Physico-Chemical Properties of Gelatin Films Incorporated with Different Hydrocolloids

Effect of different hydrocolloids (chitosan, rice flour, soy protein isolate and curdlan) at different ratios (gelatin/hydrocolloid = 10/0, 8/2, 6/4, and 5/5 (w/w)) on some properties of fish gelatin film was investigated. Incorporation of chitosan at the ratio of 8/2 yielded the blend film with higher tensile strength (TS) and elongation at break (EAB), compared to the control gelatin film (p<0.05). However, incorporation of chitosan at other ratios as well as addition of other hydrocolloids at all ratios studied resulted in decreased TS of the resulting blend film as the amount of hydrocolloids increased (p<0.05). Among blend films tested, incorporation of chitosan rendered the blend films with better mechanical properties, compared to those added with other hydrocolloids of the same ratio. Moreover, all gelatin-based blend films added with all types of hydrocolloids of all ratios exhibited lower water vapor permeability (WVP) than did the control gelatin film without hydrocolloid addition (p<0.05). Nevertheless, blend films added with all types and ratios of hydrocolloids studied were more yellowish (higher b*-value) and less transparent than the control gelatin film, especially for those incorporated with soy protein isolate. Therefore, incorporation of appropriate type and amount of hydrocolloid (i.e. chitosan at 8/2 in this study) could improve water vapor barrier and mechanical properties of gelatin-based film.