Bacteria associated with processed crawfish and potential toxin production by Clostridium botulinum type E in vacuum-packaged and aerobically packaged crawfish tails

Detection of Zoonotic Bacteria and Paragonimus kellicotti in Red Swamp Crayfish (Procambarus clarkii) and the Assessment of Traditional Crayfish Boils

ABSTRACT

Studies of red swamp crayfish (Procambarus clarkii) outside of the United States confirm the presence of a variety of zoonotic pathogens, but it is unknown whether these same pathogens occur in P. clarkii in the United States. The U.S. commercial crayfish industry generates $200 million yearly, underscoring the need to evaluate this consumer commodity. The study objectives were to evaluate specific zoonotic pathogens present on P. clarkii from Alabama and Louisiana, states in the southeastern United States, and to determine the effectiveness of traditional food preparation methods to reduce pathogens. Experiment A evaluated the presence of Escherichia coli, Salmonella, Staphylococcus aureus, and Vibrio spp. in crayfish and environmental samples over a 2-month collection period (May to June 2021). Crayfish sampling consisted of swabbing the cephalothorax region; 15 samples were tested for E. coli, Salmonella, and S. aureus, and an additional 15 samples for Vibrio spp. Additionally, crayfish shipping materials were sampled. In experiment B, 92 crayfish were evaluated for Paragonimus kellicotti. Experiment C compared live and boiled crayfish for the presence of Vibrio spp. In experiments A and B, all 60 (100%) crayfish samples and 13 (81.25%) of 16 environmental samples showed growth characteristic of Vibrio spp. Three (5%) of 60 samples showed E. coli growth, with no statistical difference (P = 0.5536) between farms. P. kellicotti, Salmonella, and S. aureus were not recovered from any samples. In experiment C, all 10 (100%) of the live preboiled crayfish samples showed characteristic growth, whereas 1 (10%) of 10 samples of crayfish boiled in unseasoned water showed Vibrio growth (P < 0.0001). These results confirm that Vibrio spp. and E. coli may be present on U.S. commercial crayfish and that care should be taken when handling any materials that come into contact with live crayfish because they can potentially be contaminated.

HIGHLIGHTS

Influence of Button mushroom (Agaricus bisporus) on quality and refrigerated storage stability of patties prepared from sutchi catfish (Pangasius hypophthalmus)

The ability of button mushroom (Agaricus bisporus) in changing physical, chemical, microbial and sensory properties of fish patties prepared from sutchi catfish (Pangasius hypophthalmus) was investigated. Two batches of fresh patties were prepared, one batch was treated with 15 % button mushroom (TP) and other batch was a control (CP) without mushroom. The patties were packed in polythene bags and stored under refrigerated condition (6 ± 2 ºC) without adding any preservatives for the estimation of storage stability. The analyses of patties were conducted at regular intervals of 3 days. The results showed that, Peroxide value, Thiobarbituric acid value, Free fatty acids increased significantly in CP at the end of 12 days whereas the TP was within the acceptable limit up to 16 days. Total volatile base nitrogen and Trimethylamine nitrogen also showed a similar trend. The Total plate count and Aerobic spore formers showed an increasing trend in CP when compared to TP. The sensory scores showed that the overall acceptability of CP were lower than TP, which was acceptable even after 16 days of storage. The present study showed that, the quality and storage stability of TP were observed to be in good condition up to 16 days and started deteriorating 20th day onwards, whereas the CP were acceptable only up to 12 days. Therefore it can be recommended that, addition of 15 % of button mushroom to sutchi catfish patty not only increases the nutritional quality but also increases the shelf life of patties under refrigerated storage.

Effects of modified atmosphere packaging on toxin production by Clostridium botulinum in raw aquacultured summer flounder fillets (Paralichthys dentatus)

Packaging fishery products under vacuum atmosphere packaging (VAC) and modified atmosphere packaging (MAP) conditions can significantly extend the shelf life of raw, refrigerated fish products. There is considerable commercial interest in marketing VAC and MAP refrigerated (never frozen) raw fish fillets. The objective of this study was to determine if Clostridium botulinum toxin development precedes microbiological spoilage in raw, refrigerated flounder fillets. Aquacultured flounder (Paralichthys dentatus) individual fish fillets either were packed with a film having an oxygen transmission rate (OTR) of 3000 cm3 m(-2) 24 h(-1) at 22.8 degrees C or were vacuum packaged or packaged under 100% CO2 with a film having an OTR of 7.8 cm3 m(-2) 24 h(-1) at 21.1 degrees C and were stored at 4 and 10 degrees C. Samples were analyzed by aerobic plate count (APC) for spoilage and qualitatively for botulinum toxin with a mouse bioassay. The results demonstrate that flounder fillets (4 degrees C) packaged with a film having an OTR of 3,000 were microbiologically spoiled (APC, > 10(7) CFU/g) on day 15, but there was no toxin formation, even after 35 days of storage. However, at 10 degrees C, toxin production occurred (day 8), but it was after microbial spoilage and absolute sensory rejection (day 5). Vacuum-packaged fillets and 100% CO2 fillets (4 degrees C) packaged with a film having an OTR of 7.8 were toxic on days 20 and 25, respectively, with microbial spoilage (APC, >10(7) CFU/g) not occurring during the tested storage period (i.e., >35 days). At 10 degrees C, in vacuum-packaged flounder, toxin formation coincided with microbiological spoilage (days 8 to 9). In the 100% CO2-packaged fillets, toxin formation occurred on day 9, with microbial spoilage occurring on day 15. This study indicates that films with an OTR of 3,000 can be used for refrigerated fish fillets and still maintain the safety of the product.

Botulism: a laboratory investigation on biological and food samples from cases and outbreaks in Brazil (1982-2001)

Laboratory investigation of botulism from 1982 to 2001 confirmed the occurrence of eight positive outbreaks/cases of botulism in Brazil. From those, type A botulism was observed in seven of them. Biological material of one case (serum and feces) was positive in the first step of the bioassay, but the amount of sample was not sufficient for typification. One of the outbreaks that occurred in 2001 was negative for botulinum toxin in samples of serum, gastric washing and feces, collected eight days before the onset of the symptoms in the affected person who was clinically diagnosed as presenting the disease. Other two cases presenting compatible clinical diagnoses presented negative results. However, in those cases, the collection of samples was (1) after antiserum administration or (2) later than eight days of the onset of symptoms. Investigation was performed by mouse bioassay, as described in the Compendium of Methods for the Microbiological Examination of Foods (compiled by American Public Health Association--APHA)11, using specific antiserum from Centers for Disease Control (CDC), USA.