Germination kinetics and amylolytic activity of ultrasound‐pretreated purple corn during malting

BACKGROUND Purple corn ( Zea mays L.) is a pigmented cereal of Andean origin with documented nutraceutical and brewing potential. Malting performance depends critically on amylolytic enzyme activity, and power ultrasound has been proposed as a pretreatment to enhance germination and enzymatic potential in cereals. RESULTS Hydrated corn grains were sonicated (37 kHz, 32.5 W L −1 ) for 5, 10, and 15 min in an ultrasound water bath prior to germination. Germination kinetics were evaluated for 4 days using a modified Gompertz model, and α ‐ and β ‐amylase activities were monitored throughout germination and drying (50 °C, 0.2 m s −1 ). Ultrasound pretreatment tended to reduce germination percentage at exposure times ≥10 min, although no significant changes were observed in the intrinsic kinetic parameters. α ‐Amylase activity was not significantly affected, whereas β ‐amylase activity decreased by approximately 40% after 72 h germination at longer treatments. Drying kinetics, moisture–water activity relationships during drying, and enzymatic stability during drying were not influenced by ultrasound. CONCLUSION These results indicate that power ultrasound, under the tested conditions, which included a temperature rise consistent with thermosonication, does not enhance purple corn malting performance and may negatively affect β ‐amylase activity. Future studies should incorporate temperature‐matched controls, starch and reducing sugar quantification, and evaluation of additional malt‐quality endpoints to fully characterize the impact of ultrasound on pigmented maize malting.