Application of lignin nanoparticles in polybutylene succinate based antifungal packaging for extending the shelf life of bread

The shift of using biodegradable materials for food packaging is becoming a global trend, as environmental consciousness constantly being raised. Enhancing the antimicrobial performance of biodegradable packaging has greatly received much attention for minimizing environmental impacts by reducing food and plastic wastes. This work explored the potential of utilizing an abundant industrial waste lignin as antimicrobial packaging. The effects of lignin nanoparticles (LNPs) incorporated into polybutylene succinate (PBS) composite film, against Aspergillus niger and Penicillium spp., the major microorganisms causing fungal spoilage in bread were investigated. At a low concentration of 0.5 % (w/v), LNPs showed fungal growth inhibition (FGI) in vitro of 51.89 % and 55.94 % against A. niger and Penicillium spp. When incorporated into PBS composite containing 5 % cinnamaldehyde (CIN), 1 % (w/w) LNPs showed stronger antifungal activities against Penicillium spp. than A. niger. Barrier properties and water contact angle were also enhanced with the presence of 1 % (w/w) LNPs in the PBS, but there were no effects on tensile strength, glass transition temperature, and melting temperature (Tm). Bread packed in PBS containing 1 % LNPs + 5 % CIN showed lowest yeast and mold count (YMC) of < 1.0 log CFU g–1, which was the same as the initial count, whereas YMC in other bread samples increased to > 2.0 log CFU g–1 after storage for 14 days at 25 ± 2 °C. Results suggest that LNPs in biodegradable materials such as PBS could help extend the shelf life of bread and possibly be applied to other food products that are susceptible to fungal spoilage.