Quantification of Bioactive Metabolites Derived from Cell-Free Supernatant of Pediococcus acidilactici and Screening their Protective Properties in Frankfurters.

The specific aims of the current study were to determine and quantify the bioactive compounds derived from the cell-free supernatant (CFS) of Pediococcus acidilactici and screen their protective effect in frankfurters by applying an edible coating. This was achieved by immersing the peeled frankfurters in the CFS (CFS: 50% and 100%) alone or in combination with chitosan (CH: 0.5% and 1%) solutions for 3 min. Untreated frankfurter samples (control) exceeded the maximum acceptable total viable count limit (7.0 log10) on the 14th day, whereas samples treated with 100% CFS + 1% chitosan reached the limit on day 28 during refrigerated storage (P < 0.05). This treatment provided a 14-day extension to the shelf life of frankfurters without causing any significant changes in color and sensory attributes (P > 0.05). Additionally, this treatment inhibited oxidation in the frankfurters, leading to no significant changes in TBA and TVB-N within this group during storage (P > 0.05). This protective effect was mainly attributed to the wide variety of bioactive compounds identified in the CFS, including a total of 5 organic acids, 20 free amino acids, 11 free fatty acids, 77 volatiles, and 10 polyphenols. Due to these bioactive compounds, CFS exhibited a strong radical scavenging capacity (DPPH: 435.08 TEAC/L, ABTS: 75.01 ± 0.14 mg TEAC/L; FRAP: 1.30 ± 0.03 mM FE/L) and antimicrobial activity against microorganisms primarily responsible for the spoilage of frankfurters. In conclusion, the results indicate that the CFS contains high levels of bioactive metabolites, and an edible chitosan coating impregnated with CFS can be utilized to extend the shelf life of frankfurters through its antimicrobial effects and oxidation stabilization.

Evaluation of homemade fermented pickle juice as a marinade: Effects on the microstructure, microbiological, physicochemical, textural properties, and sensory attributes of beef strip loin steaks.

The current study aimed to characterize homemade fermented pickle juice and evaluate its efficacy as a marinade on physicochemical, microbiological, textural properties, microstructure, and sensory attributes of the strip loins. Organic acids, phenolics, flavonoids, volatiles, total phenolic content (TPC), and in-vitro antioxidant capacity (ABTS and FRAP) analyses were carried out. Furthermore, minimum inhibitory concentration (MIC), and the diameter of inhibition zones of the pickle juice were determined against Escherichia coli O157:H7, Salmonella Typhimurium, S. enteritidis, and Listeria monocytogenes. The strip loins were marinated with five different concentrations (10%, 25%, 50%, 75%, and 100%) of pickle juice at 4 °C for 24 h. A total of 4 organic acids, 23 phenolic and flavonoid compounds, and 69 volatiles were identified in the pickle juice. The TPC, ABTS, and FRAP values of the pickle juice were found to be 184.24 ± 33.28 GAE/L, 44.48 ± 0.41 mg TEAC/L, and 2.79 ± 0.01 mM FE/L, respectively. The MIC and inhibition zones were recorded between 7.81 and 12.50% and 8.25-13.80 mm against pathogenic bacteria, respectively. The textural properties of the strip loins marinated with 100% pickle were improved compared to the control (P < 0.05). Moreover, this concentration decreased the number of pathogens in strip loins, ranging between 1.07 and 2.77 log10 CFU/g (P < 0.05). Regarding sensory attributes, the strip loins marinated with 50% and 100% pickle juice had higher scores compared to the non-marinated samples. The results of this study indicated that pickle juice can be evaluated as a marinade to improve the microbiological quality and textural properties of strip loins.

Inhibitory effect of bioactive compounds derived from freeze-dried paraprobiotic of Pediococcus acidilactici against food-borne pathogens: In-vitro and food model studies.

It was aimed to assess the antimicrobial potential of lyophilized/freeze-dried paraprobiotic (LP) of P. acidilactici against some food-borne pathogens under in-vitro conditions and food model, and determination of bioactive compounds that contribute to the antimicrobial activity of LP. For this purpose, minimum inhibitory concentration (MIC), inhibition zones were determined against Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7. The MIC value was 6.25 mg/mL and a 20 µL LP displayed 8.78 to 10.0 mm inhibition zones against these pathogens. In the food matrice challenge, two concentrations of LP (3% and 6%) alone or in combination with EDTA (0.02 M) were added to pathogenic bacteria spiked meatballs, and antimicrobial activity of LP was also determined during refrigerated storage. 6% LP + 0.02 M EDTA treatment provided 1.32 to 3.11 log10 CFU/g reductions in the numbers of these pathogens (P < 0.05). Furthermore, this treatment provided significant reductions on psychrotrophs, TVC, LAB, mold-yeast, and Pseudomonas spp. over the storage (P < 0.05). Regarding characterization results, LP contained contained a wide variety of bioactive compounds, including 5 organic acids (2.15 to 30.64 g/100 g), 19 free amino acids (6.97 to 699.15 mg/100 g), free fatty acids (short-, medium-, and long-chain fatty acids), 15 polyphenols (0.03 to 383.78 mg/100 g), and some volatile compounds such as pyrazines, pyranone and pyrrole derivatives. These bioactive compounds are not only involved in antimicrobial activity but also contribute to the free radical scavenging activity according to the DPPH, ABTS and FRAP assays. In conclusion, the result revealed that the LP improved the chemical and microbiological quality of foods due to containing biologically-active metabolites involved in antimicrobial and antioxidant capacity.

Characterization of lactic acid bacteria postbiotics, evaluation in-vitro antibacterial effect, microbial and chemical quality on chicken drumsticks.

The aims of this study were to characterize postbiotics, and to evaluate their antibacterial effects in-vitro and on chicken drumsticks. Postbiotics [Pediococcus. acidilactici (PA), Latilactobacillus sakei/Staphylococcus xylosus (LS)] exhibited strong antioxidant activity, and their total phenolic contents were found as 2952.78 ± 0.4 and 1819.44 ± 0.39 mg GAE/L, respectively (P < 0.05). A total of 19 different phenolic and flavonoids were determined in the postbiotics. The results of the study revealed that 5% and 10% postbiotics + EDTA decreased the number of L. monocytogenes nearly 5.0 log10 in 6 h in TSB. S. Typhimurium count in the chicken drumstick decontaminated with 10% PA was found as 2.1 log10 lower than the control group on day 0. L. monocytogenes counts in the chicken drumstick decontaminated with 10% Postbiotics+1% LA groups were found to be 1.1 log10 lower than the control group (P < 0.05). The lowest total mesophilic aerobic bacteria counts in the chicken drumsticks were found in the 10% Postbiotics+1% LA samples, and postbiotics did not change the color properties of the drumstick samples on day 0 (P > 0.05). In conclusion, postbiotics and their combinations with natural preservatives may be an alternative approach to reduce the food-borne pathogens and to extend the shelf-life of poultry meat and meat products.

Impact of chitosan embedded with postbiotics from Pediococcus acidilactici against emerging foodborne pathogens in vacuum-packaged frankfurters during refrigerated storage.

The objective of the study was to carry out characterization of postbiotics from Pediococcus acidilactici and to assess their efficacy (50% and 100%) in combination with chitosan (0.5 and 1%) against Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes on frankfurters during refrigerated storage for 35 days. High amounts of total phenolic content (1708.15 ± 93.28 mg GAE/L) and carboxylic acids, which comprised 74.89% of the total volatiles, were found in the postbiotics. On day 0, the postbiotic-chitosan combinations decreased the E. coli O157:H7, L. monocytogenes and S. Typhimurium counts ranging from 1.58 to 3.21 log10 compared to the control in frankfurters (P < 0.05). Total viable count and number of lactic acid bacteria were effectively reduced in all treatment groups (P < 0.05), and postbiotic and chitosan treatments did not cause any changes in pH and color of the frankfurters. In conclusion, postbiotic-chitosan combinations can be used to reduce the risks that might be associated with E. coli O157:H7, L. monocytogenes, and S. Typhimurium in frankfurters.

Characterization of Pediococcus acidilactici postbiotic and impact of postbiotic-fortified chitosan coating on the microbial and chemical quality of chicken breast fillets.

This study was carried out to characterize antioxidant activity, total phenolic content, and the phenolic and flavonoids profile of postbiotic of Pediococcus acidilactici and to evaluate the effects of postbiotics (10% and 50%) alone and in combination with chitosan coating (1%) on the microbial and chemical quality of chicken breast fillets during storage at 4 °C. Antioxidant activity and total phenolic content of the postbiotics were found to be 1291.02 ± 1.5 mg/L TEAC and 2336.11 ± 2.36 mg/L GAE, respectively. The most abundant phenolic was vanillic acid, followed by t-caffeic, gallic, and caftaric acids. The postbiotic-chitosan (50% + 1%) combination decreased L. monocytogenes and S. Typhimurium counts by 1.5 and 2.1 log10 CFU/g, respectively, compared to the control (P < 0.05). This combination decreased the total viable count (TVC), lactic acid bacteria (LAB), and psychrotrophic bacteria count compared to the control (P < 0.05). No differences were found in thiobarbituric acid (TBA) values among the samples during storage (P > 0.05). Postbiotic treatment did not significantly change the pH values and color properties of the breast fillets (P > 0.05). Postbiotic-chitosan combinations extended the shelf-life by up to 12 days compared to the control. In conclusion, the postbiotic-chitosan combination can be used to preserve and improve the microbial quality of chicken meat products.