Microbiological determination of lactic acid bacteria from fermented dairy products in different storage times.

Identification by using MALDI-TOF mass spectrometry of lactic acid bacteria isolated from non-commercial yogurts in southern Anatolia, Turkey.

Yoghurt is made from milk processing through fermentation by Lactic Acid Bacteria (LAB), Lactobacillus bulgaricus and Streptococcus thermophilus. Adding black mulberry’s juice can improve yoghurt’s functional characteristic through anthocyanin. Bioactive compounds was known unstable on storage and reportedly capable both to inhibit pathogen bacteria’s and stimulate LAB’s growth. The aim of this research is observe the effects of different proportion of fresh juice and cow’s milk, storage time and the interaction both of them on bioactive compounds and viability of LAB. This research used factorial Randomized Block Design (RBD) with two factors, proportion of fresh juice with fresh cow’s milk 5:95 (M1), 10:90 (M2), 15:85 (M3) % (v/v) and storage time 3 (L1), 10 (L2), 20 (L3) days with three replications. The parameters observed were total phenol, total flavonoid, anthocyanin content, total of LAB and pH as complement data. Data statistically analyzed by ANOVA test (Analysis of Variance) at α = 5% and continued with DMRT (Duncan's Multiple Range Test) at α = 5%. Used different proportion of fruit juice and storage time had significant effect on bioactive compounds and viability of LAB but there is no interaction both of them. The higher level proportion of fresh juice made amount of bioactive compounds increased and viability of LAB decreased. Increased storage time made bioactive compounds and viability of LAB decreased. The amount of bioactive compounds on black mulberry yoghurt after 20 days storage ranged from 49,20-99,14 µg GAE/g yoghurt, 101,91- 146,27 µg CE/g yoghurt, and 7,96-23,89 µg cya-3-glu/g yoghurt with ALT value ranged from 9,4804-9,5997 log cfu/mL and pH 3,877-3,961.

Yogurt is a dairy products through fermentation lactic acid bacteria (LAB) by Lactobacillus delbrueckii ssp. bulgaricus dan Streptococcus salivarius ssp. thermophilus. Isomalt has a lower caloric value can be used in yogurt. Addition of pineapple-carrot juice can also be done as a natural coloring gents, aroma and flavor enhancer in yogurt. The experimental design was a nested Randomized Block Design (RBD) with type of sugar (as the nest) consist of sucrose and isomalt, and pineapple-carrot juice addition (as the nested part) consist of 3 levels of 20%, 25%, and 30% with 4 replications for each treatment. The parameters observed were pH, acidity, syneresis, total LAB and sensory (preferences of taste, color, and aroma). Data statistically analyzed by ANOVA (Analysis of Varians) at α = 5%. If there was a significant difference, then it was continued by DMRT (Duncan's Multiple Range Test) test to determine which level of treatment that showed significant differences. Increased concentration of pineapple-carrot juice reduced pH, meanwhile acidity, syneresis, and viability of LAB were increased. The best yogurt in this research were yogurt with sucrose (30% pineapple carrot juice) with pH 4,442, acidity 34,48oSH, syneresis 1,87%, total of LAB 10,4491 log cfu/mL, consumer perception defined as neutral for color, rather liked for taste and aroma, and yogurt with isomalt (25% pineapple carrot juice) with pH 4,468, acidity 34,75oSH, syneresis 2,31%, total of LAB 10,2410 log cfu/mL, consumer perception defined as rather liked for color, neutral for aroma, and rather not liked for taste.

The water buffalo mozzarella cheese is a typical Italian cheese which has been introduced in the thriving Brazilian market in the last 10 y, with good acceptance by its consumers. Lactic acid bacteria (LAB) play an important role in the technological and sensory quality of mozzarella cheese. In this study, the aim was to evaluate the diversity of the autochthones viable LAB isolated from water buffalo mozzarella cheese under storage. Samples were collected in 3 independent trials in a dairy industry located in the southeast region of Brazil, on the 28th day of storage, at 4 ºC. The LAB were characterized by Gram staining, catalase test, capacity to assimilate citrate, and production of CO2 from glucose. The diversity of LAB was evaluated by RAPD-PCR (randomly amplified polymorphic DNA-polymerase chain reaction), 16S rRNA gene sequencing, and by Vitek 2 system. Twenty LAB strains were isolated and clustered into 12 different clusters, and identified as Streptococcus thermophilus, Enterococcus faecium, Enterococcus durans, Leuconostoc mesenteroides subsp. mesenteroides, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus helveticus. Enterococcus species were dominant and citrate-positive. Only the strains of L. mesenteroides subsp. mesenteroides and L. fermentum produced CO2 from glucose and were citrate-positive, while L. casei was only citrate positive. This is the first report which elucidates the LAB diversity involved in Brazilian water buffalo mozzarella cheese. Furthermore, the results show that despite the absence of natural whey cultures as starters in production, the LAB species identified are the ones typically found in mozzarella cheese.

Lactic acid bacteria (LAB) are widely distributed in nature such as in dairy, fish as well as vegetables and grains. LAB fermented foods are less susceptible to microbial spoilage and prolong shelf life in food preservation. Previous studies showed that metabolites produced from LAB including organic acids (lactic acid, acetic acid), diacetyl, hydrogen peroxide, bacteriocins and some low molecular weight compounds have antimicrobial abilities. Among these antimicrobial metabolites, peptides or the low molecular weight compounds with bacteriostatic and bactericidal action, attracted interest of researchers and food producers for the potential to be biopreservative additives. In this study, we investigated the antimicrobial activity of supernatant of Lactobacillus paracasei subsp. paracasei NTU 101 and Lactobacillus plantarum NTU 102 and demonstrated the broad inhibitory spectrum. The antimicrobial substances were purified, characterized and identified by nuclear magnetic resonance (NMR) techniques. In animal experiments, we assessed Streptococcus mutans counts and caries scores to evaluate the decay process during a 68-day period. These agents significantly reduced oral cariogenic bacteria and caries scores (p < 0.05). The results revealed that the bacteriological factors involved in the caries process can be suppressed. These results suggested that the antimicrobial substances produced by L. paracasei subsp. paracasei NTU 101 and L. plantarum NTU 102 have protective functions against dental caries development. The production of antimicrobial substances was optimized by the Box-Behnken experimental design. An empirical model was developed through response surface methodology to describe the relationship between variables (molasses, soy-milk, and incubation temperature). The results revealed that an alternative medium could be used for large-scale commercial production of the antimicrobial substances, with potential prospects for application.

Low fat fermented milk (1% fat) was supplemented with green bell pepper juice as a source of antioxidant compounds, and also carotenoids was produced and the impact of this ingredient on LAB was investigated. Pepper juice, in a ratio of 1:2 and 3%, was added to the low heat reconstituted milk powder. Lactobacillus rhamnosus (2%) was used only or with yoghurt starter (2%), and the growth rate of all probiotic strains and the viable count of lactic acid bacteria (LAB) during storage in refrigerator were determined. Moreover RSA, TPC and TCC of fermented milk samples were evaluated. Pepper juice was effective in enhancing the growth rate of L. rhamnosuswhen compared to the control, while the others of LAB count in the fermented milk, which contain pepper juice, was decreased. Furthermore, it was obvious that increasing the concentration of pepper juice increased RSA (%), TPC and carotenoids of the resultant low fat fermented milk, inoculated with L. rhamnosus for fresh and stored samples. During cold storage, RSA (%) slightly increased until 7 days and then decreased especially for samples supplemented with low concentration of pepper juice (1%), while TPC was gradually decreased by a prolongation of the storage period (15 days). The TCC was highly increased during the storage until 15 days. Moreover, adding yoghurt starter with L. rhamnosus strain in preparing fermented milk fortified with pepper juice also increased the RSA (%), TPC and TCC of the media. During storage, the TPC gradually decreased, whereas TCC was inversely increased. The percentage of RSA also increased during storage until 7 days and then decreased, in which case, it could be recommended that the addition of pepper juice has no effect on viability of probiotic strain. Key words: Lactic acid bacteria, probiotic, carotenoids.

Molecular organization and functionality of exopolysaccharide gene clusters in lactic acid bacteria

Integrity of the microalgal cell plays a major role in the lipolytic stability during wet storage

Development of a functional Greek sheep yogurt incorporating a probiotic Lacticaseibacillus rhamnosus wild-type strain as adjunct starter culture

The Effect of Holder and Flash Pasteurization on some Flavors of Milk. I. The Effect on Miscellaneous Flavors Common to Commercial Raw Milk

Microbial analysis, antioxidant activity, and sensory properties of yoghurt with different starter cultures during storage

Evaluation of Combination Treatment Processes for the Microbial Decontamination of Pork Trim

In this study, Salmonella typhimurium and Bacillus cereus were subjected to acid adaptation at pH 5.5 for 1-4 h and pH 6.3 for 40-90 min, respectively. Effect of acid adaptation on the acid tolerance of Sal. typhimurium and B. cereus at pH 4.0 and 4.6, respectively, was first examined. Furthermore, growth and survival behavior of these pathogens during the lactic fermentation of skim milk by Streptococcus thermophilus or Lactobacillus bulgaricus and during the 10-day storage of laboratory-prepared and commercial dairy lactic fermented products at 5 ℃ were also investigated. It was found that the acid adaptation, regardless the adaptation time, increased the acid tolerance of test organisms. The highest enhanced effect was noted for Sal. thphimurium and B. cereus after subjected to acid adaptation for 4 h and 40 min, respectively. During the lactic fermentation of skim milk, survival of acid-adapted cells of Sal. typhimurium and B. cereus was higher than the non-adapted cells. Similar phenomenon was also noted during the storage of laboratory-prepared and commercial lactic fermented product at 5 ℃. While acid-adapted cells of B. cereus showed a less magnitude of enhanced acid tolerance in the commercial lactic fermented products of milk during the storage period. In addition, acid adaptation may also enhance the tolerance of Sal. thphimurium and B. cereus to refrigerated temperature and other antimicrobial principles in fermented milk.

Aim: This work was carried out to investigate the influence of Lactic Acid Bacteria (LAB) on organoleptic quality and proximate composition of yoghurt, and viability of starter cultures in yoghurt.&#x0D; Methods: The LAB starter cultures were selected based on their ability to produce diacetyl and lactic acid.&#x0D; Results: Lactobacillus caseiN1 produced the highest quantity (2.72 g/L) of diacetyl at 48 hrs of incubation while Pediococcus acidilacticiG1 had the lowest amount (0.50 g/L). The pH of produced yoghurt ranged between 4.40 and 5.58 while the corresponding lactic acid contents ranged between 0.70 and 0.96 g/L. Yoghurt produced with cow milk inoculated with L. PlantarumN24 and L. BrevisN10 had the lowest pH (4.40) at significant level of P≤0.05. Yoghurt with mixed culture of L. PlantarumN24 and L. PlantarumN17 had the highest protein content (5.13%) while spontaneous fermentation (control) produced the least (0.48%). Yoghurt produced from cow milk inoculated with L. PlantarumN24 and L. PlantarumN17 was rated best with overall acceptability (9.0) during first day of storage while the commercial yoghurt (5.8) and spontaneous fermentation (6.8) had least overall acceptability at P≤0.05.&#x0D; Conclusion: Yoghurt samples stored in refrigerator had more viable LAB counts for a period of 21 days while the samples stored at room temperature had a day count except for yoghurt produced with cow milk inoculated with L. plantarumN24 which retained its viability at the second day. The yoghurt produced with selected LAB starters are better than commercial yoghurt in terms of sensory properties, proximate composition, pH and viability.

Inhibition of Clostridium tyrobutyricum by Bacteriocin-Like Substances Produced by Lactic Acid Bacteria