Effect of O₂CO₂ enriched atmospheres on microbiological growth and volatile metabolite production in packaged cooked peeled gray shrimp (Crangon crangon)
2012
Noseda, Bert | Goethals, Joke | De Smedt, Lies | Dewulf, Jo | Samapundo, Simbarashe | Langenhove, Herman Van | Devlieghere, F. (Frank)
This study evaluated the effect of modified atmospheres (MAs) with different O₂ concentrations on microbial growth and volatile metabolite production in gray shrimp (Crangon crangon) during storage at 4°C. Eight MAs were evaluated in total. Four of the MAs evaluated were without CO₂: 0/0/100, 0/10/90, 0/30/70, 0/50/50 (% CO₂/O₂/N₂) whilst the other four MAs all contained 50% CO₂: 50/0/50, 50/10/40, 50/30/20, 50/50/0 (% CO₂/O₂/N₂). Volatile spoilage metabolites were identified by thermal desorption GC-MS and quantified during storage by selective ion flow tube mass spectrometry (SIFT-MS). In comparison to microbial growth observed with an atmosphere of 100% N₂, microbial growth was stimulated by the addition of O₂ in the MAP in the absence of CO₂. Under these conditions the total psychrotrophic counts exceeded 7 log cfug⁻¹ after just 3days of storage. However, in the presence of 50% CO₂ the total psychrotrophic count exceeded 7 log cfug⁻¹ after 5days of storage. The combination of 50% CO₂ and 50% O₂ significantly inhibited microbial growth. For this MA condition, a diminishing effect on the production of metabolites was also observed, especially for amines and sulfur compounds, which constituted the major fraction of components causing the offensive odor.
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