Synergetic Effect of Metschnikowia pulcherrima and Lachancea thermotolerans in Acidification and Aroma Compounds in Airén Wines.

On the one hand, the species Lachancea thermotolerans is known for its high genetic diversity, allowing for the existence of strains that produce high concentrations of lactic acid. In contrast, the species Metschnikowia pulcherrima is renowned for its high enzymatic activity capable of producing aromatic esters during fermentation. By enhancing acidity and boosting the concentration of aromatic compounds, both species are currently used to enhance the organoleptic profile of wines. In this regard, ternary fermentations with M. pulcherrima and L. thermotolerans were carried out and the wines produced were further analysed with GC-FID, FTIR, and UV-Vis spectrophotometry. The outcomes showed that the species M. pulcherrima favored an increase in ethyl lactate (between 37 and 41 mg/L) along with an increased concentration of 2-phenylethyl alcohol (between 30 and 35 mg/L), whereas the species L. thermotolerans was able to produce 1 g/L of lactic acid in ternary fermentations. Additionally, pH levels were slightly lower in these fermentations and the color of the white wines produced showed less chemical oxidation as hue values were lower than the control. Finally, the ternary fermentations of L. thermotolerans and M. pulcherrima had higher overall rating in the tasting. In conclusion, ternary fermentations involving these two non-Saccharomyces species are suggested as a substitute for spontaneous fermentations in the production of wines from neutral varieties to express freshness more vividly. This biotechnology may be further favored by the possibility of applying emerging technologies for the removal of microorganisms in grapes and musts.

Co-inoculations of Lachancea thermotolerans with different Hanseniaspora spp.: Acidification, aroma, biocompatibility, and effects of nutrients in wine.

The use of non-Saccharomyces yeast in the winemaking industry and even more their co-inoculations to maximize their growth and to express phenotypic characteristic is gaining more and more relevance. This study aimed to shed light on the biocompatibilities between Lachancea thermotolerans and Hanseniaspora spp., using different types of nutrients and considering the effect on Yeast Assimilable Nitrogen (YAN), at low temperature (16 °C) and medium SO2 (50 mg/L), in white must. L. thermotolerans has been used for its positive effect on pH reduction and Hanseniaspora spp. for improving the sensory profile. The behaviour of these yeasts was evaluated in co-inoculation, always finishing the fermentation with the sequential inoculation of S. cerevisiae. Significant results were obtained on the population count (CFU/mL) in CHROMagar™, with higher populations of Hanseniaspora spp. with respect to L. thermotolerans. Fermentations with L. thermotolerans/H. vineae, showed inhibition of acidification, generating up to 0.41 g/L of lactic acid. On the contrary, a synergistic effect when L. thermotolerans/H. opuntiae was used, achieved 2.44 g/L of lactic acid and a pH reduction of up to 0.16 and always more significant with Nutrient Vit BlancTM. At the same time ethanol concentration decreased by 3.4 % and volatile acidity never exceeded 0.5 g/L. Aromatic composition was analysed and it was found that all fermentations retained more aromatic esters and that on day 7 the amount of 2-phenylethyl acetate was at least 3 times higher in all fermentations compared to the control (Sc + Nutrient Vit BlancTM) which had 5.96 mg/L. Less yellow intensity (-17.3 %) typical of oxidation were observed in all fermentations in which Nutrient Vit BlancTM had been used and in the sensory analysis the co-inoculations with H. vineae generated better scores.

Biomodulation of Physicochemical Parameters, Aromas, and Sensory Profile of Craft Beers by Using Non-Saccharomyces Yeasts.

Beer is an alcoholic beverage produced by the metabolism of yeasts and made from water, malt, and hops. In recent years, the interest in craft beers has increased considerably due to the demand for new beverages and the consumer's willingness to pay higher prices. This article explores the sensorial changes produced in craft beers by using different Saccharomyces and non-Saccharomyces yeasts with several instrumental and sensory analyses performed. After a primary fermentation process with Saccharomyces cerevisiae or Lachancea thermotolerans, it was observed that green beer brewed with L. thermotolerans had a lower pH (3.41) due to the significant production of l-lactic acid (3.98 g/L) compared to that brewed with S. cerevisiae. Following, the bottle conditioning was carried out with a culture of S. cerevisiae, L. thermotolerans, Hanseniaspora vineae, or Schizosaccharomyces pombe. Of note is the increased production of aromatic esters, including 2-phenylethyl acetate in the H. vineae conditioning, which is associated with a high aromatic quality, as well as ethyl lactate in all samples, whose main fermentation was carried out with L. thermotolerans. Although this research is at an early stage, future complementary studies may shed more light on this topic.

Contribution of Grape Juice to Develop New Isotonic Drinks With Antioxidant Capacity and Interesting Sensory Properties.

Nowadays, the sector of isotonic beverages has developed its market based on fruit juices that provide a sports drink with antioxidant and biological activities in addition to their principal role of rehydration and replacement of minerals and carbohydrates during physical exercise. Consumption of grape juice is increasing worldwide because of its sensory characteristics and nutritional value. It contains mainly water, sugars, organic acids, and phenolic compounds. Phenolic compounds play a major role in prevention of various diseases through their biological activities linked to antioxidant, anti-inflammation, anticancer, anti-aging, antimicrobial, and cardioprotective properties. Several studies have demonstrated that grape juice is able to improve performances of antioxidant activity, protect against oxidative damage, and reduce inflammation during sports activities. Polyphenol content also provides a great sensory profile, mainly color which is an important indicator for consumers when choosing beverage products. The contribution of grape juice through its nutritional value and sensory properties makes it an alternative for the development of a new isotonic drink that will be a novel and healthy product in the field of healthy beverages.

Elaboration of an organic beverage based on grape juice with positive nutritional properties.

The present study aimed to develop a natural beverage with interesting phytochemical composition and biological activity based on grape juice without added sugars or artificial additives. Two groups of blends were made by diluting concentrate grape juice with a sugar content of 65 °Brix with two different mineral waters (BA: Bezoya with low mineralization; BB: Solan de Cabras with high mineralization). Lemon juice was used for pH correction, and mixtures of extractions of hop with tea and hop with mint were used to increase aroma. Samples were stored under refrigeration (4°C) then subjected to physicochemical and sensory analysis. The results demonstrated that malvidin-3-O-glucoside pigment was the predominant pigment with a concentration ranging from 75.71 ± 12.49 to 84.87 ± 1.70 mg/L. The levels of sugars ranged from 79.90 ± 1.37 to 82.37 ± 0.55 g/L and total soluble solids were between 5.47 ± 0.12 and 5.77 ± 0.06 °Brix. Total acids presented a significant difference, ranging from 1.40 ± 0.00 to 1.43 ± 0.06 g/L in BA samples and from 1.10 ± 0.10 to 1.20 ± 0.00 g/L in BB samples. For 20 days, the color increased in all beverages. However, BA drinks presented higher acidity and higher red color intensity than BB drinks, so the type of water and pH influenced the color of beverages. The sensory evaluation showed that the beverage made with low mineral water and flavored with a mixture of hop with tea was preferred.

Pulsed Electric Fields to Improve the Use of Non-Saccharomyces Starters in Red Wines.

New nonthermal technologies, including pulsed electric fields (PEF), open a new way to generate more natural foods while respecting their organoleptic qualities. PEF can reduce wild yeasts to improve the implantation of other yeasts and generate more desired metabolites. Two PEF treatments were applied; one with an intensity of 5 kV/cm was applied continuously to the must for further colour extraction, and a second treatment only to the must (without skins) after a 24-hour maceration of 17.5 kV/cm intensity, reducing its wild yeast load by up to 2 log CFU/mL, thus comparing the implantation and fermentation of inoculated non-Saccharomyces yeasts. In general, those treated with PEF preserved more total esters and formed more anthocyanins, including vitisin A, due to better implantation of the inoculated yeasts. It should be noted that the yeast Lachancea thermotolerans that had received PEF treatment produced four-fold more lactic acid (3.62 ± 0.84 g/L) than the control of the same yeast, and Hanseniaspora vineae with PEF produced almost three-fold more 2-phenylethyl acetate than the rest. On the other hand, 3-ethoxy-1-propanol was not observed at the end of the fermentation with a Torulaspora delbrueckii (Td) control but in the Td PEF, it was observed (3.17 ± 0.58 mg/L).

Biocompatibility in Ternary Fermentations With Lachancea thermotolerans, Other Non-Saccharomyces and Saccharomyces cerevisiae to Control pH and Improve the Sensory Profile of Wines From Warm Areas.

Global warming is causing serious problems, especially, in warm regions, where musts with excess sugars and high pH produce wines with decreased freshness and unstable evolution. This study aimed to determine biocompatibility between yeast species, the capacity for microbiological acidification, and the aromatic profile produced in ternary fermentations in which Lachancea thermotolerans has been co-inoculated with Hanseniaspora vineae, Torulaspora delbrueckii, or Metschnikowia pulcherrima, and the fermentation process is subsequently completed with sequential inoculation of Saccharomyces cerevisiae. For this purpose, different cell culture media and instruments were used such as infrared spectroscopy, enzymatic autoanalyzer, chromatograph coupled with a flame ionization detector, spectrophotometric analysis, among others. The behavior of these yeasts was evaluated alone and in co-inoculation, always finishing the fermentation with sequential inoculation of S. cerevisiae, at a stable temperature of 16°C and with a low level of sulfites (25 mg/L) in white must. Significant results were obtained in terms of biocompatibility using population counts (CFU/ml) in differential plating media that permitted monitoring. Quantification of the five species was studied. Concerning acidification by L. thermotolerans in co-inoculations, we showed some metabolic interactions, such as the inhibition of acidification when H. vineae/L. thermotolerans were used, generating just over 0.13 g/L of lactic acid and, conversely, a synergistic effect when M. pulcherrima/L. thermotolerans were used, achieving 3.2 g/L of lactic acid and a reduction in pH of up to 0.33. A diminution in alcohol content higher than 0.6% v/v was observed in co-inoculation with the L. thermotolerans/M. pulcherrima yeasts, with total sugar consumption and very slow completion of fermentation in the inoculations with H. vineae and T. delbrueckii. The aromatic composition of the wines obtained was analyzed and a sensory evaluation conducted, and it was found that both L. thermotolerans and co-inoculations retained more aromatic esters over time and had a lower evolution toward the yellow tones typical of oxidation and that the best sensory evaluation was that of the Lt + Mp co-inoculation. Lachancea thermotolerans and co-inoculations produced wines with low levels of volatile acidity (<0.4 g/L). This work shows that good consortia strategies with binary and ternary fermentations of yeast strains can be a powerful bio-tool for producing more complex wines.

Industrial Performance of Several Lachancea thermotolerans Strains for pH Control in White Wines from Warm Areas.

In the current scenario of climatic warming, the over-ripening of grapes increases the sugar content, producing flat and alcoholic wines with low acidity, high pH and low freshness. Additionally, a high pH makes wines more chemically and microbiologically unstable, requiring a higher sulphite content for preservation. Some strains of Lachancea thermotolerans can naturally lower the pH of wine by producing lactic acid from sugars; this pH reduction can reach 0.5 units. The industrial performance of four selected strains has been compared with that of two commercial strains and with that of Saccharomyces cerevisiae. The yeasts were assessed under variable oenological conditions, measuring lactic acid production and fermentative performance at two fermentation temperatures (17 and 27 °C), and in the presence or absence of sulphites (25 and 75 mg/L). Lactic acid production depends on yeast populations, with higher concentrations being reached when the microbial population is close to or above 7-log CFU/mL. A temperature effect on acidification can also be observed, being more intense at higher fermentation temperatures for most strains. Ethanol yield ranged from 7-11% vol., depending on the fermentation conditions (temperature and SO2) at day 12 of fermentation, compared with 12% for the S. cerevisiae control in micro-fermentations. The production of fermentative esters was higher at 27 °C compared with 17 °C, which favoured the production of higher alcohols. Volatile acidity was moderate under all fermentation conditions with values below 0.4 g/L.