Search Results (465)

To study the effect of cold plasma (CP) on the refrigerator shelf life of coconut water, microorganism growth and diversity and physicochemical properties were investigated. Results indicated that CP treatment did not cause significant color changes in coconut water, with turbidity remaining lower than the control even after 6 days of storage. Enzymatic activity analysis revealed reduced polyphenol oxidase (PPO) and peroxidase (POD) levels in treated samples. Specifically, the 12 s CP treatment resulted in the lowest antioxidant capacity values: 15.77 Fe²⁺/g for ferric reducing antioxidant power (FRAP), 37.15% for DPPH radical scavenging, and 39.51% for ABTS⁺ radical scavenging. Microbial enumeration showed that extended CP treatment effectively inhibited the growth of total viable counts, psychrophilic bacteria, lactic acid bacteria, and yeast. High-throughput sequencing identified Leuconostoc, Carnobacterium, and Lactobacillus as the dominant bacterial genera. During storage, Carnobacterium was the primary genus in the early stage, while Leuconostoc emerged as the dominant genus by the end of the storage period. In summary, CP as an effective non-thermal technology was able to maintain quality and antioxidant capacity, inhibit microbial growth, and delay the spoilage in coconut water to help extend the refrigerated shelf life of the product. Full article

Yeasts possess a range of environmental adaptations that allow them to colonize soil and sand. They can circulate seasonally between different components of lake ecosystems, including beach sand, water, and the coastal phyllosphere. The accumulation of people on beaches promotes the development and transmission of yeasts, posing an increasing sanitary and epidemiological risk. The aim of this study was to determine the species and quantitative composition of potentially pathogenic and pathogenic yeasts for humans present in the sand of supervised and unsupervised beaches along the shores of lakes in the city of Olsztyn (northeastern Poland). The study material consisted of sand samples collected during two summer seasons (2019; 2020) from 12 research sites on sandy beaches of four lakes located within the administrative boundaries of Olsztyn. Standard isolation and identification methods used in diagnostic mycological laboratories were applied and are described in detail in the following sections of this study. A total of 259 yeast isolates (264, counting species in two-species isolates separately) belonging to 62 species representing 47 genera were obtained during the study. Among all the isolates, five were identified as mixed (two species from a single colony). Eight isolated species were classified into biosafety level 2 (BSL-2) and risk group 2 (RG-2). The highest average number of viable yeast cells was found in sand samples collected in July 2019 (5.56 × 10² CFU/g), August, and September 2020 (1.03 × 10³ CFU/g and 1.94 × 10³ CFU/g, respectively). The lowest concentrations were in samples collected in April, September, and October 2019, and October 2020 (1.48 × 10² CFU/g, 1.47 × 10² CFU/g, 1.40 × 10² CFU/g, and 1.40 × 10² CFU/g, respectively). The results indicate sand contamination with yeasts that may pose etiological factors for human mycoses. In light of these findings, continuous sanitary-epidemiological monitoring of beach sand and further studies on its mycological cleanliness are warranted, along with actions leading to appropriate legal regulations. Full article

The objective of this study was to evaluate the effects of feeding a combination of chicory–plantain silage and supplementing Se yeast on the response of early-lactating ewes to induce subclinical mastitis. Polypay ewes (n = 32) were fed either chicory–plantain silage or grass silage and supplemented with 3.6 mg Se yeast/ewe/day for approximately 2 months prior to the infusion of S. uberis into both mammary glands (i.e., intramammary infection or IMI). The ewes had a typical subclinical mastitis response with an 8-fold increase in milk somatic cell count within 24 h post-IMI, a decrease in milk yield, and changes in all milk components measured. The ewes experienced a mild systemic inflammation post-IMI as determined by an increase in rectal temperature and decrease in feed and water intake and, in blood, by an increase in the concentration of ceruloplasmin, haptoglobin, and myeloperoxidase and a decrease in paraoxonase, Zn, advanced oxidation protein products, and hematocrit with no effect on pro-inflammatory cytokines. No effect of silage type, likely due to a low concentration of secondary compounds, or Se supplementation was detected in response to IMI. In summary, the subclinical mastitis model used was effective in mounting an inflammatory response, although this was mild; however, feeding chicory–plantain silage with a low concentration of secondary compounds and supplementing Se yeast had no significant effect on the response of ewes to mammary infection. Full article

Utilizing edible films/coatings promises to extend the shelf life of fruits by controlling various physiological parameters (e.g., respiration and transpiration rates), maintaining firmness, and delaying fruit senescence. The influence of composite-based edible coatings made from sodium or calcium caseinate: carboxymethyl chitosan (75:25) on the postharvest quality of fresh blueberries was assessed over a 28-day storage period, on the basis of weight loss and changes in pH, firmness, color, titratable acidity, soluble solids content, mold and yeast count, and respiration rate. The pH of the blueberries increased over the period of storage, with significant differences observed between uncoated and coated (e.g., pH was 3.89, 3.17, and 3.62 at the end of the storage time for uncoated, Ca 75-1% SO, and Na 75-1% SO, respectively. Desirable lower pH values at the end of storage were obtained with the calcium caseinate formulations. Over the duration of storage, other quality parameters (e.g., firmness) were better retained in coated fruits compared to the uncoated (control) one. At the last storage day, the firmness of the uncoated sample was 0.67 N·mm⁻¹ while the sodium and calcium caseinate was 0.63 and 0.81 N.mm⁻¹, respectively. Moreover, the microbial growth was reduced in coated fruits, indicating the effectiveness of coatings in preserving fruit quality. The mold /yeast count was 1.4 and 2.3 log CFU/g for CaCa 75-1% SO and NaCa 75-1% SO compared with uncoated with 4.2 log CFU/g. Adding soybean oil to the caseinate–carboxymethyl chitosan composite edible coating has the potential to positively influence retention of various quality parameters of blueberries, thereby extending their shelf life and maintaining overall quality. Further research could explore the optimization of coating formulations and application methods to enhance their effectiveness in preserving fruit quality during storage. Full article

This study analyzes the aromatic profiles of kiwi-based fermented beverages, inoculated with varying proportions of milk kefir grains and incubated under different shaking rates. The experiments were designed using response surface methodology and three consecutive batch cultures were performed under each experimental condition. At the end of each fermentation, the grains were separated from the beverage and reused as the inoculum for fermenting fresh kiwi juice in the subsequent batch. Based on the results, together with the previously determined microbiological and chemical characteristics, two beverages were identified as having broader aromatic profiles, lower contents of sugars, ethanol, and acids, and high counts of lactic acid bacteria (LAB) and yeasts (>10⁶ CFU/mL). These beverages were produced under relatively low agitation rates (38 and 86 rpm) and high inoculum proportions (4.33% and 4.68% w/v) during the second and third batch cultures, respectively. Over 28 days of refrigerated storage, the pH values of both beverages remained relatively stable, and the LAB counts consistently exceeded 10⁶ CFU/mL. Yeast counts, along with the production of ethanol, glycerol, lactic acid, and acetic acid, increased slightly over time. In contrast, the concentrations of citric acid, quinic acid, total sugars, and acetic acid bacteria declined by day 28. Full article

Modified nano-clays, alone or combined with probiotics, may offer a novel and sustainable approach to improve ruminal fermentation and mitigate CH₄ emissions in high-fiber diets. This study evaluated the properties and effects of modified nano-bentonite (MNB), with or without yeast (Saccharomyces cerevisiae), compared to natural bentonite (NB) and monensin, using the in vitro gas production (GP) technique. The substrate used was a basal diet composed primarily of forage (Trifolium alexandrinum clover) in a 70:30 forage-to-concentrate ratio. The treatments were a control group receiving the basal diet without additives; a monensin-added diet containing 40 mg/kg of dry matter (DM); a yeast-added diet with Saccharomyces cerevisiae at 2 × 10⁸ CFU/g of DM; a NB clay-added diet at 5 g/kg of DM; and MNB diets added at two levels (0.5 g/kg of DM (MNB_Low) and 1 g/kg of DM (MNB_High)), with or without S. cerevisiae. MNB showed a smaller particle size and improved properties, such as higher conductivity, surface area, and cation exchange capacity, than NB. Sulfur and related functional groups were detected only in MNB. No differences were observed in total GP, while both the monensin diet and the MNB_High-with-yeast diet significantly reduced CH₄ emissions compared to the control (p < 0.05). The MNB_High-without-yeast combination significantly (p < 0.05) reduced hemicellulose degradation, as well as total protozoal counts, including Isotricha and Epidinium spp. (p < 0.05), compared to the control. Ammonia levels did not differ significantly among treatments, while NB and MNB_High diets tended to have (p = 0.063) the highest short-chain fatty acid (SCFA) concentrations. These findings suggest the potential modulatory effects of yeast and MNB on rumen fermentation dynamics and CH₄ mitigation. Full article

The lyophilised sumac (Rhus coriaria L) extract (LSE), in amounts of 0.25, 0.5, 1.0, 1.25, and 1.5 g/100 ml of juice, was incorporated into carrot juice, and its properties were assessed after 24, 48, and 72 h. A product without the lyophilised sumac extract served as the control. The highest supplementation level enhanced the physicochemical characteristics of carrot juice, increasing carotenoid and polyphenolic contents by 22% and 70% on the first day. The LSE significantly boosted antioxidant activity, yielding over a tenfold increase, while reducing capacity was elevated more than sevenfold. LC-MS analysis confirmed the presence of bioactive compounds, such as chalcones, flavonols, flavones, and phenolic acids, further validating the extract’s functional potential. Acidity and redness exhibited a proportional increase with the rising concentrations of the additive used. Additionally, microbial growth, including aerobic mesophiles, yeasts, and moulds, was markedly suppressed. After 72 h, the total count of aerobic microorganisms and yeasts/mould was reduced by 5.64 log and 4.94 log, respectively, compared to the control. The lyophilised sumac extract, rich in valuable bioactive compounds with antioxidant properties, effectively preserved freshly pressed carrot juice, mitigating spoilage and extending its shelf life. This form of sumac serves as a sustainable beverage additive, minimises food waste, and aligns with clean-label trends. Full article

Edible insects are gaining traction worldwide; however, the existing data regarding their microbiological quality remain inadequate. This study investigated the bacterial communities and microbiological quality of five types of frozen edible insects commercially available in Thailand. Amplicon sequencing revealed Firmicutes (Bacillota) and Proteobacteria (Pseudomonadota) as the main phyla across all samples; Bacteroidota was predominant in house crickets, Actinobacteriota in silkworms, and Desulfobacterota was exclusively found in house and mole crickets. Culture-based assays showed total viable counts, lactic acid bacteria, yeasts–molds, and spore-formers ranging from 3.41–6.58, 2.52–7.41, 1.83–5.62, to 2.00–4.70 log CFU·g⁻¹, respectively. In some samples, Enterobacteriaceae and Escherichia coli, key hygiene indicators, reached 5.05 and 2.70 log CFU·g⁻¹, respectively. Among foodborne pathogens, presumptive Bacillus cereus was found to vary from <1.70 to 3.93 log CFU·g⁻¹, while Clostridium perfringens and Staphylococcus aureus were under the quantitation limit, and Salmonella was absent. Overall, the results indicate significant variation in microbial diversity and quality among different insect types. The high levels of microbial hygiene indicators and foodborne pathogens in some samples raised food safety concerns and point to the need to develop or implement production guidelines and microbiological criteria for frozen edible insects to ensure food safety. Full article

Pomegranates are rich in nutrients and classified among ready-to-eat fruits and vegetables. Although this ready-to-eat produce offers convenience, it presents risks associated with pathogenic microorganisms, highlighting the need for pre-sale disinfection. Ultraviolet light-emitting diodes (UV-LEDs) constitute an innovative non-thermal processing technology for food products, offering reduced heat generation and lower energy consumption compared to traditional ultraviolet (UV) irradiation methods. This study analyzed the effects of UV-LED technology on pomegranate seed quality over 0 to 5 days of storage. The results demonstrated significant increases in anthocyanins, polyphenols, ascorbic acid, and the antioxidant capacity in pomegranate following treatment, peaking on day 3. In contrast, the control group showed declining trends. After treatment, the aerobic mesophilic counts and counts of mold and yeast levels during storage measured between 2.73–3.23 log CFU/g and 2.56–3.29 log CFU/g, respectively, significantly lower than the control group. Non-targeted metabolomic analysis showed that UV-LED treatment prompted modifications in the biosynthetic pathways of flavonoids, flavonols, and anthocyanins. The expression of peonidin-3-O-rutinoside chloride increased by 46.46-fold within the anthocyanin biosynthesis pathway. In conclusion, UV-LED treatment represents a potential approach to the disinfection of ready-to-eat fruits and vegetables. Full article

Traditional methods of microbial quantification of irrigation water using colony counts from agar culture require dedicated laboratory space and trained personnel, limiting their on-site applicability. Dehydrated Petrifilm™ plates are a simpler alternative but still require 2–3 days to culture. Adenosine triphosphate (ATP) tests may offer a fast and reliable method for quantifying microbes in water. In this study, we compared (a) microbial quantification based on ATP assays with Petrifilm™-based assays, and (b) we evaluated the effectiveness of cold plasma or ozone treatments in controlling microbial growth at various oxidation–reduction potential (ORP) levels. Lake water was recirculated through an ozone or cold plasma treatment system until a target ORP of 700 mV was reached. Samples were collected at various ORP levels and plated for aerobic bacteria and yeast and mold counts using Petrifilm™ plates. The free and total ATP concentrations were measured using the Hygiena EnSURE luminometer and its accompanying free and total ATP swabs. Microbial ATP was calculated by subtracting the free from the total ATP. Cold plasma and ozone showed similar effects on microbial inactivation at 700 mV (p < 0.05). Both treatments achieved complete fungal inactivation at 600–700 mV ORP, bacterial inactivation at 600 mV ORP, and near-complete inactivation of microbial ATP at 600–700 mV. A moderate positive correlation (Pearson’s correlation = 0.39 and Spearman’s rank correlation = 0.39) was observed between the Petrifilm™ bacterial counts and microbial ATP levels, suggesting ATP quantification could complement Petrifilm™ for rapid and non-selective onsite microbial assessment of irrigation water. Full article

Honey is a sugar-rich product produced by Apis mellifera bees, with significant variability in properties due to the influence of geographic and climatic conditions and the predominant flora in the production region. Economically, beekeeping is an activity that generates profit and fulfills environmental and social functions, reinforcing the pillars of sustainability. This study aimed to characterize samples of honey sold in southern Brazil, including physicochemical analyses, the detection of microbiological contaminants with potential impact on human health, and the detailed identification of bacterial composition through the Next-Generation Sequencing (NGS). The present study was divided into five main stages: (1) sample collection; (2) sample fractionation; (3) physicochemical analysis; (4) microbiological analysis; (5) 16S metataxonomy analysis. The physicochemical analyses agreed with the regulated values, indicating the good quality of the honey and the absence of adulteration. The microbiological analyses indicated the absence of Salmonella spp., in addition to a low count of total coliforms. The limits for molds and yeasts were exceeded in three samples, indicating non-compliance with current MERCOSUR legislation. Metabarcoding analysis identified a total of 15,736 OTUs divided into three different genera: Bacillus (41.54%), Lysinnibacillus, and Rossellomorea, all belonging to the Bacillaceae family. Some pathogenic species were identified, namely the Bacillus cereus group and Bacillus pumilus. Our results point to an increased need for surveillance, as honey contamination can lead to public health problems, requiring improvements in legislation and control parameters. 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

The Demarcated Region of Madeira (DRM) is one of the oldest wine regions in Portugal, where the famous Madeira Wine (MW) is produced by spontaneous fermentation using endogenous yeasts. Several studies reported the role of endogenous Saccharomyces cerevisiae strains in the regional identity of wines, but only a few studies have been published in the DRM. The PCR-Interdelta (Polymerase Chain Reaction-Interdelta) analysis is a reliable method for S. cerevisiae strain identification. Here, we report the S. cerevisiae strains isolated from six Vitis vinifera grape varieties, namely, Tinta Negra, Boal, Sercial, Verdelho, Malvasia de São Jorge, and Complexa, which are widely used in MW production. During the 2020 campaign, eleven samples were collected from licensed vineyards and a winery, and submitted to spontaneous microfermentations and yeast isolation. Of the 1452 isolates counted, 1367 (94.2%) presented morphological characteristics of S. cerevisiae. We randomly selected 330 isolates from the positive colonies for strain identification. First, the PCR-Interdelta was optimized in ten commercial strains, using δ2–δ12 and δ12–δ21 pairs of primers, and δ2–δ12 primers were selected to screen the 330 isolates. We detected three fermentative profiles and a total of 25 PCR-Interdelta patterns were obtained, representing 7.6% of intraspecific variability, starting with the first non-official collection. The findings underscore the pivotal role of S. cerevisiae strain diversity in shaping the regional identity and quality of wines, with molecular tools like PCR-Interdelta analysis proving essential for monitoring intraspecific variability. Full article

Untreated olive oil mill wastewater (OOMW) from conventionally farmed olives was used in bread production to create a new functional product. Two types of bread were developed with 50% OOMW (EXP-1) and 100% OOMW (EXP-2) replacing water. Two leavening processes were tested: sourdough inoculum (S) vs. biga-like inoculum (B), with controls (CTR) without OOMW addition. The doughs were monitored throughout the acidification process by measuring pH, total titratable acidity, and the development of key fermentative microorganisms. To assess the hygienic quality during fermentation, plate count techniques were employed. After baking, the breads were evaluated for various quality parameters, including weight loss, specific volume, crumb and crust colors, image analysis, and the presence of spore-forming bacteria. Volatile compounds released from the breads were identified using solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC/MS). Polyphenolic compounds were analyzed via liquid chromatography–mass spectrometry (LC-MS). To assess the functional properties of the final products, the breads were homogenized with synthetic human saliva and subjected to in vitro digestion. OOMW did not significantly affect the growth of yeasts and lactic acid bacteria (LAB) or the acidification process. However, in terms of the specific volume and alveolation, breads from the S process and OOMW had poor quality, while those from the B process had better quality. Experimental breads (EXP_B-1 and EXP_B-2) contained higher levels of alcohols (especially ethanol and isobutyl alcohol), carbonyl compounds (like benzaldehyde), esters (such as ethyl caproate and ethyl caprylate), and terpenes. OOMW introduced phenolic compounds like hydroxytyrosol, coumaric acid, caffeic acid, and trans-hydroxycinnamic acid, which were absent in CTR_B breads. Functionalization of EXP_B-1 and EXP_B-2 breads was demonstrated by a 2.4- and 3.9-fold increase in Trolox equivalents, respectively. However, OOMW did not reduce post-prandial hyper-glycemia, as starch digestibility was similar between CTR_B and EXP_B breads. The sensory analysis, which focused solely on the visual, structural, and olfactory characteristics of the breads, excluding taste testing to prevent potential health risks from residual pesticides, showed a high appreciation for EXP_B-1 and EXP_B-2 breads, scoring higher than CTR_B in the overall assessment. Full article

This study investigated the role of Lacticaseibacillus paracasei K-68 (LABK) and cocktail LAB (LABC) as silage inoculants to enhance corn silage fermentation quality and microbial stability. Silage spoilage is primarily caused by undesirable microbes such as Clostridium, Klebsiella, yeasts, and molds. The isolated LAB strain K-68 exhibited strong antibacterial and antifungal activity, particularly against spoilage organisms, and was identified as L. paracasei. Experimental silages inoculated with LABK or a LABC significantly improved fermentation profiles, with reduced pH and increased lactic acid levels. Microbial counts revealed that LAB-inoculated silages had higher LAB counts and significantly reduced yeast and mold populations. Furthermore, there were no significant differences in acetic acid, isobutyric acid, and propionic acid levels. High-throughput sequencing confirmed that LABK-treated silage was dominated by Lacticaseibacillus paracasei, whereas LABC-treated silage supported more diverse microbiota, including Pediococcus pentosaceus, Lacrimispora xylanolytica, and Levilactobacillus brevis. Both treatments suppressed spoilage-associated genera such as Clostridium and Klebsiella. Furthermore, correlation analysis showed that Lacticaseibacillus abundance was positively associated with lactic acid production and negatively correlated with pH and yeast levels. L. paracasei K-68 is a promising bio-inoculant for corn silage production since it promotes beneficial microbial dominance and suppresses spoilage organisms better than cocktail LAB. Full article