Effect of organic acid on survival of Staphyococcus aureus and enterotoxin production in fish during drying

Abstract

This study was aimed to investigate the effect of organic acid against S.aureus and enterotoxin production in fish during drying. Shark procured from the local fish market was deskinned, cut into small pieces and then decontaminated with 5ppm chlorine. Shark meat pieces were inoculated with three different levels of S.aureus: a low level of 3 log cfu per gram, a medium level of 5 log cfu per gram and a high level of 7log cfu per gram. The meat was then washed with four different concentrations of propionic acids separately and dried in an electric drier for 24hr. Moisture and water activity of fresh meat was 75.9 per cent and 0.98, which decreased to 10.6 per cent and 0.63 during drying. In 3log cfu per gram inoculated samples there was about 1.52, 2.63, 2.73 and 3.31 log reduction in S.aureus for 1, 3, 5 and 7 per cent treated samples at the end of drying. Enterotoxin was not detected in any of the samples including the control samples after drying. In 5 log cfu per cent inoculated samples, there was remarkable reduction in the S. aureus count for 5 per cent and 7 per cent treated samples compared with other treated samples. Enterotoxin was not detected in 5 and 7 per cent treated samples. In 7 log cfu per gram inoculated samples there was about 0.67, 1.89, 4.16 and 4.43 log reduction in S. aureus count for 1, 3, 5 and 7 per cent treated samples at the end of drying. Enterotoxin was detected in all the treated samples except in 7per cent propionic acid. Therefore 7 per cent was found effective for samples contaminated with 7 log cfu per gram. It was concluded that propionic acid was highly effective in decontaminating meat surfaces and are shown to be safe, simple, efficient, and cheap which can be highly recommended for commercial applications for decontaminating of fish during drying.