Yeast Counts Research Articles

Psychrotrophic Bacteria and Yeast Populations in Turkish White and Tulum Cheeses

In this study, pH and microbiological (psychrotrophic bacteria and yeast) properties of White and Tulum cheeses were investigated. According to the results of our study, the lowest pH value identified was 4.42, and the highest pH was 5.84 in the cheese samples. Psychrotrophic bacteria counts ranged from 4.15 to 6.21 log CFU/g for White cheese and 4.02 to 6.15 log CFU/g for Tulum cheese. Psychrotrophic yeast counts ranged from 2.98 to 7.58 log CFU/g for White cheese and 2.99 to 6.77 log CFU/g for Tulum cheese. The highest values of psychrotrophic yeast were detected in the Tulum cheese samples. As a result, it was determined that the numbers of psychrotrophic bacteria and yeast were high in both Tulum and White cheese samples. These high numbers of psychrotrophic microorganisms during cheese storage in the refrigerator may increase even further and reduce shelf life. To extend the shelf life of these cheeses, it is recommended to ensure hygienic handling practices and explore the use of natural preservatives or modified atmosphere packaging.

Process optimization of thermosonicated modhusuleng (polygonum microcephalum) leaf juice for quality enhancement using response surface methodology

The present study investigated the impacts of pasteurization and thermosonication on various aspects of modhusuleng (Polygonum microcephalum) leaf juice, including its physico-chemical, functional, and microbial attributes (total plate count, yeast and mold count). Juices underwent thermosonic treatments at varied durations (30, 45, and 60 min) and temperatures (30, 40, and 50 °C), utilizing two distinct frequencies (33 and 44 kHz). The application of pasteurization (PS) and thermosonication (TS) did not exhibit any noticeable effects on pH, total soluble solids (TSS), or titratable acidity (TA). Post TS, there were enhancements in antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC), cloudiness value, browning index, total carotenoid content, and chlorophyll content. However, the ascorbic acid content in the leaf juices decreased post TS. Process optimization was carried out through the application of response surface methodology (RSM). For 33 kHz, the predicted values were - Antioxidant - 68.23 %, TPC - 183.11 mg GAE/100 mL, TFC - 3.15 mg QE/mL, and Ascorbic acid - 24.45, while for 44 kHz, the values were obtained as - Antioxidant - 60.80 %, TPC - 212.97 mg GAE/100 mL, TFC - 3.40 mg QE/mL, and Ascorbic acid - 25.53. The model's suitability is highlighted by the small difference between the expected and actual values. The results revealed that leaf juice samples treated at 50 °C with a frequency of 44 kHz for 60 min exhibited higher TPC, TFC, and antioxidant activity when compared to samples subjected to alternative temperature and frequency conditions. TS also led to a significant reduction in bacterial populations in the juices. While thermal treatment rendered the microbes inert, it adversely impacted the quality indices. The study suggests that modhusuleng juice quality features can be preserved even after undergoing thermosonic processing. TS is suggested as a favorable technique for modhusuleng leaf juice processing, given its potential to enhance antioxidant activity, preserve quality features, and reduce bacterial populations.

Augmenting the Quality and Shelf Life of Ras Cheese by Adding Microencapsulated Allspice Berry Extract Nanoemulsion

AbstractThe current study was achieved to increase phenolic compounds and antioxidant content in Ras cheese by microencapsulation of the nanoemulsion of extract from the berries of allspice. The microencapsulation of the extract nanoemulsion from the berries of allspice using maltodextrin, whey protein concentrate, and guar gum was prepared by a freeze-drying process. The extract was cured, and nanoemulsion forms were prepared and evaluated for the antimicrobial effect and phenolic compound content. The morphology of microcapsules was studied by transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR) analysis. The prepared microcapsules were added to Ras cheese using ratios (1, 2, and 3% (w/w)) and then stored for 120 days for ripening and examined chemically, microbiologically, and organoleptically. The results indicated that the allspice extract in both forms has shown an inhibitory effect on all microorganisms. Moreover, the major phenol compound in allspice berry extract was gallic acid with quantities of 15,991 µg/g. Furthermore, the microcapsule efficiency was recorded at 80.97% and spherical with a diameter of 380 µm, while the nanoemulsion of extract as the core has a size of around 320 nm. The total lactic acid bacteria counts in all samples gradually declined during the ripening period. The mold and yeast count was not detected in fresh cheeses and appeared for cheese control more than in cheese with the extract. Cheese control and treatments contained lower titratable acidity, total nitrogen, soluble nitrogen, and ash ratio than the other cheese with extract treatments. The total volatile fatty acids (TVFAs) were increased through the storage period in all cheese treatments. Correspondingly, Ras cheese acceptability for sensory evaluation increased during the ripening periods in all treatments, whereas cheese supplemented with 1% microcapsules ranked the highest score for flavor and body and texture during storage gaining a high accepted point of 93.62.

Dietary supplementation with copper nanoparticles enhances broiler performance by improving growth, immunity, digestive enzymes, and gut microbiota

The aim of this work is to measure the influence of copper nanoparticles (CuNPs) on growth performance, carcass traits, renal and hepatic indices, immunity, lipid profile, antioxidant status, blood minerals, digestive enzymes, and cecal microbiota in broilers. 300 unsexed one-week-old Arbor Acre broiler chicks in total were randomly assigned into 5 treatment groups of 60 chicks per eachwhich were divided into 5 replicates of 12 chicks. The 1st group (G1) was given basal diet (only); the 2nd group (G2), the 3rd group (G3), the 4th group (G4) and the 5th group (G5) were given basal diet treated with CuNPs at a rate of 5, 10, 15, and 20 mg/kg diet, respectively. The result revealed a significant improvement (P < 0.01) in performance paramters where the best values of body weight, weight gain, and feed conversion ratio were achieved at 15 mg/kg diet (CuNPs). Moreover, CuNPs supplementation significantly (P < 0.05) improved carcass traits specially carcass, dressing, giblets, and liver percentage, particularly at 15 mg/kg diet which revealed the best results. Furthermore, CuNPs supplementation at all tested levels increased the immune organ's weight (spleen and thymus). Plasma total protein and globulin were increased with CuNPs supplementation at levels 10 to 20 mg/kg diet. CuNPs supplementation (10-20 mg/kg diet) significantly improved liver and renal function by lowering the levels of AST, creatinine and uric acid. Moreover, CuNPs supplementation significantly (P < 0.05) improved lipid profile indicated by decreased the levels of cholesterol, triglyceride, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol as well as malondialdehyde (MDA). CuNP supplementation significantly improved broiler immunity indicated by increased IgA, IgM, complement (C3) and lysozyme, where CuNPs at 15 and 20 mg/kg diet revealed the best results. CuNPs supplementation increased reduced glutathione (GSH), total antioxidant capacity (TAC), and superoxide dismutase (SOD) as well as increased blood minerals (Cu, Fe, P, and Ca). Also, the digestive enzymes of broiler chicks treated with CuNPs significantly increased (P < 0.05), such as lipase, protease, and amylase enzymes. The findings revealed a significant elevation in total bacterial count (TBC) and lactic acid bacteria and significantly decreased total yeast and mold count (TYMC), E. coli, Salmonella and Coliform. In conclusion, CuNPs supplementation significantly improves performance, carcass yield, renal and hepatic indices, lipid profile, immunity, antioxidants, blood minerals, digestive enzymes, and cecal microbiota of broiler chicks.

Effects of fruit and vegetable waste addition on corn stalk silage quality.

In this study, we explored the effect of fruit and vegetable waste addition on the quality of corn stalk silage. Corn stalks were ensiled 20 days after ear harvesting and mixed with fruit and vegetable waste (FVW) consisting of apple, orange, broccoli, and Chinese cabbage waste as 3% of fresh matter. Fruit waste consisted of solid residue obtained after juicing, and vegetable waste was collected from farms and cut into small pieces (2 to 3 cm). The materials were stored anaerobically in 20-L silo buckets and opened after 60 days of fermentation. There were significant differences in dry matter (DM), acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrient (TDN), and relative feed value (RFV) levels in FVW derived from all tested raw materials (p<0.05). Corn stalk mixed with orange waste (CSOW) had the highest DM content (28.77%), lowest ADF and NDF content (47.78% and 26.62% of DM, respectively), and highest TDN and RFV content (69.21 and 133, respectively). After 60 days, there were significant differences in all chemical parameters examined (p<0.05). Corn stalk mixed with broccoli waste (CSBW) had the lowest DM loss (2.23%), and the CSOW group had the lowest NDF and ADF content and highest in vitro DM digestibility. CSBW had the lowest pH and ammonia nitrogen content, but the highest lactic acid/acetic acid ratio among the treatment groups. CSOW had the highest lactic acid content (2.27% of DM). The microbial contents of each group differed only in lactic acid bacteria counts before and after ensiling, showing a slight increase (p>0.05) and significant decreases in yeast and mold counts (p<0.05) after ensiling. These findings confirmed that mixing various FVW materials, particularly orange waste, with corn stalks improved the nutritional value of silage. Adding broccoli waste resulted in better fermentation quality than the addition of other FVW materials.

The effect of lemon juice addition and cold storage on the total phenolic content and antioxidant activity of cold mate tea

Although mate tea, made from the infusion of the Ilex paraguariensis plant, is typically consumed cold, it should be properly prepared, stored, and consumed within the appropriate time frame to fully appreciate the tea’s aroma and components. This study aimed to investigate the impact of adding lemon juice to mate tea and cold storage on the total phenolic content, antioxidant activity, and total mold and yeast count of the tea. It was hypothesized that the addition of lemon juice would increase the total phenolic content and antioxidant activity and extend shelf life. At the start of storage, the sample with 2% (v/v) lemon juice added showed the highest total phenolic content (14.06 ± 0.05 mg GAE/100 mL). The antioxidant scavenging activity of the tea samples was investigated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. While all the studied sample showed higher DPPH inhibition than the control group, the highest value was found for tea sample with 4% lemon addition on 3rd day (97.618 ± 1.429). No mold or yeast growth was observed in the control group and the samples with 2% and 4% lemon juice addition up to day 21. In the sensory evaluation, the tea that contained 4% lemon juice was the most preferred. In conclusion, if mate tea is prepared and stored appropriately, it can maintain its antioxidant capacity for an extended period without the formation of harmful molds or yeasts and any deterioration in its sensory properties.

The effect of washing for the shelf-life parameters of spinach (Spinacia oleracea L.)

Spinach is a very popular green leafy vegetable because of its versatile usage and beneficial for the health. However, spinach may contain several pathogen bacteria: Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Citrobacter spp., Shigella spp. and Listeria monocytogenes, which can cause several serious health problems. This study investigates the effects of washing with citric acid for the shelf-life parameters of spinach in comparison to the effect of washing with water and control. Washing of spinach with 0.5% citric acid solution decreased the elasticity of the spinach leaves, as well as the chlorophyll content. On the other hand, the total plate count, as well as the yeast and mold count could be decreased with this treatment, but difference was not detectable at the forth storage day. The fecal indicator E. coli did not change, indicating washing was not effective in this case. Further optimisation of treatment and storage conditions may decrease microbial risk of fresh spinach consumption without decreasing its sensory quality.

Storage Stability of jaggery based sesame spread: A comprehensive study

The shelf life of a spread product is a critical factor in its formulation, production, and marketing. Consumers expect sesame spread products retain a fresh appearance, odor, and flavor for an extended period, as a longer shelf life decreases costs for both producers and consumers. Therefore, the objective of this investigation was to evaluate the storability of jiggery based sesame spread (JSS). The storability of developed JSS were of analyzed for physicochemical characteristics (Moisture, Protein, Carbohydrate, Fat, Crude fibre, Ash, Calorific value, Oil separations, Oxalic acid, Peroxide value and Acid value), Rheological parameters (Adhesiveness, Cohesiveness, Hardness and Viscosity), sensory attributes (Taste, Colour, Appearance, Spreadability, Flavour and Overall Acceptability) and microbiological quality (Standard plate count, Yeast and Mould count and Escherichia coli.) of JSS. The investigational storages were carried out for 90 days at room temperature storage (24 ± 4°C, 40-50% RH) and refrigerated (8°C, 17-20% RH) storage. The results indicated significant increase in oil separations, peroxide value, acid value, microbial counts, and sensory parameters of the spread. However, the remaining analyzed quality attributes of the spread demonstrated stability. The oil separations in spread sample were found to be highest during room temperature storage, which could be attributed to the temperature fluctuations experienced during storage. In conclusion, it is highly recommended to carefully manage the storage temperature of sesame spread to ensure its stability.

The effect of chitosan-furcellaran biopolymeric films and coatings incorporated with LL-37 and RW4 bioactive peptides on the microbiological and sensory quality of cheese

The study objective was to investigate the influence of chitosan-furcellaran films and coatings with bioactive peptides on cheese properties. The films were prepared using the casting method while the coatings by the dip-coating process. The yeast and mold count (YMC) was positive in the control Gouda after the 2nd week of storage. However, only after week 3 were yeast and mold detected in the samples covered with the RW4 film and in the coatings with no peptide or containing LL-37 (3.1–3.8 log cfu g−1). Regarding Mozzarella, a significant increase in YMC was determined after week 2 of storage in samples having coatings with no peptide or with LL-37 (6.2–6.3 log cfu g−1), whereas after the 1st week, YMC was increased in the control (6.6 log cfu g−1). The coatings with no peptide and with LL-37 demonstrated the best influence on microbiological quality, while having no negative impact on Gouda or Mozzarella sensory properties.

Evaluation of Microbial Quality of Fufu Samples Prepared Using Conventional and Mechanical Methods in Kumasi Metropolis

Aim: The study aimed at evaluating the microbial quality of conventionally (CV) and mechanically (MC) prepared fufu samples in the Kumasi Metropolis of Ghana. Study Design: The study used 2 x 5 x 2 experimental design constituting two fufu preparation methods (CV and MC), five different vending locations, and two sample types (fufu samples and water samples) from each vendor. Materials and Methods: A total of ten (10) fufu and water samples each were conveniently collected and analysed using standard microbiological procedures. Place and Duration of Study: The study was carried out in the Kumasi Metropolis of Ghana, in March 2022. Results: The total aerobic count in the conventional and mechanical prepared samples ranged from 5. 2×107cfu/g to 4.5×108cfu/g and 5. 4×107cfu/g to 1.35×108cfu/g respectively. The total aerobic count in the water samples ranged between 9.7×106cfu/ml and 1.35×109cfu/ml in (CV) and 1.53×106cfu/ml – 6.3×108cfu/ml in (MC). Both the fufu and water samples from the vendors had unsatisfactory levels of total and faecal coliform count, Staphylococcus aureus count, and yeast count irrespective of the processing method (CV and MC). Conclusion: The fufu processing methods did not influence its microbial qualities positively. Hence Good Hygienic Practices are essential to ensure its microbiological safety.

Drying Kinetics and Quality Attributes of Solar-Dried Red Peppers: A Comparative Study with Traditional and Industrial Methods

Red pepper is a valuable ingredient known for its abundance of vitamins and antioxidants. But, it usually needs to be dried for longer preservation. Hence, this research is aimed at examining the drying kinetics and quality attributes of dried red peppers utilizing various solar drying methods, in comparison with traditional open sun drying (OSD) and industrial laboratory thin layer dryers (LTLD). Analysis parameters employed include determining moisture content, measuring color properties, evaluating antioxidant capacity, analyzing capsaicinoid content, and assessing microbial presence. The drying process took place in a sunny environment with fluctuations in temperature and relative humidity as evidence of the dynamic conditions experienced within the solar dryers. It was observed that the logarithmic model was the most accurate in predicting moisture ratio over time, estimating a drying time of 25 hours to achieve 10% moisture content. The result demonstrated that direct solar dryers (DSD), indirect solar dryers (ISD), and mix mode solar dryers (MMSD) methods showed moderate changes in color parameters, with average ΔL∗, Δa∗, and Δb∗ values of -5.08, -23.71, and -13.62, respectively. The average overall color difference (ΔE) for these methods was 27.96. In addition, after comparing it to the LTLD method, which showed the highest content of phenolic compounds at 47.89%, MMSD displayed a slightly lower content of 44.71%. Similarly, MMSD exhibited higher levels of DPPH radical scavenging activity and ferric reducing power, measuring at 44.22% and 1163.75 μmol Fe2+/L, respectively. The capsaicin content remained relatively consistent across all drying methods, with MMSD, DSD, and LTLD demonstrating similar levels of approximately 31 mg/g. Although MMSD had slightly higher mold and yeast counts compared to LTLD, ISD, and DSD, it remained lower than OSD (less than 0.56 log10cfu/g). Furthermore, MMSD showed a lower total microbial count in comparison to other drying methods. These findings suggest that MMSD shows promise as a drying technique for preserving the phenolic compounds and antioxidant activity of the dried product.

Microbial assessment of commercial pet foods marketed in the United Arab Emirates

Examining the microbiological characteristics of pet food is imperative to safeguard the health and well-being of companion animals, pet owners, and the surrounding environment. Domestic animals, known for carrying harmful microorganisms, pose a significant health risk, especially in close proximity to people and children. Notably, no studies have previously investigated pet food quality in the Gulf Cooperation Council countries, in particular, the United Arab Emirates (UAE). This study examined the microbiological quality of all stock keeping units (SKUs) of pet foods marketed in UAE (n = 118). Parameters assessed include Total Aerobic Microbial Count (TAMC), Enterobacteriaceae, Total Yeast and Mold Count (TYMC), Salmonella, Listeria monocytogenes, and Clostridium species. Among the 118 samples, 33 (28%) exceeded the acceptable TAMC limit of 106 CFU/g, highlighting significant variations based on manufacturers and ingredients. Eight samples (7%) surpassed the maximum Enterobacteriaceae limit of 3 × 102 CFU/g. TYMC levels exhibited variation, with 33 (28%) exceeding the limit of 104 CFU/g. L. monocytogenes was identified in 44 (37%) of the samples, while Salmonella was not detected. Clostridium contamination was observed in 28 (24%) of the samples. Statistical analyses revealed associations between pet food characteristics and microbial quality, underscoring the imperative for international standards to ensure the safety of pet food. These findings carry significant implications for pet owners, regulatory bodies, and the pet food industry, emphasizing the need for ongoing efforts to enhance the overall quality and safety of pet food products.

The predominant lactic acid bacteria and yeasts involved in the spontaneous fermentation of millet during the production of the traditional porridge Hausa koko in Ghana

Spontaneous fermentation of cereals like millet involves a diverse population of microbes from various sources, including raw materials, processing equipment, fermenting receptacles, and the environment. Here, we present data on the predominant microbial species and their succession at each stage of the Hausa koko production process from five regions of Ghana. The isolates were enumerated using selective media, purified, and phenotypically characterised. The LAB isolates were further characterised by 16S rRNA Sanger sequencing, typed using (GTG)5 repetitive-PCR, and whole genome sequencing, while 28S rRNA Sanger sequencing was performed for yeast identification. The pH of the millet grains ranged from mean values of 6.02—6.53 to 3.51—3.99 in the final product, depending on the processors. The mean LAB and yeast counts increased during fermentation then fell to final counts of log 2.77–3.95 CFU/g for LAB and log 2.10–2.98 CFU/g for yeast in Hausa koko samples. At the various processing stages, the counts of LAB and yeast revealed significant variations (p < 0.0001). The species of LAB identified in this study were Limosilactobacillus pontis, Pediococcus acidilactici, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Pediococcus pentosaceus, Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Schleiferilactobacillus harbinensis, and Weissella confusa. The yeasts were Saccharomyces cf. cerevisiae/paradoxus, Saccharomyces cerevisiae, Pichia kudriavzevii, Clavispora lusitaniae and Candida tropicalis. The identification and sequencing of these novel isolates and how they change during the fermentation process will pave the way for future controlled fermentation, safer starter cultures, and identifying optimal stages for starter culture addition or nutritional interventions. These LAB and yeast species are linked to many indigenous African fermented foods, potentially acting as probiotics in some cases. This result serves as the basis for further studies into the technological and probiotic potential of these Hausa koko microorganisms.

Fungal population and physicochemical properties of bioethanol produced from cassava (&lt;i&gt;Manihot esculenta&lt;/i&gt;)

The quest for affordable and environmentally friendly fuel has led to the production of bioethanol from agricultural products. This study was undertaken to produce alcohol from cassava by the fermentative action of Aspergillus niger and Saccharomyces cerevisiae. The fermentation process comprised of two (2) set ups- one was fermented by Aspergillus niger and the other was fermented by Saccharomyces cerevisiae. The fermentation process lasted for 12 days and it was distilled on the 14th day. The process was monitored and controlled by carrying out physicochemical (pH, temperature, specific gravity, alcohol content) and microbiological analyses using standard methods. There was a decrease in the pH for both set ups during the course of the fermentation. The temperature was between 25.0oC to 30.5oC for both setups. The specific gravity decreased during the course of the fermentation from 1.03 to 0.01 which led to an increase in the alcohol content from 0 to 55% for the setup that involved Aspergillus niger and 1.02 to 0.03 which led to an increase in the alcohol content from 0 to 50% for the setup that involved Saccharomyces cerevisiae. There was an increase in the total fungal count from 4.4 ×102 to 5.9×102 CFU/ml from day1 to 7 and a decrease from 5.9 ×102 to 0 CFU/ml from days 7 to after distillation for the setup that involved Aspergillus niger. There was also an increase in the total yeast count from 1.6 ×102 to 2.9 ×102 from days 1 to 7 and a decrease from 2.9 ×102 to 0 from days 7 to after distillation for Saccharomyces cerevisiae. This study shows that alcohol can be successfully produced from cassava using Aspergillus niger and Saccharomyces cerevisiae.

Characterizing the antioxidant and antifungal properties of nano-encapsulated pistachio hull extract in fenugreek seed gum to maintain the quality and safety of fresh pistachio.

The quality of pistachio, one of the export products of Iran, will be decreased during storage as a result of mold spoilage, toxins production, and oil oxidation. This study aimed to investigate the capability of pistachio hull extract (PHE) loaded in fenugreek seed gum (FSG):whey protein isolate (WPI) nanoemulsion to control oil oxidation, and fungi growth in fresh pistachio nut during storage at 4°C. The total anthocyanin and total phenolic content of the PHE were 125.44 μg/g and 675.18 mg/g, respectively. The DPPH radical scavenging activity of PHE at 100 ppm was higher than that of tert-butylhydroquinon (TBHQ). In comparison with other concentrations, 50 ppm showed the strongest antifungal activity against Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nomius. All nanoemulsions have a mean size lower than 265 nm. The polydispersity index (PDI) of different nanoemulsions was lower than 0.3, and a negative zeta potential was observed. The encapsulation efficiency was higher than 67.0% and all nanoemulsions had spherical morphology. The pistachio nuts were coated with different coating solutions containing 0 and 100 ppm of PHE and stored at 4°C for 8 weeks. The results showed that the pistachio sample coated with a composite coating of WPI and FSG containing 100 ppm of PHE has a higher moisture content and lower changes in L*, a*, and b* indexes, oil oxidation, fungi development, and total mold and yeast count. This treatment exhibited higher overall acceptance than other samples at the end of storage time. The results of this study suggest the use of biodegradable coatings enriched with natural extracts that have high antioxidant and antifungal activities.

Enhancing Quality Properties of Fresh Orange Juice through the Addition of Freeze-Dried Cassia javanica Extracts’ Coacervates

This study investigated the impact of freeze-dried coacervates at various concentrations (0.5, 1, and 1.5%) on physicochemical and microbiological properties of orange juice. Either 60% ethanol freeze-dried coacervates (EFC) or absolute ethanol freeze-dried coacervates (AFC) were used. The addition of EFC or AFC to orange juice did not significantly (p&lt;0.05) affect pH, viscosity, or electric conductivity, as pH was unchanged for a 0.5% concentration and slightly increased from 3.99 to 4.01 at 1% and 1.5% concentrations. After adding AFC and EFC, viscosity were 52, 53, and 53 mPas at 0.5, 1, and 1.5% concentrations, respectively. Electric conductivity increased from 0.278 s.m-1 (control) to 0.334, 0.347, and 0.375 s.m-1 at 0.5, 1, and 1.5% concentrations after adding EFC, while were 0.325, 0.335, and 0.373 s.m-1 at the same concentration after adding AFC, respectively. However, after adding EFC, total phenolic content increased to 77.25, 115.96, and 154.95 mg.100mL-1, total flavonoid content (TFC)increased to 34.76, 52.18, and 69.73 mg.100mL-1, and antioxidant activity (AA) enhanced to 70.36, 74.36, and 79.58% at concentrations 0.5, 1, and 1.5%, respectively. Also, after adding AFC, total phenolic content increased to 79.26, 117.78, and 156.25 mg.100mL-1, TFC increased to 35.67, 53.00, and 70.31 mg.100mL-1, and AA enhanced to 71.65, 75.84, and 81.21% at concentrations 0.5, 1, and 1.5%, respectively. At concentrations 0.5, 1, and 1.5%, EFC decreased total plate count (TPC) to 2.12, 2.02, and 1.78 log cfu.mL-1, respectively and mold and yeast counts decreased to 1.5, 1.35, and 1.1 log cfu.mL-1, respectively. Also, adding AFC caused TPC to decrease to 2.18, 2.04, and 1.84 log cfu.mL-1, respectively and mold and yeast count decreased to 1.53, 1.33, and 1.12 log cfu.mL-1, respectively. Overall, the results indicate that adding EFC or AFC to fresh orange juice can enhance its nutritional and microbiological qualities without degrading its sensory qualities.

A novel Nanocoating with zein, gallic acid, and flaxseed oil: Enhancing stability of chicken meatballs

In this study, nanofibers loaded with zein (ZN), flaxseed oil (FSO)-loaded zein (ZNF), gallic acid-loaded zein (ZNG), and a combination of flaxseed oil and gallic acid (GA) loaded zein (ZNFG) nanofibers were obtained. FSO and GA were highly encapsulated within the nanofibers with a high encapsulation efficiency (EE) ranging from 97.13% to 98.03% for FSO and 91.46%–92.53% for GA, respectively. ATR-FTIR analysis also confirmed the successful encapsulation of these bioactive compounds. The obtained nanofibers exhibited diameters ranging from 170.79 ± 61.47 to 318.55 ± 37.90 nm. Incorporating FSO and GA, with their antioxidant bioactive properties, into chicken meatballs aimed to delay oxidation. Additionally, the antimicrobial property of flaxseed oil was intended to delay microbial growth. All nanofibres were collected on aluminum foil on the collector plate of the electrospinning device. Chicken meatballs were coated with aluminum foils (containing zein-based nanofibres). Coating chicken meatballs with nanofibers presented a novel approach, and this study demonstrated that it was a highly successful preservation method during storage compared to the control samples. On the 3rd day of storage, the total mesophilic aerobic bacteria (TMAB) load in control samples was 6 log CFU g−1, while the TMAB load in samples coated with ZNF nanofibers reached 6 log CFU g−1 on the 10th day. ZNF nanofibers provided better protection in terms of the total yeast and mold count (TMY).

Dynamics of microbial ecology and their bio-preservative compounds formed during the panettones elaboration using sourdough-isolated strains as starter cultures

The present study evaluated the application of Limosilactobacillus fermentum IAL 4541 and Wickerhamomyces anomalus IAL 4533 isolated from sourdoughs and their combinations, for bio-conservative action in panettones, as well as to identify the antifungal volatile compounds. Samples from different fermentation steps were submitted to physicochemical and microbiological evaluation, as to know: sourdough after 48 h (A), 96 h (B), and 144 h (C); dough of the first fermentation (D); final dough after second fermentation (E), and baked panettone (F). In all treatments, lactic bacteria and yeast counts demonstrated a mechanism of proto-cooperation. Panettones containing L. fermentum or W. anomalus in their composition had longer shelf life, which indicates their effect as potential biopreservatives. The genetic sequencing data demonstrated the dominance of the Lactobacilli throughout the process, corroborating the data obtained by cultivable methods. A total of 59 volatile organic compounds were found in this study, and a hierarchical cluster analysis presented the separation between the production stages (C, E) and the most recurrent compounds in the final product (F). Of these compounds, the following stood out (n = 26): acids (7.7%), alcohols (23.1%), aldehydes and ketones (34.6%), and esters (34.6%). The treatments containing L. fermentum presented more diversity of volatile organic compounds with potential antifungal effect. There was a higher production of acetic (1.17–8.85 mmol/kg), phenyllactic (5–10.4 mmol/kg), and propionic (3.5–4.3 mmol/kg) acids in the final product. This study demonstrates the feasibility of applying endogenous starter cultures from sourdoughs, with great biopreservative activity, enabling the production of healthier and more natural panettones.

Effect of combining ultrasound and UVC treatments for processing orange juice and mango nectar on their microbiological, physicochemical, and sensory characteristics

The present study aims to evaluate the effect of ultrasound (US), UVC radiation, and combined US+UVC treatments on the inactivation of total aerobic mesophilic bacteria (TAMB) and mold and yeast in orange juice and mango nectar. The microbial inactivation after each treatment, physicochemical and sensory properties of treated products, and the microbial response during their storage at 4 °C for 12 days were assessed. Fresh squeezed orange juice and mango nectar were treated by US, UVC, or US+UVC treatments for 20 min at 15 °C; the initial TAMB and mold and yeast counts were determined. The combined treatment US+UVC showed a better inactivation level in TAMB, molds, and yeasts in orange juice and mango nectar, resulting in lower microbial counts at the storage end. Titrable acidity, °Brix, and pH remained unchanged, while ascorbic acid losses and color changes were observed. Additionally, the sedimentation index (SI) was analyzed during the storage of orange juice, observing that US+UVC reduced the SI and stabilized the orange juice for 12 days. For all tested conditions, mango nectar preserved its sensory properties. Industrial relevanceCombining food processing technologies such as ultrasound (US) and UVC radiation can improve the process's effectiveness. The US+UVC treatment enhanced the microbial inactivation (total aerobic mesophilic bacteria and mold and yeast) of orange juice and mango nectar, reduced the orange juice's sedimentation index during storage, and did not modify the sensory properties of mango nectar. Thus, the combined US+UVC treatment is an alternative to sustainably preserving and stabilizing orange juice and mango nectar.

Tulane Virus Persistence and Microbial Stability in 3D Food Ink under Various Storage Conditions: A Pre- and Post-Printing Analysis

3D food printers facilitate novel customization of the physicochemical properties of food. This study aimed to investigate the impact of storage conditions on the inactivation of the human norovirus surrogate, Tulane virus (TuV), within 3D printed foods. TuV-inoculated protein cookie food ink (∽ 4 log PFU/g) was distributed into 18 3D food printer capsules (50 g each); half immediately underwent extrusion. Storage of the capsules and printed food products at 20 °C (0, 6, 12, and 24 h), 4 °C (0, 1, 3, and 5d), and − 18 °C (0, 1, 3, and 5d) was completed before analysis for TuV via plaque assays in addition to aerobic plate count, yeast and mold counts, and pH and water activity (aw) measurements. A significant 3-way interaction effect was observed between time, temperature, and storage method (capsule/print) (p = 0.006). Significant findings include: (1) A greater reduction in virions was observed in capsules after 24 h at 20 °C and (2) a substantial reduction in virions at 4 °C from day 0 to day 1 was observed, independent of storage method. Microbial indicators remained steady across temperatures, with storage temperature significantly impacting pH and aw. A significant two-way interaction effect (p = 0.006) was found between microorganism type (yeast/aerobic counts) and temperature. This research seeks to provide insights for the food industry and regulatory bodies in crafting guidelines for the safe storage and handling of 3D printed foods and inks.