Utilization of tofu liquid waste for the manufacture of bioplastic food packaging

Abstract

Bioplastic food packaging is manufactured from natural ingredients with no threat of polluting the environment. There have been no reports using tofu liquid waste as material for making bioplastics using sorbitol concentration treatment. Therefore, this study aimed to determine the effect of sorbitol concentration on the characteristics of bioplastic generated from tofu liquid waste. Before being processed into bioplastic, tofu liquid waste was analyzed for carbohydrates, pH, protein, biological and chemical oxygen demand, as well as total and volatile solids. Data were analyzed with one-way analysis of variance (ANOVA), while sorbitol concentrations used were 0 %, 1 %, 2 %, 4 %, and 8 % with three repetitions. The results of analysis of tofu liquid waste show that this waste can be used as material for making bioplastics. The results showed that the bioplastic produced had thickness values ranging from 0.049 to 0.365 mm, water vapor permeability rates of 0.239–4.644 g m⁻² h⁻¹, tensile strength of 146, 3 to 186.3 kgf. cm⁻², and elongation of 8.52–150.227 %. Variations in sorbitol concentrations had a significant effect on the thickness and elongation values but not on water vapor permeability rate and tensile strength. The best result was obtained with 1 % sorbitol concentration, which produced bioplastic with a thickness value of 0.110 mm, water vapor permeability rate of 0.584 g m⁻² h⁻¹, tensile strength of 146.3 kgf. cm⁻², and elongation of 97, 04 %.