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Soybean consumption has been associated with health benefits. However, the effect of ultrasound (US) soybean pretreatment in terms of potential health benefits has not been investigated so far. Accordingly, the total phenolic content (TPC) and the total aglycone content (TAC) were optimized using the Box–Behnken design. Contrasting samples regarding isoflavones aglycones and TPCs were screened for their antioxidant and anti‐inflammatory potentials using RAW 264.7 macrophages. US pretreated soybeans (55°C, 15 min, and 24 W/cm2) showed greater TPC and TAC compared to the control and this translated to higher antiradical activity and reduction of nuclear factor kappa B (NF‐κB) activation. The concentration of genistein in treated soybeans increased by 95%. Furthermore, US pretreated soybeans rendered phenolic extracts that reduced the NF‐κB activation by 86%. Therefore, this contribution demonstrates the beneficial effects of US pretreatment of soybeans, which provides a better feedstock for the functional food industry. Practical applications Soybeans can be consumed as such or used as a feedstock to produce soy yogurt, fermented soymilk, tofu, and protein concentrate, among others. The greatest bioavailability of isoflavones compared to other flavonoids has recently been highlighted, and this has been explained by the relatively moderate lipophilicity of isoflavones as aglycones. The present contribution supports the use of US pretreatment of soybeans to obtain a feedstock with improved contents of isoflavones as aglycones. We have confirmed that phenolic extracts obtained from the US pretreated samples showed higher bioactivity as radical scavengers and by reducing the activation of nuclear factor kappa B (NF‐κB) in a cell model, which is mediated by oxidative species. The clinical importance of NF‐κB activation is derived mainly from its role in inflammatory responses. Therefore, our investigation may have a practical application in the procurement of soybean products and/or ingredients with improved functional properties related to their health benefits.

Soymilk is consumed as such or used in the preparation of tofu, fermented soymilk, and soy yogurt, among others. In this study, hemicellulase-assisted extraction (HAE) and ultrasound-assisted extraction (UAE) were used during soymilk manufacturing. The activity of endogenous β-glicosidases was increased 1.3 and 1.5-fold in soymilk produced upon HAE and UAE, respectively. Likewise, the concentration of isoflavones in the aglycone form increased 1.7 and 2.4 times in samples subjected to HAE and UAE, respectively. UAE, but not HAE, rendered an equimolar conversion from conjugated isoflavones to their respective aglycones. In addition, HAE and UAE showed higher antiradical activity towards ABTS radical cation and peroxyl radical, compared to those of the control. The aglycone isoflavones/conjugated isoflavones (aISO/cISO) ratio correlated with the antiradical activity, thus suggesting that the soybean industry may use this new quality index to indicate the antioxidant potential of products. Food formulations containing soymilk with high aISO/cISO ratio may translate to higher oxidative stability of the final product. Likewise, the higher absorption of aglycone isoflavones compared to that of their conjugated counterparts is well recognized. Therefore, high aISO/cISO ratio of soymilk and/or its products may provide a better antioxidant protection under physiological conditions.

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How to cite SILVA, M.B.R.; LEITE, R.S.; OLIVEIRA, M.A. de; IDA, E.I. Germination conditions influence the physical characteristics, chemical composition, isoflavones, and vitamin C of soybean sprouts. Pesquisa Agropecuária Brasileira, v.55, e01409, 2020. DOI: https://doi.Abstract -The objective of this work was to evaluate the effects of the germination conditions of 'BRS 216' soybean (Glycine max) on the length, yield, and isoflavone contents of sprouts. A 2 3 factorial arrangement was used to evaluate the variables soaking time, irrigation frequency, and germination time. Sprouts that showed better length and yield and higher isoflavone contents were evaluated for their chemical composition and vitamin C content. Soaking and germination time of soybean showed a positive and significant linear effect on sprout length. However, only germination time showed a significant positive linear effect on yield, and a significant negative linear effect on the content of malonylglycosides, aglycones, and total isoflavones. Soybean germination conditions were established at 6 hours of soaking, three days of germination, and 8 hours of irrigation frequency. Under these conditions, the obtained sprouts show a more preserved chemical composition, besides higher contents of β-glycosides, malonylglycosides, aglycones, total isoflavones, and vitamin C than the nongerminated soybean. Under suitable germination conditions, it is possible to produce soybean sprouts with better physical characteristics, higher yield, and higher contents of isoflavones, aglycones, and vitamin C. Condições de germinação influenciam as características físicas, isoflavonas e vitamina C de brotos de sojaResumo -O objetivo deste trabalho foi avaliar os efeitos das condições de germinação da soja (Glycine max) 'BRS 216' sobre o comprimento, o rendimento e o teor de isoflavonas dos brotos. Um delineamento fatorial 2 3 foi utilizado para avaliar as variáveis tempo de maceração, frequência de irrigação e tempo de germinação. Os brotos que apresentaram melhor comprimento e rendimento e maior teor de isoflavonas foram avaliados quanto à composição química e ao teor de vitamina C. Os tempos de maceração e germinação da soja apresentaram efeito linear positivo e significativo sobre o comprimento dos brotos. No entanto, apenas o tempo de germinação apresentou efeito linear significativo e positivo sobre o rendimento, e efeito linear significativo e negativo sobre o teor de malonilglicosídeos, agliconas e isoflavonas totais. As condições de germinação da soja foram estabelecidas em 6 horas de maceração, três dias de germinação e 8 horas de frequência de irrigação. Nessas condições, os brotos obtidos apresentam composição química mais preservada, além de maior teor de β-glicosídeos, malonilglicosídeos, agliconas, isoflavonas totais e vitamina C do que a soja não germinada. Em condições adequadas de germinação, é possível produzir brotos de soja com melhores características físicas, maior rendimento, e maiores teores de isoflavonas, agliconas e vitamina C. M.B.R. Silva...