Embalagens expandidas de amido: influência do bagaço de malte, glicerol e fosfato tricálcico nas características físicas

Abstract

Expanded starch-based packaging presents itself as an alternative to expanded polystyrene (EPS), given its renewable and biodegradable nature. However, water resistance, good flexibility, as well as tensile and flexural strength, are essential for both food and non-food packaging applications, qualities often lacking in starch foams when compared to petroleum-based derivatives. Additionally, the revaluation of agro-industrial waste becomes imperative for the food-chain sustainability. Plant-derived residues, rich in lignocellulosic compounds, offer the potential to enhance certain properties of expanded starch packaging. This study aimed to assess the influence of spent grains from brewing, glycerol, and tricalcium phosphate in the development of expanded starch trays. The anti-humectant desiccant tricalcium phosphate (0-5%), plasticizer glycerol (0-5%), and spent grains reinforcement (0-10%) were used in a multivariate design to fabricate expanded starch trays through thermal expansion. Response variables included density (g/cm3), hygroscopicity (%), moisture content (%), water absorption capacity (WAC), flexural strength (MPa), maximum deflection (mm) via three-point rupture testing, and tensile strength (MPa), elongation (%), and elasticity modulus (MPa) via tension testing. Density ranged from 0.1577 to 0.2356 g/cm3, with trays exhibiting lower density when no spent grains were added. Tensile strength ranged from 0.369 MPa to 1.454 MPa, influenced by the addition of tricalcium phosphate and spent grains. The treatment without the phosphate resulted in lower tensile strength and elasticity modulus. Elongation ranged from 0.45 to 1.45%, and the elasticity modulus ranged from 46.34 to 126.64 MPa. Flexural strength (0.996 to 1.500 MPa) and maximum deflection (2.09 to 3.35 mm) were influenced by the quantity of spent grains, glycerol, and tricalcium phosphate. WAC up to 1 minute was mainly affected by the phosphate and the spend grains. Interactions among spent grains, glycerol, and tricalcium phosphate require further investigation, as the phosphate positively impacted mechanical properties but did not affect the hygroscopicity (%) as expected. Cassava starch-based expanded trays reinforced with lignocellulosic residues could serve as a viable alternative to petroleum- based packaging, particularly EPS.