Gels of collagen hydrolysate (H) crosslinked with dialdehyde starch (DAS) are marked by a strong tendency to aging, which
means a certain problem during their processing into biodegradable packaging materials. Applying casting technology and drying
these materials by heating air-dry films and foils for a limited time (1–4 h) at 105 °C may eliminate the aging problem. Solubility
of heat-treated films in an aqueous environment remains preserved, but depending on how long this temperature acts and on
the DAS content in the film, time of film disintegration prolongs from 1–1.5 h to 1300 h (≈54 days). It is probably caused
by the functional groups initially blocked by sorbed water, which get released to produce hydrogen inter-chain crosslinks.
The decrease in glass transition temperature (Tg) of such films varies with content of water sorbed in films in an interval of 90.2–189 °C.