石井 克枝

In this second paper, the authors examined the questionnaire results in detail and proposed that teachers adopt new information about foods in home economics classes to make students think about nutrition and foods, because there is a huge difference between what is taught in school and the reality of students' everyday lives. We selected foods based on a variety of information, but in reality students focus on only one specific nutritional aspect. They need to look at the total nutritional picture when selecting food. The proposed points for home economics classes are as follows. (1) Make students understand the relationships between foods and their various roles. (2) Teach high school students to understand about their own health and encourage them to have an awareness about food and their health. (3) Have students become knowledgeable about selecting foods and correcting their misunderstandings about foods information gained from the media.

Recently, there have been many problems concerning children's health and food. Home economics education has had a lot of classes about health and food issues but now more effective classes are required. The aim of this study is to clasify high school students' way of thinking about food and health; in terms of good classes about food and nutrition. In this study, the authors examined the results of a questionnaire about "good" or "bad" foods. The questionnaire was given to 512 senior high school students from November 2002 to July 2003. In this first paper, the authors reviewed the results. They are as follows : 1) High school students mentioned vegetables are better than animal products. 2) They recognized good animal foods in this order : fish, milk and dairy products meat, eggs. 3) They recognized good vegetable foods in this order : vegetables, fruits, beans, grains, seaweed, potatoes. 4) They recognized bad foods in this order : confectionery, grains, multiple foods, beverages, meats. 5) The reasons why foods are considered good are vitamins, calcium, and iron. 6) The reasons why foods are considered bad are lipids, calories, and cholesterol. Other reasons are salt, sugar, and food additives.

Peptides in beef which had been heated at 60℃ for 6 h were fractionated into four groups according to their molecular weight (MW): I, less than 500; II, 500-1,000; III, 1,000-10,000; and IV 10,000 and more. The combination of fractions I and n increased the "umami" sensation. While the presence of II, III and IV with fraction I did not increase this sensation. Umami was increased when fraction n was added to onion soup which has few peptides. The major fractions with molecular weights of 500-1,000 and l,000-10,000 were both basic.

Peptides in beef which had been heated at 60℃ for 6 h were fractionated into four groups according to their molecular weight (MW): I, less than 500; II, 500-1,000; III, 1,000-10,000; and IV 10,000 and more. The combination of fractions I and n increased the "umami" sensation. While the presence of II, III and IV with fraction I did not increase this sensation. Umami was increased when fraction n was added to onion soup which has few peptides. The major fractions with molecular weights of 500-1,000 and l,000-10,000 were both basic.

Peptides in the beef which was heated at 60℃ for 6 h were fractionated into those possessing the molecular weight (MW) of less than 500, 500-1,000, 1,000-10,000, and more than 10,000. The content of peptides possessing MW of less than 500 was largest. The basic extract was prepared from the non-aging beef which was heated at 100℃ for 10 min. Effect of adding the peptide fractions on the taste of the basic extract was examined by sensory evaluation. Adding the peptides with MW 1,000-10,000 to the basic extract improved the taste by depressing its sourness and enhancing its mildness. Existence of the peptide fraction with MW of less than 500 in beef extract enhanced mildness of fraction with MW of less than 500 in beef extract. A major amino acid in some acidic peptide fractions with MW of less than 500 was glutamic acid.

Peptides in the beef which was heated at 60℃ for 6 h were fractionated into those possessing the molecular weight (MW) of less than 500, 500-1,000, 1,000-10,000, and more than 10,000. The content of peptides possessing MW of less than 500 was largest. The basic extract was prepared from the non-aging beef which was heated at 100℃ for 10 min. Effect of adding the peptide fractions on the taste of the basic extract was examined by sensory evaluation. Adding the peptides with MW 1,000-10,000 to the basic extract improved the taste by depressing its sourness and enhancing its mildness. Existence of the peptide fraction with MW of less than 500 in beef extract enhanced mildness of fraction with MW of less than 500 in beef extract. A major amino acid in some acidic peptide fractions with MW of less than 500 was glutamic acid.

本研究は牛肉の低温加熱による呈味物質と呈味性の変化についてみたものである.牛肉を薄切りにし,真空パックしたものを40,60,80℃で,10分,1,3,6時間加熱した.遊離アミノ酸は40℃,6時間加熱したときにもっとも多く生成し,酸可溶性ペプチドは60℃,6時間加熱したときにもっとも多く生成した.60℃,6時間加熱した牛肉エキスと,60℃,10分加熱した牛肉エキスの呈味を官能検査により比較すると,60℃,6時間加熱した牛肉エキスの方がまろやかだった.二つの牛肉エキス中の遊離アミノ酸,5'-IMPはほとんど同量であったので,まろやかさは加熱によって増加したペプチドによるものではないかと考えられた.

Wheat gluten was hydrolyzed by actinase and deamidated in 0.5_N HCL at 120℃ 15min. The peptides with molecular weight 500 to 1,000 were divided into acidic, nuetral and basic fraction by ion-exchange chromatographies. Threshold values of tastes of acidic, nuetral and basic fractions were 0.025, 0.025 and 0.000625%, respectively. The acidic fraction elicited sweet and slightly umami tastes. The addition of an acidic fraction into the niboshi soup stok has shown to enhance its umami and body. About 30 peptides were detetected by the fractionation of acidic fraction on HPLC using ODS column. The major constituent amino acid of them was glutamic acid.