Application of whey protein-based edible coatings containing lemon peel powder and extract to maintain the antioxidant properties of table grapes during ambient storage

Table grapes are among the most widely consumed fruits worldwide; however, their shelf life is limited by water loss, microbial spoilage, and degradation of antioxidants. This study examined the effects of whey protein-based edible coatings enriched with 1 % lemon peel powder (LP1), 2 % lemon peel powder (LP2), 1 % lemon peel extract (LE1), or 2 % lemon peel extract (LE2) on the quality of Red Globe table grapes during 14-day ambient storage. The highest weight loss (33.2 %) occurred in uncoated samples, while LP1 had the lowest (20.4 %), indicating improved moisture retention. The initial pH of uncoated table grapes (3.63) increased to 4.23 by the end of storage. All coatings slowed this increase, resulting in final pH values ranging from 4.03 to 4.10. Regarding antioxidant-related parameters, LP1 showed higher total polyphenol content (TPC), ascorbic acid content, antioxidant activity (DPPH assay), and total monomeric anthocyanin (TMA) by 43.7 %, 25.0 %, 24.1 %, and 10.1 %, respectively, compared to uncoated samples. Among extract-enriched coatings, only LE1 maintained significantly higher antioxidant activity (75.8 %), while TPC and ascorbic acid levels were comparable to those of the uncoated samples. TMA content in LE-treated table grapes (23.6–22.5 mg CGE/100 g) was lower than in uncoated samples (26.7 mg CGE/100 g). Multivariate analyses (PCA, HCA) revealed distinct clustering between coated and uncoated samples, with LP1 showing the most pronounced separation. These results indicate that LP1 treatment may help reduce weight loss and support antioxidant stability, offering a potentially sustainable postharvest strategy for table grapes. • Application of whey protein-based edible coatings: lemon peel powder improved grape preservation, extract had no effect. • Coating reduced grape weight loss during storage. • 1 % lemon peel powder significantly enhances antioxidant properties in coated grapes. • Edible coatings with citrus by-products support circular agricultural strategies.