Effect of edible coating combined with pomegranate peel extract on the quality maintenance of white shrimps (Parapenaeus longirostris) during refrigerated storage

The present study aimed at assessing the potential of edible coatings based on chitosan (Ch) and locust bean gum (LBG) incorporating pomegranate peel extract (PPE) to maintain quality of shrimps during cold storage. Firstly, the study evaluated different PPE concentrations applied to Ch and LBG against Pseudomonas putida in vitro. Then, in vivo trials were carried out on headed and peeled shrimps coated with Ch and LBG incorporating the most effective PPE level, to evaluate the effect during storage of different coatings on Pseudomonas spp., total psychrotrophic bacteria counts, total volatile basic nitrogen (TVB-N) and visual color as quality indexes. Results proved the effective synergy of PPE with Ch at reducing microbial spoilage during storage: indeed, Ch incorporating PPE was able to reduce the Pseudomonas spp. count by about 2 log units and to maintain the psychrotrophic microbial load below 7 CFU/g for 6 days. In addition, after 6 days, TVB-N levels in shrimps coated with Ch incorporating PPE were as low as the values recorded in the control samples after 2 days.