Toward shrimp without chemical additives: A combined freezing-MAP approach.

The combined effects of freezing and modified atmosphere packaging (MAP) containing two different gas mixtures (100% N2 or 50% N2e50% CO2) on the chemical properties and melanosis of deep-water rose shrimp (Parapenaeus longirostris) was investigated and compared to both a traditional sulfiting treatment and vacuum packaging (VP). Changes in pH, total volatile basic nitrogen (TVB-N) levels, thiobarbituric acid (TBA) levels and melanosis were measured over a one-year storage period. Treatment with sodium sulfite solution before storage raised the pH and TVB-N levels rapidly, whereas both the MAP and VP samples exhibited minor increases in pH and TVB-N levels during the first six months of storage. Additionally, shrimp packed in MAP conditions, especially those packaged in 100% N2, showed completely inhibited lipid oxidation (TBA levels remained very close to those of the sulfited samples) during the storage period. The melanosis scores revealed that the samples packed in 100% N2 maintained natural color for up to six months of storage. These data suggest that the use of modified atmosphere packaging in combination with freezing during shrimp processing could be a safe and effective alternative to artificial additives.