Dried seafood products are one of the most popular seafood items in Thailand. This study was divided into two experiments. In first experiment, a survey in intrinsic and bacteriological characteristics of twenty dried seafood products distributed in Chon Buri province, Thailand was performed. Values of water activity, pH and NaCl content were 0.35 ± 0.01-0.72 ± 0.00, 5.47 ± 0.03-9.24 ± 0.01, and 0.66 ± 0.06-2.26 ± 0.03%, respectively. Based on the Thai regulatory standard, half of dried seafood products contained total viable count over acceptable level. Predominant isolated bacteria in dried seafood products were Staphylococcus spp. (39.7%), Bacillus spp. (30.1%), and Pantoea sp. (19.2%). Foodborne pathogens, i.e., B. cereus and Salmonella enterica serovar Weltevreden were found in dried seafood products. In second experiment, two forms of antimicrobials (concentrated (CBV) and partially purified (PBV) substances) prepared from B. velezensis BUU004 and two commercial preservatives (nisin and lactic acid) were introduced into crushed dried seasoned squids to investigate inhibitory activity against pathogens, B. cereus TISTR 687, S. aureus ATCC 25923, Salmonella Typhimurium TISTR 292, and Escherichia coli ATCC 25922. PBV had broader antagonistic activity than CBV, nisin and lactic acid against tested pathogens. Scanning electron microscopy analysis represented bacteriostatic action of PBV on tested pathogens through cell lysis evidenced by an irregular cell shape along with pore formation on cell membranes. Our study demonstrates that PBV has a preservative potential to control pathogen growth and improve biosafety of dried seafood products.

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Controlling the growth of food-borne pathogens in foodstuffs is important to enhance food safety and promote higher food safety standards. A number of naturally occurring compounds (e.g., bacteriocins and plant-derived compounds) have been widely reported to be safe and effective antimicrobial agents against spoilage and food-borne pathogenic bacteria. The aim of the present work was to evaluate the antibacterial potential of a semi-purified preparation (SPP) containing bacteriocin from Bacillus velezensis BUU004, a mixture of lemongrass (Cymbopogon citratus (DC) Stapf.), chili spur pepper (Capsicum frutescens L.) extracts, and their combination to control the growth of Escherichia coli and Salmonella Typhimurium in dried, crushed, and seasoned squid during 28 d of storage. The mixed herb extracts (160 mg/mL) showed stronger inhibitory activity against E. coli and S. Typhimurium than the SPP (800 AU/mL) from B. velezensis BUU004. Interestingly, the combination of SPP from B. velezensis BUU004 and the mixed herb extracts substantially decreased the numbers of both pathogens in dried seasoned squid during storage as compared to that observed with the individual additives. The bactericidal activity of the SPP from B. velezensis BUU004 in combination with the mixed herb extracts against the food-borne pathogens involved cell lysis as ruptured cell walls were observed by a scanning electron microscopy. Therefore, the SPP from B. velezensis BUU004 combined with the mixed herb extracts offers tremendous advantages as a novel, safe, natural, and effective way to improve the biosafety of dried seafood products.

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