Reduction in salt fermentation time of Indian mackerel (Rastrelliger kanagurta) using Halobacterium salinarum as a starter culture

Abstract

 Salt fermentation is a preservation technique in which higher salt concentrations areintroduced to inhibit the growth of most spoilage microbes. This process takes severalmonths to attain maturity. The present study was designed to accelerate the fermentationrate and shorten the maturation time employing the haloarchaeal strain Halobacteriumsalinarum (HS1). H. salinarum was inoculated in the salt fermentation medium and thefermentation time and quality were compared to the control salt fermentation withoutinoculation of HS1. The lot inoculated with HS1 matured by the 60th day with higher sensoryscores, whereas the control (C) took 120 days for maturation, indicating that the saltfermentation process can be accelerated using haloarchaea. The final moisture contentat the end of 120 days in the control and HS1 were 56.31 and 56.78% respectively. pHshowed decreasing trend initially and was found to be stable in later phases. Protein contentreduced from 24.29 to 18.95% and 15.03% in control and HS1 respectively. Fat contentfluctuated throughout the fermentation period (6.99 to 8.81%) showing an increasingpattern initially and then a reduction during later stages of fermentation. Trimethylamine(TMA, 3.12 to 14.09 mg%), total volatile base nitrogen (TVBN, 18.23 to 38.35 mg%),alpha-amino nitrogen (AAN, 31.87 to 126.43 mg%) and non-protein nitrogen (NPN,0.18 to 0.83%) contents increased throughout the salt fermentation process but werefound to be within limits suggesting controlled degradation. Present results suggest thatH. salinarum (HS1) as a starter culture can accelerate salt fermentation and maturation canbe attained by 60 days compared to 120 days of maturation time taken by control without HS1.  Keywords:Haloarchaea, Halobacterium salinarum, Indian mackerel, Maturation,  Salt fermentation