokawa, Y. (1979): Cleavage of thiamine by chlorine in tap water. J. Nutr. Sci. Vitaminol., 25, 281-287. Ariyama, T. (1948): Studies on the decay of thiamine in the processes of storage, processing and cooking of foods. Vitamins (J. Vitamin Soc. Jpn. ), 1, 51-56. The Ministry of Public Welfare, Health & Medical Bureau (1988): Nutritional status in Japanese-Syowa 63 years-, Daiichi Syutsupan. Kimura, M., Sayama, N., Takashima, M., Nakabayashi, J., Itokawa, Y., and Tun36, Suppl.
I, 1990
S24
7)
8) 9)
M.
KIMURA
et al .
ematu, T. (1982): A field survey on nutritional status of vitamin B1 in Shimane prefecture. Vitamins (J. Vitamin Soc. Jpn. ), 56, 479-486. Kimura, M., Souen, S., Saga, T., Umehara, Y., Itokawa, Y., and Fujiwara, M. (1978): Thiamine contents in food taken by students . Vitamins (J. Vitamin Soc. Jpn.), 52, 25-29. Fujiwara, M., and Matui, K. (1953): Determination of thiamine by the thiochrome reaction. Analy. Chem., 25, 810-812. Resources Council, Science and Technology Agency , Japan (1982): Standard tables of food composition in Japan. Fourth serviced edition .
J. Nutr.
Sci. Vitaminol.
Cooking
Losses
of Thiamin
Nutritional
Mieko KIMURA, Yoshinori
Sci.
in Food
Vitaminol.,
and
36, S17-S24,
1990
Its
Significance
ITOKAWA, and Motonori
FUJIWARA
Department of Hygiene, Faculty of Medicine, Kyoto University, Sakyoku, Kyoto 606, Japan
Summary To clarify the discrepancy between values of thiamin intake reported in national nutrition survey in Japan and judgment which was concluded by medical and biochemical examination in our field survey, thiamin of various daily foods were analyzed pre and post cooking in the various cooking methods, the following results were obtained. (1) The thiamin contents in cooked daily meals were 50-60 percent of the cal culated values on an average. (2) The cooking losses of thiamin were particularly large in rice and green vegetables. (3) The loss of thiamin largest in boiling, followed by baking, parching and frying. (4) High temperature, pH, and chlorine on the public water acclerated thiamin losses. (5) The decrease of thiamin in cooked foods is caused by both of getting away of thiamin from foods and cleavage of thiamin of foods. Key Words thiamin, cooking loss, temperature, pH, chlorine
Large cooking loss of thiamin, a water soluble vitamin, has been known widely (1-4). Recently, it has been reported by the Japan Nutritional survey that thiamin intake of Japanese is enough, and there is 1.4 times high of recommended value (5). However, we reported that there is a great discrepancy between the value of thiamin intake reported in Japan nutritional survey and thiamin status in Japanese judged by medical and biochemical examination in our field survey (6, 7). To elucidate this discrepancy authors have studied both of field survey and experimental studies. MATERIALS AND METHODS Field survey. Daily meals of 21 persons living in Simane and Kyoto prefec tures were collected. Each one day's meals were homogenized and made the volume to 1,000ml with distilled water. A part of the homogenate (25-50ml) was deproteinized by trichrolic acid and thiamin concentrations were determined by thiochrome method (determined value) (8). Thiamin contents of these menu were also calculated using a personal computer program prepared by ourselves based on S17
Table
1.
Cooking
methods
of spinach
and pork
at fundamental
experiment.J. Nutr. Sci. Vitaminol.
COOKING
LOSS
OF THIAMIN
S19
a Japanese standard food table (calculated value) (9). From this two data, cooking losses of thiamin calculated. Experimental studies. (a) Thiamin contents in various foods cooked by various methods were determined and at the sametimes thiamin values of these foods were calculated. (b) To make clear the decrease of thiamin of cooking in detail, various experimental cooking studies have made with pork and spinach as shown in Table 1. (c) Effects of pH and temperature on cleavage of thiamin were studied. (d) Effect of chlorine in tap water on cleavage of thiamin was investigated with rice. RESULTS
Field
Table
Vol.
survey.
2.
36, Suppl.
Analyzed
I, 1990
Table
2 shows
and calculated
AND
METHODS
determined
values
and calculated
of thiamin
of daily
values
meals
of thiamin
of 21 persons.
in
S20
M. KIMURA
et al.
daily meals of 21 persons (energy intakes of their daily meals were 1,381kcal to 3,840kcal). Thiamin intakes in calculated values were 0.67mg to 4.53mg and those of determined values were 0.32mg to 3.54mg. Consequently, the range of values of percentage of analyzed to calculated were 34 to 78%, showing the fact that approximately 45% of thiamin in foods has been lost in the process of cooking. Experimental studies. (a) Figure 1 shows the percentage of analyzed values to the calculated values of various foods in various cooking methods. Although almost of the materials showed the loss of thiamin by cooking. (b) Figure 2 shows thiamin contents of spinach before and after cooking by various methods. Cooking loss was largest in long time boiling, followed by short time boiling, microwave heating, steaming and parching. Thiamin was found in
Fig.
1.
Cooking
determined / calculated
losses
of thiamin
in various
foods.
value value •~100
J. Nutr.
Sci.
Vitaminol.
COOKING
LOSS
OF THIAMIN
S21
Fig. 2. Changes of thiamin content in spinach cooked by various methods. * thiamin content of raw material showed as 100% .
soup
of
squeezing
Thiamin shown
in
time
7.0 (d)
of
steaming, of
at
100•Ž
Effect
pork
of
before
loss
was
pH
and
and
high
in
heating,
temperature by
after
largest
microwave
is cleaved
processes tap
boiling.
Cooking
Thiamin
cooking
Vol.
3.
Effects
4.
above
with
Fig.
boiling, (c)
Fig.
or contents
on
cooking
long
parching of
above
various
boiling,
and
cleavage
temperature
by
time
methods
followed
are
by
short
frying.
thiamin 140•Ž,
standard high
pH
solution above
8.0
in and
temperature. chlorine is shown
(0.2ppm) in
Table
in 3.
tap
Thiamin
water
on
content
thiamin of
rice
content
of
decreased
by
rice
in
boiling
water.
Cleavage
of
36, Suppl.
I, 1990
thiamin
by
chlorine
depended
upon
temperature,
pH
and
con
S22
M. KIMURA
et al.
Fig. 3. Changes of thiamin content in pork cooked by various methods. * thiamin content of raw material showed as 100% .
centration of chlorine. Thiamin cleaved by chlorine results in hydroxymethyl pyrimidine and 4-methyl-5-hydroxyethylthiazole (3). The measures to prevent cooking loss of thiamin are; (a) eating the boiled foods with the soup, (b) using previously boiled tap water for cooking, to wash away chlorine, (c) avoiding heating for long time and high pH condition, (d) selection of a cooking method causing less thiamin loss (raw, stewing, parching or frying). It is clear that; (1) cooking losses are about 40% in thiamin on an average of daily meals, (2) the decrease of mineral content in cooked foods is mainly caused by getting away of minerals from foods. On the other hand, the decrease of thiamin in cooked foods is caused by getting away of thiamin from foods and cleavage of thiamin in foods, (3) accordingly, in conclusion, there is question in the quantity of J. Nutr.
Sci.
Vitaminol.
COOKING
Fig.
Table 3.
thiamin
4.
Effects
LOSS
OF
of pH and temperature
THIAMIN
S23
on the cleavage
of thiamin.
Cooking loss of thiamin in rice by tap water. (percentage of loss)
intakes
of the people
reported
by the national
servey.
REFERENCES
1) 2) 3) 4) 5) b) Vol.
Somogyi, J. C. (1945): Versuche uber Wirkstoffe, die den Ascorbinsaureabbau hemmen. Z. Vitaminforsch., 16, 134-168. Kimura, M., Saito, N., and Itokawa, Y. (1982): Cooking loss of vitamin B1 in foods and its nutritional significance. Vitamins (J. Vitamin Soc. Jpn.), 56, 415-423. Yagi, N., and Itokawa, Y. (1979): Cleavage of thiamine by chlorine in tap water. J. Nutr. Sci. Vitaminol., 25, 281-287. Ariyama, T. (1948): Studies on the decay of thiamine in the processes of storage, processing and cooking of foods. Vitamins (J. Vitamin Soc. Jpn. ), 1, 51-56. The Ministry of Public Welfare, Health & Medical Bureau (1988): Nutritional status in Japanese-Syowa 63 years-, Daiichi Syutsupan. Kimura, M., Sayama, N., Takashima, M., Nakabayashi, J., Itokawa, Y., and Tun36, Suppl.
I, 1990
S24
7)
8) 9)
M.
KIMURA
et al .
ematu, T. (1982): A field survey on nutritional status of vitamin B1 in Shimane prefecture. Vitamins (J. Vitamin Soc. Jpn. ), 56, 479-486. Kimura, M., Souen, S., Saga, T., Umehara, Y., Itokawa, Y., and Fujiwara, M. (1978): Thiamine contents in food taken by students . Vitamins (J. Vitamin Soc. Jpn.), 52, 25-29. Fujiwara, M., and Matui, K. (1953): Determination of thiamine by the thiochrome reaction. Analy. Chem., 25, 810-812. Resources Council, Science and Technology Agency , Japan (1982): Standard tables of food composition in Japan. Fourth serviced edition .
J. Nutr.
Sci. Vitaminol.
