title: Isoflavones and antioxidant capacity of commercial soy-based beverages: effect of storage.
abstract: Samples of 11 different brands of commercially available soy-based beverages (n = 65), including products made from soy protein isolate (SPI) and soy milk, mixed with fruit juice and/or flavoring, were analyzed for their isoflavone content and in vitro antioxidant activity. There was a large variation in isoflavone and total phenolics contents ranging from 0.7 to 13 mg of isoflavones/200 mL and from 6 to 155 mg equivalents of catechin/200 mL, respectively. The antioxidant activity also varied significantly among products. Storage of the beverages at room temperature caused a significant decrease of antioxidant capacity, soluble phenolics, and isoflavone contents after 9 months. When soybeans used for beverage production were stored for up to 6 months in silos, the resulting products were not affected. However, a decrease of malonyl and a proportional increase of free glucosidic forms of isoflavones were observed after storage of both the raw material and the beverages.
authors.affiliation: Laboratorio de Quimica, Bioquimica e Biologia Molecular de Alimentos, Departamento de Alimentos e Nutricao Experimental, FCF, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Katia
authors.initials: K
authors.lastname: Rau De Almeida Callou
authors.forename: Shamil
authors.initials: S
authors.lastname: Sadigov
authors.forename: Franco Maria
authors.initials: FM
authors.lastname: Lajolo
authors.forename: Maria Ines
authors.initials: MI
authors.lastname: Genovese
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D007529:Isoflavones / Q000032:analysis*; D041942:Soy Milk / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D007529:Isoflavones