No abstract

7The turmeric dye extraction residue whole did not form film. Therefore, four turmeric 8 flour fractions (F1, F2, F3, and F4) were produced from the turmeric residue by wet 9 milling and sieving. F2, which presented the lowest lignocellulosic and the highest 10 starch content, afforded the best material for film production. The main objectives of the 11 present study were (i) to evaluate the effect of heating temperature (T) and pH on the 12 mechanical and functional properties of F2 film plasticized with glycerol, and (ii) to 13 optimize the process conditions (T, pH) by response surface method and multi-response 14 analyses. Higher T (>90ºC) and alkaline pH produced a denser and mechanically 15 stronger polymer matrix and more soluble film. In contrast, less soluble films were 16 produced at intermediate T and pH. The effect of T and pH on the mechanical properties 17 and solubility of turmeric films is associated with starch gelatinization and protein 18 solubilization and denaturation. High T produced loss of the curcuminoids and 19 antioxidant activity of turmeric films. The optimal conditions were T of 85.1 ºC and pH 20 of 8.1. These conditions yielded films with high mechanical strength (9 MPa), low 21solubility (37%), and low water vapor permeability (0.296 g.mm.h -1 .m -2 .kPa -1 ).