Nutritional Quality and Overall Acceptability Optimization of Ultra-Fast Air-Superchilled Golden Rainbow Trout (Oncorhynchus mykiss, Stevanovski) Using the Response Surface Methodology

Abstract

Temperatures below the cryoscopic point help to partially freeze most of the water in the fish muscle tissue. This reduces water activity and makes the remaining free water hardly accessible to microorganisms. The objective of this study was to determine the best process regime of ultra-fast air-superchilling, giving us the optimal quality of golden rainbow trout. Two hundred and thirty-four live golden rainbow trout (Oncorchynchus mykiss, Stevanovski) (18 groups of 13 fish in a group) were caught and immediately stunned by an electric current (P = 42 W). The stunned fish was placed in styrofoam cans and covered with flaked ice. The sensory analysis, total nitrogen volatile bases (TVB-N), total number of microorganisms (TVC), and presence of biogenic amines were determined. According to the optimized values for TVB-N, TVC, and sensory scores, giving us a better quality of ultra-fast air-superchilled golden rainbow, the process regime has been found at the following parameters: air temperature T = −11.3 °C; airflow velocity υ = 6.5 m s−1; and packaging layer thickness D = 79.2 μ. The superchilled golden rainbow trout processed by this regime has the lowest degree of proteolytic degradation, delayed development of the microflora, and retains the best possible sensory properties and freshness.