Trends and challenges of starch-based foams for use as food packaging and food container

Expanded polystyrene (EPS), an inexpensive and widely available polymer, has been extensively employed in foam packaging. However, EPS-based foams cause environmental problems because they are non-biodegradable and little recycled. Therefore, developing foams from renewable sources for application in biodegradable packaging for food and express food delivery is essential to tackle pollution issues of synthetic plastics. Starch is a renewable, abundant, and low-cost source with thermoplastic properties. For this reason, starch has been used as raw material to develop foams for packaging. This review emphasizes different strategies for improving the mechanical properties, processibility, and antimicrobial activity of starch-based foams and for decreasing their sensitivity to humidity, aiming at employing them as competitive replacement for EPS in packaging. Starch source, foaming process conditions, plasticizer concentration, fiber type and concentration, and addition of other polymers to form blends can affect the properties and morphology of biodegradable foams, so these factors should be better studied and optimized. Agroindustrial residues have become an interesting alternative to reduce the cost of foams, aiming at a competitive replacement for EPS. Few works have been developed on bioactive starch-based foams. Searching for starch-based foams with antiviral properties against SARS-Cov-2 is also necessary. •Modified starch and starch blends are alternatives to improve starch-based foam properties.•Biofoam properties depend on starch type, foaming process conditions, and additive concentration.•Addition of agroindustrial residues can improve the water resistance and mechanical properties of starch-based foams.•Use of agroindustrial residues is a cheap alternative to lower the cost of bio-based foams.•Foam with antibacterial/antiviral properties should be developed to be applied as food packaging.