Changes in Microstructure, Germination, Sprout Growth, Phytochemical and Microbial Quality of Ultrasonication Treated Adzuki Bean Seeds

Sprout is a nutritious ready-to-eat vegetable. In this study, we examined the effects of ultrasonication treatments (treated with 28, 40 or 80 kHz frequency for 10 min at 25 degrees C) on the changes in microstructure, seed hydration and germination, sprout growth, sprout quality, and microbial load of two adzuki bean (Vigna angularis) varieties (Kaohsiung 8 and Kaohsiung 10). The results indicated that the ultrasonication at 40 kHz or 80 kHz improved seed hydration and enhanced germination; this is linked to the ultrasound-induced microstructure changes in the hilum and seed coat surface of treated seeds. The ultrasonication-increased sprout growth and yield were possibly attributable to the increased alpha-amylase activity during germination. Ultrasonication also improved total polyphenols, total flavonoids, and total saponins contents and further enhanced the anti-oxidative activities (FRAP and DPPH) of produce sprouts. The results further indicated that the 40 kHz or 80 kHz treatment decreased microbial loads of treated sprouts to an acceptable level; therefore, these two treatments can be used for germination improvement and an effective microbial control treatment for adzuki bean sprout production.

Automated summary

In this study, the effects of ultrasonication treatments on adzuki bean sprouts were examined. The results showed that ultrasonication improved seed hydration, germination, sprout growth and yield, as well as enhanced the nutritional content and antioxidant activity of the sprouts. The treatments at 40 kHz or 80 kHz also effectively reduced microbial loads, making them suitable for adzuki bean sprout production.