Reductions of Escherichia coli, Staphylococcus aureus, and Bacillus cereus on Seasoned Dried File Fish Using UV and COP as Light Sterilization

Introduction: Seafood is known as the best natural food including various beneficial nutrients to promote and maintain the health of human body. Processed seafood products are mainly distributed at traditional markets with inadequate hygiene.  Also, most processed seafood products can be manufactured without thermal processing.  Based on above reasons, the hygiene for processed seafood products is the main concern in the food industry and distribution. Staphylococcus aureus and Bacillus cereus are the main potential pathogenic contaminants in seasoned dried seafood products including file fish. Ultraviolet (UV) light irradiation and cold oxygen plasma (COP) light can be used for application of surface sterilization on during the manufacturing process of seafood dried products

Purpose: The objective of the current study was to examine the UV light and COP in reducing Escherichia coli, a hygiene indicator and S. aureus and B. cereus.

Methods: E. coli ATCC 10536, S. aureus ATCC 6538 or B. cereus F4810/72 were inoculated with approximately 8-9 log CFU/sample on the surface of seasoned dried file fish. The prepared samples were exposed to 396, 660, 1,320, 2,640 and 3,960 mW∙s/cm² of COP irradiation that TiO₂ content was 100% or exposed to UV irradiation at 180, 300, 600, 1,200 and 1,800 mW∙s/cm². All treated samples were rinsed with 90 ml of 0.1% peptone and inoculated selective media.

Results: In case of UV at 1,800mW∙s/cm², the maximum reduction values of total bacteria and E. coli, S. aureus and B. cereus are 1.01, 1.65, 2.42, 2.63 log CFU/g, respectively. In case of COP at 2,640 mW∙s/cm², the maximum reduction value of total bacteria and E. coli, S. aureus and B. cereus are 1.38, 2.41, 2.54, 2.93 log CFU/g, respectively. The reduction effect of total bacteria is smaller than food poisoning bacteria. The result indicated that UV and COP treatment have an effect to reduce food poisoning bacteria on seasoned dried file fish. Especially, COP has effect to reduce food poisoning bacteria than UV on seasoned dried file fish.

Significance: According to this study, COP treatment is more suitable for reducing food poisoning bacteria on seafood processing industry.