Physicochemical properties of soy flour of Korean, Japanese and Chinese species

초록

Properties of full-fat soyflours of Korean(yellow), Japanese(yellow) and Chinese (yellow and green) species were compared in terms of their water and oil absorption, foam capacity and stability, and gel strength. Solid content, acidity and apparent viscosity of soymilk upon heating also were determined. Soy flour was passed through a 300 mesh sieve and soymilk was prepared by dispersing it in distilled water. There was no significant difference (p<0.05) in foam capacity and stability among samples with different species, even though Japanese soy flour which showed the highest oil absorption and ratio of lipid to protein tended to have the lowest foam capacity. The lowest foam stability was shown in Korean soy flour, and gel strength of samples was not much different with species. Solid content of soymilk of Japanese and Korean species tended to become higher as heating time increased from 0 to 10, 20, 30 and 40 min at 80 or 90℃. The pH of soymilk of Japanese, Chinese green, and Korean species decreased slightly with heating time at 100℃. Apparent viscosity of soymilk increased with heating time at 80 or 90℃ and the largest changes was found in soymilk of Japanese species after 30 min heating. The finding positively suggest that good soy gel can be obtained by heating the soymilk consisted of full-fat soy flours of Korean or Japanese species at 80 or 90℃℃ for 30 or 40 min.