Potential of Probiotic Frozen Blackcurrant Products: Consumer Preference, Physicochemical Characterization, and Cell Viability.

Blackcurrant is a healthy, affordable, and traditionally gardened berry that, thus far, has been underused in food applications. From the consumers' point of view, the acidic taste of blackcurrants is a challenge; therefore, these berries have mainly been utilized for sugary juice production. This research study aimed to develop a frozen vegan blackcurrant product with pleasant sensory properties and potential probiotic function. A candidate probiotic, Lactoplantibacillus plantarum Q823, was used in the manufacturing process. The physicochemical properties, nutritional composition, and consumer preference for the developed product were assessed, as was the viability of L. plantarum Q823 during storage time and in an in vitro gastrointestinal model. Consumers (n = 71) perceived the developed product to be pleasant. L. plantarum Q823 had high viability counts (log colony forming units (cfu) g-1 7.0 ± 0.38) in the final product, although the viability of L. plantarum Q823 during storage time needs to be enhanced to obtain a probiotic product. Thus, within an optimized formulation, blackcurrant berries represent a potential raw material for functional frozen food products.

Sand bedding as a reservoir for Lactococcus garvieae dissemination in dairy farms.

Lactococcus garvieae is now recognized as a species with clinical significance for human and veterinary medicine. The aim of this study was to evaluate the presence of this pathogen in sand bedding and milk samples. Two farms in Minnesota with problems of clinical and subclinical mastitis due to streptococci-like organisms were selected. Twenty-four Lactococcus garvieae isolates from sand bedding and 18 isolates from quarter milk were comparatively studied using a genotypic approach. RAPD (random amplification of polymorphic DNA) PCR and REP (repetitive element palindromic) PCR experiments highlighted a similar electrophoretic profile. When genes belonging to the core genome of L. garvieae were tested through a MLRT (multilocus restriction typing), we again observed that all L. garvieae isolates coming from sand bedding and milk shared a common profile, distinguishable from previously studied representative L. garvieae strains. These data indicate that the L. garvieae isolated from sand bedding and milk originated from a few strains adapted to persist in the same habitat. This supports the hypothesis that sand bedding can represent a reservoir of L. garvieae strains and be a potential vehicle for their dissemination in dairy farms.

Development of a fermented quinoa-based beverage.

Quinoa is a crop that originated from the Andes. It has high nutritional value, outstanding agro-ecological adaptability, and low water requirements. Quinoa is an excellent crop alternative to help overcome food shortages, and it can also have a role in the prevention of developed world lifestyle diseases, such as type-2 diabetes, cardiovascular diseases, osteoporosis, inflammatory and autoimmune diseases, etc. In order to expand the traditional uses of quinoa and to provide new, healthier and more nutritious food products, a fermented quinoa-based beverage was developed. Two quinoa varieties (Rosada de Huancayo and Pasankalla) were studied. The fermentation process, viscosity, acidity, and metabolic activity during the preparation and storage of the drink were monitored, as well as the preliminary organoleptic acceptability of the product. The drink had viable and stable microbiota during the storage time and the fermentation proved to be mostly homolactic. Both quinoa varieties were suitable as base for fermented products; Pasankalla, however, has the advantage due to higher protein content, lower saponin concentration, and lower loss of viscosity during the fermentation process. These results suggest that the differences between quinoa varieties may have substantial effects on food processes and on the properties of final products. This is a factor that should be taken into account when planning novel products based on this grain.

Genome Sequence of Lactococcus lactis subsp. cremoris Mast36, a Strain Isolated from Bovine Mastitis.

The genome sequence of Lactococcus lactis subsp. cremoris Mast36, isolated from bovine mastitis, is reported here. This strain was shown to be able to grow in milk and still possess genes of vegetable origin. The genome also contains a cluster of genes associated with pathogenicity.

Biocomposites of nanofibrillated cellulose, polypyrrole, and silver nanoparticles with electroconductive and antimicrobial properties.

In this work, flexible and free-standing composite films of nanofibrillated cellulose/polypyrrole (NFC/PPy) and NFC/PPy-silver nanoparticles (NFC/PPy-Ag) have been synthesized for the first time via in situ one-step chemical polymerization and applied in potential biomedical applications. Incorporation of NFC into PPy significantly improved its film formation ability resulting in composite materials with good mechanical and electrical properties. It is shown that the NFC/PPy-Ag composite films have strong inhibition effect against the growth of Gram-positive bacteria, e.g., Staphylococcus aureus. The electrical conductivity and strong antimicrobial activity makes it possible to use the silver composites in various applications aimed at biomedical treatments and diagnostics. Additionally, we report here the structural and morphological characterization of the composite materials with Fourier-transform infrared spectroscopy, atomic force microscopy, and scanning and transmission electron microscopy techniques.

Characterization of Lactococcus lactis isolates from bovine mastitis.

Lactococcus lactis is a widely used mesophilic dairy starter and has been included in the Qualified Presumption of Safety (QPS) list of the European Food Safety Authority. However, it is increasingly found as the cause of human or animal infections, such as bovine mastitis, probably due to the improvement of the identification of the infective microorganisms. Since there are some grounds to suspect that at least certain variants of L. lactis may cause animal or human diseases, it is important to properly identify the differences between the strains associated with infections and the safe starter strains. Bovine mastitis isolates and dairy starter strains were genotypically characterized and clustered by the 16S rRNA gene sequence and RAPD-PCR fingerprint patterns, and phenotypically characterized by their tolerance to different stress conditions typically found in the intestinal tract of mammals, the carbohydrate- and antibiotic resistance profile, as well as the in vitro adhesion capacity to udder epithelial cells. Genotypically, there were no differences between the mastitis isolates and the dairy starter strains. However, there were clear phenotypic distinctions between mastitis isolates and typical starter strains, the former showing an increased tolerance to temperature, lysozyme, bile salts, pH and antibiotics, as well as improved carbohydrate fermentation capacity, and in vitro adhesion to udder epithelial cells. Although these differences might not be considered as actual virulence factors, they improve the ability of the strain to survive in the body of homeothermic animals and, interestingly, are also typical properties associated with potential probiotic strains.

The antimicrobial effects of wood-associated polyphenols on food pathogens and spoilage organisms.

The antimicrobial effects of the wood-associated polyphenolic compounds pinosylvin, pinosylvin monomethyl ether, astringin, piceatannol, isorhapontin, isorhapontigenin, cycloXMe, dHIMP, ArX, and ArXOH were assessed against both Gram-negative (Salmonella) and Gram-positive bacteria (Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus) and yeasts (Candida tropicalis, Saccharomyces cerevisiae). Particularly the stilbenes pinosylvin, its monomethyl ether and piceatannol demonstrated a clear antimicrobial activity, which in the case of pinosylvin was present also in food matrices like sauerkraut, gravlax and berry jam, but not in milk. The destabilization of the outer membrane of Gram-negative microorganisms, as well as interactions with the cell membrane, as indicated by the NPN uptake and LIVE/DEAD viability staining experiments, can be one of the specific mechanisms behind the antibacterial action. L. monocytogenes was particularly sensitive to pinosylvin, and this effect was also seen in L. monocytogenes internalized in intestinal Caco2 cells at non-cytotoxic pinosylvin concentrations. In general, the antimicrobial effects of pinosylvin were even more prominent than those of a related stilbene, resveratrol, well known for its various bioactivities. According to our results, pinosylvin could have potential as a natural disinfectant or biocide in some targeted applications.

Antimicrobial activity of weak acids in liquid feed fermentations, and its effects on yeasts and lactic acid bacteria.

BACKGROUND: The efficacy of weak organic acids in the control of yeasts in pig liquid feed was studied taking into account the effects on lactic acid bacteria (LAB) responsible for beneficial fermentation. RESULTS: The yeast population in pig liquid feed was taxonomically identified. Kazachstania exigua, Debaryomyces hansenii and Pichia deserticola dominated the fermentation in liquid feed and whey. Pichia deserticola was found in whey and foaming liquid feed and dominated the fermentation after incubation. The sensitivity of the isolates against weak acids was measured in culture medium as well as in fermented and non-fermented liquid feed. Formic acid and potassium sorbate successfully reduced the growth of yeasts in all media without interfering with LAB development. Both of these organic acids showed an increased antifungal effect when used in liquid feed fermented by a Lactobacillus plantarum strain. CONCLUSION: The loss of energy, reduced palatability and other practical problems due to the high growth of yeasts in fermented liquid diets can be reduced by organic acids without affecting lactic acid fermentation.

Comparative study of sugar fermentation and protein expression patterns of two Lactobacillus plantarum strains grown in three different media.

A comparative study of two strains of Lactobacillus plantarum (REB1 and MLBPL1) grown in commercial medium (MRS broth), cucumber juice, and liquid pig feed was performed to explore changes to the metabolic pathways of these bacteria, using a proteomics approach (two-dimensional electrophoresis and liquid chromatography-tandem mass spectrometry) combined with analyses of fermentable sugars and fermentation end products. The protein expression showed that even with an excess of glucose in all media, both strains could metabolize different carbohydrates simultaneously and that hexoses could also be used via a phosphoketolase pathway with preferential expression in liquid feed. Sugar analyses showed that the fermentation of sugars was homolactic for all media, with some heterolactic activity in liquid feed, as shown by the production of acetate. Cucumber juice (the medium with the highest glucose content) showed the lowest hexose consumption (10%), followed by liquid feed (33%) and MRS broth (50%). However, bacterial growth was significantly higher in cucumber juice and liquid feed than in MRS broth. This discrepancy was due to the growth benefit obtained from the utilization of the malate present in cucumber juice and liquid feed. Despite different growth conditions, the synthesis of essential cellular components and the stress response of the bacteria were unaffected. This study has improved our understanding of the mechanisms involved in the growth performance of an appropriate lactic acid bacterium strain to be used for food and feed fermentation, information that is of crucial importance to obtain a high-quality fermented product.

Comparison of growth-phase-dependent cytosolic proteomes of two Lactobacillus plantarum strains used in food and feed fermentations.

Lactobacillus plantarum is a facultative heterofermentative lactic acid bacterium highly adapted to a wide variety of environments and widely used in food and feed fermentations. Proteomes of two strains of L. plantarum, one isolated from spontaneously fermented cereal-based feed (strain REB1), and the other from white cabbage (strain MLBPL1), were studied to elucidate the strain-specific variation and the physiological changes occurring between the growth (lag, early-exponential, late-exponential and early-stationary) phases of this bacterium when cultivated in a standard rich medium. A total of 231 protein spots were identified by LC-MS/MS. These proteins showed that strain MLBPL1 had more proteins with growth phase-dependent expression than REB1, which possesses a more constant expression profile. The proteins with growth phase-dependent expression in REB1 and MLBPL1 were mainly associated with energy metabolism (glycolysis, phosphoketolase pathway and ribose metabolism), all having preferential expression in the early-exponential phase, confirming the use of different carbohydrates simultaneously. Indication of energy production was also seen in lag and early-stationary phases.