The ultrasound-treated soybean seeds improve edibility and nutritional quality of soybean sprouts

• Soybean sprouts from ultrasound-treated seeds were chemically studied for the first time.
• Ultrasound treatment improved nutritional quality of soybean sprouts.
• Ultrasound treatment improved edibility of soybean sprouts.

Limited data are available concerning the physical and nutrient properties of soybean sprouts from the ultrasound-treated seeds. In this study, soybean seeds were treated by ultrasound at different power levels (0 W to 300 W), then germinated for 5 d in darkness. Morphological changes, protein patterns, amino acid contents, gamma-aminobutyric acid (GABA) content, IgE-binding, lipoxygenase isozyme activity, trypsin inhibitor, and isoflavone content of soybean sprouts were quantified. Results showed that ultrasound treatment increased germination rate, sprout length, and GABA content of soybean sprouts. No significant change was observed in protein patterns. The IgE-binding, lipoxygenase isozyme activity, and trypsin inhibitor content of soybean sprouts showed a power-dependent decrease after the seeds were exposed to ultrasound. As for the isoflavone content, daidzin and genstin contents markedly decreased, whereas, daidzein and genistein contents increased compared with those of the untreated sample. The present work indicated that ultrasound treatment will be a novel approach to improve the edibility and nutritional quality of soybean sprouts.