Facile preparation of solid gelatin foams by a water-lean batch foaming process

Existing polystyrenic and polyolefinic packaging foams are non-biodegradable, and persist in the environment for hundreds of years. Gelatin foams are an interesting alternative, given their biodegradability, biocompatibility, solution-based processability, low cost, and non-toxicity. However, current methods for preparing gelatin foams, such as freeze-drying, microfluidic foaming, and batch foaming, are not suitable for high-volume production. In this context, we report the preparation of solid gelatin foams by a water-lean batch foaming process that involves simply mixing bloomed gelatin with a blowing agent, selected from inorganic bicarbonates and cyclic organic carbonates, and heating the resulting mixture in an open mold. The foaming was primarily attributed to CO₂ produced by blowing agents, while the transformation from discrete gelatin granules to a continuous foam was facilitated by the melting, flowing, and fusion of the bloomed gelatin granules into a homogeneous mass upon heating. This process is simple, inexpensive, sustainable, and versatile, making it highly suitable for high-volume production of biodegradable foams, particularly for use in loose-fill packaging applications.