Impact of High-Pressure Processing on Prevention of Quality Loss and Spoilage Bacteria Diversity in Precooked Baby Clam (Paphia undulata) During Refrigerated Storage

The influence of high-pressure processing (HPP) at 200, 400, and 600 MPa on spoilage bacterial diversity, microbial load, and chemical and sensory properties of the precooked edible portion of baby clam (PC-EP) was investigated. HPP at 400 MPa for 4 min (400 MPa) significantly prolonged shelf life and sensory acceptability up to 12 days, maintaining a total viable count (TVC) below 6 log CFU/g. In contrast, the TVC of both the control (without HPP treatment) and 200 MPa-treated samples exceeded this limit by day 0 and 3, respectively. The 400 MPa-treated samples showed a reduced load of psychrophilic bacteria, <i>Aeromonas</i> species, and lactic acid bacteria over 12 days. Additionally, coincidentally lower total volatile base and trimethylamine levels confirmed the good quality of HPP-treated PC-EP. Based on next-generation sequencing, a significantly lower microbial diversity index was found in the 400 MPa-treated samples, and it was dominated by <i>Carnobacterium</i>, <i>Lactococcus</i>, and <i>Psychrobacter</i> on day 12. In contrast, the control harbored spoilage bacteria, including <i>Lactococcus</i>, <i>Aeromonas</i>, <i>Shewanella,</i> and <i>Pseudomonas</i>, which correlated with higher acetic acid and acetoin levels as confirmed by HS-SPME-GC-EI/MS. These findings demonstrated that HPP at 400 MPa for 4 min was an effective non-thermal preservation method, extending the shelf life of PC-EP by inhibiting spoilage bacteria.