Fermentation Process Research Articles

Ambient temperature-dependent variations in bitter compounds and microbial dynamics in traditional huangjiu fermentation

Huangjiu, a traditional Chinese fermented wine, often develops excessive bitterness under semi-open fermentation conditions. This study examines the impact of ambient temperature on bitterness and microbial composition during Huangjiu fermentation. Using high−performance liquid chromatography (HPLC), gas chromatography−olfactometry (GC−O), and metagenomic sequencing, we identified seven bitter amino acids and eleven bitter volatile substances. Our results indicate that lower ambient temperatures (8.21 ± 0.69 °C to 9.88 ± 0.83 °C) suppress the accumulation of bitter substances, with the total concentration of bitter amino acids reduced by up to 3.94% compared to higher temperatures (16.36 ± 0.97 °C to 4.75 ± 0.74 °C). Partial least squares (PLS) regression established correlations between electronic tongue bitterness values and the presence of bitter compounds, revealing that higher temperatures promote the formation of specific compounds, such as benzaldehyde, furfural, ethyl nonanoate, and phenylalanine, thereby enhancing bitterness perception. Metabolic pathway analysis highlighted the enzymatic processes and intermediates involved in the biosynthesis of these bitter compounds. Correlation analysis showed that Saccharomyces and Lactobacillus are closely linked to the synthesis of bitter amino acids, while Aspergillus and Rhizopus contribute to the formation of furfural and ethyl octanoate. This study offers a theoretical foundation for reducing flavor variations between Huangjiu batches and provides practical guidance for optimizing the traditional fermentation process.

Optimization of manufacturing process for serotype 14 pneumococcal capsular polysaccharide

Streptococcus pneumoniae is a pathogenic bacterium that causes infections such as pneumonia, meningitis, otitis media, and bacteremia. The prevention of pneumococcal disease by vaccination has become more urgent due to increased antibiotic resistance. Pneumococcal capsular polysaccharides (CPS) are effective vaccine antigens that stimulate the host to produce protective antibodies. S. pneumoniae serotype 14 is one of most prevalent types in Latin America and across the world. However, the yield of S. pneumoniae serotype 14 CPS from existing fermentation processes remains low and requires improvement. In this study, various aspects of the fermentation process were optimized to improve pneumococcal growth and polysaccharide productivity, including feed medium, cultivation gas environment, fermentation pH, and temperature. A simplified purification method was also developed to obtain pure CPS, including ultrafiltration, acid and ethanol precipitation, diafiltration, and lyophilization. These fermentation optimizations significantly enhanced the optical density of pneumococcal bacterial cultures and increased fermentation yields to 2.4–2.6 g/L—significantly higher than previously achieved. Furthermore, the test results of pure CPS could meet the requirements in the European Pharmacopoeia (11th edition). These optimizations provide valuable insights into the nutritional requirements and impact of varying fermentation process parameters on pneumococcal growth and CPS productivity, thus contributing to the development of a more efficient and cost-effective method for the production of pneumococcal CPS—essential for manufacturing vaccines against pneumococcal infections.

The effects of headspace volume reactor on the microbial community structure during fermentation processes for volatile fatty acid production.

The transition from traditional wastewater treatment plants to biorefineries represents an environmentally and economically sustainable approach to extracting valuable compounds from waste. Sewage sludge produced from wastewater treatment is incinerated or disposed of in specific landfills. Repurposing this waste material to recover valuable resources could help lower disposal costs and reduce environmental impact by producing other beneficial polymers. Microorganisms present in the sewage sludge can ferment organic pollutants, producing volatile fatty acids (VFA), precursors for biopolymers that could be used as an alternative to petroleum-derived plastics. To boost VFA production during sewage sludge fermentation, it is necessary to understand the operating microbial community and its metabolic capacities in anaerobic conditions. This study presents the influence of the headspace volume on the microbial community and the VFA production to define the best operational parameters in a 225 L pilot plant fermenter. The wasted sewage sludge was withdrawn from an oxic-settling-anaerobic plant that collected wastewater from the canteen and dormitory of the UNIPA Campus (Palermo University, Italy) and incubated using a 40% and a 60% headspace volume. The microbial community was analysed before and after the fermentation process through metataxonomic analysis, and VFA yields were determined by gas chromatography analysis. Our results showed that the 40% headspace volume induced a tenfold higher VFA production than the 60% headspace volume, modulating the microbial community's efforts to establish a VFA-producing factory. Notably, at 40% headspace, the relative abundance of bacteria, like Proteobacteria, Firmicutes, Actinobacteria, and Chloroflexi, significantly increased, as well as the relative abundance of Bacteroidetes and Verrucomicrobia decreased during the fermentation process. This result is consistent with the selection of efficient VFA-producing bacteria that lead to increased VFA yields that are not obtained at 60% headspace. Thus, reducing headspace is a promising strategy that can be implemented, even in full-scale plants, to optimise the wastewater reuse process and maximise VFA production to produce bioplastics, like polyhydroxyalkanoate, for the transition from linear wastewater treatment plants to circular biorefineries.

Bioactive Peptides from Fermented Foods: Production Approaches, Sources, and Potential Health Benefits

Microbial fermentation is a well-known strategy for enhancing the nutraceutical attributes of foods. Among the fermentation outcomes, bioactive peptides (BAPs), short chains of amino acids resulting from proteolytic activity, are emerging as promising components thanks to their bioactivities. Indeed, BAPs offer numerous health benefits, including antimicrobial, antioxidant, antihypertensive, and anti-inflammatory properties. This review focuses on the production of bioactive peptides during the fermentation process, emphasizing how different microbial strains and fermentation conditions influence the quantity and quality of these peptides. Furthermore, it examines the health benefits of BAPs from fermented foods, highlighting their potential in disease prevention and overall health promotion. Additionally, this review addresses the challenges and future directions in this field. This comprehensive overview underscores the promise of fermented foods as sustainable and potent sources of bioactive peptides, with significant implications for developing functional foods and nutraceuticals.

A Review of the Technological Aspects and Process Optimization of Bioethanol Production From Corn Stover Biomass: Pretreatment Process, Hydrolysis, Fermentation, Purification Process, and Future Perspective

ABSTRACTBioethanol, a sustainable energy solution derived from renewable biomass, has gained prominence, with corn stover emerging as a substantial biomass resource in Indonesia. Corn stover, a corn residue, is one of the top three agricultural wastes worldwide and is abundantly available. However, a significant portion of corn stover is burned in fields rather than utilized for bioethanol production, whereas it has potential as a bioethanol feedstock. As the world strives to realize sustainable and environmentally friendly energy security, bioethanol production from corn stover can be one of the solutions to be developed. Nonetheless, the current immaturity of bioethanol production technology is one of the causes of large‐scale production failure. The present paper comprehensively reviews the technological aspects and process optimization of bioethanol production using corn stover as a feedstock comprising pretreatment, hydrolysis, fermentation, and bioethanol purification processes. According to our critical review, ammonia fiber expansion (AFEX) pretreatment is the most effective conventional pretreatment, with glucose yield up to 90%. Moreover, ultrasound appears to be the most viable option for nonconventional pretreatment of corn stover for producing bioethanol. However, combining ultrasound pretreatment and dilute aqueous ammonia produced 80.6% sugar output. Furthermore, enzymatic hydrolysis emerges as the most effective saccharification, yielding up to 81.39%. Moreover, the fermentation process of corn stover with the saccharification and co‐fermentation (SScF) method and the process optimization with response surface methodology (RSM) could produce bioethanol with a concentration of up to 59.8 g/L and 92.07% ethanol yield, respectively. This review also reveals that pervaporation for the purification process is the best choice for producing bioethanol with high purity up to > 99%. In addition, this method could reduce the energy used by 6.6% lower, 24.2% lower carbon footprint, and have the lowest total capital and production costs compared to conventional molecular sieves and extractive distillation. We believe this review article can provide a reference for selecting the best bioethanol production process from corn stover for further research.

Dynamics of fermentation quality, bacterial communities, and fermentation weight loss during fermentation of sweet sorghum silage

BackgroundSweet sorghum is used mainly as an energy crop and feed crop in arid and semiarid regions, and ensiling is a satisfactory method for preserving high-quality sweet sorghum. The aim of this study was to reveal the dynamics of the fermentation quality, bacterial communities, and fermentation weight loss (FWL) of sweet sorghum silage during fermentation.MethodsSweet sorghum was harvested at the first inflorescence spikelet stage and ensiled without (CK) or with lactic acid bacterial (LAB) additives (L). After ensiling, samples were collected on days 0, 1, 3, 5, 15, 40, and 100 to assess the fermentation quality, bacterial communities, and FWL.ResultsFor CK and L, on day 1, the pH was 5.77 and 5.57, respectively, and the lactic acid (LA) was 1.30 and 2.81 g/kg dry matter (DM), respectively. Compared with CK, L had a lower pH and higher LA from days 1 to 5 (P < 0.05), a lower FWL from days 5 to 100 (P < 0.05), and a greater abundance of Lactiplantibacillus from days 1 to 15 (P < 0.05). The main bacterial genera were Leuconostoc and Weissella in CK and Lactiplantibacillus, Leuconostoc, and Weissella in L on day 1; Lactiplantibacillus in all silages from days 3 to 40; and Lactiplantibacillus and Lentilactobacillus in all silages on day 100.ConclusionsSweet sorghum silage fermented relatively slowly during the first day. Moreover, inoculation with LAB accelerated fermentation and optimized bacterial communities during the initial fermentation phase. Inoculation with LAB also reduced the silage FWL, and the LAB succession relay occurred in the silage throughout the fermentation process.

Advancements in synergistic fermentation of probiotics and enzymes for non‐grain feed raw materials

AbstractTo address the escalating challenge of food scarcity and the associated conflicts between human and animal consumption, it is imperative to seek alternative resources that can substitute for traditional feed. Non‐grain feed (NGF) raw materials represent a category of biomass resources that are distinct from grains in their composition. These materials are characterized by their high nutritional content, cost‐effectiveness, ample availability, and consistent supply, which contribute to their significant economic potential. Nonetheless, the extensive application of NGF is currently hindered by several limitations, including a high concentration of antinutritional factors, suboptimal palatability, and an offensive odor, among other shortcomings. The synergistic fermentation of probiotics and enzymes (SFPE) is an innovative approach that integrates the use of a diverse array of enzymes during the feed fermentation process, as well as various strains of probiotics throughout the feed digestion process. This method aims to enhance the nutritional value of the feed, diminish the presence of antinutritional factors, and improve the overall palatability, thereby facilitating the optimal utilization of NGF. This strategy holds the promise of not only replacing conventional feed options but also mitigating the pressing issue of grain scarcity. This paper delves into the practical applications of NGF and presents an overview of the latest research advancements in SFPE fermentation techniques, which can provide cutting‐edge and valuable reference for researchers who devote themselves to research in this field in the future.

Multi-omics analysis reveals the core microbiome and biomarker for nutrition degradation in alfalfa silage fermentation.

Silage fermentation is a microbial-driven anaerobic process that efficiently converts various substrates into nutrients readily absorbable and metabolizable by ruminant animals. This study, integrating culturomics and metagenomics, has successfully identified core microorganisms involved in silage fermentation, including those at low abundance. This discovery is crucial for the targeted cultivation of specific microorganisms to optimize fermentation processes. Furthermore, our research has uncovered signature microorganisms that play pivotal roles in nutrient metabolism, significantly advancing our understanding of the intricate relationships between microbial communities and nutrient degradation during silage fermentation.

Penggunaan Slurry sebagai Pupuk Organik terhadap Kualitas dan Fermentabilitas Rumput Setaria (Setaria splendida Stapf) di Rumen

Biogas slurry is an organic product derived from livestock manure and produced through an aerobic fermentation process that can be used to improve soil fertility, forage production, and quality. This study aimed to investigate the effect of slurry organic fertilizer on crude protein content, crude fiber, and total fermentation gas production in the rumen in vitro . The study was conducted in a completely randomized design (CRD), consisting of five treatments of slurry levels as organic fertilizer and four replications consisting of two experimental units. The treatments consisted of S0 = without slurry, S1 = slurry 20 g/polybag, S2 = slurry 25 g/polybag, S3 = slurry 30 g/polybag, and S4 = slurry 35 g/polybag. The variables measured in this study were crude protein content, crude fiber, and total fermentation gas production. The data obtained were analyzed using a variance analysis (ANOVA). Duncan’s test was used to determine the effect of different levels of slurry on the measured parameters. The results showed that the use of slurry as an organic fertiliser increases crude protein content by an average of 16.06%, increases crude protein production from 1.47 g/poly bag to 96.38 g/poly bag and improves fermentability in the rumen by an average of 8.08% of setaria grass (Setaria splendida Stapf). The use of slurry at the level of 35 g/poly bag is recommended for the cultivation of setaria grass (Setaria splendida Stapf).

Exploring the Addition of Mango Peel in Functional Semolina Sourdough Bread Production for Sustainable Bio-Reuse

Mango, a tropical fruit celebrated for its delightful fragrance and high nutritional value, generates significant waste during processing, with approximately 35–60% of the fruit being discarded. However, this waste contains valuable components, such as fibre, carotenoids, polyphenols, and other bioactive compounds. In an effort to repurpose mango peel, this study dehydrated it to create mango peel powder (MPP), which was then incorporated into sourdough bread to produce functional breads with enhanced nutritional value. Semolina was replaced with MPP at levels of 5% (MPP-5) and 10% (MPP-10) (w/w). After dehydration, the mango peel had a yield of 22%, and the procedure used did not cause any organoleptic changes. The bread fermentation process was conducted at 30 °C for 8 h. During dough fermentation, the pH was monitored, showing a value of 4.14 ± 0.02 in the MPP-10 dough. Overall, the MPP-10 bread received a higher score (6.51) than the control (CTR) bread (5.6) and the MPP-5 bread (6.11). The total phenolic content of the fortified breads ranged from 44.760 to 98.931 mg gallic acid equivalents (GAE)/g, and the antiradical activity ranged from 15.213 to 29.461 mmol trolox equivalent antioxidant activity (TEAC)/100 g, depending on the percentage of enrichment.

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.

Strain selection and adaptation of a fungal-yeast-microalgae consortium for sustainable bioethanol production and wastewater treatment from livestock wastewater

This study explores the potential of strain selection and adaptation for developing a fungi-yeast-microalgae consortium capable of integrated bioethanol production and livestock wastewater treatment. We employed a multi-stage approach involving isolation and strain selection/adaptation of these consortiums. The study started with screening some isolated fungi to grow on the cellulosic biomass of the livestock wastewater (saccharification) followed by a fermentation process using yeast for bioethanol production. The results revealed that Penicillium chrysogenum (Cla) and Saccharomyces cerevisiae (Sc) produced a remarkable 99.32 ppm of bioethanol and a concentration of glucose measuring 0.56 mg ml− 1. Following the impact of fungi and yeast, we diluted the livestock wastewater using distilled water and subsequently inoculated Nile River microalgae into the wastewater. The findings demonstrated that Chlorella vulgaris emerged as the dominant species in the microalgal community. Particularly, the growth rate reached its peak at a 5% organic load (0.105385), indicating that this concentration provided the most favorable conditions for the flourishing of microalgae. The results demonstrated the effectiveness of the microalgal treatment in removing the remaining nutrients and organic load, achieving a 92.5% reduction in ammonia, a 94.1% reduction in nitrate, and complete removal of phosphate (100%). The algal treatment also showed remarkable reductions in COD (96.5%) and BOD (96.1%). These findings underscore the potential of fungi, yeast, and Nile River microalgae in the growth and impact on livestock wastewater, with the additional benefit of bioethanol production.Graphical abstract

Non-Destructive Monitoring of Sweet Pepper Samples After Selected Periods of Lacto-Fermentation

Fermented food is characterized by positive health-promoting properties. The objective of this study was to distinguish and assess the changes in the flesh structure of sweet bell pepper samples after specific periods of fermentation in a non-destructive manner. Two cultivars of pepper, red and yellow, were subjected to lacto-fermentation. The experiments lasted 56 days and the samples were taken for analysis at the beginning of the study (0 days) and after 3, 7, 10, 14, 21, 28, and 56 days. The fermentation process was monitored based on image features, which were used to develop machine learning models distinguishing samples before and after various periods of lacto-fermentation (0, 3, 7, 10, 14, 21, 28, and 56 days). The average accuracy of the classification of red bell pepper samples was up to 93% for the model built using IBk (Lazy group). The yellow bell pepper samples were distinguished up to 90% accuracy by the LMT algorithm (Trees group). The performed study allowed us to determine the changes in pepper flesh in terms of image textures during lacto-fermentation.

Isolation and purification of lactic acid bacteria and yeasts based on a multi-channel magnetic flow device and rapid qualitative and quantitative detection

Rapid isolation and identification of lactic acid bacteria and yeasts during fermentation is of great significance for quality control and regulation of fermented foods. In this study, we prepared a multi-channel magnetic flow device for rapid separation and purification of lactic acid bacteria and yeast, and based on SERS spectrum, we made rapid qualitative and quantitative analysis of Lactobacillus plantarum, Lactococcus lactis and Saccharomyces cerevisiae. The results showed that the synthesized Synthesized Fe3O4-Van antibiotic magnetic beads are paramagnetic; Fe3O4-Van antibiotic magnetic beads achieved capture efficiencies of more than 98.5 % for both L. plantarum and L. lactis at 102–104 CFU/mL, respectively. Separation and purification efficiency of single S. cerevisiae, L. plantarum and L. lactis by multi-channel magnetic flow device all reached more than 98 % with good isolation and purification results. The SERS spectra of the three microorganisms were classified and analyzed using linear discriminant analysis (LDA), and the accuracy of the established LDA model was 100 %, which completely differentiated the SERS spectra of the three microorganisms,and realized the qualitative identification of L. plantarum, L. lactis, and S. cerevisiae, and finally, quantitative model was established with the logarithmic values (lg C) of different concentrations of L. plantarum, L. lactis, and S. cerevisiae as the horizontal coordinates, and the Raman intensities at their strongest characteristic peaks of 512 cm−1, 1669 cm−1, and 1125 cm−1, respectively, were used as vertical coordinates to establish a quantitative model, with the lowest detection limit of 10 CFU/mL, and the digital quantification of lactic acid bacteria and yeast were achieved. It provided an effective means for real-time monitoring and tracking of the dynamics of lactic acid bacteria and yeast in the fermentation process and the quality control of fermented foods.

Greenhouse gas emissions and net energy production of dark fermentation from food waste followed by anaerobic digestion

There are diverse estimations regarding the carbon reduction effects of alternative hydrogen production technologies. This study assessed the greenhouse gas (GHG) emissions and energy balance of a two-stage process combining dark fermentative hydrogen production and anaerobic digestion from food waste using the cradle-to-gate life cycle assessment (LCA). The system boundary included collection and transportation, pretreatment and feedstock storage, dark fermentation, H2 purification, anaerobic digestion and heat and power generation and the estimated GHG emission was compared with a single anaerobic digestion of food waste. GHG emission of the biohydrogen production was estimated as 2.48 kg CO₂-eq per kg H₂ without considering avoided emissions from heat and power generation. The environmental impacts were majorly influenced by electricity use. The net energy ratio of the two-stage process was calculated to be 8.18, confirming a net energy gain and the potential GHG emission avoidance for electricity and heat use. Given that the single-stage anaerobic digestion of 16 tons of food waste is replaced by the two-stage dark fermentation process, 76.6 kg CO₂-eq would be avoided. Sensitivity analysis revealed that energy-saving strategies are the most sensitive factors for achieving positive net energy production and low global warming potential.

Biofuser: a multi-source data fusion platform for fusing the data of fermentation process devices.

In the past decade, the progress of traditional bioprocess optimization technique has lagged far behind the rapid development of synthetic biology, which has hindered the industrialization process of synthetic biology achievements. Recently, more and more advanced equipment and sensors have been applied for bioprocess online inspection to improve the understanding and optimization efficiency of the process. This has resulted in large amounts of process data from various sources with different communication protocols and data formats, requiring the development of techniques for integration and fusion of these heterogeneous data. Here we describe a multi-source fusion platform (Biofuser) that is designed to collect and process multi-source heterogeneous data. Biofuser integrates various data to a unique format that facilitates data visualization, further analysis, model construction, and automatic process control. Moreover, Biofuser also provides additional APIs that support machine learning or deep learning using the integrated data. We illustrate the application of Biofuser with a case study on riboflavin fermentation process development, demonstrating its ability in device faulty identification, critical process factor identification, and bioprocess prediction. Biofuser has the potential to significantly enhance the development of fermentation optimization techniques and is expected to become an important infrastructure for artificial intelligent integration into bioprocess optimization, thereby promoting the development of intelligent biomanufacturing.

Efficient conversion from food waste to composite carbon source through rapid fermentation and ceramic membrane filtration

Anaerobic fermentation of food waste (FW) produces a broth rich in small-molecule organic substances, which has the potential as a composite carbon source for denitrification in wastewater treatment. In this study, the idea was tested by optimizing the fermentation process at different hydraulic residence time (HRT), refining fermentation broth through ceramic membrane filtration, and comparing the performance of fermentation filtrate and other commercial carbon sources. A short HRT of 3 days was a suitable fermentation condition with 88% polysaccharide degradation. Acetic acid contributed 40% of soluble chemical oxygen demand in the fermentation broth, followed by ethanol, propanol, lactic acid, and propionic acid, and the five products accounted for 80%. Ceramic membrane filtration can recover more than 70% of dissolved organic matter and more than 60% of small molecular organic matter and simultaneously remove 99% of SS, 41% of total nitrogen, and 62% of total phosphorus. At the rapid degradation stage, the denitrification rates reached 6.68–10.39 mg NOx−-N/(g VSS·h), which was on par with commercial carbon sources. The short fermentation and the rapid membrane separation were integrated to create an efficient treatment system, which provided a feasible pathway to utilize FW combining wastewater treatment.

Production and Characterization of Bioethanol Using Native Microbial Isolates from Decomposed Maize Cob via Simultaneous Saccharification and Fermentation

Maize cob a major component of agricultural waste composed mainly of cellulose that can be converted to bioethanol through fermentation as means of waste management. Achieving enhances bioethanol yield without ascertaining proper conversion pathway may be subjective. Therefore, this research aimed at converting maize cob to bioethanol through fermentation using natives microbial isolates from decomposed maize cob via Response Surface Methodology. Microbial strains used were Pichia kudriavzevii strains with accession number KP998095.1 and MN861069.1. A pH value of 5.5 corresponded to bioethanol yield of 52.45 g/L, pH was observed to be sensitive to fermentation hence influence the extent of fermentation process. Optical density (O. D610nm) of 2.2 after eight (8) days of fermentation corresponded to bioethanol yield of 52.45 g/L. The growth pattern observed in most of the samples followed a typical microbial growth pattern depicting lag, log and stationary phases. Reducing soluble sugar of 23.5 mg/L on enzyme hydrolysis corresponded to bioethanol yield of 52.45 g/L, reducing soluble sugar content of the experimental samples were observed to decrease as the fermentation progresses. The infrared spectra of the optimum sample distillate of bioethanol from the fermentation revealed the presence of OH at 3311.7 cm-1 stretching band and C = C at 1636.3 cm−1 stretching band. The elemental compositions of the distillate were oxygen (31.03%), hydrogen (9.74%), carbon (56.85%), nitrogen (1.92%) and sulphur (0.46%) which confirmed the presence of bioethanol. The empirical formula of the best distillate using C, H, and O compositions (%) was found to be C2H5OH, hence revealed the presence of bioethanol. The result of the GC-MS analysis showed that mass spectra comparison of the various peaks revealed the presence of bioethanol as the largest peak with 76.38% ethanol by concentration. Maize cob can be said to be a promising feedstock for bioethanol production using native microbial isolates.

Predicting biohydrogen production from dark fermentation of organic waste biomass using multilayer perceptron artificial neural network (MLP–ANN)

The focus on sustainable energy has increased interest in biohydrogen production through dark fermentation of organic waste biomass, offering dual benefits of energy production and waste management. Optimizing this process is challenging due to complex interactions among substrate composition, microbial consortia, and fermentation parameters. A multilayer perceptron artificial neural network model was developed to predict biohydrogen yield from organic waste. The model, trained on 180 data points from 35 studies, uses inputs, such as substrate type, inoculum type, concentration, pH, and temperature, with hydrogen yield as the output. The multilayer perceptron artificial neural network model achieved high accuracy, with a root mean square error of 0.3838, a mean absolute percentage error of 0.1938, and a coefficient of determination of 0.8381. These results demonstrate the model's effectiveness in predicting biohydrogen production, providing a valuable tool for optimizing the fermentation process and advancing sustainable energy solutions.

Progress and Trends in Forage Cactus Silage Research: A Bibliometric Perspective

Opuntia spp. (forage cactus or spineless cactus) is a plant native to Mexico that is commonly used as alternative nutrient-rich fodder in semi-arid regions. Due to its resistance to drought, forage cactus has become an important least-cost ingredient for formulating balanced rations for ruminants during times of scarcity. In addition, ensiling, an anaerobic fermentation process, is also a strategy used to allow a supply of bulky food all year round, since it conserves forage and maintains its nutritional value. In this sense, using the Scopus database and the visualization tool VOSviewer, the present work proposes a bibliometric analysis of forage cactus silage to track and map the evolution and main issues in the research field, current trends, and future directions. The results revealed that the first publication was in 2013; and since 2020, the number of publications has been growing. Brazil was highlighted, by far, as the most relevant country on the topic, and the top institutions were from northeast Brazil, which has been working on co-authored articles. The current hot research topics are focusing on the mixed silage of forage cactus and other forages such as gliricidia, maniçoba, and sorghum biomass, as well as evaluating the fermentative performance and chemical characteristics for improving ruminal diets, especially for goats and sheep. This study provides important information for researchers to identify gaps and direct their studies to better use the whole potential of forage cactus as an alternative roughage source.