Microbiological Properties Research Articles

Investigation of the influence of milk protein genotype on the process of fermentation of milk curds by mesophilic lactic acid streptococci

The relevance of this study lies in the fact that the majority of commercial milk processed into fermented dairy products is a mixture of β-casein genotypes. The increasing use of A2 milk in the dairy industry necessitates the development of scientifically grounded technologies for the production of fermented products, as casein genotype modifications can affect the course of technological processes and require adjustments to production parameters. The study aimed to determine the impact of genetic modification of the β-casein protein in cow’s milk on the fermentation process of milk mixtures during the production of fermented dairy products. Research methods included chemical, physical, organoleptic, and microbiological methods (determination of the quality indicators of raw milk and fermented milk curds), and technological methods (determination of acid formation activity and viscosity). The initial characteristics of raw milk were investigated according to genotype, revealing no direct correlation. Changes in the physicochemical, microbiological, and organoleptic properties of fermented milk curds during biotechnological processing and storage were examined. Optimal technological process regimes were selected, and technological methods were chosen to minimise the influence of secondary factors on the experiment. A mixed culture preparation of mesophilic lactic acid lactococci, including L. Lactis ssp., was chosen as a starter culture. It was established that all 13 milk samples were suitable for biotechnological processing using mixed cultures of mesophilic lactic acid bacteria. As a result, it was concluded that the production of fermented dairy products from raw milk with the presented β-casein genetic modifications, A1A1, A1A2, and A2A2 – using L. lactis ssp. cultures – is possible using the classical technology and does not require adjustment of the technological conditions. The obtained results can be used in the dairy industry when developing technologies for fermented dairy products from A2 raw milk

Addition of Fresh Herbs to Fresh-Cut Iceberg Lettuce: Impact on Quality and Storability

The aim of this study was to develop ready-to-eat vegetable–herb mixes with high nutritional and sensory values as well as good storability. In this regard, the suitability of fresh herbs (peppermint, oregano, green basil, red basil, and parsley) was tested for their use in mixes with fresh-cut iceberg lettuce. Lettuce–herb mixtures were stored for 6 days at 5 °C. The reason for the decrease in the appearance of the salads was the browning of the cut surface of the lettuce, as well as discoloration on the cut herbs. Comparing the storage abilities of the cut herbs, red basil and parsley retained the best appearance for 6 d at 5 °C. A small addition of herbs to fresh-cut iceberg lettuce caused a significant increase (p < 0.05) in the contents of pro-health ingredients such as chlorophyll, carotenoids, L-ascorbic acid, and polyphenols in the mixes. There were large discrepancies in the sensory quality of the mixes, but the highest quality and consumer acceptance were found for salads with parsley (5% and 10%) and red basil (5%). After harvest, the fresh herbs were more contaminated by molds than the iceberg lettuce. Bacterial, yeast, and mold contamination increased during storage, but the rate of mold growth was much lower in the mixes with parsley compared to lettuce alone. In conclusion, the addition of parsley and mint contributed the most to the health-promoting and microbiological properties of iceberg lettuce salads. However, according to sensory evaluation, parsley and red basil contributed the most to improving the acceptability of the product in terms of best taste and shelf life.

Physicochemical, Microbiological, and Sensory Properties of Almond Milk Yogurt-Like Products with Varied Concentrations of Tapioca Starch as Stabilizer

Physicochemical, Microbiological, and Sensory Properties of Almond Milk Yogurt-Like Products with Varied Concentrations of Tapioca Starch as Stabilizer

Effects of Pasteurisation on Antioxidant Activities and Microbiological Properties of Stingless Bee Honey Beverage During Storage

Effects of Pasteurisation on Antioxidant Activities and Microbiological Properties of Stingless Bee Honey Beverage During Storage

Impact of Organic and Inorganic Amendments on Microbiological and Chemical Properties and their Relationship with Rice Productivity in an Alkali Soil of Southern India

Impact of Organic and Inorganic Amendments on Microbiological and Chemical Properties and their Relationship with Rice Productivity in an Alkali Soil of Southern India

Isolation and characterization of probiotic lactic acid bacteria from local yogurt and development of inulin-based synbiotic yogurt with the isolated bacteria

Synbiotic yogurts can offer several potential benefits due to the combination of yogurts probiotics, prebiotics, and the nutritional qualities of milk. Local yogurt variants might add to the variety of probiotic alternatives because they frequently have distinct microbial communities. Employing indigenous strains not only represents cultural preferences but also increases the probability of obtaining bacteria adapted to the surrounding environment. This study was intended to isolate and characterize potential lactic acid bacterial strains from local yogurt and assess the effectiveness of inulin on the physicochemical and microbiological properties during the fermentation of synbiotic yogurt. A total of eight strains were identified and isolated. Two chosen isolates were combined with inulin at 0, 0.5, 1, and 1.5 % concentrations to produce synbiotic yogurts. The physicochemical and microbiological properties were assessed during the fermentation process of synbiotic yogurts. The result showed that the isolated Lactobacillus spp. and Streptococcus spp. strains had probiotic characteristics and good growth. After the fermentation, the yogurt sample containing 1.5 % inulin had the highest count of Lactobacillus spp. (8.17 ± 0.01 log CFU/ml) and Streptococcus spp. (8.03 ± 0.03 log CFU/ml), highest optical density (2.931 ± 0.001), acidity (1.43 ± 0.03), and water-holding capacity (63.54 ± 0.51), and lowest syneresis (34.75 ± 0.48). The addition of inulin did not affect color during the fermentation of synbiotic yogurt. This study concluded that inulin could boost yogurt's stability when combined with local lactic acid bacteria strains.

Microstructural characterization, mechanical and microbiological properties of acrylic resins added with reduced graphene oxide.

To evaluate the microstructural characterization, mechanical properties and antimicrobial activity of acrylic resins incorporated with different concentrations of reduced graphene oxide (rGO). Specimens were made of self-cured and heat-cured acrylic resins for the control group and concentrations of 0.5%, 1%, and 3%. The microstructural characterization was evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS). For mechanical testing, flexural strength, and Knoop hardness tests were performed. Microbiological evaluations were performed by colony forming units (CFU) analysis, tetrazolium salt reduction (XTT), and SEM images. The modified acrylic resins showed increased mechanical properties at low concentrations (p < 0.05) and with reduced S. mutans (p < 0.05). Reduced graphene oxide interfered with the mechanical performance and microbiological properties of acrylic resins depending on the concentration of rGO, and type of polymerization and microorganism evaluated. The incorporation of graphene compounds into acrylic resins is an alternative to improve the antimicrobial efficacy and performance of the material.

Application of Cinnamomum verum and Syzygium aromaticum extract-loaded liposomes as natural antifungal preservatives in packed fresh pasta

The aim of this research was to the effect of Cinnamomum verum and Syzygium aromaticum extract-loaded liposomes (from 0.1% to 0.5%) on the shelf-life of fresh pasta during 28 days of storage in the refrigerator (4 ± 1 °C). The liposomeadded fresh pasta samples were examined concerning some physical, chemical, sensory, and microbiological properties. According to the results, the addition of extract-loaded liposomes reduced weight increase, volume increase, and also increased cooking loss. The incorporation of Syzygium aromaticum-loaded liposomes resulted in a significantly higher increase in total phenolic content and antioxidant activity of fresh pasta. In which the increase of the total phenolic content and antioxidant activity at the end of storage (28 days) were from 259.20 to 288.13 mg GAE/kg and from 48.65% to 56.79%, respectively. However, moisture content and water uptake demonstrated a reduction following a 28-day storage period. The results of yeast and mold analyses revealed that after 28 days of storage, Syzygium aromaticum liposome-loaded fresh pasta samples had a lower yeast and mold count than other samples. In terms of sensory evaluation, the samples were generally found to be of an acceptable standard, with ratings above a certain average.

Evaluation of microbiological, antioxidant, thermal, rheological and sensory properties of ice cream fermented with kefir culture and flavored with mint (Menthaspicata L.).

Kefir is a healthy fermented dairy product, while ice cream is one of the most consumed dairy products. In this research, ice cream was fermented using a commercial kefir culture and flavored with a mint aroma in different proportions: 0% (KI), 0.2% (KIM2), 0.4% (KIM4), and 0.6% (KIM6). The study investigated the microbiological, thermal, rheological, textural, compositional, and sensory properties as well as antioxidant activity of kefir ice cream samples during 45-day storage. The lactic bacilli, lactic cocci, and Leuconostoc counts of samples were >7 log CFU/g, while the yeast counts were <4 log CFU/g. The microbiological properties (except for yeast counts) of the samples were coherent with legal limits. Antioxidant values (except for samples KIM2 and KIM6) values did not indicate significant differences (p < .05). The pH and melting rate values of the samples decreased with the addition of mint flavor, while acidity values increased. The addition of mint aroma caused significant changes in the thermal properties of ice cream. The overrun, a*, WI, and hardness values of the samples decreased based on the mint flavor concentration, whereas the viscosity and rheological increased. Samples KI and KIM2 were scored higher than other samples for all sensory properties. As a result, fermented ice cream flavored (0.2% mint) with mint could be produced as a desirable dairy product with potential functional properties.

Microbiological, sensory, and chemical properties of high-quality tempeh made with instant Mosaccha tempeh inoculum powder.

The combination of Saccharomyces cerevisiae and Rhizopus oligosporus liquid inoculum has been successfully used to ferment soybeans into tempeh that contains β-glucan. However, using the liquid inoculum of these two microbes as a starter is impractical; so, developing an instant tempeh dry inoculum in powdered form, called the Mosaccha inoculum powder, for ease of use is necessary. This study aimed to determine the best concentration of instant Mosaccha inoculum powder to produce high-quality Mosaccha tempeh. The study used a Complete Randomized Block Design with seven different levels of instant Mosaccha inoculum powder percentage, ranging from 0.3% to 1.8% (w/w). A commercial tempeh inoculum, RAPRIMA, amounting to 0.2%, was used as control. Then, the microbiological (total mold and total yeast) and sensory (color, aroma, texture, and taste) properties were evaluated. The data obtained was analyzed statistically using analysis of variance (ANOVA) and Honestly Significant Difference (HSD) tests at the 5% level. The results showed that the percentage of instant Mosaccha inoculum powder significantly affected the microbiological and sensory properties of Mosaccha tempeh. A concentration of Mosaccha inoculum powder between 0.6% to 1.8% could produce good quality Mosaccha tempeh, but the best Mosaccha tempeh was produced with 1.5% instant Mosaccha inoculum powder, which met the Indonesian National Standards (SNI) 3144:2015, had a very favorable taste, and contained 0.49% β-glucan. Therefore, Mosaccha inoculum in powdered form can be developed and used as a starter in making high-quality tempeh that contains β-glucan.

The Effects of Various Ethanolic Extracts on Some Microbiological Properties of Chicken Sausages

In this study, the antimicrobial effects of different levels (0%, 5%, 10%) of ethanolic extract of propolis (EEP), sage (EES), lavender (EEL), yarrow (EEY), and yellow cantaron (EEC) on total psychrotroph aerobic bacteria (TPAB), total coliform and fecal coliform, yeast-mold in chicken sausage were investigated. The sausages were divided into 7 groups. The first and second groups were the control samples. The surface of second control group of chicken sausage was sprayed with only ethyl alcohol (70%). The third, fourth, fifth, sixth and seventh groups were sprayed with EEP, EES, EEC, EEY and EEL at two levels respectively: 5%, 10%. Prior to each treatment, sausages were left to be stored at +4ºC for 10 days. All extracts significantly (P

Biomass Ash as a Substitute for Lime and Its Impact on Grassland Soil, Forage, and Soil Microbiota

In this eight-year grassland field trial, we compared the fertilization effects of biomass ashes (BMAs) and carbonated lime (CaCO3) in combined application with cattle slurry (CS). Our study focused on plant coverage, forage yield, and quality, as well as soil physicochemical and microbiological properties. The fertilization strategies included CS mixed with BMA or CaCO3 applied three times a year and a separate annual application of ash or CaCO3, independent of CS. Samplings were performed in 2010, 2014, and 2018. Despite an absence of observable effects on soil, microbial properties, and forage quality, CS application, with or without BMA/CaCO3, resulted in higher forage yields compared to the unfertilized control and plots receiving only ash or CaCO3. Forage properties remained consistent across treatments. However, the combined application of CS with both ash and CaCO3 led to a reduction in volatile organic compounds, total carbon, total nitrogen, nitrate, and electrical conductivity in the soil from 2010 to 2018. Additionally, the relative abundance of specific microbial families (Nitrosomonadaceae, Acidothermaceae, Bacillaceae, and Peptostreptococcaceae) varied based on whether soils received a single amendment or a combination thereof. Our findings suggest that BMA is a valuable substitute for traditional liming agents, regardless of the application mode.

Biochemical and Microbiological Properties of the Cotton–Copper Composite Material Obtained via Sputter Deposition

Biochemical and Microbiological Properties of the Cotton–Copper Composite Material Obtained via Sputter Deposition

The effect of free and encapsulated probiotic bacteria on some physicochemical, microbiological, and textural properties of apricot leather (pestil) during storage.

Pestil, also known as fruit leather, has emerged as a promising non-dairy carrier for probiotics, utilizing apricots and incorporating probiotics into its formulation. This study aimed to develop a healthy snack bar by incorporating three distinct strains of probiotic bacteria, both in free and encapsulated forms, into the recipe of apricot leather. The physicochemical, bioactive, microbiological, and textural attributes of the resulting apricot pestils were evaluated over a 120-day storage period. Fluctuations in pH (4.74-4.97) were observed during storage, whereas water activity (0.31-0.45) and moisture content (8.05%-13.40%) exhibited a decreasing trend over time. Incorporating free or encapsulated bacteria resulted in a darker surface, attributed to the intermolecular interactions between probiotics and the pestil matrix. The initial total phenolic content was highest and declined significantly during storage (52.13-291.73mg gallic acid equivalent/100g) (p<0.05). Viability was found to be higher in the encapsulated forms of bacteria at the conclusion of the storage period. Overall, apricot pestil emerged as a promising matrix for viable probiotics, facilitating their delivery and hosting in both free and encapsulated forms during storage.

Physicochemical, microbiological, and sensory properties of healthy juices containing aloe vera gel and probiotics and their antidiabetic effects on albino rats.

The consumption of fruit and vegetable juices is widely recognized as a healthy choice across all age groups. Orange, carrot, and aloe vera are renowned for their functional properties and health benefits. In this study, we investigated the potential incorporation of aloe vera gel into blended orange and carrot juices. We also evaluated the resulting mixed probiotic juices (chemical, microbiological, and sensory aspects) during a 14-day storage period at refrigerator temperature. The chemical composition and phytochemical structure of aloe vera gel were examined, followed by an assessment of the biological effects of these healthy juices on diabetic albino rats. The results indicated improvements in total soluble solids, reducing sugars, and total sugars with increasing storage duration. Furthermore, the study demonstrated that incorporating aloe vera into the natural mixed juices enhanced their phytochemical quality. The treatment supplemented with aloe vera gel gave the highest total content of phenolic and flavonoid substances, which were 310 mg of GAE/100 g and 175 mg of quercetin/100 g, respectively. Probiotic strains (Bifidobacterium animalis subsp lactis Bb12, Lactiplantibacillus plantarum 299V, and Lactobacillus acidophilus L10) exhibited good viable cell counts in orange and mixed orange and carrot probiotics juices with viable counts of 7.42-8.07 log CFU/mL. Regarding sensory attributes, the study found that increasing the ratio of orange juice improved the taste while increasing the ratio of carrot juice enhanced the color in juice mixtures. Incorporation of aloe vera into mixed natural juices also enhanced the reduction of blood glucose, triglyceride, cholesterol, LDL, creatinine, ALT, AST, and urea levels while increasing total protein and HDL levels in diabetic rats. Based on these findings, oranges, carrots, and aloe vera offer the potential to produce new, flavorful, nutritious, and appealing juices. Moreover, this study determined that a functional juice with favorable sensory properties can be created by blending 75% orange juice, 20% carrot juice, and 5% aloe vera gel. Additionally, aloe vera demonstrated greater efficacy as an antidiabetic agent in rats. Further research is suggested to explore the potential advantages of aloe vera gel and probiotic juices in mitigating diabetes and other metabolic syndromes.

Flammability, Toxicity, and Microbiological Properties of Polyurethane Flexible Foams.

The aim of the research was to investigate the influence of calcium phosphinate (HPCA) and aluminum phosphinate (HPAL) in synergistic systems with organophosphorus compounds, i.e., diphenylcresyl phosphate (CDP) and trichloropropyl phosphate (TCPP), on the thermal stability, flammability, smoke density, and emission of toxic gases during the thermal decomposition of polyurethane (PUR) foams. Thermogravimetric analysis (TGA), along with cone calorimetry and microcalorimetry, were used to assess the influence of fillers on the thermal stability and flammability of PUR foams. The analysis of toxic gas products was performed with the use of a coupled TG-gas analyzer system. The optical density of gases was measured with the use of a smoke density chamber (SDC). The obtained results showed an increase in thermal stability and a decrease in the flammability of the PUR composites. However, the results regarding smoke and gas emissions, as well as toxic combustion by-products, present ambiguity. On one hand, the applied flame retardant systems in the form of PUR-HPCA-CDP and PUR-HPCA-TCPP led to a reduction in the concentration of CO and HCN in the gas by-products. On the other hand, they clearly increased the concentration of CO2, NOx, and smoke emissions. Microbiological studies indicated that the obtained foam material is completely safe for use and does not exhibit biocidal properties.

Tap Water Microbial Contamination in Prayagraj: Isolation, Purification and Characterization of Pathogenic Bacteria and Their Antibiotic Susceptibility Patterns

Since water is necessary for life, it is crucial for preserving human health and biological processes. However, serious health dangers are associated with drinking water contamination, especially in areas where access to clean water is scarce. The purpose of this study was to assess the physicochemical and microbiological properties of tap water from 10 distinct locations in Prayagraj, Uttar Pradesh, India. Water samples were collected and analyzed microbiologically to isolate and identify harmful bacteria. The study detected the presence of several gram-negative bacteria, including Leminorella grimontii, Morganella morganii, and Citrobacter braakii, among others. Temperature and pH levels varied throughout the sampling sites, according to physicochemical analysis, and some samples had levels of alkalinity over the WHO-recommended safe limits. Antibiotic susceptibility tests indicated that the isolated bacterial strains displayed varying levels of resistance to different antibiotics, with higher resistance to Gentamicin than to Ampicillin. These findings highlight the significance of ongoing water quality monitoring and improvement to reduce the risk of waterborne illnesses, particularly in areas with poor access to clean water and sanitation. Ensuring the safety and purity of water for human consumption is crucial for protecting public health, especially in areas vulnerable to illnesses caused by contaminated water. This study provides valuable insights into the microbiological ecology of Prayagraj tap water and emphasizes the need for effective water management strategies to protect human health and welfare.

Effect of VP, MAP and combined packaging systems on the physicochemical properties and microbiological status of veal from unweaned calves

The packaging system is one of the factors influencing the preservation of the nutritional value, microbiological safety, and sensory attributes of meat. The study investigated changes in physicochemical and microbiological properties taking place during 15-day refrigerated storage of two calf muscles, the longissimus lumborum (LL) and semitendinosus (ST), packaged in three systems, respectively, vacuum packing (VP), modified atmosphere packaging (MAP, 80% O2 + 20% CO2), and a combined system (VP + MAP, 8 d in VP followed by 7 d in MAP). LL and ST stored in VP had significantly lower levels of lipid oxidation, higher α-tocopherol content, and higher instrumentally measured tenderness in comparison with the samples stored in MAP. On the other hand, the MAP samples had lower purge loss at 5 and 15 days, a higher proportion of oxymyoglobin up to 10 days of storage, and a better microbiological status. Calf muscle samples stored in the VP + MAP system had intermediate values for TBARS and α-tocopherol content and at the same time were the most tender and had the lowest counts of Pseudomonas and Enterobacteriaceae bacteria at 15 days. All packaging systems ensured relatively good quality of veal characteristics up to the last day of storage. However, for MAP at 15 days of storage, unfavourable changes in colour (a high level of metmyoglobin and a decrease in oxymyoglobin, redness and R630/580 ratio) and in the lipid fraction (a high TBARS value and a significant decrease in α-tocopherol content) were observed.

Composite additives regulate physicochemical and microbiological properties in green waste composting: A comparative study of single-period and multi-period addition modes

Composting additives can significantly enhance green waste (GW) composting. However, their effectiveness is limited due to the short action duration of a single-period addition. Therefore, this study proposes that multi-period additive modes to prolong the action duration, expedite lignocellulose degradation, reduce composting time, and enhance product quality. This study conducted six treatments (T1–T6), introducing a compound additive (BLP) during the mesophilic (MP) and cooling periods (CP). Each treatment consistently maintained 25% total BLP addition of GW dry weight, with variations only in the BLP distribution in different periods. The composition of BLP consists of Wbiochar: Wlactic acid: Wpond sediment in a ratio of 10:1:40. Specifically, T1 added 25% BLP in CP, T2 added 5% in MP and 20% in CP, T3 added 10% in MP and 15% in CP, T4 added 15% in MP and 10% in CP, T5 added 20% in MP and 5% in CP, and T6 added 25% in MP. In this study, composting temperature, pH value, electrical conductivity, total porosity, the contents of lignin, cellulose, hemicellulose, and nutrient, scanning electron microscopy images, germination index, and the successions of different bacteria and fungi at the phylum and genus levels were detailed. Results showed T4 achieved two thermophilic periods and matured in just 25 days. T4 enhanced lignocellulose degradation rates (lignin: 16–53%, cellulose: 14–23%, hemicellulose: 9–48%) and improved nutrient content. The above results, combined with correlation analysis and structural equation model, indicated that T4 may promote the development of dominant bacteria (Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes) by regulating compost physicochemical properties and facilitate the growth of dominant fungi (Ascomycota and Basidiomycota) by modulating nutrient supply capacity. This ultimately leads to a microbial community structure more conducive to lignocellulose degradation and nutrient preservation. In summary, this study reveals the comprehensive effects of single-period and multi-period addition methods on GW composting, providing a valuable basis for optimizing the use of additives and enhancing the efficiency and quality of GW composting.

Evaluation of the efficacy of rice bran and sesame oil for producing nutritionally-superior quality functional tofu

Paneer prepared from edible-quality de-oiled soy flour is known as tofu. Functional tofu was augmented with specific antioxidants such as oryzanol and lignan obtained from rice bran oil (RBO) and sesame oil (SO), respectively. All the fortified and control tofu were evaluated for physicochemical (proximate composition, oxidative stability, antioxidant activity, penetration, and color property), microbiological, and sensory properties. The total viable count and yeast and mold counts increased slowly in the samples stored at 4 °C in the refrigerator for 9 days. Fortified tofu showed higher oxidative stability and antioxidant activity than the control tofu during storage conditions. Additionally, tartaric acid-coagulated tofu retained its quality attributes, especially taste and overall acceptability, during refrigerated storage. Functional tofu aided in an innovative technological technique for making functional non-dairy products with boosted healthy constituents.