Study on Dietary Vitamin B_6 Intake in Female Students by Duplicate Meal Method (Part II) : Effect of Cooking Methods on the Retention Ratios of Vitamin B_6 in Foods

Abstract

To study losses of vitamin B_6 (B_6) in foods by cooking, the B_6 contents in foods and the B_6 retention ratios were measured by HPLC before and after various cooking. Further, the retention of B_6 in a day's meal of female students was reconfirmed to estimate approximate cooking loss of B_6. Ten animal foods and six plant foods were cooked by three methods (sauteeing, deep-frying and boiling) basically, and the B_6 vitamers (PMP, PM, PLP, PL, PNP, PN and PNG) in foods were measured by HPLC. The results are as follows, (1) The dry heating methods had an advantage over the wet heating methods in retention ratio of B_6, which were 60〜80 % for meats and 95 % for potato. (2) The retention ratios on the wet heating methods were 30〜50 % for animal foods and this methods had the higher retentions at the short time of heating. The ratios for plant foods were 40〜75 %, because of B_6 in plant foods were more stable. (3) The difference of the retention ratios between the animal foods and plant foods suggested that the ratios depended on the compositions of B_6 vitamers. (4) The cooking loss of B_6 was considered to be approximately 20 % in daily meals which were included non-heated foods in home cooking and used processed foods in parts (40 %) of the meals, from the result of this study on female students of today.