Evaluation of the turmeric dye extraction residue in the formation of protective coating on fresh bananas (Musa acuminata cv. 'Maçã').

We evaluate the flour obtained from the residue of turmeric dye extraction, designated turmeric flour, as a protective coating to extend banana (Musa acuminata) shelf life. The coating formulation consists of 6 g of turmeric flour/100 g of solution and 30 g of glycerol/100 g of turmeric flour, produced by immersion. We also investigate how the coating affects banana weight loss, firmness, pH, titratable acidity, soluble solids and reducing sugars contents, and peel color along 15 days of storage at 27 ± 2 °C and 65% RH. Coatings based on turmeric flour display good antioxidant activity, which is attributed to the presence of curcuminoids, mainly curcumin. These coatings delay weight loss, color development, and firmness reduction, and they afford lower acidity and sugars content in coated bananas as compared to control bananas. Compared to uncoated samples, turmeric flour-based coatings extend the original characteristics of bananas stored at 27 °C by 3 days.