This study was conducted to evaluate the biopreservative potential of Lactobacillus plantarum Lp6SH (Lp6SH), Lactobacillus rhamnosus Yoba (LrYoba) and their cell‐free supernatants (CFS) on whole captured tropical pink shrimps (Penaeus duorarum notialis) during storage at 4°C for 8 days. Shrimps were inoculated with strains Lp6SH, LrYoba, their supernatants, sodium metabisulfite (2%) and stored at 4 ° C for 8 days. Sensory evaluation, physicochemical, and microbiological analyses were performed daily. Lp6SH, CFS of Lp6SH, and CFS of LrYoba were able to prolong the sensory shelf life up to 8 days. The total volatile basic nitrogen (TVBN) concentration was lower than the acceptable value at the end of the storage period. All the treatments reduced the number of total aerobic bacteria and fungi, and maintained the coliforms count for 2 days. Strain Lp6SH reduced the number of Staphylococci for 4 days. Based on the threshold values, the microbiological shelf life of shrimps was between 2 and 6 days at 4°C. L. plantarum Lp6SH and the CFS of L. rhamnosus Yoba could be used as natural preservatives to replace the use of sodium bisulfate in prolonging the microbiological and sensory shelf life of captured whole shrimps. Practical applications Microbial spoilage of raw fresh shrimps and black spots formation constitute substantial economic losses as well as serious public health problem. Due to the harmful effects of chemical preservatives, attention is paid nowadays to the search for fresh shrimp preservation methods that could obviate the use of chemicals and prevent blackspot formation. In this respect, the results of this study supported that Lactobacillus plantarum Lp6SH strain and the cell‐free supernatant of Lactobacillus rhamnosus Yoba are suitable biopreservatives that could be used to increase the safety, prevent melanosis, and extend the sensory shelf life of captured whole shrimps stored under refrigeration. After studies for their application at large scale, the fishermen and food industries can use the bacterial suspension and the cell‐free supernatant as spray or immersion solutions for the treatment of shrimps (or other seafood) prior to freezing.
Objective: Post-harvest shrimp losses are a big problem due to the proliferation of spoilage bacteria. Presence and multiplication of these bacteria promotes the emergence of food-borne diseases. This study was carried out to characterize some spoilage bacteria from tropical brackish water shrimps and black tiger shrimps stored in ambient temperature (25 °C). Results: 22 isolates of Bacillus spp; 09 isolates of Coagulase Negative Staphylococci (CNS) and 04 isolates of enterobacteria such as Pantoea spp (01); Serratia plymutica (01) and Serratia rubidaea (02) have been identified. Resistance and virulence genes were then detected. All isolates expressed resistance to at least three of antibiotics tested. 03 isolates of enterobacteria were susceptible to cetfazidim and amoxicillin-clavulanic acid. Bacillus spp showed total susceptibility to cefixim, ertapenem and cetfazidim. Staphylococci were susceptible to clindamycin. Pantoea spp was resistant to all antibiotics but exhibited intermediate susceptibility to amoxicillin-clavulanic acid. 04 isolates of Staphylococci were positive to mecA resistances genes. All the enterobacteria harbor no tetracycline resistance genes. All the isolates of Bacillus exhibited the presence of enterotoxin genes. Also, a high prevalence of 21 isolates to hemolytic enterotoxins was noted. 17 isolates from them kept ability to cell-lyse factor production like sphingomyelinase activities. The majority of Bacillus isolates identified by the present study poses a potential risk of food poisoning due to the prevalence of toxin genes found.
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