RESUMEN
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.
RESUMEN
The effects of the amylose content and the preparation sequence in physicochemical properties of starch/montmorillonite (MMT) composites were studied in this work. Native (30%) and high amylose Hylon VII (70%) starches were considered for assessing the effects of amylose content. Glycerol and MMT were used as additives to evaluate the effects of the former as plasticizer and the latter as reinforcer. The glycerol was incorporated before (Method M1) and after (Method M2) the addition of MMT. FTIR studies indicated that water bonding was affected by amylose content. Sorption isotherms indicated that method M2 favoured water adsorption and method M1 reduced water adsorption due to competition for active sites for interaction. TGA showed that method M1 induced a higher degradation rate than method M2. Wettability analysis by contact angle measurements showed that plasticizer promoted the hydrophilicity of the film, whereas MMT promoted a hydrophobic surface for both cases of amylose content.