Search Results (147)

In recent years, ultrasound has been integrated into fermentation technology due to its activating effect on microorganisms, and the possible effects of ultrasound-assisted fermentation on the fermentation process, yield and quality of the final product have also attracted attention. This study aimed to reveal the effects of sonication applied before the fermentation on the fermentation process and the quality of fermented black carrot juice. The samples were sonicated at a frequency of 35 kHz and an amplitude of 60% for 0, 5, 15 or 30 min before the fermentation. During the fermentation, the pH, acidity, organic acid profile, ethanol and soluble solid content (SSC), color, turbidity, total lactic acid bacteria (LAB), total mesophilic aerobic bacteria (TMAB) and yeast counts were determined. The amount of SSC in the samples increased at the beginning of fermentation as the sonication time increased. Lactic, acetic and propionic acids were detected in the samples. The amount of lactic acid in all the samples treated with ultrasound was higher than in the control sample and the amounts of acetic acid, propionic acid and ethanol were lower. Ultrasound application caused an increase in the TMAB and yeast counts. A five-minute ultrasound application caused a decrease in the number of LAB, while 15- and 30-min applications caused an increase. Thirty minutes of ultrasound treatment resulted in the reddest fermented black carrot juices with the highest level of color saturation. The most appreciated sample in terms of taste, aroma and general acceptability was the sample subjected to a five-minute ultrasound application. As a result, ultrasound application before fermentation positively supports different quality parameters of fermented black carrot juice and the use of sonication in production can be recommended. Full article

Organic amendments provide a sustainable strategy to enhance soil quality in degraded environments while also helping to reduce greenhouse gas emissions, for example, by improving soil structure, minimizing the use of synthetic fertilizers, and promoting a green economy. This study assessed the comparative effects of two organic amendments—vermicompost leachate and biochar—on the performance of popcorn maize (Zea mays L. var. everta) cultivated in saline soil conditions. Four treatments were evaluated: T0 (Control), T1 (Vermicompost leachate), T2 (Biochar), and T3 (Vermicompost leachate + Biochar), each with 10 replicates arranged in a Completely Randomized Design (CRD). Although various soil physicochemical, microbiological, and agronomic parameters displayed no significant differences compared to the control, the application of biochar resulted in considerable improvements in soil total organic carbon, the microbial community (mesophilic aerobic bacteria, molds, and yeasts), and increased seed length and diameter. In contrast, vermicompost leachate alone negatively impacted plant growth, leading to decreases in leaf area, stem thickness, and grain yield. Specifically, grain yield declined by 46% with leachate alone and by 31% when combined with biochar, compared to the control. These findings emphasize the superior effectiveness of biochar over vermicompost leachate as a soil amendment under saline conditions and highlight the potential risks of widely applying compost teas in stressed soils. It is recommended to conduct site-specific assessments and screenings for phytotoxins and phytopathogens prior to use. Additionally, the combined application of leachate and biochar may not be advisable given the tested soil characteristics. Full article

Adequate treatment of the organic fraction of municipal solid waste (OFMSW) in co-digestion with sewage sludge (SS) through dark fermentation (DF) technologies has been widely studied and recognized. However, there is little experience with a high-solids approach, where practical and scalable conditions are established to lay the groundwork for further development of feasible industrial-scale projects. In this study, the biochemical hydrogen potential of OFMSW using a 7 L batch reactor at mesophilic conditions was evaluated. Parameters such as pH, redox potential, temperature, alkalinity, total solids, and substrate/inoculum ratio were adjusted and monitored. Biogas composition was analyzed by gas chromatography. The microbial characterization of SS and post-reaction percolate liquids was determined through metagenomics analyses. Results show a biohydrogen yield of 38.4 NmLH₂/gVS OFMSW, which forms ~60% of the produced biogas. Aeration was proven to be an efficient inoculum pretreatment method, mainly to decrease the levels of methanogenic archaea and metabolic competition, and at the same time maintain the required total solid (TS) contents for high-solids conditions. The microbial community analysis reveals that biohydrogen production was carried out by specific anaerobic and aerobic bacteria, predominantly dominated by the phylum Firmicutes, including the genus Bacillus (44.63% of the total microbial community), Clostridium, Romboutsia, and the phylum Proteobacteria, with the genus Proteus. Full article

This study investigated the meat quality, sensory properties and microbiology of Angus beef after a short dry or wet aging. For that, a total of 16 Biceps femoris muscles from female Aberdeen Angus x Charoles calves were used. Half of these underwent a technological aging process in the carcass (dry aging) for 7 days, whilst the remaining were filleted, vacuum-packed and stored at refrigerated conditions (wet aging) for 7 days at 4 ± 2 °C. The type of aging affected the ratio of the myoglobin forms but did not translate into differences in the instrumental colour measurements. Dry aging led to minor water release after the application of a force (17.58 dry-aged vs. 31.09 wet-aged) or after cooking and yielded higher hardness and lower shear force in the Warner–Braztler shear force test compared to wet aging. Nevertheless, these differences were not appreciated at the sensory level. Higher counts of mesophilic aerobic bacteria (11.66%) and enterobacteria (3.68%) were found in samples subjected to dry aging. Full article

The popularity of small-scale and local fruit and vegetable production has increased in recent years due to perceived economic, environmental, and social benefits. However, these operations face contamination risks that both consumers and small-scale producers may underestimate. The present study aimed to assess the microbiological and chemical hazards on fruit, vegetables, soil, and water samples from small-scale farms in north-western Portugal during pre-harvest activities. Additionally, the study investigated farmers’ non-compliance with food safety regulations and good agricultural practices (GAPs), exploring how their behaviour might contribute to the identified hazards. A before-and-after analysis of non-compliant behaviours was conducted to determine the impact of training on improving food safety practices. The analysis identified the presence of pathogenic bacteria, pesticides, flame retardant residues, nitrates, and heavy metals. Lead (Pb) concentrations exceeded EU limits in organic carrots from one producer (0.156 ± 0.043 mg/kg) and in chard from another (0.450 ± 0.126 mg/kg). Cadmium (Cd) levels were also above regulatory thresholds in bell peppers (0.023 ± 0.009 mg/kg) and organic tomatoes (0.026 ± 0.015 mg/kg) from two different producers. Elevated levels of heavy metals were detected in irrigation water from two sites, with zinc (Zn) at 0.2503 ± 0.0075 mg/L and Pb at 0.0218 ± 0.0073 mg/L. Among food samples, the most prevalent microorganisms were Pseudomonas spp. (88.2%), Bacillus cereus (76.5%), and aerobic mesophilic bacteria (100%). Phosphorus flame retardants (PFRs), particularly tris(2-butoxyethyl) phosphate (TBEP), were detected in all food and soil samples. Some EU-banned pesticides were detected in food and soil samples, but at levels below the maximum residue limits (MRLs). Chlorpyrifos (35.3%) and p,p’-DDD (23.5%) were the most detected pesticides in food samples. After the training, GAP behaviour improved, particularly that related to hygiene. However, issues related to record-keeping and soil and water analyses persisted, indicating ongoing challenges in achieving full compliance. Full article

The aim of this paper is to propose mathematical models to predict and optimize the cost of wastewater treatment using bacteria and oxygen under fluctuating resource and cultivation conditions. We have thus developed deterministic mathematical models based on dynamic systems and applied optimal control theory to reduce treatment costs. Two wastewater treatment models are proposed: one using only one type of aerobic bacteria, thermophilic bacteria; and the second using two types of aerobic bacteria, thermophilic and mesophilic bacteria. For each model, an optimal control problem is solved and numerical simulations illustrate the theoretical results. Full article

Seed quality is vital for agricultural productivity, as it directly influences the crop yield and resilience to environmental stressors. This study evaluated the effectiveness of a pulsed electric field (PEF) treatment in enhancing the tomato (Solanum lycopersicum) seed quality, seedling growth, and microbial safety. Tomato seeds were treated with PEFs at energy levels ranging from 1.07 to 17.28 J, and several parameters were assessed, including the germination rate, normal seedling development, tolerance to cold and salinity stress, electrical conductivity, and microbial inactivation. The highest germination rate (72.81%) was observed at 15.36 J on the seventh day of germination, whereas the highest normal seedling rate (94.62%) was recorded at 17.28 J (p ≤ 0.05). The germination under cold stress (5 days at 24 °C) was highest, with a 46.67% germination observed at both 1.92 and 10.88 J. PEF-treated seeds exposed to 100 and 200 mM of NaCl exhibited significantly improved germination compared to the controls (p ≤ 0.05). The electrical conductivity (EC) was more influenced by the incubation time than by the PEF intensity, as the EC of all samples showed a significant increase from 4 to 8 h. The samples treated with 17.28 J exhibited the highest germination rates under salt stress, reaching 62.00 ± 0.90% and 50.00 ± 0.60% under 100 mM and 200 mM of NaCl, respectively (p ≤ 0.05). The initial mean counts of the total mesophilic aerobic bacteria and the total mold and yeast—4.00 ± 0.03 and 3.06 ± 0.03 log cfu/g, respectively—were reduced to undetectable levels by the application of 17.28 J, with higher energy levels yielding greater inactivation. These findings demonstrate that the PEF is a promising technique for enhancing seed quality, promoting seedling vigor, and reducing microbial contamination, supporting its application in sustainable agriculture. Full article

Maize (Zea mays) is a critical staple crop whose post-harvest losses, predominantly due to infestations by the maize weevil, Sitophilus zeamais, threaten food security. This study explores the possibility of utilizing S. zeamais, traditionally known as a pest, as an alternative protein source by assessing its nutritional profile and food safety attributes. Cultured under controlled conditions, S. zeamais specimens were processed into flour, which was subsequently analyzed for microbiological safety, protein content, and amino acid composition. Microbiological assays confirmed that the flour met established food safety standards, with aerobic mesophilic bacteria, fungi, and yeast present at negligible levels and no detection of coliforms, Salmonella spp., or Escherichia coli. Protein quantification revealed a high total protein content (48.1 ± 0.3%), although the salt-soluble fraction constituted only 13.7% of the total. The amino acid profile exhibited elevated levels of isoleucine, valine, and threonine, while deficiencies in leucine, lysine, sulfur amino acids, and tryptophan were noted. These findings suggest that, despite certain limitations, S. zeamais flour represents a viable protein source. Integrating targeted insect harvesting for protein into pest management strategies could help reduce post-harvest losses and contribute to improved food security and nutritional availability. Full article

The industrial processing of broiler chickens has become increasingly automated to scale up meat production. However, certain procedures may cause rupture of the gastrointestinal tract, contaminating the products. The objective of this study was to evaluate the efficiency of the removal of visible contaminated broiler carcasses from the slaughter line based on their microbiological quality compared to non-contaminated ones. Carcasses were analyzed for Escherichia coli and aerobic mesophilic microorganisms counts, as well as Salmonella spp. detection. Carcasses with gastrointestinal contamination had significantly higher counts of aerobic mesophilic microorganisms and E. coli than those without contamination. However, carcasses without visible contamination also showed high counts of bacteria, indicative of the hygiene and sanitary concerns during slaughter. Salmonella spp. were detected in both types of carcasses, with no significant difference in the frequency of positive samples. The most frequently identified serovar was Salmonella Minnesota. The most frequently detected bacteria were E. coli, Klebsiella pneumoniae, Citrobacter freundii, and Pseudomonas aeruginosa. In conclusion, both contaminated and non-contaminated carcasses exhibited high bacterial counts, including potentially pathogenic microorganisms, highlighting the need for post-evisceration steps to reduce microbial contamination. Full article

Sweet potatoes play an important role in the global food supply, as they are rich in bioactive components and have numerous health benefits. Their minimally processed, ready-to-eat form is increasingly popular among consumers; however, discoloration and microbiological problems threaten the safety of these products. The aim of this study is to investigate the shelf life of cleaned, cut, ready-to-eat, vacuum-packed, and refrigerated Bonita (white) and Covington (orange) varieties of sweet potatoes after soaking in apple and chokeberry pomace extracts and treatment with citric and ascorbic acids. A series of microbiological and analytical tests was conducted during the storage period. The microbiological tests included the enumeration of cells of mesophilic aerobic and facultative anaerobic microbes, as well as lactobacilli, lactococci, Enterobacteriaceae, yeasts, and moulds. The analytical tests encompassed the determination of the total phenolic content, antioxidant capacity, water-soluble solid content, and pH value. The prevalent microbial groups detected in the examined sweet potato varieties were lactic acid bacteria, which were present in both fresh samples and following storage. This study established that low-temperature refrigeration (5 °C), vacuum packaging, and organic acid treatment can effectively control lactic acid bacteria, which are pivotal to spoilage. The combination of preservation steps is of particular significance for ready-to-cook sweet potatoes, as this approach effectively extends the shelf life of these products. Full article

Natural casings are integral components in the production of various meat products, including sausages, and their quality and safety have to be controlled to eliminate any risks to consumers’ health. A total of 35 samples of salted natural sheep casings from Turkey, Iran, China, Mongolia, Pakistan, New Zealand, the United Kingdom, and Belgium were tested for microbial contamination and the concentrations of potentially toxic heavy metals. The mean log values of microbial counts were determined at 3.45 ± 0.44 log CFU/g for aerobic mesophilic bacteria, 0.5 ± 0.43 log CFU/g for anaerobic sulfide-reducing bacteria, and 1.24 ± 0.63 log CFU/g for coagulase-positive staphylococci. Typical or suspected colonies of Salmonella spp., E. coli, and Listeria spp. were not identified on selective and differential agar. The examined casings were contaminated mainly with lead (0.077 ± 0.045 mg/kg), followed by arsenic (0.036 ± 0.029 mg/kg) and cadmium (0.009 ± 0.008 mg/kg). The concentrations of mercury in all samples were below the limit of quantification. The study demonstrated that the quality and safety of natural casings were not affected by their region of origin and that microbial contamination was not correlated with heavy metal concentrations. Full article

The Sjenica sheep stelja is a characteristic, traditional dry-cured meat product from Serbia with unique and recognizable sensory attributes. The methodology involved examining physicochemical measurements, followed by sensory evaluation and microbiological analyses, over a 120-day ripening period across three years and three different villages, as well as the correlation between chemical characteristics and the number of specific groups of bacteria. Results showed consistent quality parameters across producers and production periods, with notable variation in fat, protein, and ash content. Sensory evaluation confirmed that the product met the quality standards outlined in the Elaborate for the Protection of Geographical Indication, with minor differences in color, aroma, chewiness, and taste among samples. The microbiological analysis demonstrated the dynamic nature of microbial communities throughout maturation, including changes in the counts of aerobic mesophilic bacteria, Enterobacteriaceae, Pseudomonadaceae, lactic acid bacteria, and molds. Penicillium species, particularly P. nalgiovense and P. solitum, were consistently identified, while other fungal genera exhibited varying distribution patterns. The correlation analysis highlights the complex influence of chemical parameters on microbial dynamics throughout the aging process. These findings emphasize the influence of traditional production methods, regional variations, and chemical composition on the sensory quality and microbial safety of Sjenica Sheep Stelja, providing valuable insights for future research and quality control. Full article

This study evaluated the efficacy of active packaging containing albumin (ALB) and pectin (PEC) cryogels loaded with pink pepper essential oil in preserving strawberries during 7 days of storage at 4 °C. The cryogels were prepared in different ratios (ALB:PEC 50:50 and 30:70) and applied in sachets within the strawberry packaging, varying the amounts from 0.4 g to 1.0 g. Analyses included the evaluation of mass loss, soluble solids, pH, titratable acidity, color, firmness, anthocyanin content, volatile compound composition and release from the essential oil (GC-FID and GC-MS), and microbiological analyses. Results showed that the cryogels maintained the stability of soluble solids and pH, and did not significantly affect the color or anthocyanin content. Strawberry firmness was influenced by the amount of cryogel, with 0.4 g of the ALB:PEC 30:70 cryogel’s best-preserving texture. A GC-MS analysis identified monoterpenes (α-pinene, 3-carene, and D-limonene) and sesquiterpenes (caryophyllene and germacrene D) as the major volatile compounds of the essential oil, with a controlled release over time. Cryogels, especially ALB:PEC 30:70, reduced the count of mesophilic aerobic bacteria (1 g) and yeasts and molds (0.4 g). This formulation extends shelf life and preserves the quality of strawberries through controlled antimicrobial release and firmness preservation. Full article

Poultry meat is the most consumed meat worldwide due to its low fat content, sensory qualities, and affordability. However, its rapid spoilage, especially when minced for products like hamburgers, is a challenge. Strategies such as sulfite addition or modified-atmosphere packaging (MAP) can help control spoilage and microbial growth. This study evaluated both approaches by analyzing bacterial development in poultry hamburgers through total viable counts and MALDI-TOF identification, combining food-pathogens detection. The addition of 5 mg/kg sulfites had a limited effect, whereas increasing CO₂ levels in the packaging significantly extended the shelf life by reducing the bacterial growth rates and prolonging the lag phases. The most affected bacteria were aerobic mesophilic and psychrotrophic bacteria, as well as Brochothrix thermosphacta. Carnobacterium spp. dominated the aerobic mesophilic group, while Enterobacter spp. was prevalent in Enterobacteriaceae and aerobic mesophilic isolates, highlighting its role in spoilage. Hafnia alvei was also relevant in the final spoilage stages. These results suggest the importance of these bacteria in poultry hamburger decay and demonstrate that MAP is an effective method to delay spoilage. Full article

In this present study, bovine blood plasma suspensions (12 w/v%) were HHP-treated at 300, 400, 450, 500, 550 and 600 MPa for 5 min. The effect of HHP treatment on the color, rheological properties and digestibility of the samples was investigated. The changes in proteins due to HHP treatment were monitored using SDS-PAGE. Furthermore, the HHP-treated samples were subjected to a 44-day storage experiment and the development of mesophilic aerobic bacterial counts was investigated. Even the application of 300 MPa of pressure induced a significant change in the color of the samples. With the application of a pressure of 300–550 MPa, dilatational rheological behavior was observed, while at 600 MPa, the sample was characterized by pseudoplastic flow properties. The SDS-PAGE study found that there was no significant effect of HHP treatment on the protein fractions in plasma. The application of 450 MPa of pressure improved the digestibility of the plasma suspension. Blood plasma produced in this way has better nutritional value in accordance with consumer needs. The study of mesophilic aerobic bacteria count found that HHP treatments at 550 and 600 MPa improved the shelf life of the samples by 30 days. Additionally, the observed microbial stability improvements suggest that HHP-treated blood plasma could be a viable alternative for extending shelf life in processed food applications, reducing the need for synthetic preservatives. These results suggest that HHP treatment can enhance the functional properties of blood plasma suspensions, enabling their use in food formulations such as protein supplements, emulsifiers and texturizing agents. This approach aligns with the industry’s need for sustainable protein sources and clean-label ingredients. Full article