Effect of Whey Protein Edible Coating Incorporated with Mango Peel Extract on Postharvest Quality, Bioactive Compounds and Shelf Life of Broccoli

Abstract

The present study evaluated the impact of edible coatings based on whey protein concentrate (WPC) and mango peel extract (MPE) on the shelf life, physicochemical, and microbial properties of minimally processed broccoli preserved at 5 ± 1 °C for 28 days. The variations in the physicochemical and microbial properties of the broccoli fresh-cuts were evaluated by determining the following parameter changes: weight loss, color, respiration rate, ascorbic acid content (AsA), sulforaphane content (SF), total phenolic content (TPC), antioxidant activity (AOA), total bacteria, fungi counts, and sensory evaluation. Broccoli fresh-cuts were treated with WPC alone or in combination with MPE (WPC/MPE) at 1% or 3%, and uncoated broccoli fresh-cuts were a control. The obtained results revealed that all the coated broccoli fresh-cuts showed lower weight loss than the uncoated broccoli fresh-cuts. The coating with WPC/MPE at 3% recorded the lowest weight loss among all treatments; however, it wasn’t significantly lower compared to WPC/MPE at 1%. The addition of MPE to WPC in coating solution at 1% and 3% resulted in a higher value of the (-a*), indicating better green color retention and decreased floret yellowing. All applied coatings significantly conserved the bioactive compounds (AsA, SF, and TPC) and AOA of broccoli fresh-cuts compared to uncoated ones. At the end of the storage period, the maximum values of the aforementioned bioactive compounds were recorded in the broccoli fresh-cuts coated with WPC/MPE at 3% followed by WPC/MPE at 1%, and WPC alone compared to uncoated broccoli fresh-cuts. The broccoli fresh-cuts coated with WPC/MPE at 3% recorded a higher score on sensory evaluation than those coated with WPC/MPE at 1%, followed by broccoli fresh-cuts coated with WPC alone. The WPC-based edible coating combined with MPE (WPC/MPE) at 3% showed the highest reduction in the total fungi and bacterial counts compared to all the other treatments.