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

Abstract

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 °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 α-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.

Enzyme and Antioxidant Activities of Malted Bambara Groundnut as Affected by Steeping and Sprouting Times

“…There was an increase in the activities of the αand β-amylases as sprouting time increased. However, a decrease was observed after 96 h for the β-amylase activities and, thereafter, an increase at 144 h. The increase in the αand β-amylase activities in BGN malted seeds agreed with the results of enzyme activities of germinated mung bean (Phaseolus aureus), cowpea (Vigna catjang), lentil (Lens culinaris), chickpea (Cicer arietinum), and adzuki bean (Vigna angularis) increasing with an increase in sprouting time [24,38,167]. The increase in amylase activity resulted from the seeds absorbing water while steeping, subsequently mobilising their dormant reserve [166,168].…”

Adzuki bean (Vigna angularis): Chemical compositions, physicochemical properties, health benefits, and food applications

“…Ultrasonication and pressurization have been employed to modify the water absorption ability of adzuki beans (Chiu, 2021; Ueno et al., 2015). The effective diffusion coefficient of the pressurized adzuki bean seeds at 200 MPa for 10 min showed similarity to that of certain cereals, like brown rice, barley, and wheat (Ueno et al., 2015).…”

“…The effective diffusion coefficient of the pressurized adzuki bean seeds at 200 MPa for 10 min showed similarity to that of certain cereals, like brown rice, barley, and wheat (Ueno et al., 2015). The structural deformation of the hilum and surface of the seed coat caused by sonication at 20−80 kHz for 10 min accelerated the water absorption of seeds (Chiu, 2021). The adzuki bean seeds with higher water absorption ability tended to accumulate more polyphenols during germination (Chiu, 2021).…”

“…Germination is an effective and economical method to increase the nutritional value of edible seeds and acquire fresh vegetables (Gan, Lui, et al., 2017). Adzuki bean sprouts are sources of minerals (e.g., magnesium and calcium), phenolic compounds, and saponins (Chiu, 2021; Świeca, Gawlik‐Dziki et al., 2019). Besides, the germination process can increase phytase activity in the adzuki bean seed, accompanied by a decrease in phytate content (Luo et al., 2012).…”

“…Regarding whole seeds, they are traditionally cooked with rice in these countries (Wang et al., 2019). Adzuki beans can also be consumed in the form of sprouts (or microgreens) (Chiu, 2021; Świeca et al., 2020). Recently, food self‐sufficiency has gained increasing attention due to the fragility of the food supply chain highlighted by the pandemic of COVID‐19 (Babbitt et al., 2021).…”