Effect of storage temperature and water activity on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of soy protein isolates and defatted soy flours.
The aim of this work was to study the effect of 1 year of storage at different temperatures and 1 month of storage at different water activities on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of defatted soy flours (DSF) and soy protein isolates (SPI). The storage for up to 1 year, at temperatures from -18 to 42 degrees C, had no effect on the total content of isoflavones, but the profile changed drastically at 42 degrees C, with a significant decrease of the percentage of malonylglucosides with a proportional increase of beta-glucosides. A similar effect was observed for SPI stored at a(w) = 0.87 for 1 month. For DSF, however, there was observed a great increase in aglycons (from 10 to 79%), probably due to the action of endogenous beta-glucosidases. The antioxidant activity decreased after storage at 42 degrees C, but the in vitro protein digestibility did not change.
Pinto
Marcia da Silva
Mda S
Departamento de Alimentos e Nutrição Experimental, FCF, Universidade de São Paulo, Av. Prof. Lineu Prestes 580, 05508-900 São Paulo, SP, Brazil.
Lajolo
Franco Maria
FM
Genovese
Maria Inés
MI
D000975:Antioxidants / Q000032:analysis*; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D005519:Food Preservation / Q000379:methods*; D007529:Isoflavones / Q000032:analysis*; D009584:Nitrogen / Q000737:chemistry; D012995:Solubility; D045730:Soy Foods / Q000032:analysis*; D030262:Soybean Proteins / Q000378:metabolism*; D013696:Temperature; D014867:Water
D000975:Antioxidants; D004044:Dietary Proteins; D007529:Isoflavones; D030262:Soybean Proteins; D014867:Water; D009584:Nitrogen