Shelf life determination of the brined golden mullet Liza aurata during vacuum refrigerated storage using some quality aspect.

ABSTRACT

BACKGROUND: Salted fi sh products are popular in many countries around the world. Salting is one of the oldest techniques for fi sh preservation, and is essentially intended to increase the shelf-life of the product depressing water activity by means of dehydration and salt uptake by the fi sh muscle. However, the current demand for salted fi sh is driven more by the flavour of the product than for preservation purposes. Vacuum-packaging represents a static form of hypobaric storage. It is widely used in the food industry because of its effectiveness in reducing oxidative reactions in the product at relatively low cost. Low temperature storage is one of the primary methods to maintain fi sh quality, based on the reduction in the rates of microbiological, chemical and biochemical changes. MATERIAL AND METHODS: Fresh Golden mullets were rapidly beheaded, scaled, gutted and immediately washed with tap water then, samples were taken to the laboratory in ice box for chemical and microbial analysis of fresh fish, other samples were put in the brine (6 liter water and 2160 g salt was used for brine solution). After 14 days of brining, fish were taken out of brine solution and drained, then they were Vacuum Packed and labelled (each pack contained two fish about 1500 g weight). All the packs were stored in a refrigerator 4°C. Some quality aspects including Total Volatile Nitrogen (TVN), Peroxide Value (PV), Thiobarbituric Acid (TBA), Total Viable Count (TVC), Halophilic Bacteria (HB) and presence of Clostridium Botulinum were determined in fresh mullets, fresh brined mullets after 14 days of brining, and in (Vacuum Packed) VP samples stored at 4°C at intervals of 30, 60 and 90 days. RESULTS: TVN increased from ten mg/100 g in fresh brined after 14 days to 30.80 mg/100 g in VP brined Golden mullet after 90 days of storage at 4°C, PV increased after brining from 1.50 meq/kg in fresh brined to 28.90 meq/kg in VP brined Golden mullet after 90 days of storage at 4°C, TBA increased from 0.07 mg MDA/kg in fresh brined to 0.10 after 60 days and then, decreased to 0.09 mg MDA/kg in VP brined Golden mullet after 90 days of storage and TVC decreased from 4.70 log CFU/gr in fresh brined to 4.40 log CFU/ gr after 30 days and then, increased to 5.70 log CFU/gr in VP brined Golden mullet after 90 days of storage at 4°C, HB increased from 4.55 log CFU/gr in fresh brined to 6.30 log CFU/gr after 90 days of storage period at 4°C and exceeded the permissible level. Clostridium botulinum toxin was not detected in any of the samples throughout the storage. CONCLUSIONS: The results from this study clearly suggested that a combination of brining, vacuum packaging and storage at refrigerated temperature prolongs the shelf-life of Golden mullet to a great extent. Our findings revealed that the longest shelf-life was for VP brined Golden mullet stored at 4°C is 30 days.