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

Antimicrobial and antioxidant features of "Gabsi" pomegranate peel extracts

The work aimed at optimizing the extraction protocol of "Gabsi" pomegranate peel (PP) and evaluating the total phenol content and profile, antioxidant activity and antimicrobial effect of the extracts obtained. Water and methanol as solvents were compared at different peel/solvent ratios; three different temperatures were also compared for the water extraction. Methanol pomegranate peel extract (MPPE) and water extracts (WPPE) were analysed for their DPPH antioxidant activity and polyphenol profile and content by HPLC/DAD and HPLC/MS. Different concentrations of MPPE and WPPE (ranging from 0.061 to 0.304 and from 0.072 to 0.361 g dry extract/mL, respectively) were also tested in vitro against Penicillium digitatum, Pseudomonas putida and Saccharomyces cerevisiae to determine the minimum inhibitory concentration (MIC). The MPPE and WPPE had comparable antioxidant activity (4081.43 and 3497.02 mmol Trolox/g, respectively). Hydrolysable tannins represented the main polyphenols in pomegranate peel, with punicalagin as the major compound. In general, MPPE dilutions tested in well-diffusion assays were more effective against targeted microorganisms compared with WPPE; indeed, only the highest WPPE concentration, was able to inhibit the growth of targeted microrganisms. Viability tests in liquid medium confirmed the highest antimicrobial capacity of MPPE, although even the WPPE was able to reduce P. putida and S. cerevisiae populations by up to 3.15 and 2.52 log CFU/mL, respectively

Edible coatings incorporating pomegranate peel extract and biocontrol yeast to reduce Penicillium digitatum postharvest decay of oranges

This study investigated the potential use of two edible coatings, chitosan (CH) and locust bean gum (LBG), which incorporated chemically characterized water pomegranate peel extract (WPPE) or methanol pomegranate peel extract (MPPE) and the biocontrol agent (BCA) Wickerhamomyces anomalus, to control the growth of Penicillium digitatum and to reduce the postharvest decay of oranges. CH and LBG including pomegranate peel extracts (PPEs) at different concentrations were tested in vitro against P. digitatum to determine their antifungal efficacy; at the same time, the tolerance of viable cells of W. anomalus to increasing concentrations of WPPE and MPPE extracts was assessed. The potential application of selected bioactive coatings was evaluated in vivo on oranges, which had been artificially inoculated with P. digitatum, causal agent of green mold decay. CH incorporating MPPE or WPPE at all concentrations was able to inhibit in vitro P. digitatum, while LBG was active only at the highest MPPE or WPPE concentrations. W. anomalus BS91 was slightly inhibited only by MPPE-modified coatings, while no inhibition was observed by WPPE, which was therefore selected for the in vivo trials on oranges artificially inoculated with P. digitatum. The experimental results proved that the addition of 0.361 g dry WPPE/mL, both to CH and LBG coatings, significantly reduced disease incidence (DI) by 49 and 28% respectively, with respect to the relative controls. Besides the combination CH or LBG + WPPE, the addition of W. anomalus cells to coatings strengthened the antifungal effect with respect to the relative controls, as demonstrated by the significant reduction of DI (up to 95 and 75% respectively). The findings of the study contribute to the valorization of a value-added industrial byproduct and provide a significant advancement in the development of new food protectant formulations, which benefit from the synergistic effect between biocontrol agents and natural bioactive compounds