Biopolymer Film Based on Rice Straw Carboxymethyl Cellulose (CMCr) and Chiang Mai University (CMU) Purple Rice Carboxymethyl Flour (CMF)

Abstract

Carboxymethyl Flour (CMF) is a starchy material with high anthocyanin content, produced from Chiang Mai University (CMU) purple rice by alkalization with sodium hydroxide (NaOH, %w/v) at 10% concentration, and subsequently etherified with monochloroacetic acid. The aim of this study was to develop a biopolymer film based on carboxymethyl cellulose (CMCr) and CMF, and characterize their thermal, physicochemical, mechanical, barrier and morphological properties. In this film production experiment, CMCr was combined with CMF by using 2:1 (% w/v); and glycerol was used as a plasticizer at various concentrations, i.e. 0, 0.25, 0.5 and 1 (%w/v). The results informed that the thermal, physical, chemical, mechanical and barrier properties of plasticized biopolymer film were improved by increasing of glycerol content (without the deterioration of anthocyanin). At 1% (w/v) glycerol addition, CMCr/CMF blended film had the highest film water solubility, elongation at break and water vapor permeability (WVP) (but not tensile strength), which were 83.56%, 61.26% and 7.15´10-4 g×m/m2×day×mm×Hg, respectively. In addition, CMF can be used as a raw material for film production, as it contains high anthocyanin, which acts as an antioxidant. It is new alternative modified flour for biopolymer film production or natural additives, which has more anthocyanin than commercial starches.