Effect of reduced oxygen atmosphere and sodium acetate treatment on the microbial quality changes of seer fish ( Scomberomorus commerson) steaks stored in ice

Abstract

The effect of reduced oxygen atmosphere and sodium acetate treatment on the microbial quality of seer fish ( Scomberomorus commerson) steaks was determined during chilled storage (1–2 °C). The O 2 absorber reduced the oxygen content in the pack to less than 0.01% corresponding to 99.96% reduction within 24 h. The use of O 2 absorber with sodium acetate dip treatment (2% w/v) extended the sensory shelf life up to 25 days compared to only 12 days for control air packs and 20 days for untreated samples with O 2 absorber. A prominent lag phase was observed for many bacterium studied, particularly for the sodium acetate treated samples with O 2 absorber. On the day of sensory rejection, both the total mesophilic and psychrotrophic counts reached 7.7–8.1 and 7.1–7.9 log cfu/g, respectively. The sodium acetate treatment and reduced O 2 atmosphere affected the type of major spoilers. In air packed samples, H 2S-producers predominated followed by Brochothrix thermosphacta, Pseudomonas spp., where as in the untreated samples with O 2 absorber, H 2S-producers predominated the microbial flora followed by Lactobacillus spp. For treated samples with O 2 absorber, B. thermosphacta formed the major micro-flora followed by Lactobacillus spp. The use of O 2 absorber inhibited the growth of Pseudomonas spp., and total Enterobacteriaceae.