Quality and Safety Evaluation of Striped Catfish Processing Byproducts in Vietnam

Introduction: The Vietnam striped catfish industry has rapidly developed and, in recent years, has processed over one million tonnes per year in recent years. Approximately 30% of the total production is in fillet form and the remainder (70%) is byproducts, including head, bones, fin, skin, fat, and organs. Byproducts are normally processed within 24 hours so that the evaluation of lipid oxidation and bacterial contamination during storage is necessary to control the deterioration and environmental impacts.

Purpose: This study evaluated the quality of byproducts during preservation.

Methods: Byproducts from five different catfish processing factories in Mekong Delta were randomly sampled to investigate the quality evolution through lipid oxidation and microbiological count (n=20). Belly fat and byproducts analyzed to determine the fluctuation of fat and microbiological count after the fillet process and after 24 hours of preservation. Crude fat, free fatty acid and acid value of belly fat were determined and bacteria consisted of coliforms, Escherichia coli, Salmonella spp., Staphylococcus aureus, Clostridia spp. Total yeasts and molds were counted. Data were statically analyzed by using SPSS version 18 with statistical significance (P<0.05)

Results: The results indicated that after 24 hours of preservation, the fat quality tended to reduce. This, in turn, resulted in increases in the free fatty acids from 1.42±0.10 to 1.79±0.03% and acid value from 2.83±0.20 to 3.56±0.07 mg KOH/100 g. Coliform bacteria counted from 1,100 to 290,000 (MPN/g), Clostridia spp. from 0 to 1,100 CFU/g, total counts of yeasts and molds presented from 0 to 500,000 CFU/g, while S. aureus numbered from 0 to 10 CFU/g and E.coli from 0 to 7.4 MPN/g. Salmonella bacteria were not found.

Significance: The storage time and conditions of byproducts should be carefully controlled to avoid reducing lipid quality and microbiological contamination.