Counts Of Lb Research Articles

Physicochemical, microbiological and sensory characterization of yogurt fermented by Weissella confusa SW1 and traditional starters

Starter cultures play important roles in the quality and functional activity of yogurt. In this study, a novel strain Weissella confusa SW1 was isolated from naturally fermented milk. The potential application of this strain in yogurt preparation was investigated and the unique qualities it conferred on yogurt was characterized. W. confusa SW1 could efficiently metabolize lactose and galactose, and the whole-genome sequencing showed that it has a complete Leloir metabolic pathway. Besides, W. confusa SW1 had strong antioxidant capacity, and could significantly promote the growth of Streptococcus thermophilus. Subsequently, W. confusa SW1 was co-cultured with traditional starters (Lb. bulgaricus and S. thermophilus) to prepare yogurt. The results showed that the scavenging rates of DPPH and ABTS radicals of W. confusa SW1 fermented yogurt increased from 79.51% to 85.19% and 80.14%–85.47%, respectively. Meanwhile, the viable bacterial counts of Lb. bulgaricus and S. thermophilus were increased in yogurt when co-cultured with W. confusa SW1. Furthermore, the addition of W. confusa SW1 reduced the curd time and improved the water holding capacity of yogurt. Thus, this study laid a theoretical foundation for the development of functional yogurt with the application of W. confusa SW1.

Role of GBA variants in Lewy body disease neuropathology.

Rare and common GBA variants are risk factors for both Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, the degree to which GBA variants are associated with neuropathological features in Lewy body disease (LBD) is unknown. Herein, we assessed 943 LBD cases and examined associations of 15 different neuropathological outcomes with common and rare GBA variants. Neuropathological outcomes included LBD subtype, presence of a high likelihood of clinical DLB (per consensus guidelines), LB counts in five cortical regions, tyrosine hydroxylase immunoreactivity in the dorsolateral and ventromedial putamen, ventrolateral substantia nigra neuronal loss, Braak neurofibrillary tangle (NFT) stage, Thal amyloid phase, phospho-ubiquitin (pS65-Ub) level, TDP-43 pathology, and vascular disease. Sequencing of GBA exons revealed a total of 42 different variants (4 common [MAF > 0.5%], 38 rare [MAF < 0.5%]) in our series, and 165 cases (17.5%) had a copy of the minor allele for ≥ 1 variant. In analysis of common variants, p.L483P was associated with a lower Braak NFT stage (OR = 0.10, P < 0.001). In gene-burden analysis, presence of the minor allele for any GBA variant was associated with increased odds of a high likelihood of DLB (OR = 2.00, P < 0.001), a lower Braak NFT stage (OR = 0.48, P < 0.001), a lower Thal amyloid phase (OR = 0.55, P < 0.001), and a lower pS65-Ub level (β: -0.37, P < 0.001). Subgroup analysis revealed that GBA variants were most common in LBD cases with a combination of transitional/diffuse LBD and Braak NFT stage 0-II or Thal amyloid phase 0-1, and correspondingly that the aforementioned associations of GBA gene-burden with a decreased Braak NFT stage and Thal amyloid phase were observed only in transitional or diffuse LBD cases. Our results indicate that in LBD, GBA variants occur most frequently in cases with greater LB pathology and low AD pathology, further informing disease-risk associations of GBA in PD, PD dementia, and DLB.

Role of cysteine in the improvement of γ-aminobutyric acid production by nonproteolytic Levilactobacillus brevis in coculture with Streptococcus thermophilus

Previous research has showed that nonproteolytic Levilactobacillus brevis 145 (L) in coculture with Streptococcus thermophilus 1275 (S), not Lactobacillus delbrueckii ssp. bulgaricus (Lbu), was able to produce γ-aminobutyric acid (GABA) during milk fermentation in the presence of monosodium glutamate (MSG). It was assumed that differences of casein hydrolysis patterns between Strep. thermophilus 1275 and L. bulgaricus caused the phenomenon. Moreover, the GABA content was low and residual MSG was high in SL-fermented milk. In our research, comparison of peptide profiles determined by liquid chromatography/tandem mass spectrometry showed that αS2-casein, β-casein, and κ-casein degradation by L. bulgaricus and Strep. thermophilus varied. Importantly, the peptide number in the L and Lbu coculture group increased compared with the Lbu monoculture group, whereas the peptide number in the SL coculture group decreased in comparison with S monoculture group, suggesting that L. bulgaricus was not able to provide peptides for the growth of Lb. brevis 145. Furthermore, we found that after supplementation with cysteine (50 mg/L) during milk fermentation by SL, 10 g/L MSG was converted into 4.8 g/L GABA with a minimum level of residual MSG, viable cell counts of Lb. brevis and lactic acid production were increased, and the casein hydrolysis pattern was not influenced. Moreover, sulfhydryl group-containing chemicals including cystine, reduced glutathione, and oxidized glutathione showed effects similar to that of cysteine in improving GABA production. Finally, when L. bulgaricus YIB2 was combined with SL, supplementation of cysteine was also able to significantly improve GABA production.

Use of Fourier Transform Infrared Spectroscopy for Monitoring the Shelf Life and Safety of Yogurts Supplemented With a Lactobacillus plantarum Strain With Probiotic Potential.

The current study aimed to explore the performance of a probiotic Lactobacillus strain as an adjunct culture in yogurt production and to assess Fourier transform infrared spectroscopy as a rapid, noninvasive analytical technique to evaluate the quality and the shelf life of yogurt during storage. In this respect, bovine milk (full-fat) was inoculated with the typical yogurt starter culture without (control case) or with the further addition of Lactobacillus plantarum T571 as an adjunct (probiotic case). The milk was also inoculated with a cocktail mixture of three strains of Listeria monocytogenes in two different initial levels of inoculum, and the fermentation process was followed. Accordingly, yogurt samples were stored at 4 and 12°C, and microbiological, physicochemical, molecular, and sensory analyses were performed during storage. Results showed that the lactic acid bacteria exceeded 7 log CFU/g during storage in all samples, where the probiotic samples displayed higher acidity, lower pH, and reduced counts of Lb. monocytogenes in a shorter period than the control ones at both temperatures. Pulsed-field gel electrophoresis verified the presence of the probiotic strain until the end of storage at both temperatures and in adequate amounts, whereas the survival and the distribution of Listeria strains depended on the case. The sensory evaluation showed that the probiotic samples had desirable organoleptic characteristics, similar to the control. Finally, the spectral data collected from the yogurt samples during storage were correlated with microbiological counts and sensory data. Partial least squares and support vector machine regression and classification models were developed to provide quantitative estimations of yogurt microbiological counts and qualitative estimations of their sensory status, respectively, based on Fourier transform infrared fingerprints. The developed models exhibited satisfactory performance, and the acquired results were promising for the rapid estimation of the microbiological counts and sensory status of yogurt.

Microbiological and SEM assessment of atraumatic restorative treatment in adult dentition.

To investigate the practicability of atraumatic restorative treatment (ART) in adults in terms of marginal adaptation of restorations and microbiological changes in residual carious dentin. The occlusal dentin caries of 25 permanent molar teeth were removed with hand instruments. The total counts of bacteria (TCB) and the facultative anaerobic bacteria (FAB), mutans streptococci (MS), and Lactobacillusspp. (LB) counts in the affected dentin were evaluated quantitatively. The weights of the samples were measured with an electronic balance (Shimadzu, Type AX200, Japan). The cavities were restored with glass ionomer cement (KetacTM Molar Easymix, ESPE Dental AG, Seefeld, Germany). Twenty replicas of randomly selected ART restorations were prepared and marginal adaptation was evaluated by scanning electron microscopy (SEM). After 6 months, the same protocols were repeated. Data were analyzed with paired sample t-tests, Wilcoxon t-tests, Pearson and Spearman correlations, and chi-square tests (p<0.05). In the sixth month, restoration loss and pulpitis were not observed. The mean weight of samples removed from the cavity floor was less than the baseline (0.014±0.009 and 0.023±0.013 g, respectively) (p<0.01), and the counts of total bacteria, FAB, MS, and LB significantly decreased compared to baseline (p<0.01). The frequency of marginal gaps was increased (p< 0.01). ART showed that the counts of microorganisms decreased after 6 months although the marginal gap rates of restorations increased. ART can be a reliable treatment approach in adults for 6 months due to the decrease in microorganism counts, although gaps exist.

Correspondence between plaque index and Streptococcus mutans and Lactabacillus spp. counts in a child population: A cross-sectional study

Background: The identification of microorganisms such as Streptococcus mutans (SM) and Lactobacillus spp. (LB) is a predictor of the development of caries, however the identification methods are of limited access due to their high cost. Aim: the objective of this study was to determine the correlation between the dental biofilm measured by the modified Silness and Löe dental plaque index (DPI)) and the SM and LB count, in preschool children from Colombia. Materials and methods: This is a descriptive cross-sectional and correlational study. We took 202 samples from children between 3 and 4 years of age from three kindergartens in Cali, Colombia, belonging to socioeconomic stratum 1 and 2, evaluated at four times (0, 3, 6 and 9 months). Results: We found a correlation between the highest IPB and the highest count of SM colony forming units only at 3 months (p = 0.003*). LB counts were homogeneous in all children and there was no correlation with IPB. Conclusion: We observed mixed results on the relationship between IPB and the counts of SM present in the saliva, therefore an analysis of multiple factors is required.

Comparative studies on the effect of probiotic additions on the physicochemical and microbiological properties of yoghurt made from soymilk and cow's milk during refrigeration storage (R2)

Soymilk yoghurt is an option to consumers who are allergic to cow's milk yoghurt. Probiotics can provide gut health. The objective of this study was to investigate the physicochemical characteristics, including pH, colour, firmness and syneresis of yoghurt made from soymilk and cow's milk as affected by the addition of probiotics during storage at 4 °C for 28 days at 7-day intervals. Microstructure and bacterial populations were also determined. Two types of yoghurt were prepared. The first type was prepared with the additions of commercially available yogurt starter containing Lactobacillus delbrueckii ssp. bulgaricus (LB) and Streptococcus thermophilus (ST). The second type was prepared with the same yogurt starters plus three probiotics, including Bifidobacterium animalis subsp. lactis BB-12 (BB), L. acidophilus La-5 (LA), and L. rhamnosus (LGG). Probiotics reduced syneresis and increased compact network of soymilk yoghurt significantly (p < 0.05) and shortened the time needed to reach pH 4.5 in both cow's milk and soymilk yogurts. During storage, the pH of cow's milk yoghurts slightly decreased (4.37–4.26 with probiotics and 4.54 to 4.33 without probiotics), however, the pH of soymilk yoghurts remained relatively constant. The firmness of yoghurt made from cow's milk was significantly decreased with the addition of probiotics, however, it remained stable in soy milk yoghurt during storage. Soymilk yoghurt (34–50 g force during compression) was generally firmer than cow's milk yoghurts (9.8–12.5 g force). The cow's milk yogurt had slightly higher counts of ST, LB and LA than soymilk yogurt, but the count of BB in soymilk yogurt is significantly higher than that in cow's milk yogurt.

Probiotic viability in yoghurts containing oligosaccharides derived from lactulose (OsLu) during fermentation and cold storage

We studied the viability of probiotics Lactobacillus acidophilus and Bifidobacterium animalis ssp. lactis and microorganisms of a starter culture for set-style yoghurt, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus, during manufacture and cold of storage of synbiotic yoghurts containing lactulose and the emerging prebiotic lactulose-derived oligosaccharides (OsLu). The evolution of the carbohydrate fraction, pH and microbial metabolites, such as organic acids, were assessed. Supplementation of yoghurts with lactulose significantly increased counts of Lb. delbrueckii ssp. bulgaricus, Lb. acidophilus and B. animalis ssp. lactis during fermentation in comparison with control yoghurt, in agreement with partial lactulose consumption. OsLu content was unchanged during fermentation or subsequent storage. These results demonstrated that the chemical structure of the oligosaccharide plays a remarkable role in the fermentation of probiotics, suggesting OsLu as an alternative prebiotic to conventional lactulose in dairy products with adequate cell counts of probiotics while preserving the initial levels of added prebiotic.

Yoghurt-Type Gels from Skim Sheep Milk Base Enriched with Whey Protein Concentrate Hydrolysates and Processed by Heating or High Hydrostatic Pressure.

An objective of the present study was the enrichment of skim sheep yoghurt milk base with hydrolysates (WPHs) of whey protein concentrate (WP80) derived from Feta cheesemaking. Moreover, the use of high hydrostatic pressure (HP) treatment at 600 MPa/55 °C/10 min as an alternative for heat treatment of milk bases, was studied. In brief, lyophilized trypsin and protamex hydrolysates of WP80 produced under laboratory conditions were added in skim sheep milk. The composition and heat treatment conditions were set after the assessment of the heat stability of various mixtures; trisodium citrate was used as a chelating agent, when needed. According to the results, the conditions of heat treatment were more important for the physical properties of the gel than the type of enrichment. High pressure treatment resulted in inferior gel properties, irrespective of the type of enrichment. Supplementation of skim sheep milk with whey protein hydrolysates at >0.5% had a detrimental effect on gel properties. Finally, skim sheep milk base inoculated with fresh traditional yoghurt, resulted in yoghurt-type gels with high counts of Lb. delbrueckii subsp. bulgaricus and Str. thermophilus -close to the ideal 1:1- and with a high ACE inhibitory activity >65% that were not essentially affected by the experimental factors.

Characteristics of fermented camel&rsquo;s milk fortified with kiwi or avocado fruits.

The aim of this study was to develop nutritious fermented milk products from camel&rsquo;s milk fortified with kiwi fruit and avocado puree, and fermented using probiotic strains. Stirred yoghurt made from camel&rsquo;s milk, supplemented with avocado and kiwi fruit puree as natural additives at different levels (2, 4 and 6%) and fermented with a mixture of yoghurt culture and probiotic Lb. acidophilus and B. lactis. The stirred yoghurt was chemically analyzed, and the microbial count, antioxidant activity and total phenolic content were determined. The stirred yoghurt from different treatments was assessed for viscosity and sensory properties. The highest viable counts of Lb. acidophilus and B. lactis were enumerated in yoghurts fortified with 6% avocado, whereas the control had significantly lower counts. The radical scavenging activity (RSA) and the total phenol content (TPC) decreased for the control of the stirred camel&rsquo;s milk yoghurt after 21 days of storage, whereas the samples fortified with kiwi or avocado puree retained high RSA and TPC content throughout the storage period compared to the control. Addition of 4% avocado or 6% kiwi pastes to fermented camel&rsquo;s milk produces a higher quality and acceptability of camel&rsquo;s milk.

Effect of Greek-style yoghurt manufacturing processes on starter and probiotic bacteria populations during storage

This study compared viable counts of Streptococcus thermophilus (starter) and Lactobacillus helveticus R0052 (probiotic), as a function of two manufacturing processes of Greek-style (GS) yoghurt: centrifugation of a curd (GS-CF process) or ultrafiltration of milk prior to fermentation (GS-UF process). Fresh GS-UF and GS-CF yoghurts had between 3 and 7 times higher counts of Lb. helveticus R0052 and S. thermophilus than the regular stirred yoghurt (Control). Strain R0052 was three times more stable in the GS-CF yoghurt than in the Control over the 44 d storage period. The highest lactose content (44 g L−1) was obtained in the Control, while 60% less was obtained in the GS-UF yoghurt; the opposite trend was observed for lactic acid and galactose. Free amino acid levels were 33% higher in the GS products. GS yoghurt can be 10 times better than traditional yoghurt to deliver probiotic bacteria, as a function of the process used.

Are dairy products containing probiotics beneficial for oral health? A systematic review and meta-analysis.

To evaluate the effect of probiotic containing in dairy products on oral and salivary parameters. Electronic searches were performed based on the PICO criteria. Randomized controlled trials in adults/children (P) in which dairy products containing probiotics (I) were compared to controls (C) for establishment of oral health (O) were included. Risk of bias and data extraction were performed. The meta-analysis evaluated the influence of probiotics on Streptococcus mutans (SM), Lactobacillus spp. (LB), and yeast counts, plaque index, and salivary pH. Random or fixed effect models were used, and heterogeneity was tested. Thirty-two studies were included in the qualitative synthesis, and 24 in the meta-analysis. For dichotomous results, individuals who consumed probiotics exhibited decreased scores in SM concentrations (RD 0.15 [0.02, 0.28] p = 0.03, I2 = 70%), but no change was observed for LB (RD 0.10 [- 0.03, 0.23] p = 0.13, I2 = 94%), or yeast levels (RD 0.05 [- 0.02, 0.12] p = 0.7, I2 = 48%). For continuous analysis, both probiotic and control groups presented similar results for SM and LB (MD - 0.55 [- 1.16, 0.07] p = 0.08, I2 = 62%, and RD 0.10 [- 0.03, 0.23] p = 0.13, I2 = 94%, respectively). The consumption of probiotics increased salivary pH (MD 0.20 [0.04, 0.35] p = 0.01, I2 = 46%) and plaque index (MD 0.38 [0.11, 0.65] p = 0.005, I2 = 0%). The probiotic milk reduced SM (MD - 0.59 [- 0.96, - 0.22] p = 0.002, I2 = 0%), and the probiotic yogurt decreased LB counts (RD 0.35 [0.19, 0.51] p < 0.0001, I2 = 0%). In general, dairy probiotics were effective in reducing SM, increasing salivary pH, and promoting a higher plaque index. Liquid matrices, such as milk and yogurt, seem to be more effective in reducing SM and LB levels. Consumption of dairy products containing probiotics could be a supporting method in caries prevention.

Effect of Spirulina (Arthrospira platensis) powder on probiotic bacteriologically acidified feta-type cheese

Effects of Spirulina (Arthrospira platensis) addition were evaluated on probiotic Lactobacillus casei growth in bacteriologically acidified feta-type (BAF) cheese. The chemical, textural, and sensorial characteristics of cheese were measured. After 60 days of storage, there were significantly higher viable counts of Lb. casei (9.10–9.35 log CFU g⁻¹) in Spirulina samples in comparison with the control (8.68 log CFU g⁻¹). The viable counts of Lb. casei were maintained more successfully in the probiotic BAF cheese which contained Spirulina. The values of titratable acidity, dry matter, and protein contents of Spirulina samples were higher than the control. Furthermore, samples with Spirulina exhibited softer textures which led to an easier disintegration and chewing of the BAF cheese. Based on the results of the sensorial evaluation, no significant difference was observed between the control and the samples with 0.5 or 1.0% Spirulina. In conclusion, Spirulina is deemed a satisfactory nutritional source which can be added to BAF cheese without having any adverse effects on its characteristics. Graphical abstract Effect of Spirulina powder on probiotic BAF cheese

Effects of six substances on the growth and freeze-drying of Lactobacillus delbrueckii subsp. bulgaricus.

The efficacy of Lactobacillus delbrueckii subsp. bulgaricus as starter cultures for the dairy industry depends largely on the number of viable and active cells. Freeze-drying is the most convenient and successful method to preserve the bacterial cells. However, not all strains survived during freeze-drying. The effects of six substances including NaCl, sorbitol, mannitol, mannose, sodium glutamate, betaine added to the MRS medium on the growth and freeze-drying survival rate and viable counts of Lb. delbrueckii subsp. bulgaricus were studied through a single-factor test and Plackett-Burman design. Subsequently, the optimum freeze-drying conditions of Lb. delbrueckii subsp. bulgaricus were determined. Lb. delbrueckii subsp. bulgaricus survival rates were up to the maximum of 42.7%, 45.4%, 23.6%, while the concentrations of NaCl, sorbitol, sodium glutamate were 0.6%, 0.15%, 0.09%, respectively. In the optimum concentration, the viable counts in broth is 6.1, 6.9, 5.13 (&times;108 CFU/mL), respectively; the viable counts in freeze-drying power are 3.09, 5.2, 2.7 (&times;1010 CFU/g), respectively. Three antifreeze factors including NaCl, sorbitol, sodium glutamate have a positive effect on the growth and freeze-drying of Lb. delbrueckii subsp. bulgaricus. The results are beneficial for developing Lb. delbrueckii subsp. bulgaricus.

Parkinson's disease susceptibility variants and severity of Lewy body pathology

IntroductionMeta-analyses of genome-wide association studies (GWAS) have established common genetic risk factors for clinical Parkinson's disease (PD); however, associations between these risk factors and quantitative neuropathologic markers of disease severity have not been well-studied. This study evaluated associations of nominated variants from the most recent PD GWAS meta-analysis with Lewy body disease (LBD) subtype (brainstem, transitional, or diffuse) and pathologic burden of LB pathology as measured by LB counts in five cortical regions in a series of LBD cases. Methods547 autopsy-confirmed cases of LBD were included and genotyped for 29 different GWAS-nominated PD risk variants. LB counts were measured in middle frontal (MF), superior temporal (ST), inferior parietal (IP), cingulate (CG), and parahippocampal (PH) gyri. ResultsNone of the variants examined were significantly associated with LB counts in any brain region or with LBD subtype after correcting for multiple testing. Nominally significant (P < 0.05) associations with LB counts where the direction of association was in agreement with that observed in the PD GWAS meta-analysis were observed for variants in BCKDK/STX1B (MF, ST, IP) and SNCA (ST). Additionally, MIR4697 and BCKDK/STX1B variants were nominally associated with LBD subtype. ConclusionThe lack of a significant association between PD GWAS variants and severity of LB pathology is consistent with the generally subtle association odds ratios that have been observed in disease-risk analysis. These results also suggest that genetic factors other than the susceptibility loci may determine quantitative neuropathologic outcomes in patients with LBD.

Effect of Propolis Extract as a Natural Preservative on the Microbial Content of Kareish Cheese

The present study aimed to utilize propolis extract as natural preservative and attractive healthy ingredients on the microbial content of kareish cheese during storage. Effect of two extracts of proplis (ethanolic and water extract) were used at different concentrations on the growth of three bacterial strains, Streptococcus thermophilus, Lactobacillus bulgaricus and Bifdobacterium bifidium being used as starter. The affect of these extracts on some spoilage contaminants of dairy microorganisms in milk medium were also studied. The resultant kareish cheeses from different treatments (with ethanol and water propolis extracts) were analyzed for phenolic compounds, antioxidant activity, microbiological and sensory properties when fresh and during storage (28 day) at 5±1°C. The counts of Str. thermophilus and Lb. bulgaricus in milk with different concentrations of propolis extracts were significantly higher than those in control. Ethanol extraction of propolis (EEP) and water extraction of propolis (WEP) at 600 and 1000 mg /100ml displayed a bactericidal effect with all of the tested spoilage microorganisms.The addition of propolis extract had a negligible effect on the content of cheese moisture, and slight decrease in total protein of cheese was observed along the storage period. High acidity of kareish cheese observed with increasing the concentration of added propolis extracts. Addition of different concentrations (6 and 10%) of propolis extracts (ethanolic and water) increased of the phenolic compounds, flavonids and antioxidant activity with the increase of propolis extracts. The counts of Lb. bulgaricus and Str. thermophilus in kareish cheese treatments were significantly (p ≤ 0.05) higher than these in the control. However, counts of mesophilic (MBC) and psychrophilic (PBC), coliform bacteria and moulds & yeasts in kariesh cheese treatments were not detected until 21 days. Kareish cheeses made with water propolis extract (T3 andT4) were of higher sensory evaluation and with the best acceptablility during storage period, compared with cheese made by ethanolic propolis extract (T1 and T2).

Bacteriocin production and inhibition of Listeria monocytogenes by Lactobacillus sakei subsp. sakei 2a in a potentially synbiotic cheese spread

Survival, bacteriocin(s) production, and antilisterial effect of Lactobacillus sakei subsp. sakei 2a were evaluated in a potentially synbiotic cheese spread, throughout storage at 4 °C and 15 °C for up to 28 days, using culture-dependent (plate count) and culture-independent (qPCR) methods. Bacteriocin(s) production in the food product was monitored by phenotypic and molecular (RT-qPCR) techniques. Three cheese spread trials (T) containing the prebiotic fiber inulin were produced in duplicates and studied: T1 (control – without inoculation of lactic acid bacteria); T2 (inoculated with the non-bacteriocinogenic Lb. sakei ATCC 15521 strain), and T3 (inoculated with the bacteriocinogenic Lb. sakei 2a strain). The cheese spreads were challenged with Listeria monocytogenes serotypes 4b and 1/2a, individually added to the food product. The counts of Lb. sakei 2a in the cheese spread T3 remained high during storage and the growth of L. monocytogenes was inhibited at both temperatures, especially L. monocytogenes 4b in the food product kept at 15 °C due to the production of bacteriocins (up to 6,400 AU/mL). Expression of the genes sakP and sakQ encoding for bacteriocins production during the cheese spread storage was demonstrated. Lb. sakei 2a can be used for production of potentially synbiotic cheese spreads with increased safety.

Decrease in lactobacilli in the intestinal microbiota of celiac children with a gluten-free diet, and selection of potentially probiotic strains.

The intestinal microbiota would be implicated in pathology associated with celiac disease caused by an abnormal immune system reaction against gluten present in cereal grains. The objectives of this work were to detect through basic methods the changes in the composition of the most common genera of bacteria from the intestinal microbiota of symptom-free celiac disease children with a gluten-free diet compared with healthy children from Tucumán and to select lactobacilli (Lb) strains with probiotic potential from the feces of healthy children. Results demonstrated that the feces of celiac children with a gluten-free diet showed significantly lower counts of Lb (P < 0.05) compared with healthy children, while enterobacteria tended to increase in celiac children. On the basis of these results, isolation of some Lb from the feces of healthy children was carried out. Thus, 5 Lb strains were selected because of their high resistance percentages to gastrointestinal tract conditions. In addition, their autoaggregation and hydrophobicity properties were evaluated: Lactobacillus rhamnosus (LC4) showed the highest percentage of autoaggregation while Lactobacillus paracasei (LC9) showed high hydrophobicity. Based on these results, LC4 and LC9 were selected, and their use as potential probiotic strains to improve signs and symptoms associated with celiac disease is discussed. This is the first study performed in Argentina concerning the relationship between intestinal microbiota and celiac disease in celiac children with a gluten-free diet. In addition, the development of a probiotic food addressed towards celiac patients and designed with Lb isolated from the feces of healthy children from our province represents a promising alternative to improve the quality of life of celiac patients.

Influence of some prebiotics and transglutaminase (TGase) on the viability of probiotic bacteria and quality of non fat bio-yoghurt

Results of prebiotics addition (3% inulin and 3% lactulose), yoghurt starter producing expolysaccharides (EPSYS) and transglutaminase (TGase, 0.07%) revealed that the fermentation of bio-yoghurt samples containing inulin and lactulose lasted shorter than fermentation of EPSYS - and TGase -contained samples as well as control. Inulin and lactulose resulted in slightly higher acidity (after overnight cooling) than fresh control without additives then, the acidity gradually increased with different rates during cold storage for all samples. The pH showed an opposite trend for that of acidity. The lowest pH values were recorded for inulin and lactulose- treated fresh samples, whereas the pH gradually decreased with different rates during storage. Fresh bio-yoghurt with inulin and TGase had the highest curd tension values compared with all samples while those containing inulin showed the highest significant values after 5 and 10 days of storage. Concerning curd syneresis (CS), the fresh samples made with inulin had the lowest significant CS, while the differences among the rest treatments were insignificant. The differences among the treated samples of 5 days age were insignificant and were significantly lower than those of the control, which showed the highest value after 10 days of storage. Addition of inulin and lactulose significantly increased the viability and counts of Lb. delbruekii spp. bulgricus and B. bifidum bacteria at any given storage time. On the tenth day of storage, the counts of Lb. delbruekii spp. bulgricus showed a sharp decline which was significantly different (P<0.05) from the initial counts. It was also found that adding inulin and lactulose were the best in increasing survival and counts of bifidobacteria followed by the samples containing EPSYS and TGase in order. Sensory evaluation showed that using inulin and lactulose improved body, texture and flavour compared with bio-yoghurt without additives and manufactured with adding TGase. So, this study recommended using inulin and lactulose for their functional properties to guarantee the existence of bifidobacteria with suitable counts in bio-yoghurt to gain its healthy benefits.

Growth, survival, and peptidolytic activity of Lactobacillus plantarum I91 in a hard-cheese model

In this work, we studied the growth, survival, and peptidolytic activity of Lactobacillus plantarum I91 in a hard-cheese model consisting of a sterile extract of Reggianito cheese. To assess the influence of the primary starter and initial proteolysis level on these parameters, we prepared the extracts with cheeses that were produced using 2 different starter strains of Lactobacillus helveticus 138 or 209 (Lh138 or Lh209) at 3 ripening times: 3, 90, and 180d. The experimental extracts were inoculated with Lb. plantarum I91; the control extracts were not inoculated and the blank extracts were heat-treated to inactivate enzymes and were not inoculated. All extracts were incubated at 34°C for 21d, and then the pH, microbiological counts, and proteolysis profiles were determined. The basal proteolysis profiles in the extracts of young cheeses made with either strain tested were similar, but many differences between the proteolysis profiles of the extracts of the Lh138 and Lh209 cheeses were found when riper cheeses were used. The pH values in the blank and control extracts did not change, and no microbial growth was detected. In contrast, the pH value in experimental extracts decreased, and this decrease was more pronounced in extracts obtained from either of the young cheeses and from the Lh209 cheese at any stage of ripening. Lactobacillus plantarum I91 grew up to 8 log during the first days of incubation in all of the extracts, but then the number of viable cells decreased, the extent of which depended on the starter strain and the age of the cheese used for the extract. The decrease in the counts of Lb. plantarum I91 was observed mainly in the extracts in which the pH had diminished the most. In addition, the extracts that best supported the viability of Lb. plantarum I91 during incubation had the highest free amino acids content. The effect of Lb. plantarum I91 on the proteolysis profile of the extracts was marginal. Significant changes in the content of free amino acids suggested that the catabolism of free amino acids by Lb. plantarum I91 prevailed in a weakly proteolyzed medium, whereas the release of amino acids due to peptidolysis overcame their catabolism in a medium with high levels of free amino acids. Lactobacillus plantarum I91 was able to use energy sources other than lactose to support its growth because equivalent numbers of cells were observed in extracts containing residual amounts of lactose and in lactose-depleted extracts. The contribution of Lb. plantarum I91 to hard-cooked cheese peptidolysis was negligible compared with that of the starter strain; however, its ability to transform amino acids is a promising feature of this strain.