Search Results (18)

Ultraviolet B (UV-B) irradiation has been investigated as a non-thermal treatment for fresh produce, but its antimicrobial effectiveness may vary during storage. This study evaluated the effects of UV-B irradiation on microbial populations and quality attributes of fresh-cut spinach during cold storage. Prior to packaging, spinach leaves were treated with 0, 0.3, 0.6, or 0.9 kJ m⁻² UV-B and stored at 5 °C for 12 days. Total mesophilic aerobic bacteria (TMAB), total psychrophilic aerobic bacteria (TPAB), Enterobacteriaceae, and yeast and mold counts, together with total soluble solids (TSS), visual quality, and color characteristics, including lightness (L*), hue angle (h°), and yellowness index (YI), were evaluated during storage. UV-B exerted only a temporary suppressive effect on microbial growth, particularly on days 5–7, whereas some microbial populations increased during later storage, demonstrating the absence of sustained microbial control. In contrast, the highest UV-B dose (0.9 kJ m⁻²) maintained the highest overall visual quality and a favorable color profile, characterized by relatively low L* and high h° values. TSS showed treatment- and time-dependent response without a consistent dose-dependent pattern. Integrated hierarchical clustering and heatmap analyses revealed pronounced temporal organization and demonstrated that microbial and quality responses did not necessarily progress in parallel. Overall, UV-B treatment contributed to the preservation of selected quality attributes but did not provide sustained suppression of microbial populations during refrigerated storage, indicating that complementary preservation technologies may be necessary for effective microbial management. Full article

This study evaluated the microbiological quality, phenolic compound profile, antimicrobial activity against foodborne pathogens, and the presence of potential chemical markers associated with microplastic polymers in 35 commercial bee pollen samples obtained from the seven geographical regions of Türkiye. Microbiological analyses included the enumeration of total mesophilic aerobic bacteria, coliforms, yeasts and molds, lactobacilli, lactococci, and psychrophilic bacteria. Antimicrobial activity was determined against Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella Enteritidis using the disk diffusion method. Phenolic compounds were analyzed by HPLC-DAD, while characteristic pyrolysis products associated with microplastics were analyzed by PY-GC/MS. The results indicated that the pollen samples generally exhibited low microbial contamination levels and variable antimicrobial activity, depending on their geographical origin. Quercetin was identified as the predominant phenolic compound, and samples with higher phenolic content tended to show stronger antimicrobial effects, particularly against S. aureus. PY-GC/MS analyses revealed the presence of several chemical markers potentially associated with plastic polymers in a considerable proportion of the samples. Spearman correlation analysis showed a positive correlation between total phenolic content and particularly S. aureus inhibition. These findings highlight the nutritional and functional value of bee pollen while also drawing attention to emerging food safety concerns related to possible exposure to plastic-associated environmental contaminants. Regular monitoring of bee pollen is therefore recommended to ensure product quality and consumer safety. Full article

The influence of passive and active modified-atmosphere packaging (MAP), antioxidants (citric acid and ascorbic acid) and their combinations with a mild thermal process on the shelf life of cut eggplants was evaluated. Eggplant slices were subjected to different treatments (a—MAP: packaged in air with 35 μm polypropylene; b—MAP1: packaged with 3% O₂ + 15% CO₂; c—MAP2: packaged with 5% O₂ + 15% CO₂; d—citric acid 1% + MAP; e—ascorbic acid (A2) 1% + MAP; f—A2 + MAP1; g—TT (50 °C for 1 min) + A2 + MAP; h—TT + A2 + MAP1; and i—control: no treatment) and stored for 12 days at 5 °C. The evolution of sensory characteristics such as color and the browning index, ascorbic acid (AA), total phenols (TP), antioxidant capacity (AC), microorganism count (mesophilic and psychrophilic aerobes, enterobacteria, molds and yeasts) and polyphenol oxidase PPO activity were periodically evaluated. Treatment h was the most effective in prolonging shelf life, maintaining eggplant’s optimal sensory characteristics for up to 10 days, with greater retention of AA and AC and without significantly varying the initial level of TP. Full article

Milk jam (dulce de leche) is a dairy product obtained by boiling milk with sugar, characterized by high sugar concentration and low water activity. Consumption of this product, which has unique color, taste, and consistency, has been increasing in Türkiye in recent years. However, scientific studies examining the microbiological and chemical quality of milk jam are quite limited. This study aimed to determine quality parameters of milk jams on the Turkish market, evaluate results against relevant standards and provide comprehensive information about current product quality. Twenty packaged milk jam samples from different brands were analyzed. Chemical analyses included pH value, acidity in terms of lactic acid, dry matter content, fat content, reducing sugar, total sugar, and sucrose. Microbiological analyses included counts of Total Mesophilic Aerobic Bacteria (TMAB), psychrophilic bacteria, yeast-mold, lactic acid bacteria, Enterobacteriaceae, coliform bacteria, and proteolytic bacteria. Relationships between obtained data were evaluated by Pearson correlation analysis. Chemical results showed pH 7.54 ± 0.63 (6.70–8.99), acidity 0.49 ± 0.19%, dry matter 62.42 ± 8.85%, and fat 1.51 ± 1.50%. Sugar analyses revealed reducing sugar 17.25 ± 6.16 g/100 mL, total sugar 37.88 ± 8.67 g/100 mL, and sucrose 19.59 ± 8.74 g/100 mL. Microbiological analyses detected TMAB in 50% of samples (4.51 ± 1.91 log CFU/g), yeast-mold in 45% (3.92 ± 1.26 log CFU/g), Enterobacteriaceae in 30% (3.15 ± 1.26 log CFU/g), coliforms in 25% (3.63 ± 1.06 log CFU/g), and proteolytic bacteria in 55% (4.21 ± 1.57 log CFU/g). Positive correlation was found between pH and sucrose (r = 0.466, p ≤ 0.05), and strong negative correlation between dry matter and proteolytic bacteria (r = −0.732, p ≤ 0.05). Significant standardization deficiencies and microbiological quality problems were identified in milk jam samples. High pH values and the presence of hygiene indicator microorganisms indicate the need for HACCP system implementation and increased hygiene controls in production. Full article

The effect of active packaging on maintaining the quality of cherry tomatoes and kale during storage was investigated. The active packaging consisted of kraft paper sheets coated with thymol/eugenol (50:50) encapsulated in β-cyclodextrin. Cherry tomatoes were stored at 10, 15, and 22 °C for 15, 14, and 8 days, respectively, while kale was stored at 2, 8, 15, and 22 °C for 21, 16, 9, and 7 days. Physicochemical (pH, total soluble solids, titratable acidity, colour, and firmness), microbiological (mesophilic, psychrophilic, enterobacteria, moulds, and yeasts) and pigment/bioactive/nutritional (chlorophylls, carotenoids, total phenolic content, vitamin C, and total antioxidant capacity) characteristics were analysed. Active packaging significantly reduced microbial growth, particularly enterobacteria and moulds, in cherry tomatoes and psychrophiles and moulds in kale, without negatively affecting the physicochemical quality. The microbial kinetics were successfully described using the Baranyi–Ratkowsky predictive model, which quantified the effects of temperature and active packaging on microbial growth parameters. This modelling approach revealed that active packaging increased the minimum growth temperature and reduced the specific growth rate of key microbial groups, confirming its inhibitory action under different storage conditions. The use of active packaging slowed colour degradation in kale by reducing chlorophyll loss up to 50% at 22 °C and maintained tomato firmness and colour during storage. Furthermore, a strong correlation (R² = 0.87) between colour index and carotenoid content was found, enabling the non-destructive prediction of ripening in tomatoes. Overall, active packaging enhanced microbial stability, delayed visual deterioration, and sustainably extended the shelf life and post-harvest quality of perishable products, offering a promising alternative to conventional preservation methods. Full article

This study examines the impact of added elderberry (EDB) extract on the physico-chemical, microbiological, and sensory properties of yogurt over a 21-day storage period. Two separate experiments were conducted: the first focused on testing concentrations of 0.05%, 0.1%, 0.2%, and 0.5% (w/w) EDB extract for impoving antioxidant properties and replacing potassium sorbate, a chemical preservative commonly used in dairy products, while the second aimed to enhance the bioactive compounds’ concentration by adding 0.5% EDB extract, and to assess the effect of a sweetener (agave syrup) on the sensory profile. Both experimental approaches demonstrated a significant increase (p < 0.01) in total phenolic content. In the first experiment, there was approximately 2.6 times more total phenolic content compared to the control (with a maximum of 11.71 mg GAE/100 g for the sample with 0.2% EDB extract), and about 6 times more with the addition of 0.5% EDB extract and agave syrup (with a maximum of 25.29 mg GAE/100 g). Additionally, the IC₅₀ value decreased for all samples with EDB extract, suggesting enhanced antioxidant activity. Specifically, the antioxidant activity was approximately 3.3 times higher for the control for samples obtained from homemade yogurt with EDB extract, and about 8 times higher for samples obtained by adding EDB extract to commercial yogurt, compared to their respective controls. The high stability of bioactive compounds during the storage period highlights the potential of EDB extract as a functional antioxidant ingredient. Microbiological analysis confirmed the safety of the yogurt, with lactic acid and mesophilic bacteria showing stable counts and minimal declines over time. In the first experiment, a reduction of about 2.3 CFU/g was observed from day 0 to day 21 in samples with 0.1% and 0.2% EDB extract, while the control sample showed a reduction of 1.84 CFU/g. However, the control sample recorded the growth of psychrophilic bacteria, yeasts, and molds. In the second experiment, the samples with 0.5% EDB extract showed an average reduction of approximately 0.35 CFU/g, while the control showed a reduction of 0.51 CFU/g, maintaining stable counts and no detectable growth of psychrophilic bacteria, yeasts, molds, or coliforms. Additionally, the inclusion of different concentrations of EDB extract, along with the combination of a higher concentration of EDB extract and agave syrup, improved the yogurt’s sensory attributes, thereby enhancing consumer acceptance. For the first experiment, 68% of the panelists expressed their preference for the samples with EDB extract, and 10% preferred the control sample. In the second experiment, 49% preferred the sample with 0.5% EDB extract and agave syrup, while 23% preferred the control sample. These findings support the integration of EDB extract into yogurt formulations to boost antioxidant properties while preserving microbiological stability. Future research should explore the potential health benefits and long-term effects of these functional dairy products. Full article

Pumpkin (P) production in Santiago del Estero, Argentina, is of high quality. The product is sold whole and fresh, and is traditionally consumed after being cooked in water. Due to its pleasant flavor (semi-sweet), it is widely accepted among consumers, being a potentially versatile product to be consumed fresh or minimally processed (MP). Processing increases food’s susceptibility to microbial spoilage, making it necessary to use sanitizers. In this work, the effect of different application methodologies at different concentrations of rosemary essential oil (REO) on the sensory characteristics and microbiological quality of grated P was evaluated. The product was washed, sanitized, cut, peeled, grated and centrifuged, and then REO was superficially incorporated in two concentrations (4 and 8 μL/mL), applied in three ways: sprayed (TA), immersion (TI) and by strips embedded in EO being adhered to the storage container (TV). The product was subsequently stored at 5 °C in sealed polypropylene bags of 35 μm. In addition, an immersion treatment with NaClO-100 ppm-3 min and a control without any additive were included. Samples were taken at 24 h and 8 days of storage, evaluating mesophilic aerobic microorganisms (MA), psychrophilic (Psy), enterobacteria (E) and mold and yeasts (MY). Sensory evaluation was carried out by trained judges, determining that aroma and flavor were the critical attributes for acceptability. At the end of storage, microbiological analysis showed that REO treatments presented levels of 10⁷ CFU/g, similar to NaCLO treatment, except TI with both concentrations, which was more effective in inhibiting the development of Psy and MY. Regarding aroma evaluation, at 8 days all treatments were acceptable, with the exception of TI and TV (8 μL/mL), while for flavor all treatments were acceptable with the exception of TI for both concentrations. Therefore, the application of TA and TV treatments at the lowest concentration could be considered for further studies to increase the shelf life of MP P. Full article

Volatile compounds contribute to aroma and flavor, these being the main sensory attributes in food acceptance. This work addresses the physicochemical, volatile compounds, polyphenols, and flavonoids content and, antioxidant activity of apple-raspberry (90/10%) juice treated by thermal and ultraviolet radiation (UV-C) alone or in combination with moderate heat-treatment. Nineteen volatile compounds were identified which experienced changes depending on the treatment. Compounds such as α-ionone and β-ionone, that contribute to raspberries characteristic aroma, were present in a greater concentration in the UV-C treatment and lower in the thermal treatment. Likewise, 2-methyl butyl acetate, which give a fruity-sweet aroma typical of apples was present in a greater concentration in the UV-C treatment. Regarding polyphenol content, control and combined treatment presented the greater concentrations. However, after twenty days of storage, control and combined treatment presented the lower flavonoid concentration. Nevertheless, at this time, treatments showed no variations in antioxidant activity. Yeast and mold and total aerobic mesophilic and psychrophilic counts were reduced in the heat and combined treatments. In conclusion, UV-C and moderate heat might successfully be used to process a stable apple-raspberry juice while maintaining its quality and safety. Full article

According to many national legislations, biological agents represent an occupational hazard that must be managed in order to ensure safety at workplace. Bioaerosols have been associated to many pathological conditions but, despite many efforts, precise threshold limit values (TLV) are still undefined. We planned and conducted an environmental study concerning a typical restaurant that aimed to evaluate: (1) the occupational exposure to bacterial and fungal bioaerosol; (2) the efficacy of a photocatalytic air purifier device in mitigating such exposure. This observational study evaluated two dining rooms (Area 1 and Area 2) of a restaurant which can be considered typical during two consecutive weeks. Based on a national protocol, we monitored total bacterial and mycotic loads searching for two typologies of bacteria, psychrophilic bacteria (environmental contamination) along with mesophilic bacteria (human or animal origin source), and two types of fungi, mold and yeast. Baseline total bacterial load was 346.8 CFU/m³ for Area 1 and 412.9 CFU/m³ for Area 2. When the sanitizing device was operative, the total bacterial load decreased to 202.7 CFU/m³ (−41.50%—p value: <0.01) for Area 1 and to 342.2 CFU/m³ ($-1$7.10%—p value: 0.06) for Area 2. Considering the fungal load, the mean baseline value was 189.7 CFU/m³ for Area 1 and 141.1 CFU/m³ for Area 2. When the device was kept on, the total fungal load was 108.0 CFU/m³ ($-4$3.10%—p value: 0.055) for Area 1 and 205.0 CFU/m³ (+45.30%—p value: 0.268) for Area 2. Our findings supported the conclusion that, concerning the occupational risk derived from biological agents, a typical restaurant should be considered relatively safe. In order to mitigate or limit any possible increase of such risk, a photocatalytic device may be helpful, but not against the pollution caused by mold or yeasts. Our research also reaffirmed the need of further research assessing the kind of relationship between diseases and exposure levels, before considering the need of setting precise threshold limit values. Full article

Ready-to-eat fresh fruit have an increasing presence in international markets due to their convenience and health benefits. However, these products are highly perishable and efficient technologies to increase their shelf life are needed. In the present research, different citrus fruit species and cultivars from organic farming were assessed to obtain enzymatically peeled citrus segments. The best results in terms of segment quality were observed for ‘Hernandina’ clementine, which was chosen to make a new ready-to-eat product based on peeled citrus segments that were packaged in glass jars with a light syrup made of citrus juice and organic sugar cane. Different citrus juice mixtures were assayed and the most appreciated syrup, based on the sensory scores given by panellists, was that containing 50–50 (v/v) of ‘Fino’ lemon and ‘Hernandina’ clementine juices. In addition, different pasteurization treatments were assessed for their effects on conserving the safety, nutritional quality and sensory properties of the product during cold storage. The results show that pasteurization treatment at 50 °C for 45 min was sufficient to prevent microbial contamination with mesophilic and psychrophilic aerobic bacteria or yeast and mould and to maintain sensory properties until five weeks of storage at 4 °C. In addition, only a 10% reduction in vitamin C concentrations was observed in fresh-segments or syrup until the end of the storage period, showing that a high bioactive compound content and health benefits were conserved in the new ready-to-eat product after pasteurization and prolonged cold storage. Full article

The main problem in processing bovine colostrum is preserving as many beneficial compounds as possible, most of which have low thermal stability. The present study evaluates the possibility of using cold plasma (CP) as a decontamination technology and its effect on selected biologically active fractions of freeze-dried bovine colostrum. The plasma process was carried out in air, nitrogen, and oxygen environments. The results revealed that the sterilization process using CP caused slight changes in the colour of the samples expressed by the attributes ΔC, ΔL, Δh and ΔE. The decontamination effect depended on the gas used and the type of microorganism. The highest decontamination effects were gained under oxygen conditions, where reductions were obtained for total psychrophilic bacteria (THPC) by log 1.24, mesophilic bacteria (THMC) by log 1.02, Enterobacteriaceae by log 1.16, E. coli by log 0.96, yeast (TYMC) by log 0.92. A significantly lower decontaminating effect was obtained for Gram-positive bacteria and sporophytic forms. Additionally, the application of CP, regardless of the gas used, affected the modification of protein structure and reduction of immunoglobulin concentration. as proven by proteomics analyses (1-DE, 2-DE, MALDI–TOF MS). The same applied to β-lactoglobulin in air and oxygen and BSA in nitrogen and air. Full article

Psychrophilic yeasts are distributed widely on Earth and have developed adaptation strategies to overcome the effect of low temperatures. They can adapt to low temperatures better than bacteriophyta. However, to date, their whole-genome sequences have been limited to the analysis of single strains of psychrophilic yeasts, which cannot be used to reveal their possible psychrophilic mechanisms to adapt to low temperatures accurately and comprehensively. This study aimed to compare different sources of psychrophilic yeasts at the genomic level and investigate their cold-adaptability mechanisms in a comprehensive manner. Nine genomes of known psychrophilic yeasts and three representative genomes of mesophilic yeasts were collected and annotated. Comparative genomic analysis was performed to compare the differences in their signaling pathways, metabolic regulations, evolution, and psychrophilic genes. The results showed that fatty acid desaturase coding genes are universal and diverse in psychophilic yeasts, and different numbers of these genes exist (delta 6, delta 9, delta 12, and delta 15) in the genomes of various psychrophilic yeasts. Therefore, they can synthesize polyunsaturated fatty acids (PUFAs) in a variety of ways and may be able to enhance the fluidity of cell membranes at low temperatures by synthesizing C18:3 or C18:4 PUFAs, thereby ensuring their ability to adapt to low-temperature environments. However, mesophilic yeasts have lost most of these genes. In this study, psychrophilic yeasts could adapt to low temperatures primarily by synthesizing PUFAs and diverse antifreeze proteins. A comparison of more psychrophilic yeasts’ genomes will be useful for the study of their psychrophilic mechanisms, given the presence of additional potential psychrophilic-related genes in the genomes of psychrophilic yeasts. This study provides a reference for the study of the psychrophilic mechanisms of psychrophilic yeasts. Full article

High-moisture mozzarella cheese (HMMC) is a highly perishable cheese with a short shelf life. In this study, the effects of UF cheese whey containing postbiotics from Lactobacillus acidophilus LA-5 (P-LA-5), Bifidobacterium animalis BB-12 (P-BB-12), and their combination on the microbial (i.e., psychrophiles, mesophiles, lactic acid bacteria, and mold-yeast population) and sensory properties of HMMC were investigated. Postbiotics were prepared in a cheese whey model medium as a novel growth media and used as a preserving liquid in HMMC. The results demonstrate that postbiotics reduced the growth of all microorganisms (1.5–2 log CFU/g reduction) and P-LA5 and P-BB12 had the highest antibacterial performance on mesophiles and psychrophiles, respectively. Mold and yeast had the highest susceptibility to the postbiotics. Postbiotics showed a significant effect on maintaining the microbial quality of HMMC during storage, proposing postbiotics as a new preserving liquid for HMMC. Full article

The effects of ozone water (OW) and ultrasound cleaning (UL) on microbial community diversity of crayfish were studied through microbial viable count and 16S rRNA gene sequencing. The results showed that compared with the control (CK), the ozone water combined with ultrasound cleaning (OCU) showed a significant reduction (p < 0.05) in total viable count (TVC), psychrophilic viable count (PVC), mesophilic viable count (MVC), Pseudomonas, hydrogen sulfide-producing bacteria (HSPB), molds and yeasts. Concretely, the TVC of the CK, OW, UL and OCU were 5.09, 4.55, 4.32 and 4.06 log CFU/g, respectively. The dominant bacterium in untreated crayfish was Chryseobacterium, and its relative abundance was reduced by combined treatment. Color measurement and sensory evaluation suggested that a satisfactory sensory experience could be obtained on the crayfish applied with OCU. In brief, OCU could be used as a cleaning strategy to control the microbial quality of crayfish and have no influence on its quality. Full article

Ready-to-eat fresh-cut salads (RTESs) are fresh-cut vegetables that have been minimally processed and remain alive until consumption. A survey with 297 respondents was performed, showing that most respondents consumed RTESs composed of various vegetables once or twice a week. The most important items for consumers’ RTESs purchasing intention were the expiration date and the absence of exudates and brown and dehydrated leaves, while after storage in domestic refrigerators, the most important item for consumption refusal was the presence of strange odours. On the other hand, among the non-consumers of RTESs, the most important reason for not buying this kind of produce was the use of plastic packaging. Microbiological analysis of RTESs (composed of corn salads, radicchio and escarole leaves) showed that moulds, yeasts and psychrophilic aerobic microflora remained unchanged from buying to the expiration date, while increases occurred in mesophilic aerobic microflora, although all of them were within safety levels for consumption even after 4 days of the expiration date. Finally, total phenolics and antioxidant activity were higher in corn salads followed by radicchio and escarole leaves, and generally, no significant changes occurred in the bioactive compounds of RTESs during storage in domestic refrigerators. Full article