Teores de isoflavonas e capacidade antioxidante da soja e produtos derivados

Abstract

RESUMOO objetivo deste estudo foi determinar a capacidade antioxidante, o teor e as formas de isoflavonas presentes nos produtos derivados de soja e compará-los à soja em grão. A capacidade antioxidante foi mensurada por meio do método de cooxidação do β-caroteno/ ácido linoléico e pelo seqüestro de radicais livres (DPPH•). Os resultados mostraram que o conteúdo de isoflavonas nos produtos variou de 95 a 711 mg/100 g (b.s.) e o teor de fenólicos totais de 101 a 413 mg equivalentes de catequina/100 g (b.s.), sendo que o grão de soja apresentou um conteúdo de 110 e 200 mg/100 g (b.s.), respectivamente, para isoflavonas e fenólicos totais. Em relação às formas de isoflavonas a farinha integral e sua respectiva farinha desengordurada e a farinha desengordurada de soja comercial apresentaram predominância de conjugados malonilglicosídeos e β-glicosídeos, similar aos grãos de soja. O suplemento à base de gérmen de soja e a farinha desengordurada de soja apresentaram a maior capacidade antioxidante por ambos os métodos (5 μmoles equivalentes de trolox/g e ~ 0,8 μmoles equivalentes de BHT/ g amostra b.s.). Os resultados demonstraram que o conteúdo total e tipo de isoflavonas e o teor de fenólicos dos produtos de soja dependem do processamento e que a capacidade antioxidante desses produtos varia significativamente. Palavras-chave: soja e derivados protéicos, isoflavonas, capacidade antioxidante. SUMMARYISOFLAVONE CONTENT AND PROFILE AND ANTIOXIDANT ACTIVITY OF SOY AND SOY PRODUCTS. The objective of this study was to determine the antioxidant activity and isoflavone content and type of soy seeds and soy products. The antioxidant activity was measured using β-carotene bleaching and 2.2-diphenyl-1-picryl-hydrazyl (DPPH•) free radical methods. The total isoflavone content of soy products varied from 95 to 711 mg/100 g DW (expressed as aglycones) and total phenolics content from 101 to 413 mg equivalents of catechin/100 g DW. Soybeans presented 110 and 200 mg/100 g DW of isoflavones and total phenolics, respectively. The β-glycosides and malonylglycosides were the main forms of the isoflavones found in the whole flour, defatted flour and commercial defatted flour, similar to the soy seeds. The soy germ (hypocotyl) and the defatted soy flours presented the highest antioxidant activities in both methods (5.0 μmoles equivalents of trolox/g DW and ~ 0.8 μmoles equivalents of BHT/g DW). Taking this into account, the results showed that total isoflavone and phenolic contents and isoflavone profile of soy products depend on processing conditions and that antioxidant activity varied significantly among products. Keywoards: soy, soy products, isoflavones, antioxidant activity. -INTRODUÇÃOOs alimentos de origem vegetal apresentam compostos não-nutrientes (fitoquímicos) com atividades biológicas ditas promotoras da saúde, tais como atividades antioxidante, antiinflamatória e hipocolesterolêmica. Entre estes podemos citar as catequinas do chá verde e do vinho, as antocianinas dos frutos vermelhos, os flavonóis das folhas e as isoflavona...

Isoflavone and Mineral Content in Conventional and Transgenic Soybean Cultivars

“…It is important to note that, in our study, this difference was statistically significant. In another study by Barbosa et al [20], the authors found 381 ± 3 mg 100 g −1 of total isoflavones in defatted soybean flour obtained from conventional commercial soybeans, which is similar to our results for conventional commercial soybean, because isoflavones were assessed on degreased samples. Duke et al [21] performed a study using a different approach to evaluate the response of transgenic cultivars DP 5806 RR and Asgrow 3701 RR subjected to different environmental conditions but similar herbicide applications.…”

“…). However, Barbosa et al [20] found different proportions of total isoflavones: 42.8 and 39.1 mg•100 g −1 of β-glycosides, 52.5 and 50.6 mg•100 g −1 of malonylglycosides, 4.0 and 7.2 mg•100 g −1 of aglycones, and 1.0 and 2.9 mg•100 g −1 of acetylglycosides in soybeans and defatted flour, respectively. However, these authors did not have information about the presence of transgenes in the tested samples.…”

Differentiated Foods for Consumers with New Demands

“…This trend was reflected in the antioxidant activity, with the greater antioxidant capacity displayed by samples with a longer fermentation time due to an increase in the aglycone forms. These results were similar to those found by Barbosa et al (2006), who evaluated the isoflavone profile and the amount of phenolic compounds in different soybean-based products and the influence of these products on the antioxidant capacity. Their results showed that the antioxidant capacity is related not only to the amount of total phenolic compounds but also to the amount and forms of the aglycones and the types of conjugation.…”

Determinação de isoflavonas e capacidade antioxidante de alimentos industrializados à base de soja e/ou produtos derivados consumidos no Brasil

“…O conteúdo total foi similar ao encontrado por Carrão-Panizzi et al (1998), em estudo realizado com variedades de soja cultivadas no Paraná, cujo teor de isoflavonas foi de 54 a 147 mg/100 g. Barbosa et al (2006 a) analisaram uma variedade de grãos de soja adquiridos no comércio de São Paulo. O teor de isoflavonas foi de 110 ± 2 mg/100 g, resultado similar ao encontrado em outros trabalhos.…”