Metabolism Of Lactic Acid Bacteria Research Articles

Traditional and New Microorganisms in Lactic Acid Fermentation of Food

Lactic acid fermentation is one of the oldest and most commonly used methods of bioconservation. This process is widely used for food preservation and also for a production technique that relies on the metabolism of lactic acid bacteria (LAB) to convert carbohydrates into lactic acid. This fermentation imparts unique flavors and texture of foods, extends their shelf life, and can offer health benefits. There are both traditional and new microorganisms involved in the lactic acid fermentation of food. The current review outlines the issues of fermented foods. Based on traditional fermentation methods, a broad panorama of various food products is presented, with the microorganisms involved. The methods of both traditional fermentation (spontaneous and back-slopping) as well as the importance and application of starter cultures in mass food production are presented. Currently, based on the results of scientific research, the health-promoting effect of fermented foods is becoming more and more important. This is due to the presence of probiotic microorganisms that are naturally presented or may be added to them, as starter cultures or additives, and from the presence of prebiotics and postbiotics. New innovative methods of using probiotic microorganisms open up new and broad perspectives for fermented functional foods.

Leaching and evolution of anthocyanins and aroma compounds during Cabernet Sauvignon wine fermentation with whole-process skin-seed contact

This study explores the leaching and evolution of anthocyanins and aroma compounds during wine-making, using an industrial-scale vinification of Cabernet Sauvignon with whole-process skin-seed contact. The results indicated that compounds within the same class displayed similar evolutionary patterns during fermentation. The extraction of anthocyanins, C6 aldehydes, and β-damascenes occurred continuously during cold soak, accompanied by the conversion of C6 aldehydes into alcohols and hydrolytic release of glycosidic β-damascenone. During alcoholic fermentation, pyranoanthocyanins, polymeric pigments, esters, benzene compounds, higher alcohols, and acids were generated. The concurrent occurrence of malolactic fermentation and prolonged maceration led to aromas associated with lactic acid bacteria metabolism. Finally, a comparison between free-run wine and pressed wine revealed high concentrations of C6 compounds and polymeric pigments with flavanol dimers in the pressed wine. These results can be used as a reference to optimize the vinification process to enhance the red due and fruity aromas of the wine.

Exploring the Cholesterol-Modifying Abilities of Lactobacilli Cells in Digestive Models and Dairy Products.

This study aimed to investigate the ability of lactic acid bacteria to remove cholesterol in simulated gastric and intestinal fluids. The findings showed that the amount of cholesterol removed was dependent on the biomass, viability, and bacterial strain. Some cholesterol binding was stable and not released during gastrointestinal transit. The presence of cholesterol affected the fatty acid profile of bacterial cells, potentially influencing their metabolism and functioning. However, adding cholesterol did not significantly impact the survival of lactic acid bacteria during gastrointestinal transit. Storage time, passage, and bacterial culture type did not show significant effects on cholesterol content in fermented dairy products. Variations in cell survival were observed among lactic acid bacteria strains in simulated gastric and intestinal fluids, depending on the environment. Higher milk protein content was found to be more protective for bacterial cells during gastrointestinal transit than fat content. Future research should aim to better understand the impact of cholesterol on lactic acid bacteria metabolism and identify potential health benefits.

Starter culture growth dynamics and sensory properties of fermented oat drink

In the present study, an oat drink, a plant-based alternative to dairy products, was developed by fermenting the oat base with different vegan starter cultures. The desired pH below 4.2 was achieved in 12 h, regardless of starter culture used. Metagenomic sequencing revealed that S. thermophilus was the dominating species, ranging from 38% to 99% of the total microbial consortia. At lower pH values, population of L. acidophilus, L. plantarum and L. paracasei continued to increase in fermented oat drinks. Lactic acid was produced between 1.6 and 2.8 g/L. The sensory panel showed that all fermented oat drinks had a sour odor and taste. The volatile compounds identified belonged to the ketone, alcohol, aldehyde, acids, and furan classes. The concentration of the most preferred volatile components, such as diacetyl and acetoin, increased during fermentation. However, sensory evaluation showed that all samples were associated with cereals and not dairy in terms of taste and odor. Rheological analysis showed the formation of weak gel-like structures in fermented oat drinks. Overall, fermentation improved flavor and texture of the product. This study provides a broad overview of the oat drink fermentation process from the perspectives of starter culture growth, microbial consortium dynamics, lactic acid bacteria metabolism, and sensory profile formation.

Complex pectin metabolism by Lactobacillus and Streptococcus suggests an effective control approach for Maillard harmful products in brown fermented milk

Harmful Maillard reaction products (HMRPs) derived from brown fermented milk pose a potential threat to human health, but the conversion mechanism during the manufacturing process remains elusive and urgently needs to be controlled. Acrylamide (FC 2.14, adjusted p-value = 0.041), 5-hydroxymethylfurfural (FC 2.61, adjusted p-value = 0.026) and methylglyoxal (FC 2.07, adjusted p-value = 0.019) were identified as the significantly increased HMRPs after browning in this study and the analysis of proteomics integrated with untargeted metabolomics demonstrated that the degradation of HMRPs was jointly accomplished by Streptococcus thermophilus and Lactobacillus bulgaricus. The galactose oligosaccharide metabolism in Streptococcus thermophilus was identified as a key biochemical reaction for HMRPs degradation, and the hydrolysates of pectin could be utilized as prebiotics for Streptococcus thermophilus. Eighteen classes of enzymes of L. bulgaricus and Streptococcus thermophilus related to energy metabolism were upregulated in the pectin-added group, indicating that the entry of acrylamide and methylglyoxal into the tricarboxylic acid cycle was accelerated. NAD-aldehyde dehydrogenase and alanine dehydrogenase are enzymes belonging to Streptococcus thermophilus, and their downregulation accelerated the efflux of acetate, which was beneficial for the proliferation of L. bulgaricus and prevented the conversion of pyruvate to l-alanine, thus facilitating the energy metabolism. The recoveries and relative standard deviations of the intraday and interday precision experiments were 89.1%-112.5%, 1.3%-8.4% and 2.1%-9.4%, respectively, indicating that the developed approach was credible. Sensory evaluation results revealed that the brown fermented milk added with pectin had a better flavor, which was due to the fact that the supplement of polysaccharide promoted the fatty acid metabolism of lactic acid bacteria and increased the aroma substances including octoic acid and valeric acid. This study provided an insight into the formation and degradation mechanism of HMRPs in brown fermented milk, aiming to reduce the intake of advanced glycation end products in the diet.

Improving anti-hypertensive properties of plant-based alternatives to yogurt fortified with rice protein hydrolysate

In recent years, an increasing demand of plant-based yogurt-like products for partially replacing milk products was related to both health and ethical needs. The objective of this study was to improve the functionality of yogurt-like products relevant for hypertension, using fortification with protein hydrolysate and lactic acid bacteria (LAB) fermentation of soy and Job’s tears beverages. Broken rice was hydrolysed by protease enzymes. Plant-based beverages and yogurt-like products with and without rice protein hydrolysate were prepared by LAB fermentation and evaluated by in-vitro assays for inhibition of free radical scavenging and angiotensin-converting enzyme (ACE) activity. Biochemical changes caused by lactic acid bacteria metabolism were characterized using chemical analysis and 1H NMR. The rice protein hydrolysate obtained using Alcalase® at pH 7.0 for 2 h at 60 °C showed the highest antioxidant activity and ACE inhibition. The ACE inhibition increased by 19.52% and 34.13% in Job’s tears and soy yogurt-like products with hydrolysate, respectively. A strongly significant correlation (R2 = 0.84) between o-phthalic dicarboxaldehyde (OPA) peptides and ACE inhibition was observed. These results indicated the promise of hydrolysate and LAB fermentation as a functional ingredient and process, respectively, for the food industry.

An animal derivative-free medium enhances Lactobacillus johnsonii LJO02 supernatant selective efficacy against the methicillin (oxacillin)-resistant Staphylococcus aureus virulence through key-metabolites

The spread of multidrug-resistant bacteria, such as the skin commensal Staphylococcus aureus, is a worldwide health challenge; new methods to counteract opportunistic pathogen growth and virulence are urgent. We compared the activity of Lacticaseibacillus rhamnosus LR06 (DSM 21981) and Lactobacillus johnsonii LJO02 (DSM 33828) cell-free supernatants (CFSs) produced in the conventional animal derivative-based MRS medium and an innovative animal derivative-free broth (TIL) versus the MDR S. aureus (ATCC 43300). CFS influence was assessed towards the viability, metabolic activity, and ability to form biofilm of the MDR strain through optical density, alamarBlue assay, and crystal violet staining; their content in short-chain fatty acids, lactic acid, and proteins was analysed via high-resolution mass spectrometry and gas chromatography. All CFSs reduce viable and metabolically active S. aureus, being TIL more efficient compared to MRS in stimulating lactic acid bacteria metabolism and decreasing S. aureus biofilm formation. Particularly, the CFS from LJO02 grown in TIL has the best efficacy, revealing a high amount of lactic acid and 59 peculiar proteins; its effectiveness is partially maintained upon trypsin and proteinase K treatments, but not by pepsin and pH basification. Therefore, antagonistic CFSs may represent a strategic prevention approach, with bacteriotherapeutic and bio-repair potential.

The influence of high frequency electromagnetic field on the growth of lactic acid bacteria used in the food industry

The objects of the study were lactic acid bacteria Lactobacillus lactis and Lactobacillus casei used in the food industry. It is proposed to use an extremely high frequency electromagnetic field (EMF EHF) with a wavelength of 4.9 mm for 5 minutes to activate the metabolism of lactic acid bacteria. The stimulating effect of EMF EHF on the growth of biomass and excretion of lactic acid during the growth was found. Physiological constants characterizing the development of microorganisms have been determined. It was found that the maximum yield from the consumed substrate Ymax increased by 40% and the maximum specific growth rate rmax by 70% when exposed to radiation, the consumption rate for maintenance ms decreased by 10% and the substrate saturation constant Ks by 23%. A change in the activity of key enzymes of metabolic pathways of lactose utilization immediately after the action of EMF of the EHF was revealed. The preservation of the achieved effect during the entire fermentation was observed. The activity of β-galactosidase and hexokinase after exposure to EMF EHF increases from 134% to 290%, depending on the strain and fermentation conditions. The increase in the activity of fumarate hydratase is 6-9%.

Changes in the free amino acid profile of pickling cucumber during lactic acid fermentation.

Free amino acid (FAA) profiles of fresh, acidified, naturally fermented, and starter culture fermented cucumbers were analyzed by liquid chromatography triple quadrupole mass spectrometry. Fermented cucumbers contained more total FAA than acidified cucumbers (1,302 ± 102mg/kg and 635 ± 35mg/kg, respectively). Total FAA content of fermented cucumber was similar regardless of brine salt levels (2-6% NaCl) and starter culture addition. Glutamine (1491.4± 69.3mg/kg), γ-aminobutyric acid (GABA, 269.6± 21.4mg/kg), asparagine (113.0± 6.4mg/kg), and citrulline (110.3±8.5mg/kg) were the most abundant FAA in fresh pickling cucumber, whereas GABA (181.3±21.5mg/kg), isoleucine (165.2± 11.2mg/kg), leucine (129.8± 10.9mg/kg), and lysine (110.9± 5.0mg/kg) were the most abundant in fermented cucumber. GABA and ornithine were produced during fermentation, indicating glutamate decarboxylase and arginine deiminase activities. Notably, ornithine was significantly higher in natural (63.3±31.5mg/kg) versus starter culture fermented cucumbers (3.0±0.7mg/kg). This new information on FAA composition of fresh and fermented pickling cucumbers shows the impact of fermentation conditions on cucumber amino acid profiles while providing insight for manipulating fermentations for health promotion and consumer acceptance. PRACTICAL APPLICATION: This study reports changes in the free amino acid profiles of raw, fermented and acidified cucumbers, which may be valuable for understanding the impact of these foods on human health and nutrition. This information is useful for food microbiologists studying the metabolism of lactic acid bacteria during fermentation and/or designing starter cultures and could contribute to the development of novel fermented cucumber pickle products with enhanced nutritional value.

Use of glycerol waste in lactic acid bacteria metabolism for the production of lactic acid: State of the art in Poland

Abstract Lactic acid is a naturally existing organic acid, which may be used in many different branches of industrial application. It can be made in the sugar fermentation process from renewable raw lactic acid, which is an indispensable raw material, including in the agricultural, food, and pharmaceutical industries. It is an ecological product that has enjoyed great popularity in recent years. In 2010, the US Department of Energy published a report about lactic acid to be a potential building element for future technology, whose demand grows year by year. The lactic acid molecule naturally exists in plants, microorganisms, and animals and can also be produced by carbohydrate fermentation or chemical synthesis from coal, petroleum products, and natural gas. In industry, lactic acid can be produced by chemical synthesis or fermentation. Although racemic lactic acid is always produced chemically from petrochemical sources, the optically pure L(+) – or D(−) – lactic acid forms can be obtained by microbial fermentation of renewable resources when an appropriate microorganism is selected. Depending on the application, one form of optically pure LA is preferred over the other. Additionally, microbial fermentation offers benefits including cheap renewable substrates, low production temperatures, and low energy consumption. Due to these advantages, the most commonly used biotechnological production process with the use of biocatalysts, i.e., lactic acid bacteria. The cost of raw materials is one of the major factors in the economic production of lactic acid. As substrate costs cannot be reduced by scaling up the process, extensive research is currently underway to find new substrates for the production of LA. These searches include starch raw materials, lignocellulosic biomass, as well as waste from the food and refining industries. Here, the greatest attention is still drawn to molasses and whey as the largest sources of lactose, vitamins, and carbohydrates, as well as glycerol – a by-product of the biodiesel component production process. Focusing on the importance of lactic acid and its subsequent use as a product, but also a valuable raw material for polymerization (exactly to PLA), this review summarizes information about the properties and applications of lactic acid, as well as about its production and purification processes. An industrial installation for the production of lactic acid is only planned to be launched in Poland. As of today, there is no commercial-scale production of this bio-raw material. Thus, there is great potential for the application of the lactic acid production technology and research should be carried out on its development.

The effect of nanosecond pulsed electric field on the production of metabolites from lactic acid bacteria in fermented watermelon juice

Lactic acid fermentation offers a processing alternative for preservation of watermelon juice, which is sensitive to heat, oxygen, and light. In this study, 8.8 × 107 CFU/mL of Lactobacillus plantarum DSM 9843 in MRS broth was inoculated in 9.9 mL of sterilized watermelon juice. Nanosecond-pulsed electric field was applied during the log growth phase of the bacteria. An 19% increase in L-lactic acid, 6.8% increase in D-lactic acid and 15% increase in acetic acid were observed over control. The final pH was 3.8. These increased levels of metabolites were dependent on the applied voltages (L-lactic acid: 5.0 kV 700 pulses, D-lactic acid: 4.5 kV 700 pulses and acetic acid: 4.5 kV 1000 pulses). The nsPEF treatment did not affect the viability of the cells and sufficient numbers remained in the product after fermentation (1.6 × 109 CFU/mL in average). These results suggest that the metabolism of lactic acid bacteria was stimulated by the PEF treatment.

How water-soluble saccharides drive the metabolism of lactic acid bacteria during fermentation of brewers' spent grain.

SummaryWe proposed a novel phenomic approach to track the effect of short‐term exposures of Lactiplantibacillus plantarum and Leuconostoc pseudomesenteroides to environmental pressure induced by brewers' spent grain (BSG)‐derived saccharides. Water‐soluble BSG‐based medium (WS‐BSG) was chosen as model system. The environmental pressure exerted by WS‐BSG shifted the phenotypes of bacteria in species‐ and strains‐dependent way. The metabolic drift was growth phase‐dependent and likely underlay the diauxic profile of organic acids production by bacteria in response to the low availability of energy sources. Among pentosans, metabolism of arabinose was preferred by L. plantarum and xylose by Leuc. pseudomesenteroides as confirmed by the overexpression of related genes. Bayesian variance analysis showed that phenotype switching towards galactose metabolism suffered the greatest fluctuation in L. plantarum. All lactic acid bacteria strains utilized more intensively sucrose and its plant‐derived isomers. Sucrose‐6‐phosphate activity in Leuc. pseudomesenteroides likely mediated the increased consumption of raffinose. The increased levels of some phenolic compounds suggested the involvement of 6‐phospho‐β‐glucosidases in β‐glucosides degradation. Expression of genes encoding β‐glucoside/cellobiose‐specific EII complexes and phenotyping highlighted an increased metabolism for cellobiose. Our reconstructed metabolic network will improve the understanding of how lactic acid bacteria may transform BSG into suitable food ingredients.

Co-culture fermentation of Pediococcus acidilactici XZ31 and yeast for enhanced degradation of wheat allergens

Previous researchers have shown the potential of sourdough and isolated lactic acid bacteria in reducing wheat allergens. As the interactions of lactic acid bacteria with yeast is a key event in sourdough fermentation, we wished to investigate how yeast affects metabolism of lactic acid bacteria, thereby affecting protein degradation and antigenic response. In this study, three strains isolated from sourdough were selected for dough fermentation, namely Pediococcus acidilactici XZ31, Saccharomyces cerevisiae JM1 and Torulaspora delbrueckii JM4. The changes in dough protein during the fermentation process were studied. Protein degradation and antigenic response in dough inoculated with Pediococcus acidilactici XZ31 monoculture and co-culture with yeast were mainly evaluated by SDS-PAGE, immunoblotting, ELISA and Liquid chromatography-tandem mass spectrometry assay. The whole-genome transcriptomic changes in Pediococcus acidilactici XZ31 were also investigated by RNA sequencing. The results showed that water/salt soluble protein and Tri a 28/19 allergens content significantly decreased after 24 h fermentation. Co-culture fermentation accelerated the degradation of protein, and reduced the allergen content to a greater extent. RNA-sequencing analysis further demonstrated that the presence of yeast could promote protein metabolism in Pediococcus acidilactici XZ31 for a certain period of time. These results revealed a synergistic effect between Pediococcus acidilactici XZ31 and yeast degrading wheat allergens, and suggested the potential use of the multi-strain leavening agent for producing hypoallergenic wheat products.

Overview of Global Trends in Classification, Methods of Preparation and Application of Bacteriocins.

This paper summarizes information about the division of bacteriocins into classes (Gram-negative bacteria, Gram-positive bacteria, and archaea). Methods for producing bacteriocins have been studied. It is known that bacteriocins, most successfully used today are products of secondary metabolism of lactic acid bacteria. It is established that the main method of bacteriocin research is PCR analysis, which makes it possible to quickly and easily identify the presence of bacteriocin encoding genes. The mechanism of cytotoxic action of bacteriocins has been studied. It is proved that the study of cytotoxic (antitumor) activity in laboratory conditions will lead to the clinical use of bacteriocins for cancer treatment in the near future. It is established that the incorporation of bacteriocins into nanoparticles and targeted delivery to areas of infection may soon become an effective treatment method. The delivery of bacteriocins in a concentrated form, such as encapsulated in nanoparticles, will increase their effectiveness and minimize potential toxic side effects. The analysis of publications on this topic confirmed that diverse research on bacteriocins is relevant.

Bioprocessing of Brewers' Spent Grain Enhances Its Antioxidant Activity: Characterization of Phenolic Compounds and Bioactive Peptides.

Brewers’ spent grain (BSG) is the major by-product of the brewing industry which remain largely unutilized despite its nutritional quality. In this study, the effects of fermentation on BSG antioxidant potential were analyzed. A biotechnological protocol including the use of xylanase followed by fermentation with Lactiplantibacillus plantarum (Lactobacillus plantarum) PU1, PRO17, and H46 was used. Bioprocessed BSG exhibited enhanced antioxidant potential, characterized by high radical scavenging activity, long-term inhibition of linoleic acid oxidation and protective effect toward oxidative stress on human keratinocytes NCTC 2544. Immunolabelling and confocal laser microscopy showed that xylanase caused an extensive cell wall arabinoxylan disruption, contributing to the release of bound phenols molecules, thus available to further conversion through lactic acid bacteria metabolism. To clarify the role of fermentation on the antioxidant BSG potential, phenols were selectively extracted and characterized through HPLC-MS techniques. Novel antioxidant peptides were purified and identified in the most active bioprocessed BSG.

Short communication: Sensory characteristics and volatile organic compound profile of high-moisture mozzarella made by traditional and direct acidification technology

In the present study, the sensory characteristics and the volatile organic compound (VOC) profiles of high-moisture mozzarella made by different acidification techniques were compared. The cheeses were manufactured at the same dairy by fermentation by autochthonous natural whey starter (traditional backslopping method) and direct acidification with citric acid (the most used industrial technology). Three cheesemaking trials were performed from February to June using raw milk from a single farm. The mozzarella samples were subjected to assessment of the chemical, microbiological, and sensory characteristics and to VOC analysis by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry. The relevant microbiological differences found between the 2 types of products were reflected in different sensory and VOC profiles. The cheeses were clearly discriminated by the panel, and traditional mozzarella had higher intensity attributes. The most discriminating descriptors were elasticity, overall odor and taste intensity, sour milk and fruity/vegetable odors, sour taste, and aftertaste. Even though some variability was observed among the trials, the VOC profile of traditional product was always much more complex than that obtained by direct acidification. In both products the carbonyl compounds were the most abundant chemical class, accounting for about 50% of the total. In detail, 51 compounds were identified in the entire set of samples, and their contribution to cheese aroma was roughly estimated by calculating the odor activity values on the basis of the odor thresholds available in the literature. The results allowed hypothesizing that only 12 of them could play a primary role. The most important among the odor-active compounds was 3-methyl-butanal that can both derive from metabolism of lactic acid bacteria and yeasts. The results of the study may be very useful in view of European Union PDO labeling of the traditional product, in terms of protecting it from imitations.

Effect of Lactobacillus acidophilus, Oenococcus oeni, and Lactobacillus brevis on Composition of Bog Bilberry Juice.

This study investigated the impact of Lactobacillus acidophilus NCFM, Oenococcus oeni Viniflora® Oenos and Lactobacillus brevis CICC 6239 on bog bilberry juice with a considerably low pH and rich in anthocyanins content. Moreover, the effects of the strains on the composition of phenolic compounds, amino acids, ammonium ion, biogenic amines, reduced sugars, organic acids, and color parameters of the juice were studied. All three bacteria consumed sugars and amino acids but exhibited different growth patterns. Lactic acid was detected only in L. acidophilus inoculated juice. The content of the phenolic compounds, especially anthocyanins, decreased in juice after inoculation. The CIELa*b* analysis indicated that the juice inoculated with L. acidophilus and O. oeni showed a decrease on a* and b* (less red and yellow) but an increase on L (more lightness), whereas the color attributes of L. brevis inoculated juice did not significantly change. Based on this study, L. brevis showed the most optimal performance in the juice due to its better adaptability and fewer effects on the appearance of juice. This study provided a useful reference on the metabolism of lactic acid bacteria in low pH juice and the evolution of primary and secondary nutrients in juice after inoculated with lactic acid bacteria.

Draft Genome Sequence of Pediococcus acidilactici Strain LPBC161, Isolated from Mature Coffee Cherries during Natural Fermentation.

Here, we report the draft genome sequence of Pediococcus acidilactici strain LPBC161, a lactic acid bacterium isolated from mature coffee cherries in Brazil. The genome sequence of P. acidilactici LPBC161 provides valuable information on the mechanisms of adaptation and metabolism of lactic acid bacteria (LAB) in the environment and stressor factors of coffee processing.

Changes in the Composition of the Lactic Acid Bacteria Behavior and the Diversity of Oenococcus oeni Isolated from Red Wines Supplemented with Selected Grape Phenolic Compounds

Phenolic compounds are important components of wine and are known to have an impact on the physiology of wine microbes. The influence of specific sub-sets of phenolic compounds on the growth and metabolism of lactic acid bacteria (LAB) and on the diversity of Oenococcus oeni in inoculated and non-inoculated red wines was investigated during malolactic fermentation (MLF) and subsequent storage. Representative O. oeni strains from wines treated with flavonols and trans-resveratrol were isolated and analyzed by pulsed-field gel electrophoresis of rare restriction enzyme digests (REA-PFGE). 28 days after MLF initiation, strains from all samples had entered the death phase, except those supplemented with trans-resveratrol. In the non-inoculated samples, the onset of lactic acid production was apparently delayed by all compounds tested, except for the flavan-3-ols. Increased levels of phenolics also delayed citrate consumption in inoculated samples. PFGE analysis revealed 22 genetic profiles, and some profiles were characteristics of specific samples. The commercial starter used in the inoculated wines did not dominate during MLF. The effect of the phenolics studied was dependent on the origin and concentration of each as well, as the fermentation stage and whether the wines were inoculated. The effect of flavonols and trans-resveratrol seemed to be strain-dependent, which could have implications on the final quality of wines.

In vitro metabolism of elderberry juice polyphenols by lactic acid bacteria.

In this study, ten strains of Lactobacillus were used to assess the in vitro metabolism of elderberry juice polyphenols. Total polyphenolic compounds increased after starter addition, especially with three L. rhamnosus and one L. plantarum strains, of dairy origin: quercetin-3-O-rutinoside was the most abundant compound (from 39.02 ± 5.28 to 127.56 ± 11.34 µg/mL) and hydroxycinnamic acids, flavonols and anthocyanins reached the highest amounts. When L. plantarum were used phenyllactic acids presented a value of 7.05 ± 2.38 µg/mL, while in the other samples it was around 5.56 ± 1.65 µg/mL. Hydroxycinnamic and hydroxybenzoic acids were subjected to lactic acid bacteria metabolism: caffeic and protocatechuic acids were consumed during fermentation while dihydrocaffeic acid and catechol were produced. Anthocyanins increased in a strain-specific way. So, by this study we highlighted that dairy strains can produced (phenyllactic acids), modified (hydroxycinnamic acids) or increased (flavonols glycosides and anthocyanins) phenolic compounds.