Diversity and screening of lactic acid bacteria in la-baicai made by Korean-Chinese in northeastern China

This study investigated the lactic acid bacteria (LAB) population in la-baicai (spicy cabbage), a traditional fermented food made by the Korean-Chinese community in northeastern China and screened for functional LAB. LAB diversity was analyzed using denaturing gradient gel electrophoresis (DGGE), and 81 LAB strains were isolated and identified based on 16S rDNA sequencing analysis. Polymerase chain reaction DGGE detected 21 LAB species, belonging to the genera Lactobacillus (Lb.), Leuconostoc (Leu.), Pediococcus and Weissella, in 45 la-baicai samples. Lb. plantarum and Lb. sakei were considered to be dominant in the bacterial community. Among 81 LAB isolated by traditional pure culture methods were Lb. plantarum (25 strains), Lb. brevis (two strains), Lb. casei, (four strains), Lb. pentosus (three strains), Enterococcus faecium (45 strains), and E. durans (two strains). The tolerances of these LAB were investigated. Six LAB with high salt (NaCl)-tolerance were screened from the isolates, and 16% (w/v) was the highest salt-tolerance reached. Among the isolates, strain N1, identified as Lb. pentosus, survived well in a simulated digestive environment. Traditional fermented la-baicai from northeastern China is a rich LAB resource. Further study is needed and would be worthwhile to advance the benefits of these LAB.     

Comparison of microbial communities between normal and swollen canned soy sauces using nested PCR‐denaturing gradient gel electrophoresis,HPLC and plate techniques

The microbial community of normal and swollen canned soy sauce was investigated using molecular biological method. The PCR‐denaturing gradient gel electrophoresis (DGGE) profiles showed that four lactic acid bacteria (LAB), including Lactobacillus acidipiscis, L. pobuzihii, L. piscium and another Lactobacillus sp., were involved in the swollen canned samples. Plate technique showed that three diverse species of Bacillus (B. subtilis, B. oleronius and B. flexus) were present in the swollen canned samples. However, much less bacterial contaminants were detected in the normal samples. According to the HPLC analysis, the lactic acid concentrations of the swollen canned samples were significantly higher than those in the normal samples. These results indicated that LAB can play a key role in contributing to the acidisation of the swollen canned soy sauce products. Our results confirmed the existence of Bacillus sp. and LAB in the packaged fermented soy sauce.     

Microbiological and Fermentative Properties of Baker's Yeast Starter Used in Breadmaking

This study assessed the levels of microbial contaminants in liquid, compressed and dry commercial baker's yeasts used as starters in breadmaking. Eumycetes, Enterobacteriaceae, total and fecal coliforms, Bacillus spp., and lactic acid bacteria (LAB), in particular enterococci, were quantified. Results obtained in this study highlighted that baker's yeast could represent a potential vehicle of spoilage and undesirable microorganisms into the baking environment, even if these do not influence the leavening activity in the dough, as ascertained by rheofermentometer analysis. Different microbial groups, such as spore‐forming bacteria and moulds, were found in baker's yeast starters. Moreover, different species of LAB, which are considered the main contaminants in large‐scale yeast fermentations, were isolated and identified by Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rDNA sequencing. The most recurrent species were Lactobacillus plantarum, Enterococcus faecalis, and Enterococcus durans, isolated from both compressed and dry starters, whereas strains belonging to Leuconostoc and Pediococcus genera were found only in dry ones. Nested‐Polymerase Chain Reaction (Nested‐PCR) and Randomly Amplified Polymorphic DNA–PCR (RAPD‐PCR) were also used to highlight the biodiversity of the different commercial yeast strains, and to ascertain the culture purity.     

Bacterial diversity of Darfiyeh, a Lebanese artisanal raw goat's milk cheese

In order to contribute to the preservation of the Lebanese dairy heritage, the aim of this study was to characterize the Darfiyeh cheese, a traditional variety made from raw goat's milk and ripened in goat's skin. Three independent batches of Darfiyeh production were analyzed after 20, 40 and 60 days of ripening. Mesophilic lactobacilli, thermophilic coccal-shaped lactic acid bacteria (LAB) and thermophilic lactobacilli were enumerated. In order to explore the Darfiyeh natural ecosystem, a combination of phenotypical and molecular approaches was applied. The latter included Polymerase Chain Reaction-temporal temperature gel electrophoresis (PCR-TTGE), classical PCR and quantitative PCR. These methods revealed the presence of Streptococcus thermophilus, Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Enterococcus malodoratus, group D Streptococcus sp., Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris, Lactobacillus plantarum, Lactobacillus curvatus, Staphylococcus haemolyticus, Escherichia coli, Clostridium sp./Eubacterium tenue. Real-time PCR enabled quantification of E. faecium, with a detection of 10⁷–10⁹ cfu g⁻¹ of product. The present molecular approaches combined with phenotypic method allowed describing the complex natural ecosystem of Darfiyeh, giving useful information for the preservation of Lebanese artisanal dairy products.     

Lactic acid bacteria profiles and tyramine and tryptamine contents of Turkish tulum cheeses

Tulum cheese, commonly produced in Turkey, is a traditional Turkish dairy product made from raw milk. In this research, 20 samples of tulum cheese were purchased from different markets in Isparta and Ankara (Turkey) and the populations of lactic acid bacteria (LAB) and contents of biogenic amines of Turkish tulum cheeses were investigated. The mean counts of LAB (as log10 cfu/g) were 7.22±0.67 on MRS agar, 6.93±1.77 on M17 agar, 7.28±0.72 on APT agar and 5.98±2.20 on ADA agar. Isolates of LAB obtained from 20 tulum cheeses were characterised as lactobacilli (48.5%), enterococci (32.7%), lactococci (15.8%) and streptococci (3.0%). Lactobacillus paracasei ssp. paracasei, Lactobacillus bifermentans and Enterococcus faecium predominated among the LAB in the samples of tulum cheeses; these organisms represented 30.2% of the isolates. As amino acids, tyrosine and tryptophan were determined in tulum cheeses. Tyramine and tryptamine, biogenic amines, were found at 0.00–329.00 and 0.32–40.44 mg/kg, respectively.     

Combined effect of an oxygen absorber and oregano essential oil on shelf life extension of rainbow trout fillets stored at 4 °C

In the present study the combined effect of an O₂ absorber and oregano essential oil (0.4% v/w) on shelf life extension of rainbow trout fillets (Onchorynchus mykiss) stored under refrigeration (4 °C) was investigated. The study was based on microbiological [TVC, Pseudomonas spp., Lactic Acid Bacteria, H₂S-producing bacteria including Shewanella putrefaciens, Enterobacteriaceae and Clostridium spp.), physicochemical (pH, PV, TBA, TVBN and Drip loss) and sensory (odor, taste) changes occurring in the product as a function of treatment and storage time. Aerobically-packaged rainbow trout fillets stored at 4 °C were taken as control samples. Results showed that TVC exceeded 7 log cfu/g on day 4 of storage for control samples, day 7–8 for samples containing oregano oil, day 9 for samples containing the O₂ absorber and day 12–13 for samples containing the O₂ absorber and oregano oil. Pseudomonas spp., Enterobacteriaceae and LAB were only partially inhibited by the O₂ absorber and/or the oregano oil. In all cases the inhibition effect was more pronounced when the combination of O₂ absorber with oregano essential oil was used. pH decreased from an initial value of 6.65–6.09 and subsequently increased to 6.86 due to formation of protein decomposition products. % Drip loss ranged between 7% and 11–12% at the end of the product shelf life. PV values ranged between 11.4 and 27.0 meq O₂/kg oil while malondialdehyde (MDA) ranged between 9.6 and 24.5 mg/kg. TVBN ranged between 10.6 and 54.6 mg/kg at the time of sensory rejection. Sensory shelf life was 4 days for the control samples, 7–8 days for samples containing oregano oil, 13–14 days for samples containing the O₂ absorber and 17 days for samples containing the O₂ absorber plus oregano oil.     

Diversity analysis and quantification of lactic acid bacteria in traditionally fermented yaks’ milk products from Tibet

Fermented yaks’ milk is a characteristic fermented dairy product with a rich microflora (especially lactic acid bacteria [LAB]), that has been produced by Tibetan people in China throughout history. Systematic analysis of the LAB composition of fermented yaks’ milk from central Tibet is essential. In the present study, 38 samples of fermented yaks’ milk were collected from three regions in central Tibet. From these, a total of 211 isolates of LAB were generated using traditional pure culture methods. To accurately analyze their biodiversity, 16S rRNA gene sequence analysis and denaturing gradient gel electrophoresis (DGGE) were used. The isolates were identified as belonging to six genera and 22 species/subspecies. Among them, Lactobacillus species predominated (117 isolates) accounting for 55.45% of all isolates. Overall, L. delbrueckii subsp. bulgaricus (60 isolates; 28.43% of the total) was the most commonly isolated species of LAB from fermented yaks’ milk from central Tibet. Seven Lactobacillus species and the Bifidobacterium genus were confirmed by quantitative PCR (q-PCR). The q-PCR results showed that the abundance of these groups in fermented yaks’ milk from central Tibet ranged from 1.12 ± 0.36 log cfu/ml (for L. sakei from Ningzhong) to 7.77 ± 0.84 log cfu/ml (for L. helvetivus from Ningzhong). Lactobacillus acidophilus, L. delbrueckii subsp. bulgaricus, L. fermentum, L. helveticus varied in concentration depending on the region. The results indicated that traditional fermented yaks’ milk from different regions of central Tibet have complex compositions of LAB species. The diversity of LAB might be related to geographical origin.     

Investigation of Microbial Communities of Chinese Sourdoughs Using Culture‐Dependent and DGGE Approaches

Sourdough is typically characterized by the complex microbial communities mainly comprising of yeasts and lactic acid bacteria (LAB). The objective of this study was to explore the microbiota of Chinese traditional sourdoughs collected from different areas of China using culture‐dependent and denaturing gradient gel electrophoresis (DGGE) methods. A total of 131 yeasts, 2 molds, and 106 LAB strains were isolated and identified. Based on the culture‐dependent analysis, the populations of yeasts and LAB were at the level of 10⁵ to 10⁷ and 10⁶ to 10⁷ cfu/g, respectively. Similarly, the results of RT‐qPCR showed that the values of total yeasts and LAB populations were in the range of 10⁶ to 10⁷ and 10⁷ to 10⁸ copies/g, respectively. Using culture‐dependent method, a total of 7 yeasts, 2 molds and 7 LAB species were identified. Results showed that Saccharomyces cerevisiae and Lactobacillus plantarum were the predominant species among the yeasts and LAB microflora. Similarly, using PCR‐DGGE approach, 7 yeasts, 1 mold and 9 LAB species were detected. The yeast, S. cerevisiae, represented the predominant, while the yeast Candida tropicalis represented the subdominant species of the yeast community. Among the LAB community, Lactobacillus sanfranciscensis was the predominant species, while Lactococcus qarvieae, Enterococcus faecium, Lactobacillus delbrueckii and Enterococcus cecorum were among the less dominant species.     

Spoilage-related microbiota associated with chilled beef stored in air or vacuum pack

In order to study the spoilage-related microbiota of beef at species level, a combination of culture-independent and culture-dependent methods was used to analyse nine different beef samples stored at 4 °C in air or in vacuum pack. Plate counts on selective agars after 0, 7 and 20 days of storage showed that vacuum packaging reduced the viable counts of Brochothrix thermosphacta, Pseudomonas spp. and Enterobacteriaceae, whereas the growth of lactic acid bacteria (LAB) was unaffected. Storage in vacuum pack mainly affected viable counts and not necessarily the species diversity of microbial populations on meat. Such populations were studied by PCR-DGGE of DNA directly extracted from meat and from bulk cells from culture media, followed by sequencing of DGGE fragments. Pseudomonas spp., Carnobacterium divergens, B. thermosphacta, Rahnella spp. and Serratia grimesii, or close relatives were detected in the meat at time zero. The use of the culture-independent method highlighted the occurrence of species that were not detected by plating. Photobacterium spp. occurred in most meat samples stored in air or in vacuum pack, which indicates this organism probably has a role in spoilage. In contrast, culture-dependent analysis allowed detection of bacterial species that were not found in DNA extracted directly from meat. This was the case for several species of Serratia or Rhanella among the enterobacteria, and Leuconostoc spp. among the LAB. Besides advancing our knowledge of the species involved in the spoilage of vacuum-packaged meat, this study shows the benefits of combining culture-based and direct approaches to enhance understanding of populations of spoilage bacteria.     

Microbiological characterisation of Robiola di Roccaverano cheese using PCR-DGGE

The aim of this study was the microbiological characterisation of a typical Italian cheese “Robiola di Roccaverano” with Protected Designation of Origin (PDO). Fresh and ripened robiola samples were collected from four artisanal and one industrial producer. Artisanal producers used raw goat's milk and natural fermentation, whilst the industrial producer used mixed cow–goat's milk and selected starters. The microbial communities were monitored during different seasons and ripening times with PCR–DGGE and culture-dependent methods.The cluster analysis showed that the DGGE bacterial patterns were related to the different manufacturing and climatic conditions, revealing the occurrence of species associated to Robiola di Roccaverano. The DGGE profiles of yeasts were affected by ripening in summer season.Moreover, the results obtained allowed the identification of microbial species such as Lactococcus lactis subsp. lactis, Geotricum spp. and Kluyveromyces lactis that are related to the production of this typical cheese.     

Incidence and antibiotic susceptibility of bacteriocin‐producing lactic acid bacteria from dairy products

Screening for bacteriocin production by strains of lactic acid bacteria (LAB) from local dairy products in Iran resulted in the detection of 10 bacteriocin‐producing strains. Among 105 isolated, 10 bacteriocin producers were phenotypically and genotypically identified as Enterococcus spp. The antimicrobial compounds produced by these novel strains were inactivated by trypsin, proteinase k. These bacteriocins also were active in a wide range of pH and temperature values, and inhibited not only the closely related LAB, but also Listeria monocytogenes.     

Preliminary screening of Bifidobacteria spp. and Pediococcus acidilactici in a Swiss cheese curd slurry model system: Impact on microbial viability and flavor characteristics

A Swiss cheese curd slurry model system was used as a preliminary screening method to determine the feasibility of the incorporation of probiotic bacteria (Bifidobacterium breve R0070, Bifidobacterium infantis R0033, Bifidobacterium longum R0175, and Pediococcus acidilactici R1001) into Swiss cheese. The cheese curd was inoculated with probiotic bacteria (8.0 log₁₀ cfu g⁻¹) and ripened anaerobically for 0, 7, and 10 days at 37 °C. Following ripening, counts of the probiotic bacteria increased to 9–10 log₁₀ cfu g⁻¹, with no significant difference in the viability of the four probiotic bacteria. Viable populations of Swiss cheese background microflora in the presence of each probiotic culture were comparable with the control. Ripening time, and to a lesser extent probiotic treatment had a significant effect on the content of several volatile flavor compounds. Similarly, ripening time contributed to a significant increase in the content of a majority of the free amino acids. The study demonstrated the feasibility of the incorporation of probiotic bacteria into Swiss cheese to produce a functional food.     

The fate of Listeria monocytogenes during the manufacture of Camembert-type cheese: A comparison between raw milk and milk treated with high hydrostatic pressure

Camembert-type cheese was produced from: raw bovine milk; raw milk inoculated with 2 or 4 log CFU/ml Listeria monocytogenes; raw milk inoculated with L. monocytogenes and subsequently pressure-treated at 500 MPa for 10 min at 20 °C; or uninoculated raw milk pressure-treated under these conditions. Cheeses produced from both pressure-treated milk and untreated milk had the typical composition, appearance and aroma of Camembert. Curd and cheese made from inoculated, untreated milk contained large numbers of L. monocytogenes throughout production. An initial inoculum of 1.95 log CFU/ml in milk increased to 4.52 log CFU/g in the curd and remained at a high level during ripening, with 3.85 log CFU/g in the final cheese. Pressure treatment inactivated L. monocytogenes in the raw milk at both inoculum levels and the pathogen was not detected in any of the final cheeses produced from pressure-treated milk. Therefore high pressure may be useful to inactivate L. monocytogenes in raw milk that is to be used for the production of soft, mould-ripened cheese.

Industrial relevance

This paper demonstrates the potential of high pressure (HP) for treatment of raw milk to be used in the manufacture of soft cheeses. HP treatment significantly reduced the level of Listeria monocytogenes in the raw milk and so allowed the production of safer non-thermally processed camembert-like soft cheese.     

Bacterial Community of Koumiss from Mongolia Investigated by Culture and Culture-Independent Methods

The bacterial community of fermented horse milk (koumiss) from Mongolia was studied using three methods: cultivation, direct identification by 16S rRNA clone library and denaturing gradient gel electrophoresis (DGGE). Ninety-eight strains were isolated by traditional cultivation and 61 of those were randomly selected for further identification by 16S rRNA gene sequencing. The strains were dominated by lactic acid bacteria (LAB; six different lactobacilli), Acinetobacter, Bacillus and Psychrobacter. Construction of the clone library analysis revealed that 16S sequences of 220 clones, genus Lactobacillus was dominant, but Streptococcus thermophilus, Acetobacter pasteurianus and uncultured clones were also detected. Ten unique bands were sequenced from the DGGE and revealed: Lactococcus lactis, Lactococcus lactis subsp. lactis, Clostridium acidurici, Acinetobacter johnsonii, Dickeya sp., Enterobacter sp., Pseudomonas sp., Raoultella sp., and Ruminococcus sp.. In vitro growth inhibition of three human pathogens, Escherichia coli, Enterobacter sakazakii and Staphylococcus aureus by 14 culturable bacteria displayed that only three of the isolates tested inhibit growth of E. sakazakii while most of the other bacteria delayed growth of the target bacteria.     

Combined effect of an O2 absorber and oregano essential oil on shelf-life extension of Greek cod roe paste (tarama salad) stored at 4 °C

In the present study the combined effect of an O₂ absorber and oregano essential oil (0.1% v/w) on shelf life extension of Greek cod roe paste (tarama salad) stored under refrigeration (4 °C) was investigated. The study was based on microbiological [Total viable count (TVC), Lactic Acid Bacteria (LAB), Enterobacteriaceae, H₂S-producing, yeast and molds and Clostridium spp.), physicochemical (pH, fatty acid composition, thiobarbituric acid (TBA), and color) and sensory (color, odor, and taste) changes occurring in the product as a function of treatment and storage time. Aerobically packaged tarama salad stored at 4 °C was taken as the control sample. Results showed that TVC exceeded 7 log cfu/g on day 12–13 of storage for control samples and day 31–32 for samples containing oregano oil. Samples containing either the O₂ absorber or the O₂ absorber plus oregano oil never reached 7 log cfu/g during the 60 day storage period. LAB were only partially inhibited by the oregano oil and/or the O₂ absorber. Yeasts and molds were totally inhibited by the O₂ absorber. Enterobacteriaceae populations were below the method detection limit (2 log cfu/g) H₂S-producing bacteria were the dominant spoilage microorganisms. Clostridum spp. was absent in 25 g sample. pH decreased from an initial value of 4.36 to 3.03 depending on specific treatment. Color parameters L and b increased and a decreased in control samples as well as in samples containing oregano oil. Color parameters remained unaffected in samples containing the O₂ absorber. TBA expressed as malondialdehyde (MDA) values increased from 1.5 mg/kg to 3.4, 3.2 and 2.9 mg/kg for samples containing oregano oil, the O₂ absorber and O₂ absorber plus oregano oil at the point of sensory rejection, respectively. Saturated fatty acids (SFA) increased during storage with a respective decrease in monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) both in control samples and samples containing oregano oil. Fatty acid composition remained unaffected in all samples containing the O₂ absorber. Sensory shelf life was 24 days for the control samples, 32 days for samples containing oregano oil, 60 days for samples containing the O₂ absorber and at least 60 days for samples containing the O₂ absorber plus oregano oil.

Industrial relevance

Oxygen absorbers as well as plant essential oils are considered natural means of preservation and may substantially extend the shelf life of foodstuffs while maintaining desirable sensory attributes (taste, odor and color).     

Lactic acid bacteria diversity of African raw and fermented camel milk products reveals a highly competitive,potentially health-threatening predominant microflora

The microflora of 59 East African camel milk samples of unfermented raw milk supply chains and spontaneously fermented milk (suusac) was analyzed to describe the diversity of predominant lactic acid bacteria (LAB), identify potential health risks and study bacteriocin-like inhibitory substance (BLIS) production. Bacterial isolates (n = 532) were identified using a genotypic approach incorporating rep-PCR, 16S rRNA gene sequencing, and species-specific PCR assays. The bacterial numbers on MRS and M17 agar exceeded log₁₀ 6.5 colony forming units (CFU) mL^?1 for raw milk supply chain samples and log₁₀ 8 CFU mL^?1 for suusac. Streptococcus agalactiae and Staphylococcus spp. were predominant in unfermented products, while suusac contained predominantly Streptococcus infantarius subsp. infantarius followed by Lactococcus lactis subsp. lactis, Streptococcus thermophilus, and lactobacilli. Fifty per cent of S. infantarius subsp. infantarius isolates originating from 15 out of 24 suusac samples produced a BLIS active against other LAB or Listeria and representing a potential selective advantage during fermentation. This study provides a detailed insight at the genotypic level into the LAB diversity of previously unstudied dairy products. It indicates potential health risks for consumers and the need for hygienic and manufacturing interventions and reports a potentially novel BLIS produced by S. infantarius subsp. infantarius.     

Use of human lysozyme transgenic goat milk in cheese making: effects on lactic acid bacteria performance

Genetically engineered goats expressing elevated levels of the antimicrobial enzyme lysozyme in their milk were developed to improve udder health, product shelf life, and consumer well-being. The purpose of this study was to evaluate the effect of lysozyme on the development of lactic acid bacteria (LAB) throughout the cheese-making process. Raw and pasteurized milk from 7 lysozyme transgenic goats and 7 breed-, age-, and parity-matched nontransgenic controls was transformed into cheeses by using industry methods, and their microbiological load was evaluated. The numbers of colony-forming units of LAB were determined for raw and pasteurized goat milk, whey, and curd at d 2 and at d 6 or 7 of production. Selective plating media were used to enumerate lactococcal species separately from total LAB. Although differences in the mean number of colony-forming units between transgenic and control samples in raw milk, whey, and cheese curd were non-significant for both total LAB and lactococcal species from d 2 of production, a significant decrease was observed in both types of LAB among d 6 transgenic raw milk cheese samples. In pasteurized milk trials, a significant decrease in LAB was observed only in the raw milk of transgenic animals. These results indicate that lysozyme transgenic goat milk is not detrimental to LAB growth during the cheese-making process.     

Monitoring the lactic acid bacterial diversity during shochu fermentation by PCR-denaturing gradient gel electrophoresis

The presence of lactic acid bacteria (LAB) during shochu fermentation was monitored by PCR-denaturing gradient gel electrophoresis (DGGE) and by bacteriological culturing. No LAB were detected from fermented mashes by PCR-DGGE using a universal bacterial PCR primer set. However, PCR-DGGE using a new primer specific for the 16S rDNA of Lactococcus, Streptococcus, Tetragenococcus, Enterococcus, and Vagococcus and two primers specific for the 16S rDNA of Lactobacillus, Pediococcus, Leuconostoc, and Weissella revealed that Enterococcus faecium, Lactobacillus casei, Lactobacillus fermentum, Lactobacillus nagelii, Lactobacillus plantarum, Lactococcus lactis, Leuconostoc citreum, Leuconostoc mesenteroides, and Weissella cibaria inhabited in shochu mashes. It was also found that the LAB community composition during shochu fermentation changed after the main ingredient and water were added during the fermentation process. Therefore, we confirmed that PCR-DGGE using all three primers specific for groups of LAB together was well suited to the study of the LAB diversity in shochu mashes. The results of DGGE profiles were similar to the results of bacteriological culturing. In conclusion, LAB are present during shochu fermentation but not dominant.     

Probiotics and Its Functionally Valuable Products—A Review

During the past two decades probiotic bacteria have been increasingly proposed as health promoting bacteria in variety of food system, because of its safety, functional, and technological characteristics. Commonly, Lactobacillus spp., Bifidobacterium spp., Saccharomyces boulardii, and some other microorganisms have been considered as probiotic strains. Possibly these bacterial strains exerted several beneficial effects into gastrointestinal tract of host while administered with variety of food system. Lactic acid bacteria (LAB) usually produce antimicrobial substances like bacteriocin which have broad spectrum of antagonist effect against closely related Gram positive and Gram negative pathogens. LAB strains often produce polymeric substances such as exopolysaccharides (EPS) which increase the colonization of probiotic bacteria by cell–cell interactions in gastrointestinal tract. LAB also produces biosurfactant which showed that the wide range of antimicrobial activity against bacterial pathogen as well as its antiadhesive properties reduces the adhesion of pathogens into gastric wall membrane. Furthermore, LAB strains have also been reported for production of antioxidants which are ability to scavenge the free radicals such as superoxide anions and hydroxyl radicals. For this sense, this review article is mainly focused on the ecology, biosynthesis, genetics, target sites, and applications of bacteriocins and EPS from LAB strains. Moreover, this review discusses about the production and functions of nutritive essential element folate and iron chelating agent such as siderophores from LAB.     

Functional and quality characteristics of the red blood cell fraction from biopreserved porcine blood as influenced by high pressure processing

The effects of high hydrostatic pressure (HHP) processing, at 400 MPa for 15 min at 20 °C, on the microbiological and functional characteristics of the red blood cell (RBC) fraction obtained from porcine blood, previously preserved by means of lactic acid bacteria (LAB) was studied. Biopreservation was achieved by incubation of inulin-enriched blood inoculated with a LAB strain (Enterococcus raffinosus PS99) for 72 h at 5 °C. Results showed that incubation of blood with added E. raffinosus followed by HHP treatment reduced the levels of contaminant coliforms, proteolytic, hemolytic bacteria, and Pseudomonas spp. on RCB. Color parameters, protein solubility, foaming and emulsifying properties, as well as texture and water holding capacity of heat-induced gels from RBC were not seriously damaged by the combined treatments. This is a new approach to process and preserve animal blood fractions for the development of functional and/or nutritional food ingredients with added value.