Optimizing Ultrasound Probe Extraction for Anthocyanin and Phenolic Content from Purple Waxy Corn's Dried Cobs: Impact of Extraction Temperature and Time

Abstract

The utilization of purple waxy corn's dried cobs as agricultural waste holds potential for the recovery of valuable anthocyanins and phenolic compounds, thereby adding value to the cobs and facilitating their application in the food industry. This study aimed to employ an ultrasound probe extraction technique in combination with the central composite face-centered design, which is widely used in response surface methodology (RSM). Specifically, this research aimed to determine the suitable extraction temperature and time that would result in the highest possible yield of anthocyanins and phenolic compounds from the purple waxy corn’s dried cobs The ultrasound probe extraction method was implemented with a solvent-sample weight ratio of 20:1 w/w, utilizing a solvent composition consisting of a water to ethanol weight ratio of 1:1 w/w. Furthermore, an ultrasonic amplitude of 50% was employed during the extraction process. The result indicated that the optimal extraction condition to obtain the high yield of anthocyanins and phenolics simultaneously was at the extraction temperature of 70 C for 25 min extraction time. Under the suitable extraction condition, the experimental extraction produced the dried cob extract with a high total anthocyanin content of 305.40 g cyanidin-3-glucoside equivalent (C3G)/g dried cob) and total phenolic content of 25.50 mg gallic acid equivalent (GAE)/g dried cob). For this optimal condition, an antioxidant activity of the extract of approximately 6.41 mg/mL was also found, resulting in 50% reduction in the initial DPPH concentration.