Enhancing post-harvest quality of Red Globe grapes using fermented cheese whey edible coatings

Red Globe grapes (Vitis vinifera) are widely consumed for their taste and bioactive compounds but are highly perishable during post-harvest handling. This study evaluated the effectiveness of an edible coating formulated from cheese whey fermented by Saccharomyces cerevisiae in maintaining grape quality during storage. Five treatments were applied: Control (no coating), non-fermented coating (NF), and fermented coatings containing 105 CFU/mL (F1), 107 CFU/mL (F2), and 109 CFU/mL (F3) yeast. Grapes were stored at 25°C for 8 d, and antimicrobial activity, Total Plate Count (TPC), pH, weight loss, hardness, color change, and qualitative changes were assessed. The fermented coating with 107 CFU/mL (F2) outperformed all the treatments. It produced bacterial inhibition zones of 4.98 mm and mold inhibition of 2.85 mm, while maintaining TPC at 20.2 × 108 CFU/g, pH 3.46 ± 0.01, reduced weight loss by 3.38 ± 0.30%, showing a day-8 hardness of 671.18 ± 320.50 g and minimized total color change (ΔE 3.63) after 8 d. Fermentation by S. cerevisiae enhanced the coating’s antimicrobial and barrier properties, helping delay spoilage. These findings indicate that integrating fermentation into edible-coating technology can improve fruit preservation and extend shelf life without compromising quality.