Electron beam (EB)‐irradiation is increasingly being preferred to radioactive‐based gamma irradiation in overcoming the constraints that affect the quality of food material. Soybean seeds of 3 soybean genotypes were exposed to 4 doses viz. 4.8, 9.2, 15.3 and 21.2 kGy of EB‐irradiation and assessed for the changes in the contents of lipoxygenase isozymes and tocopherol isomers. Densitometry of protein profile revealed decreasing intensity of lipoxygenase with increasing EB dose. All the 3 lipoxygenase isozymes viz. lipoxygenase‐1, ‐2 and ‐3 registered significant (P < 0.05) increasing reduction with increasing dose; though genotypic variation was noted for the magnitude of reduction at the same dose. Concomitantly, all the 3 genotypes exhibited significant (P < 0.05) decline in α‐, γ‐ and δ‐isomers of tocopherol. δ‐Tocopherol was the most sensitive to EB‐irradiation. EB dose, which caused minimum and maximum decline in total tocopherol content, was genotype‐dependent. Decline in vitamin E activity corresponding to the dose, which induced maximum reduction for total lipoxygenase also varied in 3 genotypes. The study showed the usefulness of EB for significant inactivation of off‐flavor generating lipoxygenases in soybean, with a non‐significant effect on oil content and varied retention of tocopherol isomers and vitamin E activity depending upon genotype.
Purpose
– In the backdrop of declining per capita availability of pulses, soybean is the alternate source to address protein deficiency in India. The study aims to assess the efficiency of soy products available in the market for meeting the daily requirement of essential amino acids (EAAs).
Design/methodology/approach
– Extruded soy products, namely, soy nuggets, granules, soy flour manufactured from sprouts, spray-dried soy milk variants, ready-to-drink (RTD) soy beverage and silken tofu, were analysed for EAAs by high-performance liquid chromatography. In addition, efficiency of these products in terms of meeting the daily requirement of EAAs for an adult weighing 70 kg through a single serving (equivalent to 6 g protein) was also computed.
Findings
– Leucine was the most concentrated EAA in all the soy products, except in variants of soy milk. Total essential amino acids’ (TEAAs) content in soy flour was significantly higher compared to soy nuggets and granules. Spray-dried plain soymilk exhibited a significantly higher level of TEAAs content compared to flavoured variant and RTD soy beverage. Among all the products, silken tofu exhibited the highest concentration of TEAAs. RTD soy beverage was the most efficient product for meeting the daily requirement of isoleucine and valine, soy flour for aromatic amino acids and silken tofu for lysine and leucine.
Originality/value
– This work pertains to the determination of EAAs of commercial soy products and assesses their efficiency in terms of meeting the daily requirement of EAAs. This type of technical evaluation of soy products has not been conducted earlier.
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