Inhibition of melanosis and microbial growth in Pacific white shrimp (Litopenaeus vannamei) using high CO₂ modified...

Preserving quality of crustaceans requires efficient modified atmosphere packaging (MAP). Effects of CO₂ (20%-80%) on quality and melanosis in chilled Pacific white shrimp (Litopenaeus vannamei) under O₂ concentrations of 5 and 15% were investigated. Increased headspace CO₂ and lipid oxidation contributed to loss of firmness due to protein degradation. Image analysis indicated increased degree of melanosis at higher O₂ concentration. High CO₂ above 60% and 5% O₂ MAP effectively prevented melanosis (below 10% for 12 days) and formation of trimethylamine (TMA) concurrent with limited total viable count (TVC), Enterobacteriaceae and reduced conversion of pro-polyphenoloxidase into polyphenoloxidase accelerated shell browning. Linear correlation was found between TVC-melanosis and TVC-firmness for all MAP mixtures, while CO₂ gave higher efficacy to inhibit melanosis at low O₂ MAP. Increased CO₂ linearly prevented melanosis and TMA formation, whereas decreased O₂ concentration gave higher efficacy of CO₂ indicated synergistic effects on melanosis and TMA inhibition.