Chitosan-gelatin coating enriched with grape seed and licorice extracts for extending the shelf life of peeled white shrimp

In this study, the efficacy of chitosan-gelatin composite edible coating enriched with grape seed extract (GSE) or licorice root extract (LRE), each tested at three concentrations (0.25, 0.50, and 1.00% w/v), on the shelf life of peeled Pacific white shrimp was evaluated during storage at 4°C. Microbial, chemical, physical, and enzymatic parameters were monitored at defined intervals. Results demonstrated that both extracts, in a dose-dependent manner, significantly (P<0.05) inhibited microbial growth (final TVC in 1.00% treatments: 6.61–6.76 log CFU/g vs. 7.41 log CFU/g in control on day 9), lipid oxidation (TBARS values at day 12: 0.70–0.74 vs. 1.21 mg MDA/kg), and volatile base production (TVB-N at day 15: 24.0–24.9 vs. 31.8 mg N/100 g on day 12 in control). Peroxide value followed a similar trend, with 1.00% GSE and LRE treatments showing significantly lower values (3.82–4.05 meq O₂/kg) compared to the control (8.47 meq O₂/kg) at day 12. Specific spoilage organisms including H₂S-producing bacteria, Enterobacteriaceae, and yeasts/molds were also significantly suppressed in extract-enriched coatings. Treatments with 1.00% GSE and LRE achieved 44% and 41% PPO inhibition respectively (0.55–0.58 vs. 0.98 U/mg protein at day 9), prevented melanosis development (scores: 5.4–5.7 vs. 8.2 on day 12), and maintained color stability (ΔE: 8.9–9.2 vs. 12.2). The shelf life extended from 9 days (control) to 17–18 days, representing an 89–100% increase. Although GSE (1.00%) exhibited slight superiority in PPO inhibition, both extracts at this concentration demonstrated comparable performance.