Effect of fish skin gelatin on characteristics and staling properties of bread made from pre-baked frozen dough

Using hydrocolloids as an additive in different foods is becoming increasingly common, especially in wheat-based products, to improve their quality. This paper investigated the effect of fish skin gelatin on the quality of the bread made from pre-baked frozen dough and its staling properties during storage. The results showed that the addition of fish skin gelatin (0.0%, 0.5%, 1.0% and 1.5% on flour) significantly reduced the hardness and the baking loss of bread and increased the specific volume of bread (P < 0.05). When 0.5% fish skin gelatin was added, the hardness of bread was reduced by 28.07%, and the specific volume increased from 2.99 cm3/g to 3.44 cm3/g. During the 7 days of storage, compared to the control group, bread and starch samples containing 0.5% gelatin had the lowest enthalpy of retrogradation at 1.90 J/g and 1.74 J/g, followed by 1.0% and 1.5% gelatin samples, indicating that gelatin can restrain the diffusion of water, and further limit water migration and vaporization. The relative crystallinity of bread and starch decreased by 17.50% and 38.45%, respectively, which demonstrated the mitigating effect of starch crystallization. The decline in absorbance ratio of FT-IR at R1047/1022 and R1022/995 also confirmed that the addition of gelatin could delay starch retrogradation. These results indicated that fish skin gelatins have potential applications in delaying starch retrogradation and extending the bread shelf-life.