The extension of the shelf-life of sardine which were packaged in a vacuum stored under refrigeration, and treated by δ-irradiation

Abstract

Sardines (Sardina pichardus) were vacuum packaged in polyethylene bags, and irradiated at 1, 2 and 3 kGy doses in a Co-60 delta-irradiator. The unirradiated and irradiated samples were stored at 2 +/- 1 degreesC. Microbiological analyses were done for total aerobic mesophiles, micrococci and staphylococci, coagulase positive staphylococci, Enterobacteriaceae, coliform. bacteria, Escherichia coli, and psychrophilic bacteria. Trimethylamine-nitrogen (TMA-N), thiobarbituric acid (TBA) and pH values were determined. Sensory attributes were also evaluated. In the unirradiated samples, TMA-N and pH values showed good correlations with sensory scores. There were no differences in TBA values between the irradiated samples. Based on microbiological criteria, the shelf-life increased two to threefold compared with the control samples. These experiments demonstrate that irradiation extends the storage life of pre-packaged sardines and that, for practical purposes, the different treatments make very little difference to the extension of shelf-life of acceptable product.