Fermentation System Research Articles

Effectively increase the L(+)-isomer proportion of ethyl lactate in Baijiu by isolating and applying L(+)-lactic acid-producing bacteria

Lactic acid (LA) is a significant byproduct in Baijiu fermentation, with both isomers of LA and ethyl lactate (EL) being present in strong-aroma Baijiu. D(-)-isomers cannot be metabolized by humans, and their excessive accumulation can be harmful. This study aims to enhance the proportion of the beneficial L(+)-isomer in Baijiu. We analyzed 106 commercially available strong-aroma Baijiu samples, along with fermented grains (Zaopei), yellow water (Huangshui), and Baijiu samples from 10 Baijiu factories, confirming the coexistence of D(-)-LA and L(+)-LA in fermentation products. Notably, a strong correlation was found between L(+)-LA in Zaopei and L(+)-EL in Baijiu. Microbial community analysis revealed that Lactobacillus and Bacillus were the dominant bacterial groups, with a succession of microbial communities throughout fermentation. We isolated two strains from Zaopei with high selectivity for L(+)-LA production: Bacillus licheniformis (A6) and Bacillus cereus (B12). Incorporating these strains into both liquid- and solid-state fermentation systems markedly increased the proportion of L(+)-EL relative to total ethyl lactate in Baijiu. This study successfully isolated and applied L(+)-LA-producing strains to fermentation models, offering a practical strategy for increasing L(+)-LA content in Baijiu.

A synergistic fermentation system of probiotics with low-cost and high butyric acid production: Lactiplantibacillus plantarum and Clostridium tyrobutyricum

Butyric acid plays a significant role in maintaining body health, and thus the research on cost-effective and efficient biological conversion strategies for butyric acid production holds great importance. This study utilized the mutual interactions between prebiotics and multiple probiotic strains to target increasing the butyric acid yield in a co-fermentation system. Briefly, xylan, an inexpensive biomass material, was used as a prebiotic to screen lactic acid bacteria that capable of being promoted for proliferation and metabolism in its presence. Subsequently, the interaction between the screened lactic acid bacteria and a butyric acid-producing strain (Clostridium tyrobutyricum) was utilized to enhance butyric acid production. The results showed that xylan significantly improved the proliferation and lactic acid metabolizing ability of Lactiplantibacillus plantarum C0502. Whole-genome analysis revealed that L. plantarum carries at least four distinct enzyme genes related to the hydrolysis and utilization of xylan. Co-cultivation of L. plantarum with C. tyrobutyricum demonstrated that the C. tyrobutyricum was able to effectively convert lactic and acetic acids into butyric acid. Furthermore, the addition of xylan into this co-culture system yielded a remarkable butyric acid production of up to 5.01 ± 0.04 g/L, which is 4.58 times higher than the yield obtained from the monoculture of C. tyrobutyricum in reinforced Clostridium medium. The results of this study suggested that the co-culture system of xylan, L. plantarum, and C. tyrobutyricum has the potential to significantly enhance butyric acid production while markedly reduce the production cost. This has immense prospects for practical applications.

Investigation of the polysaccharides synthesis enhancement mechanism from Agaricus bitoquis (Quél.) Sacc Chaidam and its fermentation regulation technology system based on multi-omics technologies

The polysaccharides (PS) of Agaricus bitoquis (Quél.) Sacc. Chaidam (ABSC) had attracted the attention of researchers due to their strong anti hypoxia, antioxidant, and anti fatigue activities. Therefore, this article focuses on studying the regulatory channels of exogenous additives-Lycium ruthenicum Murr. Anthocyanin (LRA) to delay fungus cell aging and promote the incremental synthesis of PS from ABSC, and optimizing the regulation system for pilot fermentation experiments. The joint analysis of Ultra High Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry (UHPLC-Q-TOFMS) and RNA sequencing (RNA-seq) database elucidates that at the molecular level, the crude extract of LRA inhibits the Telecommunications Association (TCA) cycle, transferring carbon metabolism to the synthesis of polysaccharide precursors (UDP-glucose, UDP-galactose, etc.), promoting the synthesis of PS, promoting the formation of key antioxidant substances (including flavonoids such as quercetin and alginate), improving cell membrane fluidity (saturated fatty acid to unsaturated conversion) and enhancing the degradation of toxic substances (oxidized glutathione), thereby promoting the anti-aging activity and PS synthesis ability of mycelial cells; LRA-adding could enhance the activity in the pilot fermentation of ABSC, which make the mycelia biomass, EPS and IPS production were significantly increased (89.04 %, 65.46 % and 37.64 % respectively) compared with the untreatment control. Based on the optimal fermentation system of PS synthesized in mycelium by adding LRA, Logistic, Gauss, and Asymptotic kinetic equations were used to describe the cell growth, product synthesis and regulatory substrate consumption from ABSC. The correlation coefficients of three models were all above 0.95, indicating a good fit between the experimental values and predicted value, this indicated ABSC fermentation kinetics model could better simulate the actual production process and provide theoretical data for the industrial production of polysaccharides. The results demonstrated that the present proposed LRA intensification approach could be useful to boost up the fermentation of ABSC, which possibly applied to yield increase and fermentation product acquisition of macrofungi.

Overlooked roles of improved substrates functions in remodeling microbial community and driving metabolic traits during sludge fermentation triggered by surfactants and antibiotics co-existence

Sludge anaerobic fermentation is a pivotal route to transit wastewater treatment plants towards energy-neutral and resource recovery-oriented plants, while the overall efficiency is commonly restrained by co-exist contaminants. This study unveiled the cooperative effect of sulfadiazine (SDZ) and linear alkylbenzene sulfonates (LAS) in driving volatile fatty acids (VFAs) biosynthesis during waste activated sludge (WAS) anaerobic fermentation. The VFAs remarkably elevated to 1189 mg COD/L in LAS/SDZ, which was approximately 1.3–3.2 folds of SDZ and LAS. SDZ and LAS synergistically disintegrated extracellular polymeric substances to provide fermentation substrates. These changes altered microbial population and enhanced microbial networks interconnection. Moreover, the proteins released from WAS might facilitate electron transfer among microorganisms. The functional anaerobic species, including hydrolytic-acidogenic bacteria (e.g., Veillonellaceae and Lactobacillus) and electroactive bacteria (e.g., Parabacteroides and Fonticella), were enriched. Also, the metabolic traits responsible for transmembrane transport, intracellular metabolism, VFAs biosynthesis and electron transfer-related process were strengthened with the upregulation of functional genes. Further analysis revealed that the functional anaerobic species activated quorum sensing and two-component systems to counteract unfavorable LAS/SDZ stress and maintain high metabolic activities. This work elucidated the overlooked roles of substrates in modulating anaerobic consortia and metabolic traits in sludge fermentation systems with mixed pollutants stressing.

The potential Impact of bacterial probiotics on ruminal greenhouse gases production in vitro of dietary Delonix regia seeds in rams and steers.

This study aimed to evaluate the influence of probiotic bacteria (Pediococcus acidilactici BX-B122 and Bacillus coagulans BX-B118) on methane, carbon monoxide, and hydrogen sulfide, and fermentation profile of dietary Delonix regia seeds in ruminant. Ruminal contents from slaughtered rams and steers were used as inoculum for in vitro fermentation system. The total gas, methane, carbon monoxide, and hydrogen sulfide volume, as well as pH and dry matter degradability, were quantified in three fermentation cycles. Probiotic bacteria reduced the production of methane and hydrogen sulfide, while also increasing (P < 0.05) dry matter biodegradability, short-chain fatty acids, and metabolizable energy in both rams and steers. Delonix regia seeds at 6, 12, and 18% reduced total gas production. Higher production of methane and carbon monoxide was observed in rams compared to steers. Interestingly, no impact (P > 0.05) on the pH of the ruminal contents was found in Delonix regia seeds alone or in combination with probiotics. However, higher (P < 0.05) methane conversion efficiency (i.e., ratios of methane: short-chain fatty acids, methane: metabolizable energy, and methane: organic matter) was observed in experimental diets with Delonix regia seeds compared to diets containing both Delonix regia seeds and probiotic bacteria. In conclusion, dietary inclusion of 6, 12, and 18% of Delonix regia seeds with probiotic bacteria (Pediococcus acidilactici BX-B122 and Bacillus coagulans BX-B118) can mitigate the production of methane and hydrogen sulfide, while also increasing dry matter biodegradability, short-chain fatty acids, and metabolizable energy both ruminant animals.

Insights into the Acute Stress of Glutaraldehyde Disinfectant on Short-Term Wet Anaerobic Digestion System of Pig Manure: Dose Response, Performance Variation, and Microbial Community Structure

The outbreak of epidemics such as African swine fever has intensified the use of disinfectants in pig farms, resulting in an increasing residual concentration of disinfectants in environmental media; however, the high-frequency excessive use of disinfectants that damage pig farm manure anaerobic fermentation systems and their mechanisms has not attracted enough attention. Especially, the complex effects of residual disinfectants on anaerobic fermentation systems for pig manure remain poorly understood, thus impeding the application of disinfectants in practical anaerobic fermentation systems. Herein, we explored the effects of glutaraldehyde disinfectant on methane production, effluent physicochemical indices, and microbial communities in a fully automated methanogenic potential test system (AMPTSII). The results show that adding glutaraldehyde led to remarkable alterations in methane production, chemical oxygen demand (COD), volatile solids (VS), and polysaccharide and phosphorus concentrations. During the anaerobic process, the production of methane displayed a notable decrease of 5.0–98% in all glutaraldehyde treatments, and the trend was especially apparent for treatments containing high levels of glutaraldehyde. Comparisons of the effluent quality showed that in the presence of 0.002–0.04% glutaraldehyde, the COD and total phosphorus (TP) increased by 12–310% and 15–27%, respectively. Moreover, the addition of 0.01–0.08% glutaraldehyde decreased the ammonium (NH4+-N) concentration and VS degradation rate by 7.7–15% and 4.9–26.2%. Furthermore, microbiological analysis showed that the glutaraldehyde treatments had adverse effects on the microbial community. Notably, certain functional bacteria were restrained, as highlighted by the decreases in relative abundance and microbial diversity by 1.3–17% and 0.06–21%, respectively. This study provides a theoretical basis for the rational use of disinfectants in anaerobic fermentation systems.

Characterization of 'borde': A traditional ethiopian cereal-based fermented beverage - Microbial analysis, rheological profiling, and functional attributes

The study focused on the characterization of an Ethiopian traditional beverage, borde, produced by lactic acid bacteria (LAB) and yeast through natural fermentation. Samples were collected from three distinct locations in Ethiopia and subjected to analyses encompassing microbiological, antioxidant, enzyme inhibition, rheological and physicochemical aspects. The early stages of fermentation exhibited prevalence of Enterobacteriaceae and aerobic mesophilic bacteria. Towards the end of fermentation, yeast (6.07–6.72) and LAB (6.52–7.12) (log CFU mL−1) dominated the microbiological profile of all borde samples. Significant difference (P < 0.05) in the number of microorganisms were noted between the samples. Antioxidant activities, assessed through DPPH and ABTS values, ranged between 51.5 and 64.6 % and 47.4–62.9.1 %, respectively. The average value of α-glucosidase and pancreatic lipase inhibition for borde samples were ranged from 36.56 to 43.23 % and 31.08–40.19 %, respectively. Rheological investigations indicated pseudoplastic fluid behavior, as evidenced by the decreasing apparent viscosity values with shear rate. Moreover, the samples displayed solid-like structures, with lower loss modulus (G″) values compared to storage modulus (G′). The shared physicochemical characteristics and the dominance of specific microbial groups suggest the potential for developing a direct fermentation system for this traditional cereal-based beverage. Overall, these findings contribute valuable insights into the multifaceted nature of borde, paving the way for further advancements in its production and quality control.

Deciphering the formation mechanism of 2-furfurylthiol by multi-omics approach

2-Furfurylthiol (FFT) emerges as an exceptional sulfur-infused constituent in Baijiu, characterized by its dual-edged attributes. Despite the isolation of several functional strains capable of synthesizing FFT from the intricate Baijiu fermentation system, the synthetic mechanism remains elusive. In this study, a Saccharomyces cerevisiae sourced from Baijiu fermentation system was obtained, and designated as baijiu_z001, screened potential FFT precursors by non-targeted metabolomics, and the speculation validated experimentally that furfuryl thioacetate and S-(2-furylmethyl) propanethioate stand as the precursors for FFT generation. Subsequently, the genomic information of the yeast was obtained by combining the genome with transcriptome sequencing, and the potential enzyme involvement in the production of furfuryl thioacetate was verified through heterologous expression in Pichia pastoris GS115. The recombinant strain carrying the gene GME4775 could produce both furfuryl thioacetate and FFT, while the recombinants carrying the respective genes GME1296, GME2059, or GME3990 could only produce furfuryl thioacetate, indicating that the enzyme encoded by GME4775 plays a crucial role in FFT synthesis. Homology modeling and molecular docking were subsequently used to investigate the possible catalytic interactions between enzymes and substrates. Lys-204, Glu-334, and Tyr-104 constitute the catalytic active sites of the enzyme GME4775, and the catalytic process was proposed. This study elucidated the formation pathway of FFT and identified the key enzymes involved in the generation of furfuryl thioacetate, the precursor of FFT.

Rape straw-driven mitigation of greenhouse gas emissions and key bacterial communities during the treatment of pig farm manure in the ectopic fermentation system

Rice chaff, sawdust, and rape straw are commonly used as padding materials in the ectopic fermentation system. However, the characteristics of greenhouse gas emissions the ectopic fermentation system using rice chaff, sawdust, as well as the effects of rape straw on these emissions, remain unclear. This study investigated the effects of different proportions of rape straw (0, 10%, 25%, and 50%) on greenhouse gas emission characteristics in this system. The experimental results indicated that the treatment group containing rice chaff, sawdust, and more than 25% rape straw significantly increased fermentation temperature, prolonged the thermophilic phase, enhanced the maturity of fermentation products, and altered microbial community structures compared to the control group with only rice chaff and sawdust. Redundancy analysis revealed that replacing rice chaff and sawdust with 50% rape straw significantly decreased the relative abundance of methanogens (e.g., Methanospirillum and Methanobacterium) and denitrifying species (e.g., Denitrificimonas caeni and Aliarcobacter butzleri), resulting in reductions in cumulative emissions of CH4 and N2O by up to 44.6% and 84.9%, respectively, compared to the treatment group with rice chaff and sawdust alone. The absolute abundance of the nosZ gene was positively correlated with N2O emissions. Therefore, rape straw has been demonstrated to be an effective padding material that reduces CH4 and N2O emissions while enhancing the maturity of fermentation products in the ectopic fermentation system.

Initial abiotic factors as key drivers in core microbe assembly: Regulatory effects on flavor profiles in light-flavor baijiu

Instability in initial abiotic factors of open solid-state fermentation systems can significantly alter Baijiu's flavor profile, but the mechanisms governing microbial interactions and flavor formation remain unclear. This study comprehensively monitored changes in abiotic factors, microbial communities, and flavor profiles across two distinct fermentation processes in a Baijiu distillery, which differed significantly in their management of initial abiotic factors. Our results revealed significant differences in abiotic factors between the two groups, including moisture, ethanol, acidity, glucose, and organic acid levels. The assembly of microbial communities in fermented grains was primarily driven by deterministic processes. The moisture content in the fermentation grains positively affected the growth and metabolism of core microbiota. The rapid proliferation and metabolism of core microbes led to a rapid increase in the acidity of the fermented grains, alongside a significant accumulation of ethyl lactate. This study provides technical support and theoretical guidance for Baijiu production.

Unraveling the regional environmental ecology dominated baijiu fermentation microbial community succession and associated unique flavor.

Chinese baijiu as one of the famous distilled liquor in which fermented in open environments, with various microorganisms (i.e., bacteria, fungi, and yeast) involved in their brewing process, and created corresponding unique flavor. However, the sources of environmentally enriched microbial communities associated with liquor fermentation are still being characterized yet. Given the dependence of microbial growth and reproduction on environmental ecology, it is important to understand the correlation between baijiu fermentation microbial community and surrounding environmental ecology (i.e., temperature, humidity, wind, and precipitation). This study systematically overviewed the sources of microorganisms in the Jiang-flavor-Baijiu fermentation system. The results showed that microorganisms in baijiu brewing (i.e., mold, lactic acid bacteria, and yeast) mainly originated from surrounding environmental matrices, including the air (i.e., Yeast, Streptomyces and Bacillus), soil (i.e., Xanthomonas, Methanococcus and Comamonas) and water (i.e., Flavobacterium, Acinetobacter, and Pseudomonas) via atmospheric transport, raw material transfer and surface runoff. In addition, the unique baijiu fermentation microbial community diversity depends on local geology and meteorological conditions, highlighting that the structural stability and diversity of the microorganisms in the Baijiu brewing process dominated by local environmental ecology. We also explored the regional environmental conditions on the microbial community and found that the unique Jiang-flavor-Baijiu fermentation microbial community diversity depends on local geology and meteorological conditions. The Jiang-flavor-Baijiu workshop is located in the basin of the middle-and low latitude mountainous areas, with sufficient solar irradiation and rainfall, high air humidity, and low wind speed that favor the growth and propagation of Baijiu fermentation microorganisms. Therefore, the obtained conclusions provide new insights unraveling the key factor controlling the unique flavor of Chinese Baijiu, where protecting the ecology of baijiu brewing-regions is fundamental for maintaining the long-term quality of baijiu.

Effects of fermented Arctium lappa L. root by Lactobacillus casei on hyperlipidemic mice.

This study aimed to establish a fermentation system based on Lactobacillus casei (LC) and Arctium lappa L. root (AR) to investigate its effects. The objectives included comparing metabolite profiles pre- and post-fermentation using untargeted metabolomics and evaluating the impact of LC-AR in high-fat diet-induced hyperlipidemic mice. Untargeted metabolomics was used to analyze differences in metabolites before and after fermentation. In vitro antioxidant activity, liver injury, lipid levels, pro-inflammatory cytokine levels, and cholesterol-related mRNA expression were assessed. 16S rRNA sequencing was conducted to evaluate changes in gut microbiota composition. LC-AR exhibited stronger antioxidant activity and higher metabolite levels than AR. It also improved liver injury as well as better regulation of lipid levels, pro-inflammatory cytokine levels, and cholesterol-related mRNA. 16S rRNA analysis revealed that LC-AR decreased the Firmicutes/Bacteroidetes ratio, which correlated negatively with triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels. These findings suggest that LC-AR may serve as a promising functional food and drug raw material for improving hyperlipidemia, particularly through its beneficial effects on gut microbiota and lipid regulation.

Evaluation of the Physico-chemical and Biological Properties of Fermented Nipa (Nypa fruticans) Sap Under Closed and Open Vessel Fermentation System for Bioethanol Production

Background The potential of Nipa (Nypa fruticans) sap in the Cagayan Region, Philippines, for bioethanol production remains largely underexplored despite its vast expanse. Methods This study investigates the key physico-chemical properties of Nipa sap from Aparri, Cagayan, with a focus on fermentation dynamics and storage conditions to optimize ethanol production. Two fermentation treatments closed and open vessel conditions, were compared to determine the optimal conditions for maximum ethanol yield. Over a 7-day fermentation period, the acetic acid production, yeast activity, sugar content, and ethanol concentration of closed vessel fermented sap (CVFS) and open vessel fermented sap (OVFS) were monitored. Results CVFS demonstrated a higher ethanol yield (7.56%v/v at peak day), characterized by minimized acetic acid accumulation and stable yeast activity. In contrast, OVFS exhibited significant fluctuations in acetic acid and ethanol levels, indicating a lower fermentation efficiency. Conclusion The presence of methanol and high acetic acid content in open-vessel fermentation systems highlights the importance of fermentation conditions to prevent impurities. This study provides valuable insights into optimizing ethanol production from fermenting Nipa sap by employing closed vessel fermentation, which is crucial for sustainable bioethanol production in the Cagayan region.

Iron (Magnetite) Nanoparticle-Assisted Dark Fermentation Process for Continuous Hydrogen Production from Rice Straw Hydrolysate

The use of metal nanoparticles (NPs) to enhance hydrogen production in dark fermentation (DF) has become a pioneering field of interest. In particular, iron-based nanoparticles (FeNPs) play a pivotal role in enhancing the activity of metalloenzymes and optimizing feedstock utilization, resulting in improved hydrogen production. This study investigated the effect of FeNPs (magnetite) supplementation at three different concentrations of 50, 100, and 200 ppm in a continuous dark fermenter for the production of hydrogen from rice straw acid hydrolysate. The highest hydrogen production rate of 2.6 ± 0.3 NL H2/L-d was achieved with the addition of 100 ppm of nanoparticles, representing a 53% increase compared to the condition without FeNPs addition. This improvement was driven by a microbial community in which Clostridium was the major dominant genus. In addition, increasing the nanoparticle concentration to 100 ppm resulted in an increase in butyrate concentration to 2.0 ± 0.1 g/L, which is 43% higher than the butyrate concentration without FeNPs. However, when the NP concentration was increased to 200 ppm, the hydrogen production rate decreased to 1.6 ± 0.2 NL H2/L-d. This study can serve as a guideline for future research aimed at evaluating the effects of FeNPs in continuous dark fermentation systems. This work highlights the potential benefits and challenges associated with the use of FeNPs, paving the way for future studies to optimize their application and improve the efficiency of dark fermentation processes.

Hexanoic acid production from anaerobic fermentation of Chinese cabbage waste with exogenous lactic acid as electron donor

The lack of electron donors is one of the key factors hindering hexanoic acid production from anaerobic fermentation. In this study, three different types of lactic acids were supplemented as exogenous electron donors to the anaerobic fermentation system of Chinese cabbage waste (CCW). The yields of hexanoic acid in the reactors supplemented with CCW lactic acid pre-fermentation broth (PFB), lactic acid diluent (LAD) and chemical lactic acid (LA) were 6996.8 mg COD/L, 4534.8 mg COD/L and 6777.1 mg COD/L, respectively. Compared with the reactor supplemented with LA, the electron efficiency of hexanoic acid in reactor supplemented with PFB increased by 188 %. Supplementing PFB shifted the microbial communities towards a direction favorable to hydrolysis and chain elongation, thereby facilitating the synthesis of hexanoic acid.

Glycerol-derived reuterin regulates human intestinal microbiota and metabolites.

Reuterin, a mixture of different forms of 3-hydroxypropanal (3-HPA), including HPA hydrate and HPA dimer, is an antimicrobial compound converted from glycerol by Lactobacillus reuteri and other strains. Although its antimicrobial function may be related to its interaction with thiol groups, its temperature stability and effect on the gut environment remain unclear. The present study evaluated the antimicrobial effects and activity of reuterin against Escherichia coli and Salmonella typhimurium. Utilization of a reliable in vitro gut microbiome fermentation system revealed that reuterin has a modulatory effect on the gut microbial community. Reuterin treatment completely inhibited H2 and NH3 production in the gut and significantly enhanced the synthesis of branched short-chain fatty acids. 16s rRNA sequencing indicated that reuterin promoted the growth of Proteobacteria and Bacteroidetes in the in vitro system and significantly modulated gut microbiota composition.

Regional Strategies for Implementing Methane Fermentation Technology in Waste Management: Environmental, Technological, and Social Perspectives

This article discusses regional strategies for implementing methane fermentation technology in waste management, considering environmental, technological, and social perspectives. Methane fermentation plays a crucial role in modern waste management and renewable energy production. The article highlights the importance of local climatic, economic, and social conditions that affect the efficiency and profitability of biogas installations. Both barriers and opportunities for technology development in various regions are analyzed, particularly in terms of raw material availability, regulatory support, and social acceptance. Examples of biogas technology applications in different countries are provided, identifying key success factors. The article offers valuable insights for decision-makers responsible for designing and implementing methane fermentation systems, taking into account diverse regional conditions and local needs.

Identification of potential volatile markers for characterizing Argentine wine vinegars based on their production process

In Argentina, the production of quality wine vinegars has been barely exploited. Currently, most of the marketed vinegars are produced using rapid industrial fermentation systems obtaining vinegars with a high production rate, but with low quality and few organoleptic nuances. This work aims to study the volatile profile by headspace solid phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC–MS) and chemometrics to differentiate Argentinian wine vinegars according to their production process (industrial or traditional). A total of 92 volatile compounds were identified on the samples by using a strategy based on volatile profile processing using PARADISe® software. The complete volatile profile of all the samples was submitted to partial least squares discriminant analysis (PLS-DA) for the selection of variables with importance in the projection (VIPs). Thus, 37 volatile compounds with the potential to be markers of the manufacturing process were selected. The results obtained revealed, for the first time, the volatile profile of Argentine wine vinegars showing that the compound groups that, on average, exhibited higher relative areas were esters, acids, and alcohols. Thus, certain acids, aldehydes and terpenes were noticeably present in industrial wine vinegar. Conversely, the alcohols were strongly associated with traditional ones. In the case of esters, they were connected to the different types of wine vinegars. These compounds could be considered as potential volatile markers of quality and authenticity of these types of vinegars.

Silage Making of Napier Grass and Sugarcane Top at Different Proportions: Evolution of Natural Fermentation Characteristics, Chemical Composition, and Microbiological Profile

The co-ensiling technique is widely used to improve silage quality; however, it remains unclear as to what high-quality silages can be made by co-ensiling Napier grass (NG) with Sugarcane top (ST). The aim of this study was to evaluate the fermentation characteristics, chemical composition, and microbiological profile of silage produced from mixtures of NG and ST in varying ratios. Silage was prepared using a small-scale fermentation system, and treatments were designed as control silage (NG ensiled alone) or with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%ST on a fresh matter basis with six replicates, respectively. Increasing ST in the silage reduced the contents of crude protein, ash, acetic acid, butyric acid, ammonia-N, as well as pH, but increased the contents of dry matter, ether extract, neutral detergent fiber, acid detergent fiber, water-soluble carbohydrate, lactic acid, and lactic acid bacteria. Lactobacillales and Enterobacterales were the dominant orders, with Lactiplantibacillus and Weissella as the dominant genera. Co-ensiling NG with ST enhanced microbial diversity and richness. ST, as a local by-product, is a viable additive to improve NG silage quality and nutrition. This study suggests that good-quality silages can be produced with NG: ST ratios of 40:60 to 20:80 and that these silages offer an opportunity to optimize the nutrient supply for ruminants.

Comparative Evaluation of Methane Yield from Continuous and Batch Fermentative Processing of Selected Agrowaste

This study investigated the influence of different agrowaste compositions on methane yield in batch and continuous operational modes, highlighting the significance of substrate characteristics in determining the efficiency of methane production. It comparatively assessed the methane yield derived from continuous and batch fermentative processing of the following agrowaste; Cassava peels (A), Maize husks (B), Pig Slurry (C), and composite (D) that represents the co-digestion of the aforementioned A, B &amp; C. Eight digesters were used in all, two anaerobic systems for each substrate, [I.e one operating in a batch mode (1) and the other in a continuous mode (2)]. The proximate properties of the substrates were determined and gas production rates were monitored over the experimental period of 45 days. Gas analysis of the generated gas revealed mainly methane and CO2, with concomitant organic compounds like; Ethanol, Methanol, Acetic Acid, Acetone, etc. Minute quantities of Phenol and Lactic Acid were mainly found in the gas generated from Cassava peels. The average percentage value of Co-digested substrates (D) yielded higher gas volume of 78.263±4.54, followed by C (74.263±4.65), B (70.240±4.38), and A (56.090±3.50). The results also revealed that the continuous fermentative process demonstrated a more stable and consistent methane production rate compared to the batch system, attributed to its steady-state operational mode and continuous substrate feed input. However, modeled graphical results showed that batch fermentation system produced higher gas yield (for all the substrates) between days 29-39 before it recorded a sharp decline curve, attributed to the reduction in substrate availability.