Gelatin, a versatile protein derived from collagen, is widely used in the food, pharmaceutical and medical sectors. However, bacterial contamination by spore-forming bacteria during gelatin ...processing represents a significant concern for product safety and quality. In this study, an investigation was carried out to explore the heat and chemical resistance, as well as the identification and characterization of spore-forming bacteria isolated from gelatin processing. The methodologies involved chemical resistance tests with drastic pH in microplates and thermal resistance tests in capillary tubes of various isolates obtained at different processing stages. In addition, phenotypic and genotypic analyses were carried out to characterize the most resistant isolates of spore-forming bacteria. The findings of this study revealed the presence of several species, including Bacillus cereus, Bacillus licheniformis, Bacillus sonorensis, Bacillus subtilis, Geobacillus stearothermophilus, and Clostridium sporogenes, with some isolates exhibiting remarkable chemical and heat resistances. In addition, a significant proportion of the most resistant isolates showed gelatinase activity (n = 19/21; 90.5 %) and the presence of heat resistance (n = 5/21; 23.8 %), and virulence genes (n = 11/21; 52.4 %). The results of this study suggest that interventions should be done in quality control practices and that process parameter adjustments and effective contamination reduction strategies should be implemented through gelatin processing.
•Spore-forming bacteria from gelatin processing showed remarkable resistance to thermal and chemical treatments.•90.5 % of the strains selected as most resistant can degrade gelatin.•Detection of genes linked to heat resistance and virulence.•Raises critical safety concerns for gelatin-based products
•The microbiological quality of packaged ice was evaluated.•The presence of E. coli and diarrheagenic E. coli pathotypes in ice was assessed.•The occurrence of nontuberculous mycobacteria (NTM) in ...ice samples was determined.•Thirty-eight (44.7%) ice samples were outside of Mexico's official guidelines.•NTM species associated with illness were identified in some ice samples.
This study aimed to determine the bacteriological quality and presence of diarrheagenic Escherichia coli pathotypes (DEP) and nontuberculous mycobacteria (NTM) species in 85 packaged ice samples from 12 different states of central Mexico. Three samples had a pH of 9.8 and therefore fell outside of the acceptable range for pH. All samples were positive for aerobic-mesophilic bacteria, with limits ranging from 1 to 3.47 log CFU/mL. In total, 35, 11, and 3 ice samples were positive for total coliforms (TC), fecal coliforms (FC), and E. coli, respectively. In the samples, the TC concentration ranged from <1.1 to >23 MPN/100 mL and from <1.1 to 23 MPN/100 mL for FC and E. coli. In total, 38 (44.7%) ice samples were outside of Mexico's official guidelines. None of the 12 E. coli strains isolated from the three ice samples belonged to DEP. NTM were recovered from 20 ice samples and included M. neoaurum (n = 7), M. porcinum (n = 2), M. flavescens (n = 2), M. fortuitum (n = 1), M. abscessus (n = 1), M. senegalense (n = 1), M. conceptionense (n = 1), and M. sp. (n = 1). In the remaining four samples, two NTM were isolated simultaneously. Thus, we recommend that producers should evaluate the microbiological quality of purified water used as a raw material as well as that of the final product, the ice should be packed in thick bags to avoid stretching and tearing during transportation or storage to prevent environmental contamination of ice, personnel involved in the production, and handling of ice should be trained in relative hygiene matters and how ice-machines should be cleaned and disinfected and the implementation of hazard analysis and critical control points must be applied throughout the chain of production. Finally, regular inspection by the authorities is also of great importance. These recommendations can be applied in different countries with low microbiological quality packaged ice.
Microorganisms used as probiotics should meet elementary safety aspects (non-toxicity, absence of antibiotic resistance genes and translocation) and functional/technological aspects (resistance and ...survival in the acid gastric environment, adhesiveness, stability, and cell viability). Probiotics with the health claim of being a dietary product or a pharmabiotic (drug category) should be clinically tested, validated, documented, and continuously controlled for quality. Important quality parameters include the identification of declared probiotic strains, the number of viable microorganisms (probiotic bacteria and/or fungi), and microbiological purity (absence of specified pathogenic/opportunistic pathogenic bacteria and fungi, and limitation of total unspecified contaminants such as aerobic bacteria, yeasts, and molds). Due to numerous reports of low-quality commercial probiotics marketed for human use, this review discusses the methods used to test the probiotic microorganism content, safety for the intended use, and proven health benefits of those probiotics whose microbiological quality deviates from the manufacturer's stated content, as well as the maintenance of cell viability, i.e., stability of the probiotic during the shelf life. In addition, the adverse effects of probiotics and the potential hazards to the health of the user are addressed.
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•Bacterial diversity of dry sausages was analysed by high-throughput sequencing.•L. plantarum and S. xylosus promoted the proteolysis and lipolysis in the sausages.•The inoculation ...with mixed strains improved the flavour of the sausages.•Growth of unwanted bacteria was inhibited in the inoculated sausages.•Flavour development was attributed to the improved microbiological quality.
The use of starter cultures helps to improve the quality and safety of traditional meat products. In this study, the effects of Lactobacillus plantarum R2 and Staphylococcus xylosus A2 inoculation on microbial community, lipolysis, proteolysis, and volatile compounds in Chinese dry fermented sausages were investigated. Culture-dependent and culture-independent high-throughput sequencing) methods were employed to evaluate the bacterial communities. Results showed that the total contents of free fatty acids (FFAs) and free amino acids (FAAs) were increased by inoculating the starter cultures, especially a mixed culture. A significant decrease in pH and water activity was observed in the inoculated sausages (p < 0.05). Moreover, the inoculation treatment enhanced the competitiveness of dominant bacteria and inhibited the growth of unwanted bacteria. This was beneficial to promote the release of FFAs and FAAs and to prevent the formation of off-flavours and rancidity. Thus, the flavour development in the inoculated dry fermented sausages was attributed to the improvements in microbiological quality.
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•Sweet cherries were coated with 1% of 4 different chitosans.•It has not been effective at reducing water loss at 4 °C, but effective at 20 °C.•Chitosans were effective in inhibiting ...microbial growth.•Chitosan coatings extend the shelf life of sweet cherry.
In this study, the effects of chitosan edible film coatings on the physicochemical and microbiological qualities of sweet cherry (Prunus avium L.) were investigated. Sweet cherries were coated with 1% chitosan two of which were produced from shrimp waste originating from the Marmara Sea in Turkey (Chitosan-1, Chitosan-2) and the other two of which were commercially produced (Commercial-1 and Commercial-2) and stored at 4 °C for 25 days or 20 °C for 15 days. Various physicochemical (weight loss, pH, titratable acidity, total soluble solids, water activity, respiration rate, total carbohydrate content) and microbiological (total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, total coliform bacteria, yeasts and molds) qualities were measured. After storage, the least weight loss was found to be 8.85% in Chitosan-2 coated sweet cherries at 20 °C and 16.18% in the control group stored at 4 °C. The lowest titratable acidity value was observed in the control group (0.657%) at 4 °C and in the Chitosan-2 coated sweet cherries (0.600%) at 20℃. The water activity value was determined at 0.969-0.974 for all sample groups and storage conditions at the end of each period. The total count of mesophilic aerobic bacteria in the sweet cherry coated with CH-1 and CH-2 was found to be below the detectable amount (<2 logCFU/g) while that for the control group was 2.74 log CFU/g at 4 °C. Coating sweet cherries with CH-1 and CH-2 inhibited yeast and mold growth at 4 °C for 25 days while the highest yeast and mold count was determined as 4.75 log CFU/g in C-2 coated sweet cherries at the end of storage. It has been determined that each tested chitosan coatings have different effects on various quality characteristics at distinct storage temperatures. When microbiological analyses are taken into consideration, it can be concluded that chitosan, especially those produced from shrimp wastes, have high antimicrobial effects and can be used effectively in increasing the shelf life of sweet cherries.
This study evaluated the influence of O2-absorbing sachets into different packages polyethylene terephthalate (PET – E1), low density polyethylene (LDPE – E2), and PET/LDPE (E3) on the quality of ...minimally processed soybean sprouts (MP-sprouts). The MP-sprouts were stored up to 12 days and characterized for physicochemical, microbiological and sensory attributes. The O2-absorbing sachet showed changes during exposure to the environment by the formation of amorphous iron hydroxide, which was observed by the analysis of functional groups and XRD. The packaging used in the study showed high transmittance and clarity, and low Haze, being a good feature for storing the MP product. All packaging systems showed an increase in the volume of absorbed oxygen (cm3) up to 9 days of storage. The physic-chemical characteristics of the MP-sprouts stored for 12 days were preserved in the different packages, showing no difference regarding the use of the O2-absorbing sachet. The O2-absorbing sachet not influenced the quality of MP-sprouts during the stored (12 days). The best visual aspect was observed in PET package (with and without O2-absorbing sachet) being classified as excellent, without color change. The MP-sprouts also fulfilled the microbiological quality standards and presented 75.11% acceptability and 72.40% purchase intention.
Improving the sensory quality of fish meat is crucial aspect to enhance fish consumption. In this study, the cooking methods in some Anatolian cities where common carp is consumed very popularly were ...investigated, and carp meat was marinated using different ratios of lemon juice (0.00%, 40.00%, 50.00%, and 60.00%) and salt (10.00%) using the traditional method. After marinating, the effects on the sensory, chemical, and microbiological quality of carp fillets stored at −18 °C were investigated. As a result of the research, it was observed that lemon had positive effects on the shelf life of fish meat. Peroxide value (PV), pH value, Thiobarbituric Acid (TBARS), the total number of psychrophilic bacteria, and the total number of yeast and molds were lower in the groups marinated with lemon juice and salt compared to the control group. In addition, it was observed that the panelists liked the carp meat of the groups marinated with lemon juice.
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 log
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.
Consumption of food from food stalls and water from vending machines has recently increased in Sakon Nakon Province, Thailand. This study investigated the microbial quality of food stalls and the ...sanitation of drinking water distributed through water vending machines. Escherichia coli, Salmonella spp., Staphylococcus aureus, and Vibrio cholerae were detected using polymerase chain reaction. In total, 33 food samples were collected from food stalls and 63 drinking water samples were collected from water vending machines. The results identified E. coli in 6.06% of the food and 11.11% of the drinking water samples. Salmonella spp., S. aureus, and V. cholerae were not detected in any of the food or drinking water samples. Food sanitation assessment indicated 21 (63.64%) of the food stalls did not meet the standards for drinking water as it was not stored in clean and closed containers equipped with a tap or nozzle. Regarding the sanitation of the water vending machines, the businesses failed to inspect the physical, chemical and biological aspects of water quality and never used a simple bacterial test kit to check water quality. It is concluded that the relevant government officials should educate the vender on food safety and hygiene as well as enforcing regular monitoring of the quality of food stall and drinking water vending machines.
