Development of a whey protein concentrate/apple pomace extract edible coating for shelf life extension of fresh-cut apple

Abstract

The present work aimed to develop a novel edible coating using whey protein concentrate (WPC) and apple pomace extract (APE) to extend the shelf life of fresh-cut apple. Apple slices were coated with a mixture of WPC and APE at concentrations of 0.5, 1.0, and 1.5%, and were stored at 5°C for 12 d. The total phenolic content and DPPH radical scavenging activity of APE were determined. The weight loss, colour, browning index, microbiological analysis, and sensory evaluation of coated and uncoated apple slices were estimated. A total phenolic content of ethanolic APE was 6.77 ± 0.339 mg gallic acid equivalent/g dry apple pomace. Apple pomace extract contained a total of 15 phenolic compounds. Also, a significant antioxidant activity was observed for APE using the DPPH method, and the inhibitory concentration (IC50) was 51.97 ± 1.576 µg gallic acid equivalent/mL extract compared with BHT (21.80 ± 0.424 μg/mL). Coating apple slices with WPC/APE decreased the weight loss as compared to the uncoated and apple slices coated with WPC only. The coated apple slices with WPC/1.5% APE had the highest lightness as compared to other coated and uncoated apple slices after 12 d of storage. In addition, the coated apple slices with WPC/1.0 and 1.5% APE exhibited the lowest browning index as compared to the uncoated apple slices. Using WPC and APE as coating agents showed antimicrobial activity, and it had little effect on the sensory evaluation of apple slices.