Effects of ozone water dipping and super-chilling on improving preservation quality of pomfret fillet

Abstract: The aim of this study was to evaluate the impact of normal cold store, super-chilling and super-chilling combined with ozone water on the quality of pomfret fillets, to prolong the shelf-life. Based on the freezing curve, the freezing point of the pomfret was ?1.2℃. Therefore the temperature of the storage of super-chilling was set at ?0.6℃ and the temperature fluctuation of refrigerator was less than ±0.5℃ measured by thermocouple multi-point temperature collection instrument. The concentration of ozone water was measured 1.8mg/L by iodimetry. The sensory evaluation, the aerobic plate count(APC), total volatile basis nitrogen(TVB-N), thiobarbituric acid(TBA), trimethylamine(TMA), pH value and the value of K were determined. The results showed that the shelf-life of the pomfret fillets was 6 days under the normal cold store and the score of the sensory evaluation of the pomfret fillets was rather lower than that under the other treatments, from the 2nd day (P<0.05). The rate of change of APC, TVB-N, TBA, and values of K of the samples under normal cold store were significantly higher than those under the other treatments. The TVB-N, TBA, and TMA of the samples treated with super-chilling and super-chilling combined with ozone water significantly increased after the 14th day, and the shelf-life was increased to 10 days and 11 days, respectively. Compared with the storage of super-chilling the initiative aerobic plate counts could be reduced by dealing with super-chilling combined with ozone water, therefore the shelf-life of the pomfret fillets could be prolonged, while the TVB-N, TBA, TMA and pH value had no difference from those by only super-chilling (P>0.05). Super-chilling could restrain the change of APC and the enzyme activity and had a remarkable effect on prolonging the shelf-life of pomfret fillets. During the storage , super-chilling combined with ozone water had no significantly effect on micoorganism and the enzyme activity, even reducing the rate of lipid oxidation. Compared with TMA and TBA, the value of K could better reflect the freshness of pomfret fillet at the beginning of storage. Super-chilling combined with ozone water has an auxiliary function on the pre-processing with low operation cost. The results will offer theory reference to the storage of pomfrets.