Influence of controlled freezing-point temperature on the freshness and taste of pickled and dried grass carp

Pickling and drying can help aquatic products with their flavor which is highly related to temperature.Taking grass carp fillets as the research objects, quality changes were studied during pickling, drying and storage under controlled freezing-point temperature (CFT:-0.5±0.5℃) and 12 ±0.5℃.Results showed that total volatile basic nitrogen (TVB-N) value of grass carp fillets under CFT were significantly lower than that in 12℃.TVB-N value of fillets was only 29.84 mg N/100g under CFT after 75 days storage and reached 30.88mgN/100g under 12℃ only after 35 days storage.Inosine 5-monophosphate (IMP) of the fillets both increased firstly and then decreased smoothly and they all increased to the highest level on first day with the value of 169.30 mg/100g under CFT and 156.20 mg/100g under 12℃ respectively.During the storage, IMP of the fillets decreased much slower and maintained a higher level.Compared to fillets under 12℃, free amino acids and equivalent umami concentration (EUC) of fillets under CFT had significant increase (P<0.05).At the end of the storage, EUC of fillets was 1.568 MSG/100g under CFT and 0.898 MSG/100g under 12℃.Therefore, fillets under CFT had higher freshness and flavor and longer storage time.