Article

Content composition and antioxidant activity of isoflavones in commercial and homemade soymilk and tofu

School of Kinesiology and Nutritional Science, California State University, Los Angeles, CA 90032, USA
Journal of the Science of Food and Agriculture (Impact Factor: 1.88). 12/2007; 87(15):2844 - 2852. DOI: 10.1002/jsfa.3041

ABSTRACT BACKGROUND: Isoflavones, found in soymilk and tofu, are one of the phytochemicals in soy-based products that may promote good health. Homemade tofu and various homemade soymilk samples were made using different soaking, grinding, and cooking methods. The homemade samples were compared to commercial tofu and soymilk for total isoflavone content and composition as well as their antioxidant capacity. All samples were freeze-dried and extracted with a 58% acetonitrile solution which was subsequently used to determine the isoflavone content by reverse-phase high-performance liquid chromatography. The antioxidant activity of extracts was determined using a modified 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) method and total antioxidant capacity was reported as ascorbic acid equivalents.RESULTS: The total isoflavone, aglycone, and antioxidant levels were significantly higher in homemade soymilk and tofu (1571 µg) than in commercial samples. Homemade soymilk made by the extended boiling method yielded the highest total isoflavone (2567 µg) and glucoside (1525 µg) content. A strong positive correlation was observed between the total isoflavone, aglycone conjugates, and genistein series concentration and antioxidant capacity of soymilk.CONCLUSION: Increased moist heating time yielded the highest concentration of total isoflavones as well as aglycone conjugates and the genistein series. Increasing the duration of boiling can increase the isoflavone content of both homemade and commercial soymilk and tofu. Copyright © 2007 Society of Chemical Industry

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    • "Wang and Murphy (1996) reported an increase in the isoflavone recovery by pressing the okara. Regarding the profile, the soymilk contains a lower percentage of aglycones and 6″-O-acetyl-genistin than the okara, but due to the low solubility of aglycones in the aqueous media, the soymilk contains a higher concentration of glucosides and malonyl conjugates (Ishihara et al. 2007; Jackson et al. 2002). "
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    ABSTRACT: Soy has been traditionally incorporated in diet as processed foods, such as soymilk, tofu, miso, tempeh, etc., and the consumption is commonly associated with a reduction of the development of chronic diseases due to their antioxidant, anti-inflammatory, and anti-allergic properties, among others. Many of the health benefits of soy have been attributed to isoflavones. They comprise a group of naturally occurring flavonoids consisting of heterocyclic phenols. Soy contains three types of isoflavones in four chemical forms: the aglycones daidzein, genistein, and glycitein; the β-glucosides daidzin, genistin, and glycitin; their 6″-O-malonyl-β-glucosides (6OMalGlc); and their 6″-O-acetyl-β-glucosides (6OAcGlc) conjugates. Industrial processing methods of soy-based food products commonly lead to the loss of isoflavones through removal of undesirable fractions. On the other hand, isoflavones can be transformed into different conjugates, which may have significant effects on the food texture and on the bioavailability and pharmacokinetics of the isoflavones. This article reviews the effect of a number of soybean processing treatments on the isoflavone content and profile. The preparation and manufacturing of different soy-based food and food ingredients, fermented and non-fermented, has been analyzed in terms of content and distribution of the three major isoflavone derivatives, daidzein, genistein, and glycitein, and their respective conjugates. KeywordsAglycone–Glucoside–Isoflavone–Daidzein–Genistein–Glycitein–Soy processing
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    ABSTRACT: The aim was to study the relationship between the isoflavone content in different soybean cultivars and in the soymilk. Seven cultivars of soybean seeds from two locations with different levels of isoflavones were processed to soymilk. The content of total and individual isoflavones was determined by high performance liquid chromatography. The total phenolic content, oil and protein content in soybean cultivars were also determined. Significant differences in the content of individual isoflavones were observed within the soybean cultivars. The strong positive correlations were observed between total isoflavone content in soybean seeds and in soymilk. The total phenolic content in soybean cultivars ranged from 83 to 143.4 mg GAE/100g of soybean. The total isoflavone content in soybean seeds ranged from 71.2 to 133.8 mg/100g of soybean which comprise from 76.7 to 98.8% of the total phenols. In soymilks, total isoflavone content ranged from 16.1 to 61.0 mg/kg of soymilk. The most abundant isoflavone in soybean seeds was genistein while in soymilk it was genistin. There was statistically significant difference (p < 0.05) among two locations in total and individual isoflavone contents.
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    ABSTRACT: Cited By (since 1996):1, Export Date: 18 October 2014
    01/2008: pages 359-366;
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