Effects of a Nanoparticle-Loaded PVA/SPI Pad on Microbial Proliferation and Quality Characteristics of Superchilled Pork

Fresh pork remains susceptible to psychrotrophic spoilage during superchilled storage. Although oregano essential oil (OEO), nisin, and active absorbent pads have each been studied, their effects on spoilage-community proliferation and concurrent quality loss remain poorly resolved. Here, we coupled longitudinal 16S rRNA gene profiling with conventional microbiological and quality measurements to evaluate a poly(vinyl alcohol)/soy protein isolate pad containing OEO-loaded soluble soybean polysaccharide-nisin nanoparticles (PS-NPs). Pork was stored at −1 °C for 24 days without a pad (CK), with a nanoparticle-free pad (PS), or with PS-NPs. Bacterial communities in CK and PS-NPs were profiled alongside total viable count, TVB-N, TBARS, protein carbonyls, color, water-holding capacity, and sensory quality. Compared with CK, PS-NPs slowed the increase in viable counts and delayed physicochemical and sensory deterioration. On day 24, Pseudomonas relative abundance was 39.48% with PS-NPs and 51.02% in CK. TBARS and protein carbonyl contents were 36.96% and 19.44% lower than CK, respectively, while cooking loss was 28.49% versus 32.18%. Among the evaluated taxon-quality pairs, Pseudomonas psychrophila showed the strongest positive association with protein carbonyl content. Unlike earlier performance-focused studies, this work links packaging-associated community shifts with concurrent chemical, physical, and sensory changes under superchilling. The findings support PS-NPs as a preservation strategy.