Administration of Lacticaseibacillus casei CSL3 in Swiss Mice with Immunosuppression Induced by Cyclophosphamide: Effects on Immunological, Biochemical, Oxidative Stress, and Histological Parameters.

The study aimed to evaluate the effects of supplementation with Lacticaseibacillus casei CSL3 in Swiss mice immunosuppressed with cyclophosphamide on immunological, biochemical, oxidative stress, and histological parameters. The animals were distributed into four groups (control, CSL3, cyclophosphamide, and CSL3 + cyclophosphamide), where two groups were treated with L. casei CSL3 (10 log CFU mL-1) for 30 days, and two groups received chemotherapy (days 27 and 30-total dose of 250 mg kg-1). Counts of lactic acid bacteria (LAB) and bile-resistant LAB in stool samples; blood count (erythrogram, leukogram, and platelets); serum total cholesterol levels; catalase enzyme activity; and thiobarbituric acid reactive substances (TBARS) levels in liver, kidney, and brain; IL-4 expression; IL-23, TNF-α, NF-κß in the spleen; and histological changes in the liver, kidneys, and intestine were evaluated. The CSL3 + cyclophosphamide group showed a significant increase in bile-resistant LAB counts in feces (p = 0.0001), leukocyte counts, and expression of IL-23, TNF-α, and NF-κß (p < 0.05) significantly reduced total cholesterol levels (p = 0.001) and protected liver damage of supplemented animals. For oxidative stress damage, the bacterium did not influence the results. It is concluded that the bacterium is safe at a concentration of 10 log CFU mL-1 and has probiotic potential due to its positive influence on the immune response and lipid metabolism.

Potentially functional lactose-free ice cream with Lacticaseibacillus casei CSL3, ginger, and honey.

AIMS: To develop and characterize a functional lactose-free ice cream with added ginger and honey, evaluate the survival of Lacticaseibacillus casei CSL3 under frozen storage and the simulated gastrointestinal tract (GIT), as well as antioxidant activity and product acceptability. METHODS AND RESULTS: The survival of Lacticaseibacillus casei CSL3 was evaluated for 180 days, under frozen storage, and GIT at 60 days. At 15 days of storage, proximal composition, antioxidant activity, color, pH, acidity, fusion, density, overrun, and sensory analysis were performed. Ice cream was an effective food matrix for maintaining the viability of CSL3, with concentrations > 7 log CFU g- 1 during storage and GIT. In addition, the analysis showed overrun and prebiotic characteristics through high values of antioxidant activity and phenolic compounds, good acceptability, and purchase intention. CONCLUSIONS: The product has satisfactory market potential (acceptance rate of 95.19% and purchase intention rate > 96%), and it could become another means of inserting probiotics in food.

Probiotic Yogurt Supplemented with Lactococcus lactis R7 and Red Guava Extract: Bioaccessibility of Phenolic Compounds and Influence in Antioxidant Activity and Action of Alpha-amylase and Alpha-glucosidase Enzymes.

The industry has increasingly explored the development of foods with functional properties, where supplementation with probiotics and bioactive compounds has gained prominence. In this context, the study aimed to evaluate the influence of in vitro biological digestion on the content of phenolic compounds, antioxidant activity, and inhibition of α-amylase and α-glucosidase activities of probiotic yogurt supplemented with the lactic acid bacteria Lactococcus lactis R7 and red guava extract (Psidium cattleianum). A yogurt containing L. lactis R7 (0.1%) and red guava extract (4%) was characterized for the content of phenolic compounds, antioxidant activity, and potential for inhibition of digestive enzymes after a simulated in vitro digestion process. After digestion, the caffeic and hydroxybenzoic acids remained, and sinapic acid only in the last digestive phase. Antioxidant activity decreased during digestion by 28.93, 53.60, and 27.97% for DPPH, nitric oxide and hydroxyl radicals, respectively, and the inhibition of the α-amylase enzyme decreased only 4.01% after the digestion process. α-glucosidase was more efficient in intestinal digestion, demonstrating an increase of almost 50% in probiotic yogurt with red guava extract before digestion. Possibly, the phenolics change their conformation during digestion, generating new compounds, reducing antioxidant activity, and increasing the inhibitory activity of α-glucosidase digestive enzymes. It was concluded that the probiotic yogurt formulation supplemented with red guava extract could interfere with the concentration of phenolic compounds and the formation of new compounds, suggesting a positive and effective inhibition of the digestive enzymes, even after the digestive process.

Development of a microencapsulated probiotic delivery system with whey, xanthan, and pectin.

Pediococcus pentosaceus is a lactic acid bacterium that has probiotic potential proven by studies. However, its viability can be affected by adverse conditions such as storage, heat stress, and even gastrointestinal passage. Thus, the aim of the present study was to microencapsulate and characterize microcapsules obtained by spray drying and produced only with whey powder (W) or whey powder combined with pectin (WP) or xanthan (WX) in the protection of P. pentosaceus P107. In the storage test at temperatures of - 20 °C and 4 °C, the most viable microcapsule was WP (whey powder and pectin), although WX (whey powder and xanthan) presented better stability at 25 °C. In addition, WX did not show stability to ensure probiotic potential (< 6 Log CFU mL-1) for 110 days and the microcapsule W (whey powder) maintained probiotic viability at the three temperatures (- 20 °C, 4 °C, and 25 °C) for 180 days. In the exposition to simulated gastrointestinal juice, the WX microcapsule showed the best results in all tested conditions, presenting high cellular viability. For the thermal resistance test, WP microcapsule was shown to be efficient in the protection of P. pentosaceus P107 cells. The Fourier transform infrared spectroscopy (FTIR) results showed that there was no chemical interaction between microcapsules of whey powder combined with xanthan or pectin. The three microcapsules produced were able to protect the cell viability of the microorganism, as well as the drying parameters were adequate for the microcapsules produced in this study.

Antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. against cariogenic Streptococcus mutans in vitro and viability when added to chewing gum during storage.

The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

Application of prebiotics in apple products and potential health benefits.

Among the fruits, the apple stands out among the most used for elaboration of processed foods. However, the importance of prebiotics in apple products has never been widely analyzed. Prebiotic is a food component resistant to gastric acidity, digestion by mammalian enzymes and gastrointestinal absorption. But following fermentation in the colon, prebiotics result in specific changes in the composition and / or metabolism of the gastrointestinal microbiota, conferring benefits to the health of the host. Therefore, fortifying apple-based products with additional prebiotics is an important strategy for improving consumer health benefits. In this review, after compiling and analyzing scientific and technological studies focusing on prebiotics in apple products, the following benefits of these prebiotics became evident: (1) reduction of water loss in the food matrix; (2) preservation of bioactive and volatile compounds; (3) texture improvement (thickening) in the food industry; (4) increased shelf-live and (5) increased survival of probiotic bacteria, promoting positive effects on microbiota. In addition, this review shows the benefits of different prebiotics for stability and sensory acceptance of apple processed foods.

Survival of Microencapsulated Lactococcus lactis Subsp. lactis R7 Applied in Different Food Matrices.

Survival of Lactococcus lactis subsp. lactis R7, microencapsulated with whey and inulin, was analyzed when added to blueberry juice, milk, and cream. For 28 days, cell viability was evaluated for storage (4 °C), simulated gastrointestinal tract (GIT), and thermal resistance. All matrices demonstrated high cell concentration when submitted to GIT (11.74 and 12 log CFU mL-1), except for the blueberry juice. The thermal resistance analysis proved the need for microencapsulation, regardless of the food matrix. The results indicate that L. lactis R7 microcapsules have potential for application in different matrices and development of new probiotic products by thermal processing.

Virulence factors of foodborne pathogen Campylobacterjejuni.

Campylobacter jejuni is a highly frequent cause of gastrointestinal foodborne disease in humans throughout the world. Disease outcomes vary from mild to severe diarrhea, and in rare cases the Guillain-Barré syndrome or reactive arthritis can develop as a post-infection complication. Transmission to humans usually occurs via the consumption of a range of foods, especially those associated with the consumption of raw or undercooked poultry meat, unpasteurized milk, and water-based environmental sources. When associated to food or water ingestion, the C. jejuni enters the human host intestine via the oral route and colonizes the distal ileum and colon. When it adheres and colonizes the intestinal cell surfaces, the C. jejuni is expected to express several putative virulence factors, which cause damage to the intestine either directly, by cell invasion and/or production of toxin(s), or indirectly, by triggering inflammatory responses. This review article highlights various C. jejuni characteristics - such as motility and chemotaxis - that contribute to the biological fitness of the pathogen, as well as factors involved in human host cell adhesion and invasion, and their potential role in the development of the disease. We have analyzed and critically discussed nearly 180 scientific articles covering the latest improvements in the field.

Probiotic fermented oat dairy beverage: viability of Lactobacillus casei, fatty acid profile, phenolic compound content and acceptability.

The combination of oats such as water-soluble oat extract (SOE) and probiotic microorganisms can add nutritional value to the food and benefits to the consumer's health. The SOE contains soluble fiber, whose major soluble fraction is composed of ß-glucan contains soluble antioxidants such as ferulic acid, avenanthramides and other phenolic acids. The purpose of this study was to develop a fermented dairy beverage containing SOE, evaluating the viability of the probiotic culture, the fatty acid profile, phenolic compounds content and sensory characteristics during the storage. It was verified that Lactobacillus casei remained viable during the 21 days of storage (count above 7 Log CFU.mL-1) and that the addition of SOE does not affect the viability of probiotic bacteria. The levels of bioactive compounds soluble in aqueous medium, increased between the beginning of the experiment and the end, being influenced by the addition of SOE. Seven fatty acids were found in all formulations with a prevalence of C16:0 followed by C18:1. The addition of SOE in the formulation contributes to a significant increase in linoleic acid (C18:2n6). The sensory evaluation of the fermented oat dairy beverage with L. casei (BAC) was positive: the product was highly appreciated by consumers, with acceptance rate of 84.4%. The combination of SOE, with L. casei in the production of novel probiotic fermented dairy beverage, was technologically feasible, improving the functional properties of the product and offering health benefits to the consumer. More studies should be made to evaluate the composition and functional properties of SOE.

Genetic diversity, biofilm and virulence characteristics of Listeria monocytogenes in salmon sushi.

Sushi is a ready-to-eat (RTE) food prepared from raw or cooked fish that is widely consumed worldwide. Listeria monocytogenes is the foodborne pathogen most commonly associated with RTE and fish products. The aim of the present study was to evaluate the presence of L. monocytogenes in salmon sushi commercialized in Pelotas city, Brazil, and to evaluate the genetic diversity, biofilm-forming ability in stainless steel, and virulence characteristics of the isolates. Four sampling events were carried out in seven specialized sushi establishments totaling 28 sushi pools. Listeria monocytogenes was detected in six samples (21.4%) from two establishments (28.6%). All isolates belonged to serotype 4b and carried the prfA, plcA, plcB, hlyA, mpl, actA, inlA, inlC, inlJ, and iap genes. The inlB gene was not detected in two isolates. The PFGE analysis grouped the isolates into four pulsotypes. All isolates had the ability to form biofilm on stainless steel and the average of biofilm formation counts varied between 6.4 and 7.2 log CFU.cm-2. The isolates harbored the biofilm-related genes agrA, agrB, agrC, agrD, and prfA, with the exception of two isolates that did not harbor the agrD gene. The presence of L. monocytogenes in RTE sushi is a concern, demonstrating that sushi consumption may be a risk of human listeriosis. Furthermore, it was possible to identify the persistence of this pathogen for at least one month (pulsotypes III and IV), in two establishments (A and G), highlighting the need for improving the cleaning and sanitation procedures in establishments that commercialize RTE sushi.

Characterization, Toxicity, and Optimization for the Growth and Production of Bacteriocin-like Substances by Lactobacillus curvatus.

This study aimed to characterize, evaluate toxicity and optimize the conditions for the growth and production of bacteriocin-like substances by Lactobacillus curvatus P99. The antibacterial activity of the cell-free supernatant (CFS) containing bacteriocin-like substances was evaluated by the agar diffusion technique. The stability of the CFS was also examined after heat treatment, refrigeration, freezing, pH variations, and treatment with different chemical substances. The toxic effect of CFS on Drosophila melanogaster diet was determined by calculating the survival rate of the flies. The effects of pH, temperature, and incubation time were the parameters used to optimize cell growth and production of bacteriocin-like substances through response surface methodology. The CFS was stable for 36 weeks under freezing and refrigeration, as well as under heat treatment, in acidic and basic pH and for all chemical substances tested. Fewer than 50,000 AU/mL of CFS added to D. melanogaster diet showed no toxic effect. The optimum growth condition was pH 6.3 at 29.3 °C for 18.6 h, and the optimum production of bacteriocin-like substances was under pH 6.22 at 30.6 °C for 17.9 h. The data on the optimization of cell growth and the characterization and optimization of bacteriocin-like substances provided information to support the industrial-scale production of this microorganism and its metabolites.

Listeria monocytogenes in sliced cheese and ham from retail markets in southern Brazil.

The aims of this study were to evaluate the occurrence of Listeria monocytogenes and Salmonella spp. in sliced cheese and ham from retail markets in southern Brazil, as well as to perform molecular characterization and to assess the antimicrobial resistance profile of the isolates. Samples (n = 160) of sliced cheese and ham were collected at retail level from the city of Pelotas, Brazil. The isolation of L. monocytogenes and Salmonella spp. was performed and the isolates were confirmed by PCR, submitted to antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE). Listeria monocytogenes was found in 9.4% (15/160) of the samples. All L. monocytogenes isolates were positive for the prs, inlA, inlC and inlJ genes. Salmonella spp. was not isolated. Regarding the antimicrobial susceptibility, one (6.6%) L. monocytogenes isolate was resistant to streptomycin and four (26.6%) to clindamycin. Macrorestriction analysis with ApaI and AscI enzymes yielded two major PFGE groups I and II. All L. monocytogenes isolates showed virulence genes, and some of them were resistant to clinically used antimicrobials, representing a risk to public health. Moreover, PFGE patterns with high similarity were visualized in L. monocytogenes isolates at different times, demonstrating adaptability of the pathogen at retail level in the region.

Development of antimicrobial and antioxidant electrospun soluble potato starch nanofibers loaded with carvacrol.

In this study, a method was developed to encapsulated carvacrol in nanofibers from soluble potato starch. The carvacrol was added in starch solutions at various concentrations (0, 20, 30 and 40% v/v) and electrospun into fibers. The morphology, size distribution, thermal stability, FT-IR spectra, relative crystallinity (RC) and antioxidant of the electrospun fibers were analyzed. For mechanical properties and antimicrobial activities evaluation electrospun nonwovens were obtain. The carvacrol-loaded nanofibers showed homogeneous morphology and average diameters ranging from 73 to 95 nm. The carvacrol encapsulated in the nanofibers had greater thermal stability than the free carvacrol. FT-IR analysis showed interactions between starch and carvacrol. The RC of the nanofibers was approximately 40%. The electrospun nonwovens mechanical properties did not present significant differences (p < 0.05). The 40% carvacrol-loaded nanofibers exhibited higher antioxidant activity with 83.1% of inhibition. The electrospun nonwoven loaded with 30% carvacrol resulted in 89.0% reduction of Listeria monocytogenes, 68.0% for Salmonella Typhimurium, 62.0% for Escherichia coli and 49.0% for Staphylococcus aureus. These electrospun nonwovens sustained antimicrobial activity for at least 30 days against S. aureus. The starch nanofibers are promising materials for application as a vehicle for carvacrol release in antimicrobial and antioxidant food packages.

Antibacterial activity, optical, mechanical, and barrier properties of corn starch films containing orange essential oil.

The incorporation of antimicrobial compounds into natural polymers can promote increased shelf life and ensure food safety. The aim of this study was to evaluate the antibacterial activity, morphological, optical, mechanical, and barrier properties of corn starch films containing orange (Citrus sinensis var. Valencia) essential oil (OEO). The corn starch films were prepared using the casting method. OEO and the corn starch films incorporated with OEO showed higher antibacterial activity against Staphylococcus aureus and Listeria monocytogenes. The addition of OEO to the films increased the morphological heterogeneity and contributed to the reduction of the tensile strength and elongation of the films, and it increased the moisture content, water solubility, and water vapor permeability. The water vapor permeability and partial or total solubility of a film in water prior to consumption of a product are of interest when the film is used as food coating or for encapsulation of specific molecules.

Selection of native bacterial starter culture in the production of fermented meat sausages: Application potential, safety aspects, and emerging technologies.

The development of standardized and safe food products with the typical characteristics of each region is highly desirable and can be obtained by using native starter cultures that influence the flavor, texture, and color of fermented foods. Therefore, scientists have been employing various techniques for screening and characterizing native bacteria (lactic acid bacteria and Gram-positive catalase-positive cocci) for application in fermented meat sausage. The present review outlines in vitro assays that evaluate the potential application and safety aspects of native isolates and introduces emerging omics technologies applied to the microbiology of fermented meat sausage. Results from current research are presented, and the strengths and limitations of each assay are provided, with references indicating where further details can be obtained. In choosing the most appropriate in vitro method, it is necessary to consider the available analytical infrastructure, the sensitivity and selectivity of the assay, the time it takes to get the results, the ease of the assay, and the costs involved.

Multivariate optimization of Staphylococcus xylosus AD1biomass production using sugarcane molasses plus yeast extract and soybean meal

Staphylococcus xylosusis a microorganism that has important physiological and technological characteristics that make it suitable for use as a starter culture in fermented meat products. For the development of these products in the food industry, it is necessary to produce biomass by the multiplication of starter cultures using low-cost media. This study developed a culture medium based on sugarcane molasses (SCM) supplemented with yeast extract (YE) and soybean meal (SM) to produce S. xylosusAD1 biomass employing a Box Behnken multivariateoptimization design,usingthe best concentrations of the constituents of the culture medium for S. xylosusAD1 growth. By combining the mathematical models by the desirability function, it was possible to establish the optimal condition for the maximum production of viable cells and biomass. The optimal experimental condition was found when the fermentative process medium was composed of 10% SCM, 2% YE and 4% SM. In addition, the results of all experiments, except for the medium formulated with only SCM,presented a better performance than the commercial medium Brain Heart Infusion for the growth of S. xylosusAD1. The culture medium with agro-industrial byproduct (SCM) supplemented with YE and SM is an excellent alternative for producing S. xylosusAD1 biomass.

Action of ginger essential oil (Zingiber officinale) encapsulated in proteins ultrafine fibers on the antimicrobial control in situ.

The ultrafine fibers were produced using a polymeric blend of soy protein isolate (SPI), polyethylene oxide (PEO), and zein at a ratio of 1:1:1 (v/v/v) by electrospinning. The ginger essential oil (GEO) was encapsulated in the ultrafine fibers and the morphology, Fourier-Transform Infrared Spectroscopy (FTIR) analysis, thermal properties and relative crystallinity were evaluated. The antimicrobial activity of ginger essential oil was evaluated against five bacteria (Listeria monocytogenes, Staphylococcus aureus, Escherichia coli 0157:H7, Salmonella typhimurium, and Pseudomonas aeruginosa). Based on the preliminary tests, the concentration of GEO selected to add in the polymer solution was 12% (v/v; GEO/polymer solution). The fiber produced with 12% (v/v) GEO was used for antimicrobial analysis and in situ application (in fresh Minas cheese) against L. monocytogenes by micro-atmosphere. The ultrafine fibers produced, regardless the concentration of the essential oil, presented homogeneous morphology with cylindrical shape without the presence of beads. The application of the active fibers containing 12% GEO showed high potential to be applied in food packaging to reduce microbial contamination.

Antimicrobial electrospun ultrafine fibers from zein containing eucalyptus essential oil/cyclodextrin inclusion complex.

The aim of this study was to produce ultrafine fibers from zein incorporated with a complex of eucalyptus essential oil (EEO) and ß-cyclodextrin (ß-CD) with antimicrobial properties by electrospinning technique. The EEO was characterized by chemical composition and antimicrobial tests against three Gram positive and four Gram negative bacteria. The inclusion complex (IC) was prepared with ß-CD and EEO by co-precipitation technique and added at different concentrations in zein polymer solution using aqueous ethanol as solvent. The morphology, thermal properties, functional groups, and antimicrobial activity against L. monocytogenes and S. aureus of the ultrafine fibers were evaluated. The composite membranes containing 24% IC exhibited a greater reduction of growth as compared to the fibers without addition of IC. For L. monocytogenes the growth reduction was 28.5% and for S. aureus it was 24.3%. The electrospun IC-ß-CD/EEO composite membranes are promising for use in antimicrobial applications, such as food packaging.

Bacteriocin-like substances of Lactobacillus curvatus P99: characterization and application in biodegradable films for control of Listeria monocytogenes in cheese.

The aim of this study was to evaluate the effectiveness of a biodegradable film, with antimicrobial metabolites produced by Lactobacillus curvatus P99 incorporated, targeting the control of Listeria monocytogenes in sliced "Prato" cheese. Tests were performed to evaluate the spectrum of action of cell-free supernatant (CFS) of P99 against different microorganisms, as well as to detect the minimum inhibitory (MIC) and bactericidal (MBC) concentrations against L. monocytogenes Scott A. The detection of genes that encode for the production of bacteriocins and evaluation of their expression were performed. Antimicrobial films were prepared, followed by in vitro and in situ analysis. The MIC and MBC of CFS against L. monocytogenes Scott A was 15.6 µL/mL and 62.5 µL/mL, respectively. Lactobacillus curvatus P99 presented two genes coding for the bacteriocins, which were expressed. Films with added MBC showed activity against different indicator microorganisms and were able to control L. monocytogenes Scott A when used in sliced "Prato" cheese.

Microbiological and physicochemical characterization of the raw milk and the colonial type cheese from the Northwestern Frontier region of Rio Grande do Sul, Brazil / Caracterização microbiológica e físico-química de leite cru e queijo colonial da região Fronteira Noroeste do Rio Grande do Sul, Brasil

This study aimed at evaluating the microbiological and physicochemical characteristics of raw milk and colonial type cheese from Northwestern Frontier region of Rio Grande do Sul, Brazil. For this purpose, the samples were collected in January and July. Microbiological analyses (aerobic mesophilic bacteria, total/thermotolerant coliform, coagulase-positive Staphylococcus, Salmonella spp. and Listeria monocytogenes, lactic acid bacteria) and physicochemical assays (pH, acidity, total solids, protein, fat, aw, moisture, NaCl) were performed. The milk and cheese samples showed low microbiological quality because high counting of aerobic mesophilic bacteria, total/thermotolerant coliform and coagulase-positive Staphylococcus were detected. High counting of lactic acid bacteria was observed. However, neither Salmonella spp. nor Listeria monocytogenes was found. The standard deviations above one (1.0) in the fat, protein, moisture and salt contents indicated that no standard procedure was followed for producing the local cheese. The sample collection period caused differences in the microbiota, total solids of milk and cheese moisture contents, aw and salt. The maturation period did not significantly influenced on the microbial counts, but it provided an increase in protein contents and a decrease in aw value in cheese samples collected in July.

Este estudo avaliou as características microbiológicas e físico-químicas de leite cru e queijo colonial da região Fronteira Noroeste do Rio Grande do Sul, Brasil. Para isto, foram feitas coletas de amostras em janeiro e julho. Análises microbiológicas (bactérias aeróbias mesófilas, coliformes totais e termotolerantes, Staphylococcus coagulase positiva, Salmonella spp. e Listeria monocytogenes, bactérias ácido lácticas) e físico-químicas(pH, acidez, sólidos totais, proteína, lipídeos, Aa, umidade, NaCl) foram realizadas. As amostras de leitee de queijo indicaram baixa qualidade microbiológica, pois houve detecção de altos níveis de bactériasmesófilas, coliformes totais e termotolerantes e Staphylococcus coagulase positiva. Altas contagens de bactérias ácido láticas foram observadas. Entretanto, não foi detectada a presença de Salmonella spp. eListeria monocytogenes. O desvio padrão acima de um (1,0) nos conteúdos de lipídeos, proteínas, umidade e sal indicou que não houve seguimento do procedimento padrão estabelecido na produção local de queijos. O período de coleta de amostras resultou em diferenças nas análises de microbiota, sólidos totais do leitee dos queijos, o teor de umidade, Aa e sal. O período de maturação não causou significativa influênciasobre as contagens microbianas, mas promoveu aumento no conteúdo de proteína e diminuição na Aa dos queijos coletados em julho.