Search Results (28)

This study evaluated the efficacy of acclimated cow manure as a seed microbiome to enhance food waste hydrolysis. Anaerobic hydrolysis was performed on simulated food waste in a hydrolytic–acidogenic leach bed reactor (LBR) operated in batch mode under mesophilic conditions (35 °C) for 16 days. The acclimation process involved three sequential runs: Run-1 utilized 20% (w/w) cow manure as seed, Run-2 employed the digestate from Run-1 (day 5), and Run-3 used the digestate from Run-1 (day 10). Run-3 achieved 70.4% removal of volatile solids (VSs), surpassing Run-1 (47.1%) and Run-2 (57.1%). Compared with the first run, the production of chemical oxygen demand (COD) and total soluble products (TSPs) increased by 48.7% and 75.9%, respectively, in Run-3. The hydrolysis rate of proteins was 48.4% in Run-1, while an increase of 16.9% was achieved in Run-3 with the acclimatized consortium. A molecular analysis of the microbial community existing in the reactors of Run-2 and Run-3 indicated that the improvement in process performance was closely related to the selection and enrichment of specific hydrolytic–acidogenic bacteria in the reactor. A functional analysis showed that the gene copy numbers for pyruvate synthesis and fatty acid synthesis and metabolism pathways were higher in all bacterial species in Run-3 compared to in those of the other two runs, indicating improved capacity through acclimation in Run-3. The experimental results demonstrate that the hydrolysis of food waste can be enhanced through the acclimation of seed microbes from cow manure. Full article

The aim of this work was to estimate the impact of polypropylene (BOPP) films with active coatings applied on their surface on the quality of sliced, plant-based meat analogue (PBMA) sausages. The coatings contained zinc oxide nanoparticles and geraniol (AG) or zinc oxide and carvacrol (AC) as active compounds. The outcomes of the study indicated that the total microbial count of ready-to-eat, sliced PBMAs bought from a local store was high, confirming that the plant-based sausage must have been contaminated during slicing. It was shown that BOPP bags and spacers covered with the AG layer reduced the number of mesophilic bacteria in sliced plant-based sausages stored for 96 h, proving that this packaging material maintained the microbial quality of PBMA samples. It has to be underlined that neither S. aureus, L. monocytogenes, Salmonella sp. nor coliform bacteria were detected in the plant sausage samples after 48 h and 96 h of storage in the BOPP packaging covered with the AG and AC coatings, confirming that these slices were acceptable for consumption. However, the textural analysis showed that bags coated with the AC layer were the best bags for 96 h of storage. Full article

This study aimed to evaluate the effect of adding shredded black chokeberry (Aronia melanocarpa) pomace on the quality of heat-treated and vacuum-packed pork burgers stored for 14 days at +4 °C. Four burger treatments—Control (BC) and products with 2%, 3.5%, and 5% chokeberry pomace (B2, B3.5, and B5, respectively)—were analyzed for physicochemical properties (thermal loss, shrinkage, content of selected chemical components, pH, color parameters, and shear force) and microbial quality (aerobic mesophilic microorganisms, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae, Pseudomonas spp., Brochothrix thermosphacta, and yeasts and molds). The addition of chokeberry pomace increased (p < 0.05) the thermal loss of pork burgers from 23.5% (BC) to 30.8% (B5) and decreased (p < 0.05) the pH from 6.93 (BC, day 1) to 6.74 (B5, day 14). The introduction of pomace into the pork burgers also significantly (p < 0.05) affected the content of chemical components. However, the nutritional value of pork burgers remained high, with a protein content not lower than 26.68% (BC) and a fat content not exceeding 13.96% (B5). The most affected quality feature of the pork burgers was color. Products B2, B3.5, and B5 exhibited lower L* and b* parameters (p < 0.05) while showing higher a* values. The b* parameter had negative values for products B3.5 and B5 on days 7 and 14. The use of chokeberry pomace did not deteriorate the microbial quality of pork burgers, as indicated by the maximum total count of aerobic mesophilic microorganisms, which reached 4.4 × 10³ cfu/g (B3.5). Moreover, on the final day of storage, moderate antimicrobial properties of chokeberry pomace were observed, with a lower (p < 0.05) number of lactic acid bacteria and Pseudomonas spp. in products B2–B5 compared to BC. The results indicate that incorporating shredded chokeberry pomace into burger-type ground pork products does not present major technological difficulties. However, raw shredded fruit pomace is a perishable microbiological material and requires rapid processing. Further research on the use of chokeberry pomace in burger-type meat products is recommended due to its nutritional value and health-promoting properties. However, this research should include a comprehensive sensory evaluation of the finished product. Full article

According to the Regulation on the Quality of Fresh Raw Milk, up to 100,000 microorganisms/mL are allowed in milk obtained by the hygienic milking of healthy cows, which represents the natural microbiota of milk and has no negative impact on the overall quality of milk. However, with unprofessional handling during and after milking, milk is easily contaminated and becomes a potential medium for the growth and reproduction of microorganisms, some of which can be harmful to human health. Since the number of aerobic mesophilic bacteria in milk is one of the indicators of the hygienic quality of milk, their number and identification are fundamental in the control of raw milk from milk vending machines. From five different milk vending machines, 35 samples were collected, from which the total number of aerobic mesophilic bacteria was determined using the flow cytometry method and the classic method of counting colonies on a nutrient medium. Randomly selected colonies based on morphological differences (n = 700) were identified by comparing MALDI-TOF mass spectra with reference spectra stored in the microorganism library and processing using the MALDI Biotyper computer program. Thirty-eight genera and eighty-one bacterial species and five genera and seven fungal species were successfully identified. The species that predominate are Lactococcus lactis, Hafnia alvei, Escherichia coli, Leuconostoc mesenteroides, and Kluyveromyces lactis. By integrating advanced methods like flow cytometry and MALDI-TOF MS for precise microbial identification, this study highlights the need for enhanced monitoring and adherence to hygienic standards in raw milk vending machines. This approach not only safeguards public health but also supports consumer confidence in milk quality from vending machines. Full article

Substances of organic origin are seeing increasing use in agriculture as rich sources of nutrients for plants. The aim of this study was to determine the microbiological contamination of sewage sludge and digestate to assess their safe use as fertilizers in Poland. The assessment of microbial soil, sewage sludge and digestate contamination was based on the total number of mesophilic bacteria and Gram-negative bacteria from the Enterobacteriaceae family. The presence of Escherichia coli and Salmonella spp. was identified via culture and the presence of Enterobacteriaceae species was determined via biochemical and molecular methods. In laboratory conditions, the survival of E. coli in soil fertilized with sewage sludge or digestate inoculated with a reference strain was determined. The average concentration of Enterobacteriaceae in soil, sewage sludge and digestate samples was 1.1 × 10⁴ CFU/g, 9.4 × 10⁵ CFU/g and 5.6 × 10⁶ CFU/g, respectively. Escherichia coli was detected in all sample types. From the soil samples, Serratia, Enterobacter, Pantoea, Citrobacter and Pseudomonas genera were identified the most frequently, while in sewage sludge and digestate, E. coli was predominant. Based on the results of our laboratory experiment, it can be concluded that after three weeks, fertilization with organic waste in acceptable doses does not significantly increase soil contamination with Enterobacteriaceae. Full article

This study investigated the bacteriological quality of raw ovine milk produced by farms located in the Banat region of Romania. Additionally, the pathogenic potential and antimicrobial resistance of the isolated Escherichia coli strains were evaluated. A total of 95.8% (69/72) of the screened bulk tank milk samples, collected at the farm level immediately after milking, demonstrated appropriate total aerobic mesophilic bacteria (TMB) counts, varying from 3.32 to 6.09 log10 CFU/mL. However, 4.2% (3/72) of the samples were above the regulatory limit of 6.18 log10 CFU/mL. E. coli was identified in 66.6% of the examined samples, and from the total number (n = 48) of isolates, 18.8% harbored the stx2 gene, highlighting pathogenic potential. Antimicrobial susceptibility testing with the Vitek2 system of the isolated E. coli strains revealed resistance against ampicillin (45.8%), gentamicin (20.8%), ticarcillin–clavulanic acid (18.8%), cephalexin (18.8%), amoxicillin–clavulanic acid (8.3%), and trimethoprim–sulfamethoxazole (2.1%). Additionally, 64.6% of the strains showed intermediate resistance against amoxicillin–clavulanic acid, while no resistance was recorded against imipenem. Five (18.5%) strains were multidrug-resistant. This study’s results underline hygienic sanitary deficiencies during the milking phase and indicate that raw ovine milk can be contaminated with pathogenic and multidrug-resistant E. coli strains, highlighting a potential risk to public health. Further studies are encouraged to better understand the risk posed to the consumer via the consumption of ovine milk and derived products. Full article

Canada is a leading producer of wild lowbush blueberries, most of which are mechanically harvested, washed, individually quick frozen (IQF), and bulk packaged. Still, some berries are harvested by more gentle methods and sold as fresh-packed products. These berries do not undergo a wash step, nor are subjected to antimicrobial treatments. The purpose of this study was to conduct a microbiological survey of berries harvested in the province of Nova Scotia to assess their potential for harborage of bacterial foodborne pathogens. A combination of standardized plate count methods and 3M-Petrifilm protocols were used to enumerate total aerobic mesophilic bacteria (APC), yeasts and molds (YMC), coliforms, and generic E. coli, the latter being an indicator of fecal contamination. Overall, APC and YMC levels were 1.2 and 0.5 log greater, respectively, for berries collected early in the harvest season versus those acquired late season and varied significantly (p < 0.05) between farm (location) and harvest practices used. Berries harvested by our team using sanitized hand rakes (SH) had consistently lower APC and YMC levels than those harvested by farm crews. Yet, when gentle harvesting (GH) methods (hand-raking, walk-behind or modified mechanical harvesters) were employed on farms, lower numbers were generally observed compared to berries harvested by traditional tractor-mounted mechanized harvesters (MH). The presence of coliforms (and their levels) was also impacted by the harvest method, with detection rates of ~29%, 73%, and 92% in SH, GH, and MH samples, respectively. Mean counts were < 2.5 log₁₀ CFU/g for both SH and GH berries, but significantly higher (p < 0.05) on MH berries (3.6 log₁₀ CFU/g). Although ~56% of all berry samples collected (n = 350) contained coliforms, only 12 were positive for E. coli, 9 of which were MH samples. Only the latter had numbers > 2 log₁₀ CFU/g, but none tested positive for Shiga toxin-producing serotype O157 (STEC O157) or Salmonella spp. when using internationally recognized selective enrichment and plating methods. ATP luminescence was used to assess the general hygiene of processing lines, whereby “hot spots” for microbial activity were identified, even after cleaning., Standard selective enrichment and plating methods were used for the detection of Listeria monocytogenes on 61 swab samples taken from berry totes or conveyor belts at different times during processing; 4 swabs tested positive for L. monocytogenes. However, the pathogen could not be detected by direct plating on selective agar without prior enrichment; this indicated its numbers were low. The results from this work demonstrated that alternative gentle harvest methods can reduce microbial numbers on wild blueberries. Although the frequency of fecal contamination in berry samples appeared to be low and targeted human pathogens were not detected; this represents a single study conducted over one harvest season. Therefore, it would be prudent for processors to seek effective antimicrobial technologies prior to packaging, while consumers should use caution and thoroughly wash produce before consumption. Where sporadic detection of L. monocytogenes was observed on environmental samples from the processing line, processors must ensure that effective sanitation programs are implemented to avoid potential food safety risks. Full article

Bread is a staple, energy-rich food for people of all ages, so quality is important to consumers. In our region, most of the commercially available bread, whether packaged or unpackaged, is produced by local bakeries, so monitoring microbial levels and the types of microbes present on bread can help to draw attention to protect the final product. It can also help to ensure the food safety, quality, and shelf life of bread. The freshly baked product is microbiologically sterile. Post-process contamination affects the microbial load of bread. In this study, the microbial load of 30 different commercial bread crumbs and crusts was determined. The different types of bread with different compositions were analyzed for total viable bacteria, Escherichia coli, Staphylococcus aureus, aerobic and anaerobic spore-forming bacteria, and culturable microscopic fungi. The K-means clustering algorithm was used to cluster the different types of bread based on the number of aerobic mesophilic bacteria. Significant differences (p < 0.05) were found in the total viable bacterial count for bread crusts and crumbs. The bacterial count of bread varied between 10.00 ± 0.00–395.00 ± 52.4 CFU/g for bread crusts and 10.00 ± 0.0–310.67 ± 94 CFU/g for bread crumbs. The results of 16S rDNA sequence analysis showed that the most frequently occurring bacterial species belonged to the genus Bacillus, but species of the genus Staphylococcus were also present. Chryseobacterium spp. predominated on multigrain bread, Marinilactobacillus spp. on rustic potato bread, and Staphylococcus warneri on sliced brown potato bread. The results contribute to a better understanding of the microbial dynamics in locally produced breads from the Eastern Carpathians of Transylvania, with the aim of improving food safety, quality control, and consumer protection. Full article

Tahiti lemon juice (Citrus aurantifolia) was evaluated for its antibacterial activity. For this purpose, microbiological parameters were assessed in vitro (measurement of the inhibition potential of bacteria using the disk diffusion method) and in vivo (the number of total aerobic mesophilic bacteria and Enterobacteriaceae on the eggshell). Tahiti lemon juice inhibited Escherichia coli and Staphylococcus aureus, with larger halos for pure juice. The values were 14.33 ± 0.58 mm for E. coli and 16.00 ± 1.00 mm for S. aureus. Compared with the load of mesophilic bacteria in the shells of non-sanitized eggs (5.49 ± 0.12 log₁₀ CFU/mL), Tahiti lemon juice significantly reduced this bacterial group on the eggshell (2.07 ± 0.18 log₁₀ CFU/mL). Combining the characteristics inherent to Tahiti lemon juice and the sanitization processes of poultry products proved helpful in guaranteeing the bacterial quality of eggs. Full article

The phenomenon of bacterial resistance to antibiotics, the emission and spread of these bacteria, and the genes that determine antibiotic resistance in the environment are now a major health security concern. This is especially important for anthropopressed surface waters used for recreational purposes. A particular threat is the occurrence of bacteria resistant to frequently applied pharmaceuticals, especially those used to treat persistent and complicated bacterial infections. Hence, a preliminary study of the occurrence of bacteria and genes determining resistance to selected antibiotics, ciprofloxacin and imipenem, was conducted in the bathing waters of the Great Rudnickie Lake. The research showed that the resistance to ciprofloxacin was exhibited by 28% of the total mesophilic bacteria present in water, while the resistance to imipenem was detected in 3.6% of them. It was found that 17–40% of ciprofloxacin-resistant isolates contained the fluoroquinolone-resistance gene qnrS, while the β-lactam-resistance gene blaTEM was found in all the imipenem-resistant strains. The increase in the number of bacteria resistant to the tested antibiotics in the waters of the river outflowing from the lake was observed compared to the inflowing waters, suggesting the potential of the water reservoir as a site for the spreading of drug resistance against tested antibiotics. Full article

Considering the sporadic number of scientific studies on vermicomposting apple pomace waste, this research conducts a comparative analysis of vermicomposting processes using Eisenia fetida, focusing on apple pomace both independently and in combination with wheat straw and/or manure (experiment 1: 60% apple pomace and 40% cattle manure; experiment 2: 60% wheat straw and 40% cattle manure; experiment 3: 80% apple pomace, 10% wheat straw, and 10% cattle manure; and experiment 4: 100% apple pomace). After a 240-day substrate transformation period, all four variations of vermicompost produced demonstrated favorable sensory properties, along with high microbiological and physicochemical quality. Throughout the vermicomposting process, the pH of all vermicomposting mixtures changed, converging towards approximately neutral values by the process’s conclusion. There was an increase in dry matter content, as well as total N, P, K, Ca, and Mg, along with organic matter. Notably, the levels of heavy metals (Zn, Cu, Cd, and Pb) in both the vermicomposting materials and resulting vermicomposts remained significantly below the maximum permissible levels stipulated by Republic of Serbia and European Union legislation, which is directly linked to the ecological origin of the raw materials used. The microbiological quality of the final vermicomposts was deemed satisfactory. Over time, there was a decrease in the counts of aerobic mesophilic bacteria as well as Escherichia coli. The counts of sulfite-reducing clostridia in all substrates remained below 10² CFU/g, while Salmonella spp. and Listeria monocytogenes were not detected in either the composting materials or the resulting composts. The vermiculture of apple pulp exhibited advantageous characteristics, notably a shortened vermicomposting period (150 days) compared to other agricultural waste. This reduction in processing time contributes an additional layer of advantage to the overall quality and efficiency of the resulting vermicompost. Full article

The number of aerobic mesophilic bacteria in milk is one of the indicators of the hygienic quality of milk. The aim of this work was to determine such aerobic mesophilic bacteria and their number in raw unpreserved milk and milk preserved with sodium azide. In 40 collected samples, the total number of aerobic mesophilic bacteria was determined using the classical method of counting colonies on a nutrient medium according to the international standard HRN EN ISO 4833-1:2013. The results showed a trend of decreasing the number of grown colonies in milk preserved with sodium azide. MALDI-TOF mass spectrometry also successfully identified 392 bacterial colonies in raw unpreserved milk samples and 330 colonies in preserved milk samples. Of these, 30 genera and 54 bacterial species were identified in the raw unpreserved milk samples, while 27 genera and 41 bacterial species were identified in the preserved samples. By using a collective approach, the present study provided a more detailed insight into milk’s hygienic quality and the presence of certain species before and after the preservation with sodium azide. Full article

Background and objective: In today’s society, meat and meat products occupy a relatively large share in terms of volume of production and have a serious epidemic potential as a source of disease. Both primary and secondary contamination with microorganisms are possible and, if any deviation in the technological process, the standardization of physico-chemical and microbiological indicators can lead to serious consequences for the health of consumers. The purpose of this study is to assess and analyze the likely medical and health hazards arising from the production, supply and consumption of meat and meat products. Methods: The object of the study is an enterprise for the production of meat and meat products in the territory of the Pleven region. For this purpose, an audit was carried out, based on an algorithm built by us, which corresponds to and is based on the Codex Alimentarius methodology, presented in the document “Food Quality and Safety Systems—A Training Manual on Food Hygiene and the Hazard Analysis and Critical Control Point (HACCP) System”. Results and discussion: Gaps and inconsistencies were found in the technological documentation, as well as in the HACCP plan in the normalization of the physico-chemical characteristics and the criteria for microbiological safety. These could lead to potential risks and health hazards for consumers of meat and meat products. Quality requirements for meat products should include added soy protein, upper limits of fat content, connective tissue proteins, as well as types and concentrations of added additives. In the developed food safety systems, it is necessary to introduce a total number of mesophilic and psychrotrophic aerobic bacteria, Enterobacteriaceae, molds and yeasts, in order to verify the elements that represent the main hazards in the food chain. The conclusions contain specific recommendations for revising the technological documentation and the HACCP system and regulations for optimizing the microbiological requirements with the inclusion of integral indicators of production process hygiene. Full article

The effects of post-harvest spray treatments with essential oils (EOs) obtained from sage and aniseed on maintaining the quality of pears of the ‘Williams’ variety during storage was studied. Harvested pears were picked when they had reached their optimal maturity and underwent a treatment involving the application of aqueous solutions of glycerin, with varying amounts of sage essential oil (SEO) and aniseed essential oil (AEO). Weight loss during storage varied according to the treatment applied with the lowest values recorded for sage essential oil at concentrations of 300 ppm (6.24%) and 250 ppm (6.60%), respectively. Aniseed essential oil had a smaller effect on weight loss compared to sage essential oil. Fruit firmness was better maintained under the influence of the essential oil treatments, with those treated with sage essential oil standing out. The concentration of the essential oils that is used influences the antimicrobial activity of the post-harvest treatment that is applied, with higher essential oil concentrations leading to more pronounced decreases in the total number of mesophilic aerobic bacteria immediately after treatment (4.05 for SEO 200; 3.00 for SEO 300, respectively). The use of post-harvest techniques involving the application of aqueous solutions containing glycerol and essential plant oils by spraying can extend the shelf life of pear fruits. Full article

The aim of the study was to determine the effect of ozone gas fumigation on the mechanical, chemical, and microbiological parameters of radish tubers. Radish plants were grown in the ground in accordance with the principles of good agricultural practice and condition suitable for the soil and climatic conditions of south-eastern Poland. At the end of the growing season, 24 h before harvest, radish plants were exposed to a variable factor, i.e., fumigation with ozone gas at various doses (1 ppm for 1 and 5 min; 5 ppm for 1 and 5 min) in order to modify selected metabolic pathways of bioactive compounds. Then, 24 h after ozonation, radish tubers were harvested and placed in a climatic chamber with controlled conditions, i.e., 2 °C and 90% humidity. Laboratory analyses were performed during storage on days 1, 5, and 10. The ozonation used did not significantly improve the mechanical properties and water content of radish tubers. There was a beneficial effect of selected gaseous ozone doses (1 ppm for 1 and 5 min; 5 ppm for 1 min on the 10th day of storage) on the biosynthesis of selected bioactive compounds, i.e., ascorbic acid content, total polyphenol content, and antioxidant potential during storage. The most beneficial effects of the use of gaseous ozone were observed in the storage process in reducing the microbiological load of radish tubers. Among the ozonation doses used, the dose of 5 ppm for 5 min had the most beneficial effect on reducing the microbiological load. It reduced the number of yeasts and molds by 14.2% and aerobic mesophilic bacteria by 20.9% compared to the control sample on the last day of storage. Additionally, between the 5th and 10th day of storage, a significant effect of each ozone dose applied on reducing the occurrence of yeasts, molds, and mesophilic aerobic bacteria during tuber storage was noted. Full article