Potential use of gelatin hydrolysate as plasticizer in fish myofibrillar protein film

The effect of fish gelatin hydrolysates having different degree of hydrolysis (DH: 23, 61 and 95%) as plasticizer at various levels (30–60%) in fish myofibrillar protein (FMP) film was investigated, in comparison with glycerol. Regardless of DH, FMP films incorporated with gelatin hydrolysates at 50 and 60% of FMP generally had higher elastic modulus (E) and tensile strength (TS) but lower water vapour permeability (WVP), compared with those added with glycerol at the same level (p < 0.05). At the same DH, both E and TS of film decreased, while elongation at break (EAB) and WVP increased with increasing levels of gelatin hydrolysate (p < 0.05). When gelatin hydrolysate at the same level (30, 40, 50 or 60%) was used, the decreases in TS and E but the increases in WVP were found as DH increased. Nevertheless, FMP film added with gelatin hydrolysate exhibited the higher b* value, compared to film containing glycerol (p < 0.05). Thus, gelatin hydrolysate could be potentially used as a plasticizer in FMP film and its plasticizing effect was governed by DH and levels used.