Mesophilic Bacteria Counts Research Articles

Characterization of psychrotrophic and thermoduric bacteria in raw milk using a multi-omics approach.

Psychrotrophic and thermoduric bacteria are the main reasons for the spoilage of dairy products. This study aims to address the composition and function of psychrotrophic and thermoduric bacteria in eight groups of raw milk samples obtained from Heilongjiang Province and Inner Mongolia (China). Microbial enumeration showed an average total bacterial count of 4.63 log c.f.u. ml-1 and psychrotrophic bacterial counts of 4.82 log c.f.u. ml-1. The mean counts of mesophilic and thermophilic thermoduric bacteria were 3.68 log and 1.81 log c.f.u. ml-1, respectively. Isolated psychrotrophic bacteria (26 genera and 50 species) and mesophilic thermoduric bacteria (20 genera and 32 species) showed high microbial diversity. Through metagenomic and proteomic analyses, significant disparities in the concentration and community structure of psychrotrophic and thermoduric bacteria were observed among different locations. A large number of peptidases were annotated by metagenomics, which may result in milk spoilage. They mainly come from some typical psychrotrophic and thermoduric bacteria, such as Chryseobacterium, Epilithonimonas, Pseudomonas, Psychrobacter, Acinetobacter, Lactococcus, Escherichia and Bacillus. However, the main proteins detected in fresh raw milk were associated with bacterial growth, reproduction and adaptation to cold environments. This investigation provides valuable insights into the microbial communities and protein profiles of raw milk, shedding light on the microbial factors contributing to milk deterioration.

Comparison of microbiological loads of enteral products at two different ambient room temperatures.

Despite the high risk of bacterial contamination, no studies have been found that evaluate the optimal hanging time of open-system enteral sets under room temperature and intensive care conditions. This study aims to determine the differences in microbial loads of solutions taken from open-system enteral feeding sets hanging for 24 h under room temperature and intensive care conditions. This study is a descriptive type of research. The study sample consisted of a total of 40 samples, with 20 samples under room temperature (25.2-23.3°C) and 20 samples under intensive care conditions (21.1-24.2°C). A simple random sampling method was used for sample selection. The assessment of microbial quality was based on the US Food and Drug Administration online Bacteriological Analytical Manual. In this study, it was determined that 5% of the samples taken from intensive care and 15% of the samples taken at room temperature exceeded the accepted limit for aerobic mesophilic bacteria count. The count of catalase and coagulase-negative Staphylococcus spp was 5% in intensive care samples and 40% in room temperature samples. The total coliform count was not detected in intensive care samples but was 35% in room temperature samples. Escherichia coli was not detected in either group. Differences in microbial loads were observed when commercial enteral solutions were administered using open-system enteral feeding sets under room and intensive care conditions for 24 h. Therefore, large-scale studies are needed to determine the safe use of open-system enteral feeding sets under room temperature conditions.

Atmospheric Cold Plasma to Maintain Sea Bass Quality: An Opportunity for International Fish Trade

Whole chilled sea bass is an essential product for the European food market, and Türkiye is the foremost supplier. The importance of sea bass in the world food trade reveals the significance of food safety risks that may arise during or after harvest. This study aimed to examine the impact of atmospheric cold plasma (ACP) on delaying the spoilage of sea bass. The ACP is generated by an original device that produces a dielectric barrier discharge plasma using an alternating current (AC) power supply, applying a 30 kV high voltage with a sinusoidal frequency of 20 kHz. Whole sea bass samples were treated for 1 min (ACP1) or 7 min (ACP7), and then stored at 2 ± 1 °C. Sensory scores of plasma-treated sea bass were higher throughout the storage period. Both treatments decreased the initial bacterial load and delayed bacterial growth (p ≤ 0.05) during storage. The mesophilic aerobic bacteria count of control samples exceeded 6 log CFU/g on the second day of storage. However, ACP1 and ACP7 did not reach this value until the third and fourth days. The control samples had higher TMA-N and TBARS (p ≤ 0.05) than plasma-treated groups. The treatment did not significantly change the texture. Although ΔE was higher in ACP samples, a discoloration that could affect acceptability was not reported during the sensory test. Cold plasma can improve the overall market value by maintaining quality, benefiting the global fish trade. It has been shown that cold plasma has promising potential in the fresh fish industry.

Tannic acid and Gallic Acid as Alternative Compounds for the Application as Preservatives in Cosmetic Products

Introduction: Tannic acid and gallic acid have been known as natural compounds with antibacterial activity. In this work, the antimicrobial efficiency of tannic acid (TA) and gallic acid (GA), as well as their mixtures, was tested. Method: During the research, the minimal inhibitory concentration, minimal bactericidal concentration, and fractional inhibitory concentration were defined. Based on them, for further study, mixtures of TA/GA in ratios 50:50 and 80:20 were chosen as a preservation mixture applied to the cosmetic emulsion. Results: The obtained cosmetics emulsions were analyzed for the total mesophilic aerobic bacteria count and the total combined yeast count. The preservation efficiency test was performed according to the ISO 11930 standard. A stability test for cosmetics formulation was also carried out. Conclusion: The preservation mixture of TA/GA in an 80:20 ratio incorporated in the cosmetics formulation showed good preservation efficiency and could be considered a natural origin preservative.

Development and Application of the Quality Index Method for Ice-Stored King Weakfish (Macrodon ancylodon).

The freshness of raw fish has become one of the industry's and consumers' main concerns regarding quality, safety, and shelf-life estimation. To determine the freshness of the king weakfish (Macrodom ancylodom), the quality index method (QIM) was employed for sensory analyses, along with the assessment of proximate composition, pH, total volatile bases (TVB-N), thiobarbituric acid reactive substances (TBARS), biogenic amines, fatty acids, texture, and microbiological parameters. The results show that the QIM obtained over the storage period exhibited a linear increase, ranging from 2 to 21 demerit points, with a high correlation (R2 = 0.9868) among the data. The microbiological results indicated an increase in the counts of psychrotrophic and mesophilic bacteria throughout the storage period. TVB-N values ranged from 11 to 28 mg/100 g, and TBARS values ranged from 0.235 to 0.298 mg MDA/kg when stored in ice. The presence of putrescine, cadaverine, spermidine, and toxic volatile compounds was a potential indicator of fish freshness. Based on the correlation between the methods considered indicators of freshness and quality, it can be concluded that the king weakfish maintains its commercial stability for up to 11 days when stored in ice.

Films of polylactic acid with graphene oxide-zinc oxide hybrid and Mentha longifolia essential oil: Effects on quality of refrigerated chicken fillet

This study was conducted to investigate the morphological, thermal, mechanical, FTIR, physicochemical (thickness, humidity, solubility in water and water vapor permeability) and antimicrobial properties of polylactic acid film (PLA) containing hybrid graphene oxide‑zinc oxide (GO-ZnO: 1.5 % w/v) and Mentha longifolia essential oil (ML:1 % v/v) on chicken fillet kept in the refrigerator. The studied groups were microbially (total count of mesophilic aerobic bacteria, psychrotrophic bacteria, Enterobacteriaceae, Staphylococcus aureus, and lactic acid bacteria), chemically (pH, TVB-N) and sensory (color, odor, and taste) evaluated at 8-day interval (0, 2, 5 and 8). In the examination of the morphological characteristics, the PLA film had a smooth and uniform surface and the addition of ML essential oil created a discontinuous structure and the addition of GO-ZnO led to the production of a denser and more homogeneous film. The presence of GO-ZnO increased the thickness, decreased moisture content and solubility in water, and added ML essential oil increased moisture content and decreased solubility in water (p˂0.05). The results of the mechanical evaluation showed that the addition of ML essential oil and GO-ZnO reduced elongation at break and tensile strength (p˂0.05). The addition of ML essential oil increased the thermal resistance and the addition of GO-ZnO decreased the thermal resistance compared to the film containing ML essential oil. The antimicrobial effect of films containing ML essential oil was confirmed in this study (p˂0.05). The addition of GO-ZnO did not change the count of any of the microbial groups. TVB-N showed that groups containing ML essential oil had lower levels of volatile nitrogenous bases than the control group (p˂0.05). Sensory evaluation of the studied groups showed that chicken fillets packed with films containing ML essential oil had the highest score in terms of color, smell and taste. The results of the present study showed that PLA film containing GO-ZnO and ML essential oil can be used to increase the shelf life and maintain the sensory characteristics of chicken fillets, and it can be used as a suitable packaging to increase the shelf life of food products.

Reduction of Total Phenols in Virgin Olive Oil as a Preservation Medium during Cold Storage of Whey Cheese and Tofu.

Virgin olive oil, known as a good source of health-promoting hydrophilic phenols, is traditionally used as a medium for preserving various foods. Phenols in general can form complexes with proteins, but there is little information on the direct contact of virgin olive oil with protein-rich food during long-term storage. In this study, the dynamics of the decline of total phenols in oil used as preservation medium for a traditional (whey cheese skuta) and a modern product (tofu) were compared. Pieces of skuta or tofu immersed in virgin olive oil at different food-to-oil mass ratios were stored in the refrigerator for up to 21 days. The oil quality indices, water content and the total count of aerobic mesophilic bacteria in the immersed materials were monitored. To determine the total phenols in the oil, the optimal conditions of the Fast Blue BB test, which is a suitable alternative to the standard method, were tested and selected. The effect of both materials on the indicators of hydrolytic and oxidative deterioration of the oil is almost identical (a gradual decrease), which is most likely due to the continuous release of water from the immersed food. A sharp decrease in total phenols in the oil (by about 50 %) after seven days of storage in contact with both materials indicates a combination of causes (water-to-oil migration and phenol-protein interactions). The form of the rational function is highly representative of the decrease in total phenols during the first seven days of tofu/oil storage, indicating a very rapid interaction with tofu proteins. The preservative effect of virgin olive oil in terms of microbiological spoilage was not observed. The results of this study contribute to the knowledge on the dynamics of phenol-protein interactions and emphasise the need for further investigations on traditional or newly used protein-rich foods preserved in direct contact with virgin olive oil, taking into account possible changes in the functional, nutritional and sensory properties of phenols and proteins.

The Effect of Grape Pomace Fiber Addition on Quality Parameters of Yogurt

Reducing food and industrial waste is essential to match the novel objectives of sustainable living. In this context, grape pomace, a fiber-rich by-product of wine production, was used as a fiber supplement in yogurt after enriching its fiber content through preprocessing. Within the aim of this study, 0.5% and 1% grape pomace fiber were incorporated into yogurt, and the effect on physicochemical, microbial, and sensory quality was investigated. Throughout the 14-day storage period, no significant changes were observed in pH, acidity, and water holding capacity. The total mesophilic aerobic bacteria count ranged between 2-3 log.cfu/g, and the addition of fiber did not result in any undesirable alterations in these counts. Similarly, the fiber did not affect the counts of specific yogurt bacteria, which was 8-9 log.cfu/g. Moreover, sensory evaluations consistently resulted in scores above “5” for all products, with acidity rated level as moderate as expected for yogurt. There were no adverse effects on sensory quality concerning color, flavor, texture, acidity, and overall acceptability. In conclusion, fiber-enriched yogurt from wine waste is feasible without compromising product quality. This study is expected to contribute to the progress of current sustainable living goals.

Combined Ascorbic Acid and Mild Heat Treatment to Improve the Quality of Fresh-Cut Carrots.

Mild heat (MH) treatment and ascorbic acid (AsA) addition can improve the quality of fresh-cut produce when used individually; however, their combined effect remains unclear. Herein, fresh-cut carrots were used as models to explore the effects of MH (50 °C)-AsA (0.5%) on quality properties including reactive oxygen species (ROS) metabolism, antioxidants, lignin metabolism, naturally present microbes, and inoculated pathogens (Escherichia coli O157: H7 and Salmonella Typhimurium) during storage (0-5 d, 4 °C). The results indicate that the antioxidant properties in the MH-AsA group were consistent with those of single treatments, resulting in a consistent ROS-scavenging effect. From day 3-5, lignin synthesis was significantly inhibited by MH-AsA as compared with single treatments, probably because the two enzymes (phenylalanine ammonia-lyase and peroxidase) responsible for lignin synthesis exhibited lower expressions. Microbial analysis revealed that MH-AsA treatment led to the lowest counts of both pathogens and aerobic mesophilic bacteria at 0-5 d. Conversely, the inhibitory effect of MH-AsA treatment on mold and yeast was consistent with the single treatments. These results suggest that MH-AsA is a low-cost and safe approach to improve the physiological characteristics of fresh-cut produce while reducing microbial risk.

Comparative Study of Vermicomposting: Apple Pomace Alone and in Combination with Wheat Straw and Manure

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.

Effects of Process Conditions on Drying of Tomato Pomace in a Novel Daylight Simulated Photovoltaic-Assisted Drying System

AbstractThe tomato pomace (TP), which is a by-product of the production of tomato paste, was dried in a novel custom-designed daylight simulated photovoltaic assisted dryer (DPVD). The different light applications (daylight, UV light, daylight + UV light, and without light), different air velocities (1.5 and 2 m/s), and different heating source modes (hot air and infrared) were applied to dry TP having a moisture content of 80.60 ± 0.73% to the moisture content of 7.66 ± 1.72%. The average water activity values of all dried samples were measured as 0.52 ± 0.08. Analysis was conducted to compare sun drying with the effects of process conditions on the quality (color properties, lycopene, β-carotene, and total mesophilic aerobic bacteria count) and performance (energy efficiency, exergy efficiency, specific moisture evaporation rate, and improvement potential) characteristics of TP. The effects of process conditions for each heating source mode were determined separately, and the improvement of the system performance for each mode was investigated. The effect of the process conditions on total aerobic mesophilic bacteria (TAMB) count was similar in general. In the infrared heating mode, the loss in lycopene and β-carotene contents was 59.55 ± 2.22 and 57.87 ± 2.51 minimum for 1.5 m/s air velocity without light application and for 2 m/s with ultraviolet + daylight application. In general, the performance of the system decreased in case of using ultraviolet light. The retention in the lycopene and β-carotene contents was higher in the infrared mode with light applications compared to hot air mode without light. The optimum drying conditions were air velocity of 2 m/s with “daylight” assistance in the hot air heating mode and with “ultraviolet + daylight” assistance in the infrared heating mode. All the energy and the daylight source used in drying applications were obtained from the sun, a renewable energy source, thanks to the photovoltaic panel and the solar tube units in the novel custom-designed drying system.

Aflatoxin and microbial safety in commercial confectionery peanut paçoca produced in São Paulo state – Brazil

Paçoca is a typical Brazilian confectionery of Indigenous origin prepared by mixing ground roasted peanuts, sugar, and salt. A total of 52 samples of paçoca (37 pressed, 15 cooked), produced and sold in the state of São Paulo, were evaluated for aflatoxin content (AFB1, AFB2, AFG1 and AFG2), moisture content and water activity. The microbiological quality was assessed by counting mesophilic aerobic bacteria, fungal and yeast counts, most likely number of thermotolerant coliforms and Escherichia coli and Salmonella sp. The limit of quantification (LOQ) by Ultra Performance Liquid Chromatography coupled to the Mass Spectrometer (UPLC-MS/MS) ranged from 0.29 μg kg−1 for AFB1 and AFG2; 0.36 μg kg−1 for AFG1 and 0.37 μg kg−1 for AFB2. The recovery averages were 89.2, 83.5, 80.5 and 82.8% for AFB1, AFB2, AFG1 and AFG2. 71% of the samples showed aflatoxin contamination, ranging from 0.29 to 38.8 μg kg−1 (mean of 7.06 μg kg−1). Six samples (16%) exceeded the limit value tolerated by the Brazilian guideline for AFT (20 μg kg−1). The mean AFT content in cooked paçocas (19.55 μg kg−1) was higher than the levels in pressed paçocas (9.08 μg kg−1) (p < 0.05). AFB1 had a higher incidence in the two groups of paçocas (75% pressed and 60% cooked). The mean moisture content and water activity of cooked paçocas (8.86% and 0.7081) were higher than those of pressed paçocas (2.08% and 0.4863). Twenty-one samples (56%) showed fungal and yeast contamination ranging from 1.0 to 4.25 log CFU g−1. The total count of aerobic mesophilic bacteria in cooked paçocas (4.85 log CFU g−1) was also higher than in pressed paçocas (2.77 log CFU g−1) (p < 0.05). E. coli was confirmed in these samples in the range of 3.0–160 NMP g−1. Salmonella sp. was detected in 2 samples of pressed paçocas, indicating poor hygiene, inefficient heat treatment or possible cross-contamination. The results of this study demonstrate the need for greater control of the paçoca production chain through the adoption of Good Manufacturing Practices and process control, to prevent exposure of the population to aflatoxins and possible pathogenic microorganisms.

Incorporation of hydrogen-producing magnesium into minced beef meat protects the quality attributes and safety of the product during cold storage

The impact of hydrogen (H2) producing magnesium (Mg) incorporation into minced beef meat (MBM) on the quality and safety of the product was investigated. The H2-producing Mg (H2-P-Mg)-incorporated MBMs were vacuumed (VP) and stored at 4 °C for 12 days. Other MBMs were vacuumed and gassed with H2 or N2. At the end of storage, the lowest browning index values were for H2 and H2-P-Mg samples. H2- PMg and VP methods generally decreased the counts of mesophilic and psychrotrophic bacteria and yeast molds and restricted the formation of thiobarbituric acid reactive substances and biogenic amines. Heat mapping, PCA, and multivariate analysis methods confirmed chemical analysis results. The volatile compounds were at their highest levels in the control samples at the end of storage, followed by H2, N2, H2-P-Mg, and VP samples. Using the H2-P-Mg method in MBM preparation could protect the quality characteristics and safety of the product during cold storage.

Effect of the High Hydrostatic Pressure Process on the Microbial and Physicochemical Quality of Shalgam.

The processing of shalgam requires the use of an appropriate processing technique due to yeast overgrowth. With advancements in processing technology, high hydrostatic pressure (HHP) as nonthermal and nonchemical preservation has gained attention for its potential. Response surface methodology with the Box-Behnken experimental design was used to make sense of the effects of HHP parameters, namely, pressure (100-500 MPa), temperature (20-40 °C), and time (5-15 min), on microbial and physicochemical factors (pH, total soluble solids, titratable acidity, bioactive compounds, color values). The reduction in the counts of total mesophilic aerobic bacteria, lactic acid bacteria, and yeast-mold increased proportionally with the increase of all pressure levels, application temperatures, and pressurization times (p < 0.05). Stability was maintained in pH, total solubility, and some color parameters such as L*, a*, ΔE, yellow color tone, and red color tone. All findings of the bioactive components (phenolic content, flavonoid content, antioxidant activity, and monomeric anthocyanin content) in the RSM design showed a significant change only in proportion to the square of time (p < 0.05). The optimum pressurization parameter combination of shalgam was determined as a pressure of 367 MPa, temperature of 31.9 °C, and process time of 10.5 min. Under these conditions, values of yeast and mold (Y&M) reduction, total flavonoid content (TFC), total monomeric anthocyanin contents (TMACs), titratable acidity (TA), and reducing sugar content (RSC) were obtained as 4.30 log cfu/mL, 192.89 mg QE/100 mL, 11.88 mg/100 mL, 2.41 glacticacid/L, and 6.78 mg/100 mL, respectively. In particular, the findings in the basic color parameters proved that there was no significant change in the saturated red color of the shalgam. Gallic acid, caffeic acid, chlorogenic acid, catechin, cyanidin-3-O-glucoside, malvidin-3-O-glucoside, and peonidin-3-O-glucoside derivatives are dominant phenolic and anthocyanin compounds, which are frequently found in turnip plants. No important losses in bioactive components were observed, despite changes in pressure and temperature parameters. The HHP method can be suggested to have great potential in the processing of shalgam (fermented turnip beverage) in terms of its ability to maintain the flavors, colors, and nutrients, in addition to ensuring microbiological safety when compared to other preservation methods.

Physical and chemical properties, hygienic quality and fatty acid profile in milk of lactating Lacaune dairy sheep

Abstract. In recent years, there has been globally increasing interest in dairy sheep breeding, including Lacaune sheep, which is supported by a high demand for sheep's milk on the market. This paper elaborates on the influence of a sheep's lactation stage on the physical and chemical properties, hygienic quality and content of fatty acids in milk produced by Lacaune sheep kept in intensive breeding. The research was conducted on 30 Lacaune sheep, which were tested in the early (60th day), middle (120th day) and late (180th day) stages of lactation. Density, freezing point and titration acidity were determined by applying the infrared spectrometry method, and indicators of the hygienic quality of milk, such as somatic cell count (SCC), were determined by the fluoro-opto-electronic method, and the total count of aerobic mesophilic bacteria (CFU) was determined by the flow cytometry method. The fatty acid profile of feed and milk was obtained by gas–liquid chromatography. Depending on the stage of lactation, results referring to the chemical composition of Lacaune sheep's milk showed a significant increase in the content of fat, protein, total dry matter and casein together with a significant decrease in the content of lactose in the late stage of lactation. There was also a significant increase confirmed for the concentration of urea and the freezing point in milk along with the lactation progress. Depending on the stage of lactation, milk yield in Lacaune sheep significantly decreased as lactation progressed. Analysis of the fatty acid composition in milk of Lacaune sheep proved a significant decrease in the concentrations of C4 : 0, C6 : 0, C11 : 0, C12 : 0, C13 : 0, C15 : 0, C17 : 1, C18 : 2n6 and C18 : 3n6 as well as the n6 concentrations and the n6 / n3 ratio. The opposite trend was observed for concentrations of C10 : 0, C14 : 1, C16 : 0, C16 : 1, C18 : 0, C20 : 2, C18 : 3n3, C20 : 3n6, C20 : 5n3 and C22 : 6n3 as well as for the n3 concentrations. When compared to the early lactation stage, the C18 : 3n6 and n6 concentrations were significantly lower in the late lactation stage, while the C20 : 2 and C20 : 5n3 concentrations were significantly lower in the middle lactation stage when compared to the late lactation stage. There were many significant positive and negative correlations determined between the researched properties of milk. The research results obtained with Lacaune sheep's milk can be compared to the results of other studies, except for the lower content of milk fat. This confirms the good adaptability of Lacaune sheep to different breeding conditions and the necessity to provide sheep with quality pastures for grazing.

Effect of ultrasound technique to improve quality of Iranian industrial honey by controlling crystallization process.

This experiment aimed to assess the effects of ultrasound techniques on the quality of Iranian industrial honey. Honey samples were subjected to ultrasound waves at different frequencies and various parameters. The results showed that both ultrasound treatments (30 or 42 kHz) changed the physical, biochemical, antioxidant, and antibacterial characteristics of honey. Ultrasound treatments at 20 or 45°C for 1, 5, or 10 min reduced moisture, acidity, sugars, ABTS levels, 5-hydroxymethylfurfural content, clostridium, aerobic mesophilic bacteria count, and osmophile count while increasing diastase, phenol, and proline levels. Ultrasound treatment of honey samples at 30 and 42 kHz and different temperatures for varying durations led to a decrease in acidity after 90 and 180 days. Treating honey samples with 42 kHz ultrasound at 45°C for 10 min led to a significant reduction in the amount of reducing sugar. Ultrasonication at different frequencies and temperatures led to higher levels of phenol, ABTS, and proline production, along with a considerable decrease in the total count of aerobic mesophilic bacteria. Our study unveils the potential of ultrasonication to enhance honey quality through multifaceted improvements. Treatment significantly augmented phenolic content and antioxidant capacity, opening avenues for novel honey preservation and quality enhancement strategies. Additionally, ultrasonication effectively controlled honey crystallization while simultaneously improving biochemical, antioxidant, and antibacterial properties. This demonstrates its potential as a comprehensive strategy for honey quality improvement.

Use of encapsulated pomegranate seed oil in novel coarse and nanosized materials for improving the storage life of strawberry

Different-sized pomegranate seed oil-based emulsions (coarse (CsP) and nanoemulsions (NsP): 1246 and 325 nm) were successfully prepared. Strawberries treated with NsP and CsP showed a significant decrease (p < 0.05) in yeast-mold counts (TMY) by 1.80 log CFU g−1, and mesophilic aerobic bacteria counts (TMAB) decreased (p < 0.05) by 0.91 log CFU g−1, respectively. CsP- and NsP-treated strawberries had a TPC of 74.45 and 82.35 mg GAE kg−1, respectively, while control samples had a TPC of 44.24 mg GAE kg−1. The strawberries treated with NsP exhibited the highest antioxidant capacity with 179.44 mol TEAC g−1. After treatment with a coarse emulsion, severity levels of A. niger and B. cinerea were 60 and 73 % while the nanoemulsion treatment significantly reduced severity levels to 55.3 and 56 %. The coarse and nanoemulsions may have potential use within the food industry owing to their antioxidant and antifungal properties as well as their ability to enhance strawberry quality and function.

Tracking the microbial communities from the farm to the processing facility of a washed-rind cheese operation.

Milk residue and the accompanying biofilm accumulation in milking systems can compromise the microbial quality of milk and the downstream processes of cheese production. Over a six-month study, the microbial ecosystems of milk (n = 24), tap water (n = 24) and environmental swabs (n = 384) were cultured by plating decimal dilutions to obtain viable counts of total aerobic mesophilic lactose-utilizing bacteria (lactose-M17), lactic acid bacteria (MRS), yeasts and molds (Yeast, Glucose, Chloramphenicol (YGC) medium). Viable aerobic lactose-M17 plate counts of milk remained well below 4.7 log CFU/ml over five of the months, except for 1 week in November where milk at the facility exceeded 5 log CFU/ml. Swab samples of the farm milking equipment showed consistent viable counts after sanitation, while the bulk tank swabs contained the lowest counts. Viable counts from swabs of the facility were generally below the detection limit in the majority of samples with occasional residual contamination on some food contact surfaces. Extracted DNA was amplified using primers targeting the V3-V4 region of the 16S rRNA gene, and the amplicons were sequenced by MiSeq to determine the shared microbiota between the farm and the processing facility (8 genera). Culture independent analysis of bacterial taxa in milk, water and residual contamination after sanitation with swab samples revealed the shared and distinct microbiota between the sample types of both facilities. Amplicon sequence variants (ASVs) of the V3-V4 region of the 16S rRNA gene revealed that the microbiota of milk samples had lower diversity than water or environmental swabs (279 ASVs compared to 3,444 in water and 8,747 in environmental swabs). Brevibacterium and Yaniella (both Actinomycetota) were observed in all sampling types. Further studies will include whole genome sequencing of Brevibacterium spp. isolates to determine their functionality and diversity within the system.

The Physicochemical, Textural, Microbiological and Sensory Properties of Skimmed Buffalo Milk Yoghurt with Tragacanth Gum During Storage.

In the food industry, research interest in the functional effects of natural polysaccharides from plants has increased in recent years. Tragacanth gum is used in dairy products because of its stabilising, thickening, fat-replacing and prebiotic properties. However, skimmed milk is considered a significant commercial loss in the production of buffalo clotted cream. Therefore, the aim of the present study is to investigate the potential of tragacanth gum in the production of yoghurt from buffalo milk residues with different concentrations of tragacanth gum (0.5, 1 and 1.5 g/L). Skimmed buffalo milk with different concentrations of tragacanth gum was pasteurised and, after cooling at 45 °C, a starter culture was added to each sample. All samples were fermented to a pH=4.80±0.2. The gross composition, acidity, water activity, water-holding capacity, whey separation, mass fractions of organic acids and volatile aroma compounds, counts of total aerobic mesophilic bacteria, yeasts and moulds, Lactococcus spp. and Lactobacillus spp. as well as sensory and textural properties were analysed during 15 days storage. The results showed that the use of tragacanth gum increased the dry matter mass fraction, water-holding capacity and mass fraction of proteins in the samples, while whey separation decreased as the concentration of gum increased. The addition of gum improved textural properties and hardness of the yoghurt. In terms of consistency, the sample with 1 g/L tragacanth gum was the most reliable. In the control group, the total aerobic mesophilic bacteria count was highest on the first and last day of storage. According to the results of the sensory evaluation, the sample with 0.5 g/L tragacanth gum was the most favourable. Research has shown that the use of stabilisers in varying ratios improves the quality of yoghurt made from fat-free buffalo milk, which is a by-product of industrial production. So instead of ending up as industrial waste, it is recycled and its value is increased.

Effects of thermal and nonthermal treatments on microorganisms, pyrrolizidine alkaloids and volatile compounds in oregano (Origanum vulgare L.)

Effects of steam sterilization, gamma-irradiation, UV-irradiation and ozonation on microbial inactivation, pyrrolizidine alkaloid degradation and volatile compound profile in oregano were investigated. Steam sterilization and gamma-irradiation were the most effective treatments in inactivating microorganisms. These treatments resulted in 0.87–2.15 log reductions in total aerobic mesophilic bacteria counts and reduced yeast-mold and Enterobacteriaceae counts below the detectable level. Steam sterilization caused increased levels of pyrrolizidine alkaloids (PAs) and decreased levels of their N-oxide forms (PANOs) demonstrating a simultaneous conversion of PANOs into the corresponding PAs. Ozone treatment caused significant decreases in the levels of individual and total PAs/PANOs. After ozone treatment, decreases of 54.4, 53.9, 61.6 and 61.4% were observed in the levels of europine-N-oxide, europine, lasiocarpine-N-oxide and lasiocarpine, respectively. Steam sterilization, UV-irradiation and ozone treatments significantly altered the composition of the volatile compounds of oregano as evidenced by decreased levels of major components and the formation of some new compounds.