Biodegradable starch composite from stale bread: effect of electron beam irradiation Available to Purchase

Bread has a short shelf-life, which leads to staling and disposal. This study aims to incorporate starch from stale bread into a bio-composite with sodium alginate, gellan gum and glycerol. The response surface methodology was used to optimize the concentrations of sodium alginate (0–4%), gellan gum (0–1%) and glycerol (0–1%) as fillers in starch bio-composites based on the resulting tensile strength, hardness and water absorption ability. The responses were the water absorption ability, hardness and tensile strength of the bio-composite. Well-fitting models were generated for water absorption ability (R ² = 0.8938), hardness (R ² = 0.8607) and tensile strength (R ² = 0.9742) with a probability value of less than 0.001, which demonstrates the high significance of the models. The optimum parameters were 3.83% sodium alginate, 0.62% gellan gum and 0.69% glycerol. Meanwhile, the water absorption ability, hardness and tensile strength were 0.44%, 49.55 mJ and 41.00 N/m², respectively. The effects of electron beam irradiation on the contact angle of the bio-composite were also studied. Electron beam irradiation increased the contact angle up to 77.56° and reduced fractures in the microstructure of the bio-composites compared with those in the non-irradiated sample. These are important properties of the bio-composite to be used in utensils.