Lactic Acid Formation Research Articles

Microwave-Assisted Acid and Alkali Pretreatment of Napier Grass for Enhanced Biohydrogen Production and Integrated Biorefinery Potential

Napier grass, a promising lignocellulosic energy crop, presents a complex composition that limits its bioconversion into fermentable products. To address this challenge, we applied microwave (MW) pretreatment assisted by acid and alkali, using varying chemical concentrations (0.5–1% w/v) and pretreatment times (3–10 min). Acid-catalyzed MW pretreatment achieved a maximal hemicellulose removal of 69.8%, while alkali-catalyzed MW pretreatment resulted in significant lignin removal of 65.5%. Without chemical catalysis, the pretreated hydrolysate significantly increased hydrogen yield to 38.0 ± 2.9 mL H2/g volatile solid (VS), five times greater than that obtained from untreated biomass. Hydrogen yield was further enhanced when the MW-pretreated solid underwent simultaneous saccharification and fermentation. The highest hydrogen yield of 89.2 ± 7.2 mL H2/g VS was achieved from alkali-catalyzed MW pretreated solid (0.5% w/v NaOH, 5 min), with a chemical oxygen demand (COD) solubilization of 62.6%. Increasing the NaOH concentration to 1% (w/v) slightly decreased hydrogen yield but significantly increased COD solubilization to 85.8%. The high carbohydrate content facilitated rapid cellulase hydrolysis, producing and accumulating a high concentration of fermentable sugars. However, this accumulation subsequently led to a shift towards lactic acid formation. The improved hydrogen yield and increased COD solubilization, along with the shift towards lactic acid production, suggest the possibility of optimizing this process for simultaneous production of multiple valuable products in an integrated biorefinery approach, potentially enhancing the economic viability of biomass conversion.

Synthesis of levulinic acid from tobacco stalk via steam explosion and oxidation–hydrolysis route

AbstractBACKGROUNDTobacco stalk, the main waste from tobacco planting, was used as raw material to produce levulinic acid, one of the most important platform chemicals. It was reported that steam explosion was an efficient method to treat lignocellulose to hydrolyze the hemicellulose component. Oxidation treatment combined with catalysis of Al2(SO4)3 proved to be efficient for the conversion of cellulose to levulinic acid in our recent report. Here, tobacco stalk was first treated by steam explosion, and then the solid residue was oxidized and converted to levulinic acid in the presence of Al2(SO4)3.RESULTSA xylo‐oligosaccharide yield of 6.6 g 100 g−1 was obtained from tobacco stalk via steam explosion. 15.4 g 100 g−1 (39.6 mol%) yield of levulinic acid was obtained from oxidized tobacco stalk in water at 180 °C in 5 h using Al2(SO4)3 as a catalyst. As high as 20.8 g 100 g−1 (53.5 mol%) yield of levulinic acid can be obtained using NaCl as a co‐catalyst.CONCLUSIONSteam explosion was efficient for the depolymerization of the hemicellulose component of tobacco stalk to xylo‐oligosaccharide. A simple salt of Al2(SO4)3 showed good catalytic activity for conversion of oxidized tobacco stalk to levulinic acid. Nicotine in tobacco stalk promoted the formation of lactic acid. Thus, the yield of levulinic acid decreased in the presence of nicotine. NaCl enhanced the catalytic performance of Al2(SO4)3. © 2024 Society of Chemical Industry (SCI).

Efficient synthesis of lactic acid from cellulose through the synergistic effect of zinc chloride hydrate and metal salts

The chemocatalystic conversion of cellulose, the main component of lignocellulosic biomass, to building-block chemicals in water under mild conditions, is an ideal but highly challenging process due to the robust crystal structure of cellulose. It is also the key to establishing a sustainable biomass-based chemical process. Here, we present a highly efficient and selective chemocatalytic hydrolysis of cellulose using ZnCl2·3H2O hydrate as the pretreatment reagent and water-compatible metal salts - ErCl3 as the catalyst, into lactic acid (LA), which is an important chemical building-block widely utilized in the food industry and in the production of chemicals and biodegradable plastic. With 94.0 % conversion of cellulose, an impressive LA yield of 84.6 % was achieved at 170 °C after 4 h under ambient air pressure in water. High yields of LA were also obtained from other carbohydrates, such as fructose (68.3 %), glucose (52.7 %), starch (54.4 %), and inulin (67 %). A series of experiments demonstrated that Er(III) combination with water catalyzed cascading steps of soluble cellulose into LA after ZnCl2·3H2O hydrate disrupted the hydrogen bonds in the cellulose, Zn(II) played an indirect role by promoting LA formation through inhibition of side reactions. A plausible mechanism was proposed for the chemocatalytic conversion of cellulose to LA.

Single-step and stepwise pyrolysis to recover high-value chemicals from mixed polyolefins and polylactide

Biodegradable plastics are increasingly utilized due to environmental concerns but are typically disposed of together with conventional plastics. Valuable chemicals could be recovered from waste plastics by chemical recycling, but the mixing of different types of waste plastic affects the efficiency of the process. In this study, high-value chemicals were produced from a mixture of polyolefins and biodegradable polylactide by single and stepwise pyrolysis processes. The pyrolysis of polyolefins yielded fuel-like hydrocarbons, and the pyrolysis of polylactide yielded lactide and lactic acid. In the stepwise process, oxygenated compounds were only produced in the low-temperature step, and fuel-like hydrocarbons produced in the high-temperature step were not contaminated by oxygenated compounds. The influence of different catalysts on yields was investigated in the single-step and stepwise processes. The yield and selectivity of each product were significantly influenced by the type of catalyst and the composition of the plastic feedstock. Using a mixed feedstock of polyolefins and polylactide, low-temperature pyrolysis with a zeolite LTA catalyst favored the formation of lactide and lactic acid, while diesel-range hydrocarbons were obtained in the second step at a higher temperature. Aromatic and gasoline-range hydrocarbons were preferably produced from the single-step pyrolysis of polyolefins with spent FCC catalyst.

Effect of Short-Term Lactic Fermentation on Polyphenol Profile and Antioxidant Capacity in White and Red Quinoa Varieties.

Quinoa (Chenopodium quinoa Willd.) is a pseudocereal originally grown in the Andean region of South America. This study focused on investigating the changes in phenolic profile and antioxidant capacity in white and red quinoa varieties after short-term fermentation with Lactiplantibacillus plantarum 299v®. During fermentation, pH and lactic acid formation were monitored every three hours until pH was below 4.6. The quinoa phenolic profile was quantified via LC-UV-MS. Total polyphenol content (TPC) and total antioxidant capacity (DPPH and FRAP) were determined via spectrophotometric methods. The findings showed that fermentation resulted in a significant increase (p < 0.001) in TPC from 4.68 to 7.78 mgGAE·100 g-1 for the white quinoa and from 5.04 to 8.06 mgGAE·100 g-1 for the red quinoa variety. Gallic acid was the most abundant phenolic acid detected in unfermented quinoa samples (averaging 229.5 μg·g-1). Fermented white quinoa showed an 18-fold increase in epicatechin, while catechin was found only in fermented red quinoa (59.19 μg·g-1). Fermentation showed a significantly positive impact on the iron-reducing antioxidant capacity (FRAP) of quinoa (p < 0.05). Red quinoa had a higher FRAP antioxidant capacity than the white variety; a similar trend was observed with the DPPH assay. There was a significant correlation (r > 0.9, p < 0.05) between TPC and antioxidant capacity. In conclusion, short-time lactic fermentation effectively increased phenolic content and antioxidant capacity in both quinoa varieties. Overall, red quinoa showed higher polyphenol content and antioxidant capacity compared to the white variety.

A mathematical model-based evaluation of yeast extract’s effects on microbial growth and substrate consumption for lactic acid production by Bacillus coagulans

The microbial production of lactic acid, a crucial platform chemical for the development of biobased products, aims to replace fossil-based materials, although current production costs remain relatively high. Fermentation requires the addition of yeast extract (YE) to exclude nutritional lag, which increases the cost of production; therefore, optimizing its amount is essential. This study explores batch fermentation with varying concentrations of YE (5 %, 10 %, 15 % and 20 %) in a medium using the strain Bacillus coagulans A166 to produce lactic acid from glucose. The results reveal that the level of YE significantly influences the product yield, substrate consumption rate, and process productivity. The kinetic model applied to experimental data indicates that higher YE concentrations lead to increased glucose uptake and microbial growth rates, while concentrations exceeding 10 % result in reduced performance. It was determined that a concentration of 10 % YE in the medium delivered the highest maximum specific rates for glucose consumption and microbial growth, leading to a 0.99 g/g yield of glucose lactic acid. Furthermore, a real-time monitoring strategy for glucose consumption and lactic acid formation was established using a mathematical model based on the rate of alkaline consumption throughout fermentation. The cross-validation results demonstrate the reliability of this approach, with mean absolute errors (expressed as a percentage of the concentration range) for the prediction of glucose ranging from 2.8 % to 5.0 % and for the prediction of lactic acid ranging from 3.4 % to 5.4 %.

Insights into the selectivity to glyceric acid and lactic acid from biomass: Reaction mechanism and temperature effect

The disclosure of the underlying reaction mechanism on biomass valorization is of significant importance but remains challenging. We here unveil the complicated reaction mechanism on the coproduction of glyceric and lactic acids from biomass (glucose as representative) in the presence of cheap but robust CaO. Interestingly, it was discovered that the selectivity to glyceric acid and lactic acid from glucose was temperature-tunable. Glyceric acid was preferentially produced at ≤70 °C, while lactic acid generation was favorable at >90 °C. Glyceric and lactic acids could be coproduced with almost 1:1 ratio at moderate reaction temperature (∼80 °C). Isotopic tracing experiment verified that at moderate temperature, glyceric acid and equivalent lactic acid were predominantly originated from glyceraldehyde and dihydroxyacetone intermediates (generated after C3-C4 cleavage), respectively. However, both glyceraldehyde and dihydroxyacetone intermediates were transformed mainly towards glyceric acid at temperature ≤70 °C, but predominantly afforded lactic acid at high temperature. Kinetic studies in combination with DFT calculation verified that glyceric acid production from both glyceraldehyde and dihydroxyacetone intermediates showed lower apparent activation energy than that for lactic acid production. This well explained the selectivity to glyceric and lactic acids via temperature control. The generated alkali in CaO aqueous solution was the major active species for glyceric acid production, while both dissolved Ca(OH)2 and solid CaO contributed to lactic acid formation. The insights into the complicated reaction mechanism will provide useful clues in biomass valorization with efficient carbon utilization.

Effect of intrinsic STING of CD8+T cells on self-metabolic reprogramming and anti-tumor effects.

e20062 Background: Many preclinical studies have demonstrated that STING agonists have effective anti-tumor effects, but their adverse effects prevent practical use. Previous research by our team has demonstrated that STING has a more significant anti-tumor role in host immune cells than tumor cells, and the level of STING mRNA is associated with the outcome of immunotherapy in non-small cell lung cancer. Although STING is necessary for CD8+T cells to exert immunological activity, its effect on CD8+T cells is debatable. Therefore, we will concentrate on the particular roles of STING in CD8+T cells. Methods: We used in vitro and in vivo models to confirm the influence of STING on CD8+T cell function. We examined the impact of STING on CD8+T cell metabolic function using RNA-seq, Seahorse, flow, electron microscopy, and other techniques. STING knockout mice were used to study the effect of competitive inhibition of glycolytic products during immunotherapy. In addition, we collected peripheral blood immune cells from 30 immunotherapy patients to examine the correlation between immune cell glycolysis levels and immunotherapy efficacy. Results: RNA-seq showed significant changes in signaling pathways such as glycolysis/glycogen synthesis, oxidative phosphorylation, tricarboxylic acid cycle, and one carbon unit in STING-/- CD8+T cells. In vitro experiments revealed that the inactivation of the STING gene reduced the number of mitochondria, altered the choice of metabolic pathways, and impaired the anti-tumor ability. Flow results showed that the mean fluorescence intensity of mitochondria in STING-/- CD8+T decreased. Seahorse experiment showed that STING-/- CD8+T glycolysis was enhanced, and oxidative phosphorylation was decreased. Meanwhile, the content of lactic acid in the culture supernatant of STING-/- CD8+ T increased dramatically, the high level of lactic acid further inhibited the proliferation of CD8+ T and the secretion of IFN-γ. Competitive inhibition of the glycolysis process or lactic acid formation can save the function of STING-/- CD8+ T cells and the secretion of IFN-γ, save the immunotherapy effect of STING-/- mice. This provides a new therapeutic idea for patients with low STING expression and poor immunotherapy response. In the peripheral blood immune cells of immunotherapy patients, we observed a negative correlation between the mRNA levels of glycolysis-associated molecules and STING. Additionally, we found a correlation between the levels of glycolysis-associated molecules in immune cells and immunotherapy efficacy outcomes. Conclusions: Our study is the first to explore the effect of STING on the metabolic process in CD8+ T cells. Intervening in the metabolic process of STING-deficient CD8+ T can save the efficacy of immunotherapy.

Study on the Effect of Ficus exasperata Aqueous Leaf Extract on the Rate of Lactic Acid Formation of Fermented Milk

Study on the Effect of Ficus exasperata Aqueous Leaf Extract on the Rate of Lactic Acid Formation of Fermented Milk

In-depth analysis of embedded-type structures of NixMg4-xAl LDO-composited catalysts and the impacts on glycerol conversion under a base- and H2-free condition

Core-shell composite catalysts composing of AgO@SnO2/ZSM-5 embedded by NixMg4-xAlO LDOs with various Ni/Mg ratios were characterized and tested for the activity on the conversion of glycerol to valuable chemicals under a base-free and external H2-free condition. As a result, the catalytic performance of an embedded composite was found greater than that of its individual constituents, owing to the synergy between a NixMg4-xAlO lodge and embedded AgO@SnO2/ZSM-5. The highest yield of 1,2-propanediol and lactic acid was achieved at the Ni/Mg ratio of 0.2/3.8. NixMg4-xAlO lodges were found to simultaneously drive glycerol dehydration to acetol and glycerol reforming, driven by Ni sites, forming in-situ H2 that enhances 1,2-propanediol formation whereas the AgO@SnO2/ZSM-5 clusters governed acetol oxidation and Cannizzaro reaction that led to the formation of lactic acid. At a high Ni/Mg ratio, the NixMg4-xAlO lodges completely covered AgO@SnO2/ZSM-5 clusters entirely, resulting in the suppression of lactic acid yield due to over-oxidation.

Evaluation of Streptococcus mutans Biofilm Formation and Acidogenicity of Infant Milk Formulas for Treating Cow Milk Allergy: An in vitro Study

Introduction: When infants cannot consume breast milk, the most commonly available alternative milk formula is cow milk-based. Due to a rise in the prevalence of cow milk protein allergy (CMPA) among children, this study aimed to assess the biofilm formation and acidogenicity of cow milk-based formulas as well as milk formulas suggested for children with CMPA. Methods: Cow milk-based formulas with 0%, 10%, or 18% sucrose added, partially hydrolyzed formula (pHF), extensively hydrolyzed formula (eHF), amino acid-based formula (AAF), and soy-based formulas with 0%, or 11% sucrose added were evaluated. Streptococcus mutans was used as a representative microorganism associated with caries. The acidogenicity after 24-h incubation was assessed by the pH of the formed biofilm and lactic acid formation. Biofilm formation was quantified using crystal violet staining. Additionally, the biofilm characteristics were determined using confocal laser scanning microscopy (CLSM). Comparisons were made among formulas without added sucrose to observe protein-based differences. Furthermore, formulas with different sucrose percentages were compared to explore the impact of sucrose content. Results: When comparing the formulas without added sucrose, the biofilm formation in the cow milk-based formula and pHF were significantly greater than the soy-based formula, eHF, and AAF. In the presence of S. mutans, all formulas reduced the biofilm pH below the critical enamel pH. The cow milk-based formula and AAF showed a significantly lower biofilm pH than the pHF, soy-based, and eHF groups, while the lactic acid production was markedly higher in the cow milk-based formula, pHF and AAF, compared with the eHF and soy-based formula. Adding sucrose into the cow milk-based and soy-based formulas substantially increased biofilm mass. The biofilm pH of the cow milk-based formulas, with or without sucrose, was significantly lower than that of the soy-based formulas. The CLSM indicated distinct biofilm characteristics among the different protein-based formulas, with sucrose supplementation promoting S. mutans aggregation in cow milk-based formula biofilm and increased density and intact biofilm in the soy-based formula. Conclusion: All assessed milk formulas had caries-inducing factors, including those without supplemental sucrose. Among them, the eHF demonstrated the least caries-inducing factors, attributed to its minimal biofilm formation and the highest biofilm pH.

New Insights into the Production of Assyrtiko Wines from the Volcanic Terroir of Santorini Island Using Lachancea thermotolerans.

Assyrtiko is a rare ancient grape variety of Greece, which is known to produce Protected Designation of Origin (PDO) Santorini white wines. Besides the famous character of the volcanic terroir, Assyrtiko of Santorini is also marked by a low pH value and sharp acidity. The aim of the present study was to apply a new inoculation procedure that modulates the fermentation process by maintaining the unique sensorial characteristics of Assyrtiko wines based on acidity. For this purpose, the Lachancea thermotolerans species, known for the formation of lactic acid, was tested in sequential fermentation with three different Saccharomyces cerevisiae strains. At the end of the fermentation process, implantation control for S. cerevisiae strains (interdelta sequence profile analysis) was performed, oenological parameters were determined according to the OIV protocols, and the volatile compounds produced were measured by gas chromatography-mass spectrometry (GC/MS). Finally, all produced wines were evaluated by quantitative descriptive analysis by two groups of experts; the Greek team of oenologists from Santorini Island specialized in Assyrtiko wines, and the French team of oenologists specialized in wine from Bordeaux. As expected, the inoculated strain was the one that dominated the fermentation process, but nine S. cerevisiae indigenous strains were also identified in the produced wines. Lachancea thermotolerans produced 1 g/L of lactic and also modulated the volatile profile of the wines independently of the S. cerevisiae strain used. The origin of the panelists played an important role in bringing up sensorial traits, such as acidity. Our results led to a new interesting application of L. thermotolerans for white wine production adapted to climate change claims.

The Influence of Chitosan on the Chemical Composition of Wines Fermented with Lachancea thermotolerans.

Chitosan exerts a significant influence on various chemical parameters affecting the quality of wine produced using multiple strains of Lachancea thermotolerans. The impact of chitosan on these parameters varies depending on the specific strain studied. We observed that, under the influence of chitosan, the fermentation kinetics accelerated for all examined strains. The formation of lactic acid increased by 41% to 97% across the studied L. thermotolerans strains, depending on the specific strain. This effect also influenced acidity-related parameters such as total acidity, which increased by 28% to 60%, and pH, which experienced a decrease of over 0.5 units. The consumption of malic acid increased by 9% to 20% depending on the specific strain of L. thermotolerans. Nitrogen consumption also rose, as evidenced by all L. thermotolerans strains exhibiting a residual value of Primary Amino Nitrogen (PAN) of below the detection limit, and ammonia consumption increased by 90% to 100%, depending on the strain studied. However, certain parameters such as acetic acid, succinic acid, and glycerol showed contradictory results depending on the strain under investigation. In terms of volatile composition, chitosan supplementation led to increased production of i-butanol by 32% to 65%, 3-methylbutanol by 33% to 63%, and lactic acid ethyl ester by 58% to 91% across all studied strains of L. thermotolerans. Other analyzed aroma compounds exhibited varying changes depending on the specific strain of L. thermotolerans.

Promoted Production of Lactic Acid from Glucose by Calcium Hydroxide in the Presence of Hydrogen

AbstractCatalytic conversion of glucose to lactic acid is a green promising strategy for the effective utilization of biomass‐derived carbohydrates to generate valuable chemicals. The generation of lactic acid would also be distinguishing in different reaction atmospheres. In this work, we firstly investigated the decomposition of lactic acid and glucose transformation to lactic acid in H2. No obvious decomposition of lactic acid was observed in H2. The activity testing results showed that glucose could be completely converted over the selected hydroxides, while the formation of lactic acid was closely related to the alkalinity of hydroxide. The yield of lactic acid was remarkably obtained to be 87 % over Ca(OH)2 at 220 °C for 3 h. Stronger alkalinity of the catalyst would facilitate glucose isomerization to fructose, and then easily be transformed into dihydroxyacetone or glyceraldehyde intermediates through reverse aldol condensation, which is beneficial to the generation of lactic acid.

ИСПОЛЬЗОВАНИЕ СМЕКТИТА ДЛЯ ЭФФЕКТИВНОСТИ ПРОБИОТИЧЕСКИХ СВОЙСТВ LACTOCOCCUS LACTIS SSP. LACTIS

Research has been conducted to develop an effective method for preserving the probiotic properties of Lactococcus lactis ssp. lactis strain 194, isolated from milk in Buryatia (Russia). The effect of 10 protective media added before freezing was compared: NaCl, skim milk, 5% sucrose+1% gelatin and smectite at concentrations of 5, 10 and 5% as a cryoprotectant. Physiological and probiotic properties: survival rate, rate of milk clot formation, lactic acid formation and antimicrobial activity were studied in lyophilized bacteria immediately after reconstitution, as well as in a number of passages after long-term storage. Optimal concentrations of smectite were selected using a toxicological method, and particle sizes and the morphology of the surface of lactococcal cells in the presence of a cryoprotector were determined using electron microscopy. It was found that the most effective method of preserving the probiotic properties of lactic acid bacteria is lyophilization with the addition of V% smectite, which ensured high cell survival in the first passage and preserved the number of bacteria and their probiotic potential after long-term storage.

In situ electrochemical regeneration of active 1,4-NADH for enzymatic lactic acid formation via concerted functions on Pt-modified TiO2/Ti.

Nicotinamide adenine dinucleotide (NAD+) and its reduced form (NADH) are key cofactors serving as essential hydrogen acceptors and donors to facilitate energy and material conversions under mild conditions. We demonstrate direct electrochemical conversion to achieve highly efficient regeneration of enzymatically active 1,4-NADH using a Pt-modified TiO2 catalyst grown directly on a Ti mesh electrode (Pt-TOT). Spectral analyses revealed that defects formed by the inclusion of Pt species in the lattice of TiO2 play a critical role in the regeneration process. In particular, Pt-TOT containing approximately 3 atom% of Pt exhibited unprecedented efficiency in the electrochemical reduction of NAD+ at the lowest overpotential to date. This exceptional performance led to the production of active 1,4-NADH with a significantly high yield of 86 ± 3% at -0.6 V vs. Ag/AgCl (-0.06 V vs. RHE) and an even higher yield of 99.5 ± 0.4% at a slightly elevated negative potential of -0.8 V vs. Ag/AgCl (-0.2 V vs. RHE). Furthermore, the electrochemically generated NADH was directly applied in the enzymatic conversion of pyruvic acid to lactic acid using lactate dehydrogenase.

Inhibitory effects of Bacillus velezensis ID-A01 supernatant against Streptococcus mutans

BackgroundDental caries is a chronic oral disease caused by microbial infections, which result in erosion of the dental enamel and cause irreversible damage. Therefore, proper disease management techniques and the creation of an environment that prevents intraoral growth and biofilm formation of Streptococcus mutans in the early stages, are crucial to prevent the potential progression of dental plaque to disease. Here, we aimed to investigate antimicrobial and antibiofilm effects of the Bacillus velezensis ID-A01 supernatant (ID23029) against S. mutans, and its inhibitory effects on acidogenesis.ResultsA killing kinetics assay showed a peak lethality percentage of 94.5% after 6 h of exposure to ID23029. In sucrose-exposed conditions, ID23029 inhibited lactic acid formation, preventing the pH from falling below the threshold for enamel demineralization, and inhibited up to 96.6% of biofilm formation. This effect was maintained in the presence of lysozyme. Furthermore, ID23029 retained up to 92% lethality, even at an intraoral concentration at which lysozyme is ineffective against S. mutans.ConclusionsThis study demonstrates the potential of the B. velezensis ID-A01 supernatant for the prevention and treatment of dental caries. Its eventual use in dental practice is encouraged, although further studies are required to confirm its beneficial effects.

Emerging biotechnologies and non-thermal technologies for winemaking in a context of global warming.

In the current situation, wine areas are affected by several problems in a context of global warming: asymmetric maturities, pH increasing, high alcohol degree and flat wines with low freshness and poor aroma profile. The use of emerging biotechnologies allows to control or manage such problems. Emerging non-Saccharomyces as Lachancea thermotolerans are very useful for controlling pH by the formation of stable lactic acid from sugars with a slight concomitant alcohol reduction. Lower pH improves freshness increasing simultaneously microbiological stability. The use of Hanseniaspora spp. (specially H. vineae and H. opuntiae) or Metschnikowia pulcherrima promotes a better aroma complexity and improves wine sensory profile by the expression of a more complex metabolic pattern and the release of extracellular enzymes. Some of them are also compatible or synergic with the acidification by L. thermotolerans, and M. pulcherrima is an interesting biotool for reductive winemaking and bioprotection. The use of bioprotection is a powerful tool in this context, allowing oxidation control by oxygen depletion, the inhibition of some wild microorganisms, improving the implantation of some starters and limiting SO2. This can be complemented with the use of reductive yeast derivatives with high contents of reducing peptides and relevant compounds such as glutathione that also are interesting to reduce SO2. Finally, the use of emerging non-thermal technologies as Ultra High-Pressure Homogenization (UHPH) and Pulsed Light (PL) increases wine stability by microbial control and inactivation of oxidative enzymes, improving the implantation of emerging non-Saccharomyces and lowering SO2 additions. GRAPHICAL ABSTRACT.

Development of new analytical methods for the quantification of organic acids, chlorogenic acids and caffeine in espresso coffee by using solid-phase extraction (SPE) and high-performance liquid chromatography-diode array detector (HPLC-DAD)

Acidity is an important parameter in coffee, contributing to aroma and flavor, imparting fruity notes, and improving the gloss of the coffee, making the beverage more interesting. In this study, two analytical methods were proposed to quantify the content of nine organic acids, caffeine, phenolic acids, and four chlorogenic acids in espresso coffee using an HPLC-DAD instrument. In addition, a new solid-phase extraction (SPE) sample clean-up procedure for organic acids has been optimized. The newly developed analytical methods were characterized by satisfactory recovery levels of sample clean-up procedure (41.798.6%) and good resolution of all peaks in both chromatography separations. In addition, the investigated validation parameters implied good repeatability, sensitivity and linearity. These methods were applied to espresso samples with three different roasting degrees (light, medium, and dark) of the same coffee variety (100% Arabica) to study the effects of the roasting process on the content of caffeine, organic and chlorogenic acids. The caffeine content was relatively stable to heat. The concentration of chlorogenic acids decreased due to roasting while the total organic acid content increased, with the formation of acetic and lactic acids in medium and dark roasting. Therefore, these new approaches can be considered as reference methods for the determination of carboxylic acids in coffee.

The Quality of Silage and Yield in Hungarian Vetch and Forage Crops and Rye Intercropping System

The aim of the study was to determine silage yield and quality of Hungarian vetch/forage pea (V/P) with rye (R) mixed in an intercropping system that provides maximum level of faulting from the field. The field experiment was conducted in 2021-2022 to examine the effects of different binary sowing ratio (20:80%R/P, 40:60%R/P, 60:40%R/P; 80:20%R/P; 20:80%R/V, 40:60%R/V, 60:40%R/V; 80:20%R/V, 100%R, 100%P, 100%V) in 3 replications. The treatments were harvested in July 2022 for silage, and hay yield and fresh yield were determined in the intercropping treatments before ensiling. On the same day, silages were filled by the same mix ratios in plastic cans. After fermentation, the dry matter ratio, pH, sucrose, crude protein, ADF, NDF, mineral matters and organic acid were defined in silages. Before ensiling the highest fresh and dry yield were obtained from 80:20%R/P. Yield values were decreased by increase of rye ratio in the mix. The dry matter, crude protein, lactic acid formation, the inhibition of undesirable micro‐organisms and nutritional quality has been improved in rye silages prepared with H. vetch and F. pea contribute. Consequently, the combinations of the H. vetch and F. pea contribute to rye silage are complementary, and the intercropping of the binary combination made profitable forage yield and silage quality, according to sole treatments. The positive effects in the investigated parameters are in all mixed ratios, but, 80:20R/P, 60:40R/P and 80:20R/V silages were more superior to the others.