Bioactive compounds and microbiological analysis of hydroalcoholic extracts of Peruvian purple corn cob var. Canteño obtained by ultrasound

Introduction. The cob is a byproduct generated from the marketing of purple corn grains. Currently, bioactive compounds are extracted from purple corn using conventional techniques that require substantial volumes of solvents and extended extraction periods. Objective. To determine the content of phenolic compounds and perform a microbiological analysis of purple corn cob extracts obtained by ultrasound. Materials and methods. The extract was prepared with 80% ethanol (pH 2.3) at a sample-to-solvent ratio of 1:12.5 (g/mL). The extraction process was performed using an ultrasonic bath (480 W, 40 KHz, 45°C for 90 minutes). Physicochemical and microbiological analyses were conducted on the purple corn cob powder and the hydroalcoholic extract, focusing on anthocyanin and phenolic compound content, as well as antioxidant activity. Results and discussion. The results indicated that the powdered cob had a high mineral and carbohydrate content, while the extract exhibited significant levels of anthocyanins (34.52 mg cyanidin-3-glucoside/g dry sample), phenolic compounds (324.59 mg gallic acid/g dry sample), and antioxidant activity (1327 μmol Trolox/g dry sample) compared to the control sample. Notably, the hydroalcoholic extract was free from molds and yeasts, unlike the purple corn cob powder. Conclusion. The ultrasound-processed extract of purple corn cob has potential applications as a food additive to retard oxidation and microbiological spoilage in food products.