The production of malolactic starter cultures requires the obtention of suitably large biomass at low‐cost. In this work it was possible to obtain a good amount of biomass, at laboratory scale, of ...two enological strains of Lb. plantarum, by formulating a culture medium based on whey permeate (WP), a by‐product of the cheese industry usually disposed as waste, when this was supplemented with yeast extract (Y), salts (S) and Tween 80 (T) (WPYST). Bacteria grown in WPYST medium exhibited good tolerance to stress conditions of synthetic wine (pH 3.5, ethanol 13% vol/vol). However, when WPYST was added with 8% vol/vol ethanol, cultures inoculated in synthetic wine, showed a lower viability and capacity to consume L‐malic acid than when they were cultured in WPYST without ethanol. Subsequently, strains grown in WPYST were inoculated in sterile wine samples (final stage of alcoholic fermentation) of the red varietals Merlot and Pinot noir, and incubated at laboratory scale. Cultures from WPYST, inoculated in Pinot noir wine, showed a better performance than bacteria grown in MRS broth, and exhibited a consumption of L‐malic acid higher than 90%. However, cultures from WPYST or from MRS broth, inoculated in sterile Merlot wine, showed a lower survival. This study allowed the formulation of a low‐cost culture medium, based on a by‐product of the food industry, which showed to be adequate for the growth of two enological strains of Lb. plantarum, suggesting their potentiality for application in the elaboration of malolactic starter cultures.
Several lactic acid bacteria (LAB) species have been recognized as probiotics and are of considerable interest due to their potential ability to confer health benefits upon consumption. In the animal ...feed sector, probiotics offer an alternative to the use of antibiotic growth promoters. The preservation and incorporation of probiotics into dry products requires carefully meeting several criteria and overcoming technological challenges to maintain their functionality. Drying is a crucial step in the process, but the probiotic properties of the resulting powder and the final cell viability in the food product are significantly influenced by the type of protective compounds and drying techniques employed. In light of the growing demand for functional animal products, this review focuses on the damages incurred during microorganism dehydration processes for food incorporation, and explores strategies to minimize such damages. It provides an overview of the effects of probiotic products in the animal feed industry, including their incorporation in low-moisture food matrices and key considerations for success. Additionally, it highlights postbiotics as an attractive alternative for live probiotic cells with many technological advantages.
The malolactic fermentation (MLF) of Patagonian Malbec wine inoculated with blend cultures of selected native strains of
and
was monitored during 14 days, analyzing the strains ability to modify the ...content of some organic acids and to change the volatile compounds profile. The performance of the LAB strains was tested as single and blends cultures of both species. An implantation control by RAPD PCR was also carried out to differentiate among indigenous and inoculated strains. The
strains UNQLp11 and UNQLp155 and the
strain UNQOe73.2 were able to remain viable during the monitoring time of MLF, whereas the
strain UNQOe31b showed a decrease of five log CFU at day 14. The four strains assayed showed a similar behavior in wine whether they were inoculated individually or as blend cultures. All strains were able to consume L-malic acid, particularly the
strains, which showed the highest consumption values at day 14, both as single or blend cultures. The changes in the volatile compounds profile of Malbec wine samples, before and after MLF, were determined by HS-SPME and GC-MS technique. Wines inoculated with blend cultures containing strain UNQLp155 showed a decrease in the total alcohols content and an increase in the total esters content. On the other hand, wines inoculated with single cultures of strains UNQLp155, UNQOe31b or UNQOe73.2 showed no significant decrease in the total alcohols concentration but a significant increase in the total esters content. When strain UNQLp11 was inoculated as single or as blend culture with strain UNQOe31b, wines exhibited an increase in the total alcohols content, and a decrease in the total esters content. The content of diethyl succinate showed the greatest increase at final of MLF, and a particular synergistic effect in its synthesis was observed with a blend culture of strains UNQLp155 and UNQOe73.2. These results suggest that the use of blend cultures formulated with strains belonging to
and
species could offer an interesting advantage to induce MLF in Malbec wines, contributing to diversify their aromatic profiles.
The ability of Patagonian L. plantarum and O. oeni strains to change the volatile profile of a sterile Pinot noir wine was studied through fermentation assays, at laboratory scale. Two strains of ...each LAB species were selected based on data regarding to their ability to survive in wine and to consume l-malic acid. Both O. oeni strains but only one L. plantarum (UNQLp 11) strain were able to remain viable, consuming l-malic acid through the fermentation assay with a concomitant increase of l-lactic acid. The volatile profile of Pinot noir wine, before and after LAB inoculation, was measured by using HS-SPME gas chromatography technique. This analysis showed that alcohols were the main volatile compounds after alcoholic fermentation and that after fermentation with the selected LAB strains, a decrease in the volatile alcohols concentration and an increase in the volatile esters concentration could be observed. The O. oeni UNQOe 73.2 strain produced the most notable change in the volatile profile, with the production of some important odorant esters at higher concentration, compared to O. oeni UNQOe 31b strain. Although, L. plantarum UNQLp 11 strain showed a better performance in the consumption of l-malic acid, this strain had a low capacity to modify the volatile compounds profile after incubation in red wine. The results found in the present work showed that different strains selected as potential malolactic starters could have different behavior when are incubated in real wine. Although L. plantarum UNQLp 11 strain showed a good consumption of l-malic acid, the O. oeni UNQOe 73.2 strain exhibited superior capacity to improve the flavor of wine due to its esterase activity that produce an increase of fruity and creamy odorants.
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•Changes in volatile profile of inoculated Pinot noir wine was studied.•Selected L. plantarum and O. oeni strains were used in the vinification assays.•Inoculation diminished alcohols concentration and increased esters concentration.•All strains assayed were able to modify the wine volatile profile.•O. oeni strain UNQOe 73.2 produced the most notable change in wine volatile profile.
The performance of Patagonian Lactobacillus plantarum and Oenococcus oeni strains as malolactic starter cultures was compared. Two autochthonous strains of each species were selected, based on the ...presence of aroma-related genes, and inoculated in sterile wine of high ethanol content. The effects of initial inoculum size and acclimation treatment on the efficiency of malolactic fermentation (MLF) were analyzed for each strain. O. oeni strains were able to successfully conduct the MLF only when the inoculum concentration was higher than 1.108 CFU/mL and cells were acclimated in sublethal ethanol concentrations. The increase of ethanol concentration in the acclimation medium also improved the kinetics of malic acid consumption. Successful MLF with L. plantarum strains required lower inocula and no acclimation treatment. In addition, these strains showed a better profile of aroma-related genes than O. oeni. L. plantarum strains appeared to be more efficient than O. oeni strains as candidates for malolactic starter cultures to be used in Patagonian red wines.
•L. plantarum and O. oeni strains were isolated and fermentation examined.•L. plantarum was more efficient at MLF than O. oeni in Patagonian wines.•Standardization of acclimation and inoculum was necessary for successful MLF by O. oeni.•Acclimation in high ethanol content improved the malic acid consumption of O. oeni.•MLF with L. plantarum strains required lower inocula and no pre-acclimation treatment.
The by-products of the food industry are an economic alternative as a source of nutrients to obtain biomass. At the same time, theiruse could solve the environmental problem related to their ...disposal, which is highly polluting due to their elevated biochemical oxygen demand. In this work, we seek to optimize the production of cellular biomass of two native Patagonian strains of Lactiplantibacillus plantarum (UNQLp 11 and UNQLp155), selected for its oenological and technological properties, using apple pomace (AP), a residue from the juice and cider industry. The supplementation of AP with yeast extract, salts, and Tween 80 (sAP), proved to maintain the growth of the Lpb. plantarum strains, similar to the commercial medium used to grow LAB (De Man, Rogosa, Sharpe, MRS). Cultures grown in sAP medium showed good tolerance to wine conditions (high ethanol content and low pH), demonstrated by its ability to consume L-malic acid. The subsequent inoculation of these cultures in sterile wines (Merlot and Pinot noir) was carried out at laboratory scale, evaluating cell viability and L-malic acid consumption for 21 days at 21 °C. Cultures grown in sAP media showed a similar performance to MRS media. Thus, sAP media proved to be a suitable substrate to grow oenological Lpb. plantarum strains where cultures (with high size inoculums) were able to drive malolactic fermentation, with an L-malic acid consumption higher than 90%.
Spontaneous malolactic fermentation (MLF) in the North Patagonian region of Argentina may have to bear low environmental temperatures, an important stress factor for the lactic acid bacteria (LAB) ...that conduct this process. Thus, inducing MLF by inoculation of a native starter culture able to lead this biological process at low temperatures is encouraged because it would allow preserving the regional character of the wine. The goal of this work was to obtain autochthonous Oenococcus oeni strains able to consume l-malic acid when MLF takes place at temperatures lower than 15 °C. Among the psychrotrophic isolates obtained from a Pinot noir wine, sixteen O. oeni strains were identified by sequencing the 16S rRNA gene and typing by RAPD PCR, allowing the differentiation of five genotypic groups. After the evaluation of the viability and metabolic performance of the strains in sterile wine at low temperatures, strains UNQOe4 and UNQOe19 were selected to evaluate their behavior in a non-sterile wine at 4 and 10 °C. The strains selected showed good implantation capacity and were able to successfully conduct MLF, suggesting that their use as starter cultures is suitable to improve this biological process in a wine region where environmental temperatures can be low.
•O. oeni strains were isolated at low temperature from a Patagonian Pinot noir wine.•Psychrotrophic O. oeni were able to consume l-malic acid in sterile wine.•O. oeni strains were able to implant and induce MLF in wine at low temperatures.•Selected psychrotrophic O. oeni strains could be used as starter cultures of MLF.
Lactiplantibacillus plantarum strain UNQLp 11 is a lactic acid bacterium with the potential to carry out malolactic fermentation (MLF) in red wines. Recently, the complete genome of UNQLp 11 was ...sequenced and this strain possesses four loci of the enzyme β-glucosidase. In order to demonstrate that these glucosidase enzymes could be functional under harsh wine conditions, we evaluated the hydrolysis of p-nitrophenyl-β-D-glucopyranoside (p-NPG) in synthetic wine with different ethanol contents (0%, 12%, and 14% v/v) and at different pH values (3.2, 3.5, and 3.8). Then, the hydrolysis of precursor n-octyl β-D-glucopyranoside was analyzed in sterile Pinot Noir wine (containing 14.5% v/v of ethanol, at different pH values) by headspace sorptive extraction gas chromatography-mass spectrometry (HSSE-GC/MS). The hydrolysis of p-NPG showed that β-glucosidase activity is very susceptible to low pH but induced in the presence of high ethanol content. Furthermore, UNQLp 11 was able to release the glycosilated precursor n-octyl, during MLF to a greater extent than a commercial enzyme. In conclusion, UNQLp 11 could improve the aromatic profile of the wine by the release of volatile precursors during MLF.
Oenococcus oeni UNQOe19 is a native strain isolated from a Patagonian pinot noir wine undergoing spontaneous malolactic fermentation. Here, we present the 1.83-Mb genome sequence of O. oeni UNQOe19, ...the first fully assembled genome sequence of a psychrotrophic strain from an Argentinean wine.
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