The global consumption of soy-based food has increased in recent decades due to its nutritional value and the link between the consumption and health benefits of soy isoflavones, such as their anticancer, hepatoprotective, cardioprotective, and beneficial effects on osteoporosis and menopausal symptoms.
The aim of the current study was to determine the profile and content of isoflavones in soy-based food available on the Serbian market, represented with 94 different products, divided into six groups: I—soy (soybeans, flakes, flour); II—meat substitutes; III—dairy substitutes; IV—tofu and related products; V—soy sauces; and VI—uncategorized products such as oil and sprouts. Sample preparation included homogenization, if needed, degreasing with hexane, and extraction with 80% methanol, while analytical determination was performed using high-performance liquid chromatography with diode array detection. Apart from the aglycones daidzein, glycitein, and genistein, which were used for the construction of calibration curves, their glucosyl, acetyl, and malonyl glycosides were quantified using calibration curves of the corresponding aglycone and taking into account correction for aglycone–glucoside difference in molecular weight.
Isoflavone content varied greatly across the soy food groups due to the differences in the raw materials and production techniques. The lowest values were recorded in soy sauces and the highest ones in the group of soybeans, flours, and flakes. The mean ± SD (range) isoflavone levels, expressed as total aglycone equivalents (mg/kg), were the following: group I: 1787.1 ± 113.3 (440.4-2546.9); II: 692.7 ± 175.0 (0-2344.8); III: 136.5 ± 22.9 (29.5-605.6); IV: 327.8± 36.2 (65.4-811.6); V: 14.6 ± 3.63 (0.38-40.0); VI: 45.5 ± 26.2 (0.08-141.2).
As differences in isoflavone profiles and content substantially influence their dietary intake and impact on consumer health, detailed and accurate compositional data regarding their most important nutritional source, soy-based food, is of the utmost importance.
