Predictive models for evaluation of mesophilic and psychrophilic bacterial loads in muscles of fresh ice-stored silver pomfret by impediometric technique

Abstract

Current microbial methodologies to determine fish quality are laborious and have long time required to obtain results. The impediometric technique as a rapid sensitive method was used to determine the correlation between impedance detection times (IDTs) and conventional reference psychrophilic and mesophilic plate counts of fish in order to develop models for predicting the microbial quality and determining fish shelf-life. The changes in sensorial factores, psychrophilic and mesophilic bacterial loads of ice stored fresh silver pomfret (Pampus argenteus) were measured by two different methods including conventional reference plating techniques and also impediometric monitoring method at 0, 3, 6, 9, 12, 15, 18, 21, 24 and 27 days of storage. The primary psychrophilic (3.44 ± 0.69 logCFU/g) and mesophilic (3.64 ± 1.08 logCFU/g) bacterial loads increased to more than acceptable limit (6 logCFU/g) on days 12 and 21, respectively. The calibration curves for the two methods and their equations were designed with linear regression models. IDTs were highly correlated with psychrophilic (r=-0.9614) and mesophilic (r=-0.9547) bacterial loads. This study suggests that impediometric technique can be used as a rapid and reliable method to accurate estimation of silver pomfret bacterial loads and determine its shelf-life as seafood. According to results, the sensorial data were correlated with psychrophic bacterial load. The shelf-life of ice stored silver pomfret determined 9-12 days based on sensorial data and psychrophic bacterial load.