Rheological and structural properties of Hemiramphus far skin gelatin: Potential use as an active fish coating agent

The present study aims to characterize black-barred (Hemiramphus far) skin gelatin (BG) gel enriched or not with its hydrolysate (BGH) in terms of their rheological and micro-structural properties, as well as to evaluate their effect on smooth hound fillet quality during chilled storage. The results of the rheological properties showed that peptides addition influenced elastic and loss modulus as observed from temperature sweep. Based on the microstructure, BG gel had a fine network with small voids that were filled by the presence of BGH peptides. On the other hand, when used as coating agents for smooth hound fillets, BG and BG-BGH showed that, in comparison to control group, fish spoilage was significantly delayed in coated samples. In fact, after 8 days of storage, samples coated with BG and BG+BGH showed the lowest weight loss levels, and preserved their initial water activity (a(w)) values. In addition, fillet coating was able to significantly reduce TVB-N content and oxidation process, as reflected by the low malondialdehyde and carbonyl contents. Furthermore, compared to the control group, all the treatments were found to reduce the degree of microbial deterioration of the fillets, leading to low the free amino acids and nucleotides contents in wrapped fish samples. Therefore, gelatin coating helps to prevent fish fillets from deterioration and oxidation processes.