Lactic Bacteria Research Articles

Development of GEM-PA-nanotrap for purification of foot-and-mouth disease virus

Vaccination is the primary preventative measure against outbreaks of foot-and-mouth disease (FMD). The efficacy of inactivated FMD vaccines is mainly determined by the integrity of foot-and-mouth disease virus (FMDV) particles (referred to as 146S particles), and impurities in the inactivated vaccines could result in side effects. In this study, we developed an effective affinity purification method for the purification of FMDV from cellular lysates, referred to as GEM-PA-nanotrap. To develop the GEM-PA-nanotrap, a nanobody (Nb205) against FMDV vaccine strain O/MYA98/BY/2010 146S particles was selected from a non-immunized library and fused to a peptidoglycan-binding protein anchor (PA). The PA-Nb205 fusion protein was non-covalently coupled to the surface of Gram-positive enhancer matrix (GEM) particles, which were prepared from the non-living, non-genetically modified, Gram-positive, food-grade Lactococcus lactis bacteria. The GEM-PA-nanotrap was used to purify FMDV from cellular lysates through a simple incubation and centrifugation step. The FMDV recovery rate was more than 99%, the efficiency of nonviral protein removal was about 98.3%, and the purification process had almost no effect on the integrity and immunogenicity of 146S particles. Therefore, the GEM-PA-nanotrap has potential as an effective method for the recovery and purification of FMDV during the vaccine manufacturing process.

Analysis of the performance of a newly designed fermenter built in local materials for improvement of cocoa fermentation, in Ivory Coast

Objective: Cocoa beans fermentation is a spontaneous chemical process, traditionally done in box or in a heap. Equipment is also important in achieving the final chocolate aroma. This study analyzes the performances of a new-designed cocoa bean fermenter. Methodology and results: In this study, a new type of fermenter, a rotating cylindrical fermenter (RCF) has been designed in order to improve the fermentation of cocoa that remains difficult to control, because of the spontaneous nature of the microbiota. The performances of this fermenter was analyzed and compared to those of the traditional wooden box (TWB) fermenter that is commonly used on farm. During the 6 days of fermentation in both fermenters, the growth of microorganisms such as yeasts, lactic bacteria, acetic bacteria, bacillus and moulds as well as chemical and physical changes of the fermenting cocoa were monitored. The results showed that in the fermenter (RCF) a rapid temperature increase was observed in the course of the fermentation process with a temperature reaching 51°C within 73 h comparatively to the traditional fermenter (48°C within 118 h). This leads to a higher proportion of brown beans, indicator of a good fermentation from RCF fermenter as assessed by the cut test. This proportion was 94.44% for RCF and 85.88% for TWB. Moreover the optimization of heat generated in the RCF fermenter, allowed a normal browning (final gray level was 77 in both fermenters) despite modification of microbiota growth order (early growth of acetic bacteria and stunted growth of yeast in RCF, but not for TWB). Conclusion and application of results: The high proportions of brown beans in RCF suggest that this equipment is liable to contribute to the improvement of standard quality of cocoa beans.

Rainbow trout (Oncorhynchus mykiss) gut microbiota is modulated by insect meal from Hermetia illucens prepupae in the diet

Insects have been identified as an economically sustainable high-value, and safe protein-rich alternative to fishmeal in compound feeds for farmed fish. Accordingly, the present study aimed to evaluate the effects of substitution of fishmeal with insect meal from Hermetia illucens in the diet of rainbow trout (Oncorhynchus mykiss), on fish growth performance, and gut microbiota composition. For this purpose, three diets, with increasing levels of insect prepupae meal inclusion (10%, 20% and 30%) in partial substitution of fishmeal and a control diet without insect meal were tested in a 12-weeks feeding trial. Fish growth and feed conversion ratio were evaluated. The Illumina MiSeq platform for high-throughput amplicon sequencing of 16S rRNA gene and QIIME pipeline were used to analyse and characterize the whole microbiome associated to aquafeeds, and fish gut. The number of reads taxonomically classified according to the Greengenes database was 1,140,534. We identified 450 OTUs at 97% identity in trout fecal samples; 62 OTUs constituted the core gut microbiota. Actinobacteria, Firmicutes and Proteobacteria represented the dominant phyla in both experimental groups. Among them, the abundance of Actinobacteria and Proteobacteria was significantly influenced by including insect meal in the diet. In summary, our findings clearly indicated that insect meal positively modifies fish gut microbiota, increasing its richness and diversity and in particular, increasing the amount of beneficial lactic acid-and butyrate-producing bacteria, which contribute to the global health of the host. In addition, based on our present and previous studies, we believe that the prebiotic effect of insect meal is principally due to fermentable chitin.

QUARK CHEESE PRODUCED WITH KEFIR AND AGAVE INULIN

Quark cheese is a cheese of fresh mass obtained by coagulation of the milk by the action mainly of lactic bacteria obtaining a cheese of refreshing flavor with high acidity, in its commercial production a specific starter culture is used, in the present work this culture was replaced by kefir, a symbiotic system of lactic acid bacteria and yeasts, which is considered a probiotic product. Agave inulin is a soluble fiber considered prebiotic with ability to improve the balance of the intestinal flora. The objective of this work was to develop Quark cheese using kefir as a starter culture and supplemented with agave inulin. Cheeses were produced by fermentation for 24h / 25ºC followed by drainage of the whey, in the supplemented cheese 3% of inulin was added, after whey drainage cheeses were kept in plastic pots under refrigeration temperature until the moment of the analyses. Microbiological evaluations, pH and acidity were performed at 1, 7 and 14 days after manufacture. The results of the physical-chemical analyses remained close to those found in the literature. Cheeses showed high counts of Lactobacilli indicating their probiotic potential, the addition of agave inulin decreased the number of these microorganisms, nevertheless they remained in high counts. It can be verified that the use of kefir in the production of Quark cheese is feasible, mainly in artisanal productions because it is usually inexpensive and easy to maintain, Lactobacilli have remained stable during the storage period.

Dissipation of Three Fungicides and Their Effects on Anthocyanins and Color of Monastrell Red Wines.

The effect of fungicides on fermentation is of paramount importance to control the quality and safety of wines. In this work, the quality (enological parameters, color, phenolic content, antioxidant activity, and fungicide residues) of wines from Monastrell grapes fortified with iprovalicarb, mepanipyrim, and tetraconazole fungicides was evaluated. Along the winemaking process, initial residues of mepanipyrim and tetraconazole were removed in more than 90% while the dissipation of iprovalicarb was around 73%. Significant statistical differences were found in the presence of iprovalicarb and mepanipyrim residues, especially at the highest concentration assayed. For both fungicides, increases in the volatile acidity (between 4 and 8.6 times), the lactic acid content (between 8.6 and 20.5 times), the percentage of polymeric anthocyanins (between 1.3 and 1.7 times), and also a slight increase of the total phenolic index and the total anthocyanin content determined by spectrophotometry were observed. On the contrary, the total monomeric anthocyanins content decreased about 16.3% and 28.6% in the presence of iprovalicarb and mepanipyrim, respectively. These results could be related to a higher development of acetic acid or lactic bacteria in the presence of these fungicides. The color of the final wines was also different in comparison with the control, with a higher yellow component, color intensity, tonality, and hue angle because of pH changes in the medium. Tetraconazole fermentations had a more similar trend to the control wine, probably due to the lower concentration of this fungicide in the grape must at the initial time. No effects on the antioxidant activity was observed for any of the target fungicides. A multivariate statistical analysis was done to view the interrelationships between different variables (color and anthocyanins profile). The obtained model allowed the wines to be separated according to the fungicide treatment applied.

Fermentation of yam (Dioscorea spp. L.) by indigenous phytase-producing lactic acid bacteria strains

The use of lactic bacteria in the development of functional foods has increased in recent years. In addition to their probiotic characteristics, they can ferment a variety of substrates, such as cereals, roots, and tubers. Phytase producer lactic acid bacteria strains and their behavior during the fermentation process of yam-based food were studied. Leuconostoc lactis CCMA 0415, Lactobacillus plantarum CCMA 0744, and Lactobacillus fermentum CCMA 0745 were selected due to phytase production, pH reduction, and growth during 24h of fermentation. Oxalate activity was not detected in all assays, suggesting its concentration was reduced due to the bleaching process. Among the selected strains, L. lactis CCMA 0415 appeared to be a promising strain in yam-based fermentations because it maintained a cell viability above 8 log CFU/mL and did not reduce diosgenin concentrations (around 8.0μg/mL) after fermentation for 24h, thereby, generating a potentially functional yam food. Furthermore, this strain promoted the decrease of pH value from 6.1 to 3.8 and produced 8.1g/L lactic acid, at 6h of fermentation. The L. lactis CCMA 0415 was reported as a starter culture in fermented products based on cereals, roots, and tubers.

Biogenic Amines as Risk Factors of Food Chain

Biogenic amines at higher doses have negative effects on the human organism. Some biogenic amines (e.g. putrescine, spermine, spermidine, cadaverine, histamine) are an essential component of living cells because they are involved in the regulation of nucleic acid and protein synthesis and membrane stabilization. Amines are produced by the decarboxylation of natural free amino acids. Decarboxylases are not common in bacteria but occur in species of many genera, particularly in Bacillus, Citrobacter, Clostridium, Escherichia, Klebsiella, Photobacterium, Proteus, Pseudomonas, Salmonella, Shigella and lactic bacteria of the Lactobacillus genera, Pediococcus and Streptococcus. Main factors influencing the biogenic amines formation are pH, water activity, storage time, temperature and salt content. Typical levels of biogenic amines in foods range from 10 mg/kg to 100 mg/kg. Occasionally, the amount of biogenic amines in food can exceed 1000 mg/kg.

The Expression of Codon Optimised Hepatitis B Core Antigen (HBcAg) of Subgenotype B3 Open Reading Frame in Lactococcus lactis

Hepatitis B treatments using immune therapy are gaining interest because of the improvements in dendritic cell performance for antigen presentation, which induces an appropriate immune response and raises patient survival rates. This research aims to produce a significant amount of the HBcAg antigen, which can induce an immune response and have a curative effect on HBV infection. In this study, the HBV subgenotype B3 of the HBcAg gene was used, which is dominant in Indonesia. Further, Lactococcus lactis bacteria was used as the host because of its safety and tightly regulated protein expression. The codon usage for the HBcAg gene was optimized to improve protein expression in L. lactis, which is important because a codon is not random between species. The HBcAg gene is attached to a pNZ8148 plasmid and transformed into the L. lactis NZ3900 expression host. The results confirm that a positive protein band (21 kDa) in two fractions of purified HBcAg was recognized by both western blotting and dot blot hybridization, even if the HBcAg optimized codon has higher GC contents than that suggested for L. lactis expression. Overall, this research strengthens the broad use of L. lactis bacteria for any protein expression, including higher protein expression of codon optimized HBcAg gene compared to non-optimized genes. Furthermore, the improvement in the codon optimization of the HBcAg gene significantly increases the total protein expression by 10-20%, and the expression level of the codon optimized HBcAg increases 1.5 to 3.2-times that of the native HBcAg.

The Role of Saccharomyces cerevisiae Yeast and Lactic Acid Bacteria in the Formation of 2-Propanol from Acetone during Fermentation of Rye Mashes Obtained Using Thermal-Pressure Method of Starch Liberation.

This study set out to assess the acetone content in rye sweet mashes prepared using the thermal-pressure method of starch liberation, and to investigate the formation of 2-propanol during the fermentation process. In the first set of experiments, we evaluated the correlation between the color and the content of acetone and furfural in industrially produced sweet mashes (n = 37). The L * value was negatively correlated with the content of both acetone and furfural, while chromatic parameters a * and b * and the yellowness index (YI) had strong positive correlations with acetone (r > 0.9) and furfural (r > 0.8 for a * and r > 0.9 for b * and YI). In the second set of experiments, we assessed the concentration of acetone and 2-propanol in distillery rye mashes, fermented by S. cerevisiae yeast and lactic acid bacteria. The influence of fermentation temperature on the formation of 2-propanol was also evaluated. The presence of 2-propanol in the post-fermentation media was confirmed, while a decrease in acetone content was observed. Fermentation temperature (27 °C or 35 °C) was found to have a significant effect on the concentration of 2-propanol in trials inoculated with lactic bacteria. The content of 2-propanol was more than 11 times higher in trials fermented at the higher temperature. In the case of yeast-fermented mashes, the temperature did not affect 2-propanol content. The acetone in the sweet mash was assumed to be a precursor of 2-propanol, which was found in the fermented mashes.

Use of Maldi-Tof MS biosensor in microbial assessment of Brazilian kefir grains

ABSTRACT The aim of this study was to evaluate the use of Maldi-Tof MS biosensor in microbial assessment of Brazilian kefir grains. Maldi-Tof MS is a new methodology for the rapid diagnosis of microorganisms. A total of 358 microorganisms were isolated, 31 were yeasts and 327 were bacteria (divided into lactic and acetic bacteria). Microbial colonies were grown in Luria-Bertani agar medium and incubated at 35 °C for 18h and used in the identification of species by Maldi-Tof MS. The microbial population identified in Brazilian kefir grains was Lactobacillus paracasei, Saccharomyces cerevisiae, Lactobacillus plantarum, Acetobacter pasteurianus, and Acetobacter syzygii. This study demonstrated a rapid and accurate identification of the Brazilian kefir grains microorganisms using the Maldi-Tof MS biosensor. In conclusion, the Maldi-Tof MS technology can facilitate the microbiological control in a fermentation process using kefir grains as starter cultures.

Молочнокислые закваски с пробиотическим действием для получения органической свинины

Молочнокислые закваски с пробиотическим действием для получения органической свинины

Compound polysaccharides ameliorate experimental colitis by modulating gut microbiota composition and function.

Inflammatory bowel disease results from a dysregulated immune response to intestinal microbial flora in individuals with genetic predisposition(s). This study aimed to determine the effects of compound polysaccharides (CP) containing yam polysaccharide and inulin on the rat model of colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) and to explain the mechanism in terms of gut microbiota composition and function. Male SD rats were divided into three groups: the control group, the model group, and the CP group. Disease activity index, serum myeloperoxidase level, and the composition and function of gut microbiota were analyzed. The data in the study showed CP reduced inflammation in the rat model of colitis induced by TNBS and ameliorated the experimental colitis. The results also indicated that CP not only reversed TNBS-induced gut dysbiosis-indexed by increased short-chain fatty acids (SCFAs)-producing bacteria, lactic acid-producing bacteria, and decreased Bacteroides, Proteobacteria as well as sulfate-reducing bacteria, but also restored the dysregulated microbiota function of colitic rats into a normal condition, including an improvement on basic metabolism and a reduction on oxidative stress, cell motility, signal transduction, xenobiotics biodegradation, and metabolism as well as pathogenesis processes. Compound polysaccharides ameliorated the experimental colitis of rats induced by TNBS by modulating the gut microbiota composition and function profiles, which makes it possible to be used as prebiotic agents to treat gut dysbiosis in colitis individuals.

The Determination of Some Microbiological and Chemical Features in Herby Cheese.

The objective of this study is to measure the amounts of biogenic amines, microbial counts, values of pH, titratable acidity, dry matter, and salt (%) in herby cheese, a very popular staple in the Turkish diet, and to evaluate the concentration of biogenic amines in terms of public health risks. A high-performance liquid chromatography (HPLC) method was used for the determination of eight biogenic amines in 100 herby cheeses sold in the local markets of Van. The bacterial load of the herby cheeses ranged between 4.0 and 8.90 log CFU/g for viable total aerobic mesophilic bacteria (TAMB), <1 and 7.0 log CFU/g for lactic bacteria (LAB), <1 and 6.08 log CFU/g for coliform bacteria, <1 and 5.81 log CFU/g for Enterobacteriaceae, <1 and 2.60 log CFU/g for Staphylococcus aureus, and 3.70 and 8.05 log CFU/g for yeasts and molds. The results obtained suggested significant changes in the pH, titratable acidity, dry matter, and salt contents of the examined herby cheese samples. The detection levels of biogenic amines in the samples ranged from <0.025 to 33.36 mg/kg for tryptamine, from <0.038 to 404.57 mg/kg for β-phenylethylamine, from 0.03 to 426.35 mg/kg for putrescine, from <0.039 to 1438.22 mg/kg for cadaverine, from <0.033 to 469 mg/kg for histamine, from <0.309 to 725.21 mg/kg for tyramine, from <0.114 to 1.70 mg/kg for spermidine, and from <0.109 to 1.88 mg/kg for spermine. As a result, these cheeses are fit for consumption in terms of the amounts of biogenic amines they contain.

Preliminary microbiological and chemical characterisation of edible goat’s rennet, a unique product of Sardinian food tradition

The edible goat rennet (EGR) namely Caggiu de crabittu, is a traditional Sardinian foodstuff deriving from the stomach of a weaned (breastfed) kid whose edible part is represented by the milk coagulated inside the abomasum that, before consumption, is subjected to a suitable ripening time. In this study, a preliminary investigation into the microbiological characteristics and physicochemical parameters of different EGRs manufactured by distinct Sardinian farms was conducted. Results showed that the edible goat rennet was free of spoilage/pathogenic bacteria and was characterised by a significant presence (6–7 log cfu/g) of mesophilic lactic acid bacteria (i.e. Lactococcus lactis, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus brevis) and Enterococci. Oleic, linolenic, palmitic and myristic acids were the most abundant free fatty acids (FFA) in all samples, while both caprylic and butyric acid contents resulted the lowest. Long chain FFA (≥C18:0) represented about 50% of total FFA. Among the polyunsaturated FFA, high content of linoleic (C18:2n-6) and alpha-linolenic (C18:3n-3) acids have been detected. In this study, EGR is shown to be microbiologically safe, with a high number of live lactic bacteria and an FFA content that is attractive from a nutritional point of view.HighlightsEdible goat’s rennet (EGR) resulted microbiologically safe with a high number of viable mesophilic lactic acid bacteria.In the EGR an intense process of lipolysis has occurred.EGR had a high content of linolenic acid.

Inhibition of Coliform Bacteria by Lactic Acid Bacteria Isolated from Nham Hed (Fermented Mushroom)

Four samples of Nham Hed which fermented from different carbon sources; Homnil rice (HN), sticky rice (SR), LeumPua rice (LP) and rice berry (RB) were evaluated for total viable count of lactic acid bacteria (LAB). The rice berry Nham Hed samples showed the highest of total lactic bacteria count with values 2.83 x 105 cfu/g. The thirty one distinct colonies of LAB were isolated and categorized into 6 groups on the basis of their colony characteristics on MRS agar, microscopic morphology and biochemical characteristic. These 6 isolates were screened for their antimicrobial activity against 2 strains of coliform bacteria and it was found that LAB isolate E exhibited the highest antimicrobial activity against Escherichia coli and Enterobacter sp. which the zone of inhibition zone 14.22 ± 1.50 mm and 13.38 ± 1.25 mm, respectively. According to the morphology characterization, isolate E was probably classified to Weissella spp. These obtained results revealed the possibility for further characterization and purification the antimicrobial compound produced by the studied isolate as food bio preservatives to control food spoilage and pathogenic bacteria.

Bacterial inoculant effect on quality of alfalfa silage and haylage

Using of silage and haylage of forage legumes in ruminant nutrition and promotion of promoting proper forage conservation techniques should be an important strategy in livestock production in our country. Forage legumes are difficult to ensile, so it is necessary to apply the starter culture of selected strains of lactic acid bacteria that support the ensiling process and prevent bacterial butyric fermentation and thus contribute to the preservation and improvement of silage and haylage quality. In this paper, the influence of bacterial inoculant ?Silko for alfalfa? on the quality of silage and haylage of alfalfa in two separate trials is presented. The inoculant is a combination of homofermentative lactic bacteria Lactobacillus plantarum and Pediococcus spp. The first-cut alfalfa in the second year was used for silage and haylage. The silage was examined in mini-silos in the laboratory, and the haylage at the cattle farm where the plant material was cuts were collected in experimental silo bags. The treatments were control (untreated silage, i.e. haylage) and silage, i.e. haylage treated with inoculant ?Silko for alfalfa? (rate of 5 ml t-1 fresh material). The silages were analyzed after 90 days, and haylage after 40. The inoculant ?Silko for alfalfa? has been found to maintain the nutritive value of silage and haylage and to improve their chemical, energy and fermentation parameters relative to the control. Since ?Silko for alfalfa? positively affects the correct lactic acid fermentation of silage and haylage and contributes to a lesser loss of nutritional value and energy it is expected that it can promote a high level of productivity of ruminants, and thus contribute to the growth of profit in livestock production.

Influence of the diet of Mexican women on the nutritional quality and the presence of beneficial microorganisms in human milk

Introduction: breast milk is the first fundamental food of newborns and it provides all the sources of energy, nutrients and the immunological protection they need during their first months of life. Unfortunately, there are specific circumstances that imply that the mother cannot feed her baby correctly, since the mother's nutritional needs differ to a certain extent during different periods of life. Especially in breastfeeding, since nutritional needs are increased, due to the loss of nutrients, first by colostrum and then by breast milk. Objective: to demonstrate the influence of the diet of Mexican women on the nutritional quality and the presence of beneficial microorganisms in human milk. Methods: seventy descriptive surveys of nutrition and sampling of milk to women in nursing state were carried out. The milks were subjected to various bromatological and microbiological analyzes to evaluate their nutritional quality and possible probiotic activity. Results: it was shown that the mother's food intake influences the nutritional quality of the milk. Likewise, it affects the development and growth of lactic acid bacteria. Several strains were isolated and identified in human milk of the genus Lactobacillus, as well as pathogenic bacteria such as Lodderomyces elongisporus among others. Conclusions: the mothers' nutrition is directly reflected in the nutritional quality of the milk. It was observed that the amount of essential nutrients of milk such as carbohydrates, lipids and proteins vary according to the diet and life rhythm of the mothers, as well as the significant decrease of lactic bacteria with probiotic potential.

Resistant starch reduces large intestinal pH and promotes fecal lactobacilli and bifidobacteria in pigs

Dietary resistant starch (RS) may have prebiotic properties but its effects on fermentation and the microbial population are inconsistent. This meta-analysis aimed to quantify the relationship between RS type 2 (RS2) and intestinal short-chain fatty acids (SCFA) and pH as well as certain key bacterial taxa for intestinal health in pigs. From the 24 included articles with sufficient information about the animal, and dietary and physiological measurements published between 2000 and 2017, individual sub-data sets for fermentation metabolites, pH, bacterial abundances and apparent total tract digestibility were built and used to parameterize prediction models on the effect of RS2, accounting for inter- and intra-study variability. In addition, the effect of pig’s BW at the start of the experiment and duration of the experimental period on response variables were also evaluated using backward elimination analysis. Dietary RS levels ranged from 0% to 78.0% RS, with median and mean RS levels of 28.8% and 23.0%, respectively. Negative relationships could be established between dietary RS and pH in the large intestine (P<0.05), with a stronger effect in the mid and distal colon, and feces (R2=0.64 to 0.81; P<0.001). A dietary level of 15% RS would lower the pH in the proximal, mid-, distal colon and feces by 0.2, 0.6, 0.4 and 0.6 units, respectively. Increasing RS levels, however, did not affect SCFA concentrations in the hindgut, but enhanced the molar proportion of propionate in mid-colon and reduced those of acetate in mid-colon and of butyrate in mid- and distal colon (R2=0.46 to 0.52; P<0.05). Backward elimination indicated an age-related decrease in mid-colonic propionate proportion and increase in mid- and distal colonic butyrate proportion (P<0.05), thereby modulating RS2 effects. In feces, increasing RS levels promoted fecal lactobacilli (R2=0.46; P<0.01) and bifidobacteria (R2=0.57; P<0.01), whereby the slope showed the need for a minimal RS level of 10% for a 0.5 log unit-increase in their abundance. Best-fit equations further supported that a longer experimental period increased fecal lactobacilli but decreased fecal bifidobacteria (P<0.05). In conclusion, dietary RS2 seems to effectively decrease digesta pH throughout the large intestine and increase lactic acid-producing bacteria in feces of pigs which may limit the growth of opportunistic pathogens in the hindgut. To achieve these physiologically relevant changes, dietary RS should surpass 10% to 15%.

Antioxidant activity of essential oils from condiment plants and their effect on lactic cultures and pathogenic bacteria

ABSTRACT: Studies about preservative and antioxidant activity of essential oils have been encouraged in recent years, given their importance to food industry. The aim of the current study was to evaluate the antioxidant properties and antimicrobial activity of essential oils deriving from Syzygium aromaticum, Cymbopogon citratus and Lippia alba against lactic and pathogenic bacteria responsible for food-borne diseases. Essential oil antibacterial activity was assessed through disc diffusion and macrodilution tests conducted in a mixed lactic culture of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus (YF-L903) and of Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538), Salmonella enterica (ATCC 6017) strains. Based on the chromatographic analysis results, the essential oils shown to be composed of eugenol (79.41%) which was the prevalent compound in S. aromaticum, geranial (31.89%), neral (24.52%) and β-myrcene (25.37%) in C. citratus, as well as of geranial (33.80%) and neral (25.63%) in L. alba. The observed antibacterial activity confirmed the dose-dependent effect of these three oils on all the assessed bacteria; there was halo inhibition at concentration 20μL mL-1. The essential oil of S. aromaticum presented better antioxidant activity, with IC50 equal to 5.76μg mL-1 and antioxidant activity index of 6.94, and it was considered strong (AAI&gt;2.0) in comparison to the other evaluated oils. This essential oil also presented excellent antioxidant activity at concentrations lower than the one required to inhibit lactic cultures. Based in this outcome, the essential oil from S. aromaticum can be used as preservative agent in processed food whose formulation presents lactic cultures.

QUALIDADE FÍSICO-QUÍMICA E MICROBIOLÓGICA DE LEITE DE CABRA PRODUZIDO NO DISTRITO FEDERAL

Resumo O objetivo desse trabalho foi avaliar a qualidade físico-química e microbiológica do leite de cabra produzido no Distrito Federal, Brasil. As amostras foram coletadas diretamente dos tetos e em pool de cada três animais (n=40) e de leite de conjunto (n=10). Nas análises físico-químicas, os resultados médios foram: gordura (animais: 3,01% ± 0,679, conjunto: 4,45% ± 1,223); sólidos não gordurosos (animais: 9,24% ± 0,651, conjunto: 9,2% ± 0,615); densidade (animais: 1,033g/mL ± 0,002, conjunto: 1,032g/mL± 0,002); proteínas (animais: 3,5% ±0,551, conjunto: 3,67% ±0,778); lactose (animais: 5,0% ± 0,035, conjunto: 4,94% ± 0,015); acidez Dornic (animais: 18,47ºD ±0,552, conjunto: 18,5ºD ± 0,5); pH (animais e conjunto: 6,9 ±0,098); crioscopia (animais: -0,560ºH ±0,010, conjunto: -0,558ºH ± 0,005). Nenhuma amostra apresentou resíduos de antibióticos. As contagens médias microbiológicas foram: aeróbios mesófilos 1,2x103 UFC/mL (animais) e 7,6x103 UFC/mL (conjunto); coliformes totais 1,0 UFC/mL (animais) e 1,2x104 UFC/mL (conjunto); Escherichia coli 2,0 UFC/mL (conjunto); psicrotróficos 1,0x104 UFC/mL (conjunto); bactérias ácido-láticas 4,7x102 UFC/mL (animais) e 7,8x103 UFC/mL (conjunto); bolores e leveduras 1,0 UFC/mL (animais) e 4,9x103 UFC/mL (conjunto) e Staphylococcus aureus 2,1x102 UFC/mL (animais) e 2,8x102 UFC/mL (conjunto). Listeria monocytogenes e Salmonella spp. não foram detectadas nas amostras analisadas. Os resultados obtidos permitem concluir que o leite de cabra produzido no Distrito Federal apresenta qualidade satisfatória e esses dados podem contribuir para o estímulo da produção na região.