Fermentation, Volume 9, Issue 10 (October 2023) – 61 articles

Deep learning is emerging in many industrial sectors in hand with big data analytics to streamline production. In the biomanufacturing sector, big data infrastructure is lagging compared to other industries. A promising approach is to combine deep neural networks (DNN) with prior knowledge in hybrid neural network (HNN) workflows that are less dependent on the quality and quantity of data. This paper reviews published articles over the past 30 years on the topic of HNN applications to bioprocesses. It reveals that HNNs have been applied to various bioprocesses, including microbial cultures, animal cells cultures, mixed microbial cultures, and enzyme biocatalysis. HNNs have been applied for process analysis, process monitoring, development of software sensors, open- and closed-loop control, batch-to-batch control, model predictive control, intensified design of experiments, quality-by-design, and recently for the development of digital twins. Most previous HNN studies have combined shallow feedforward neural networks (FFNNs) with physical laws, such as macroscopic material balance equations, following the semiparametric design principle. Only recently, deep HNNs based on deep FFNNs, convolution neural networks (CNN), long short-term memory (LSTM) networks and physics-informed neural networks (PINNs) have been reported. The biopharma sector is currently a major driver but applications to biologics quality attributes, new modalities, and downstream processing are significant research gaps. Full article

This study investigated the design of a tray bioreactor for solid-state fermentation, applying Rhizopus oryzae to oilseed meals as the substrate. Two process variables were continuously monitored in the bioreactor to ensure precise control of the environmental conditions: temperature and relative humidity (RH). The comprehensive analysis covered the effects of different fermentation conditions on the protein content, technological properties, and molecular distribution of the samples. The study revealed that the configuration factors suffered a stratification within the three trays of the bioreactor. Notably, the upper tray registered the largest dispersion, with a range of 1.5 °C. When analyzing the differences between sensors within each tray, the largest difference was found in the lower tray (10.9%). Furthermore, higher EAI (Emulsifying Activity Index) values were observed in the upper tray (T3) for rapeseed. As for ESI (Emulsion Stability Index) values, no differences were observed between the trays or fermentation periods. Using the changes induced by Rhizopus oryzae fungal enzymes, the study quantitatively examined the changes in the by-product valorization. While the bioreactor factors did not affect the protein quantity itself, they had significant impacts on specific changes within the molecular weight protein fraction. The findings of this study offer significant insights into the complex dynamics of solid-state fermentation processes. The outcomes of this study not only advance understanding of solid-state fermentation but also offer practical guidance for the design and operation of fermenters in industrial applications. Full article

Significant amounts of fermented food waste are generated worldwide, promoting an abundance of residual biomass that can be used as raw material to extract bioactive peptides, fermentable sugars, polyphenols, and valuable compounds for synthesizing bioproducts. Therefore, generating these high-value-added products reduces the environmental impact caused by waste disposal and increases the industrial economic value of the final products. This review presents opportunities for synthesizing bioproducts and recovering bioactive compounds (employing wastes and byproducts from fermented sources) with several biological properties to support their consumption as dietary supplements that can benefit human health. Herein, the types of fermented food waste and byproducts (i.e., vegetables, bread wastes, dairy products, brewing, and winery sources), pre-treatment processes, the methods of obtaining products, the potential health benefits observed for the bioactive compounds recovered, and other technological applications of bioproducts are discussed. Therefore, there is currently a tendency to use these wastes to boost bioeconomic policies and support a circular bioeconomy approach that is focused on biorefinery concepts, biotechnology, and bioprocesses. Full article

The objective of this study was to evaluate the nutritional value of dried Kishk-like products using burghal of wheat, oat, and fenugreek with cow’s milk, camel’s milk, and goat’s milk. Kishk is an artisanal product that is popular in Egypt and the Middle East. This product is made primarily with wheat; however, to our knowledge, no research has used fenugreek seeds in making it. Changes in the physicochemical, microbial, and sensory properties of Kishk samples were followed over 90 days of storage at room temperature. The proximate analysis of fenugreek–Kishk samples (CF, AF, and GF) revealed the levels of moisture content (4.05–7.86%), protein (21.49–22.66%), fat (22.07–26.07%), fiber (13.59–14.19%), carbohydrate (22.16–28.37%), and ash (8.00–9.03%), and acidity ranged from 3.00% to 5.98%. Notably, the GF sample displayed the highest a*, b*, dC*, and ΔE values, along with the lowest L* value among all samples. Counts of coliform, yeasts and molds, Staphylococci, and spore-forming bacteria were not detected at detection limit < log CFU/g for any prepared Kishk-like samples. This was due to the combined levels of organic acids, high acidity, and low moisture content in Kishk samples that resulted in a safe food with a long shelf life. The Kishk-like samples thus could provide a complementary diet for infants up to six months, as well as a suitable option for children and elderly individuals requiring specialized care, offering an alternative to commercially available extracts. Full article

Fermented coffee beans are believed to have significantly different compositions of phenolic and volatile compounds and physicochemical properties compared to unfermented coffee beans. This study evaluated the effects of fermentation on coffee beans at a commercially roasted level by characterizing their phenolic compounds and semi-quantifying their volatile compounds using liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) and headspace/gas chromatography–mass spectrometry (HS-SPME-GC-MS). Coffee beans from two varieties of Coffea arabica, Geisha (G) and Bourbon (B), both fermented beans had higher contents of total phenolic compounds (G: 33.52 mg/g; B: 29.95 mg/g), total flavonoid (G: 0.42 mg/g; B: 0.35 mg/g), total tannins (G: 3.49 mg/g; B: 3.18 mg/g), and higher antioxidant potential in all assays. In total, 131 phenolic compounds were tentatively characterized via LC-ESI-QTOF-MS/MS, where 73 and 65 phenolic compounds were characterized from fermented Geisha and Bourbon, respectively. Regarding GC-MS, the fermented coffee beans had higher levels of phenols, pyrazines, furan, and furanic compounds. These findings substantiated that fermented coffee beans exhibit elevated levels of phenolic and volatile compounds and greater antioxidant activity, which could contribute to relatively higher nutritional values and organoleptic properties. Full article

Pectinases are enzymes used in several industrial processes. Seven agroindustrial wastes—jackfruit seed meal (Artocarpus heterophyllus), cocoa seed peel (Theobroma cacao), cocoa husks (Theobroma cacao), passion fruit husks (Passiflora edulis), mangosteen husks (Garcinia mangostana), malt residue (Hordeum vulgare) and the peach palm waste (Bactris gasipaes Kunth.)—were evaluated to produce a crude extract containing pectinase activity by Penicillium rolfsii CCMB 714. The jackfruit seed meal was chosen as the best substrate for solid-state fermentation, which was optimized with 4 mL of water as a wetting agent for 2 days at 35 °C and with a 0.5% nitrogen source, whereby the pectinase production increased by 44% (362.09 U/g). The obtained crude extract was characterized and applied to wastes saccharification and orange juice clarification. The pectinase showed better activity at a pH of 3.0 to 5.0 and 55 °C, it stably maintained over 80% of activity at 30–50 °C for up to 60 min and 1 mM CuSO₄ increased the pectinase activity by 17%. The saccharification of agroindustrial wastes (cocoa husks, mangosteen husks and passion fruit husks) resulted in 126.55 µmol/mL of reducing sugars from passion fruit husks, which represents an increase of 126% after optimization (45 °C for 22 h). For the clarification of orange juice, it was possible to reduce the absorbance of the juice by 55%. These results elucidate the potential of the low-cost pectinase solution from P. rolfsii CCMB 714 cultivated in jackfruit seed meal for both the enzymatic pretreatment of plant biomass and the application in beverage industries. Full article

Biofilms enable bacterial cells to adhere and thrive on surfaces, with associated changes in growth and gene expression aiding their survival in challenging environments. While previous research has explored E. coli biofilm formation, there has been limited exploration of its application in industrial production. Prior studies have shown that immobilized fermentation can enhance L-threonine production. This study aims to augment biofilm formation and subsequently increase L-threonine production in E. coli by regulating the quorum sensing system, focusing on key AI-2-related genes, including luxS, lsrB, lsrK, and lsrR. In +pluxS and +plsrB strains, AI-2 levels were significantly altered, resulting in enhanced biofilm formation, increased curli expression, shorter free-cell fermentation periods, and improved production efficiency through immobilized continuous fermentation. In a single batch of free-cell fermentation with E. coli W1688, L-threonine production was 10.16 g/L. However, +pluxS and +plsrB strains achieved L-threonine yields of 15.27 g/L and 13.38 g/L, respectively, after seven fermentation batches. Additionally, the fermentation period was reduced from 36 h to 28 h and 30 h, respectively. Full article

A growing number of science and design scholars and design practitioners have recently embarked on studying fermentation processes to produce alternative materials. The main driver of this trend is the search for a sustainable future by proposing novel alternatives that could substitute or integrate into society’s current production and consumption models. This study presents the development of an open-source bioreactor capable of enhancing and optimizing a symbiotic culture of bacteria and yeast (SCOBY) production process. The bioreactor is part of a greater design-driven project aiming to process edible and non-edible materials. The study presents the experiments and methods that led to the development and refinement of the current bioreactor, and all the information needed to replicate it with tools and equipment currently available under the Creative Commons status. The aim of sharing open-source methods and results to reproduce the bioreactor is to support different interdisciplinary teams of scientists and designers in generating high amounts of SCOBY, accelerating R&D with this auspicious yet underexplored source of bacterial cellulose. Full article

Arabinoxylans (AXs) enter food processing and fermentation scenarios whenever grain-based ingredients are utilized. Their impacts on process efficiency and food product quality range from strongly negative to clearly beneficial, depending on both the particular food product and the AX structure. This review will focus on two structure-function relationships between AXs and fermented food production: (1) AXs’ native structure in cereal grains and structural changes that arise during production of fermented foods and (2) the impacts of AXs on processing and production of grain-based fermented foods and beverages (bread, beer, and spirits) and how variations in AX structure shift these processing impacts. Results from recently published papers have provided new insights into the connection between AXs’ structure at the molecular level and their effects on fermented food production. The purpose of this article is to review the historical progress in this area and introduce updates from recent years. Current knowledge gaps in the area are highlighted. Full article

Butifarra, with the addition of inulin, was produced for the first time. The objective of this study was to investigate the effect of inulin in butifarra fermented with Lactobacillus sakei ATCC^® 15521™ on physicochemical properties, instrumental texture, microbiology, and sensory evaluation. Initially, fermented butifarra was prepared with the addition of 5% and 7.5% inulin and a control butifarra was prepared without inulin addition. The butifarra was analyzed by physicochemical, microbiological, instrumental texture, and sensory evaluation. The results indicated that the analysis of physicochemical properties, fat, protein, and ash content showed no significant differences between the experimental and control butifarra (p > 0.05); in other words, this type of fiber did not cause alterations in the butifarra. The mesophilic microorganism count, total and fecal coliforms, and positive staphylococcus were assessed according to Colombian Technical Standard 1325 of 2008. The hardness of the butifarra with higher inulin content on day 9 was, on average, ~55% greater than the control. The adhesiveness increased in each formulation as the days of fermentation increased, showing significant differences relative to the control. In general, the best sensory properties evaluated were related to the butifarra samples with higher inulin content in the formulation, so it is established that inulin did not alter the sensory properties of the butifarra, but rather potentiated the sensory attributes, making it suitable for use in fermented meat formulations. It can be stated that the addition of inulin to fermented butifarra is possible. Full article

Millions of hectares of cover crops are planted in the U.S. and European Union to manage soil erosion, soil fertility, water quality, weeds, and climate change. Although only a small percentage of cover crops are harvested, the growing cover crop planting area provides a new biomass source to the biofuel industry to produce bioenergy. Oilseed crops such as rapeseed, sunflower, and soybean are commodities and have been used to produce biodiesel and sustainable aviation fuel (SAF). Other cover crops such as cereal rye, clover, and alfalfa, have been tested on small or pilot scales to produce cellulosic ethanol, biogas, syngas, bio-oil, and SAF. Given the various biofuel products and pathways, this review aimed to provide a comprehensive comparison of biofuel yield from different cover crops and an overview of the technologies that have been employed to improve biofuel yield. It was envisioned that gene-editing tools might be revolutionary to the biofuel industry, the work on cover crop supply chain will be critical for system scaleup, and high-tolerant technologies likely will be needed to handle the high compositional heterogeneity and variability of cover crop biomass for biofuel. Full article

Mozzarella is one of the most popular unripened Apulian cheeses. Knowledge about microbial composition and variability of artisanal mozzarella and its production chain is increasingly growing. In this study, microbial communities from natural whey starters to end products from four renowned Apulian artisanal dairy factories have been explored by means of 16S metagenomics. The chemical properties of mozzarella samples were also detected and analyzed. Lactobacillus is the core acidifying component of the used starters, while some psychrophilic or contaminants bacteria appear in site-specific products. Biodiversity was found to be quite similar between the whey and mozzarella sample pools, while a significant variability among production sites (factories) has been detected. Furthermore, mozzarella microbial diversity seems to be in positive correlation with its lactic acid content. Targeted metagenomics would then be a powerful and relatively quick technique to characterize the microbiological variability of traditional milk-based foods. Full article

Mulberry Jiaosu, derived from natural fermentation using fresh mulberry fruit as a raw material, refers to an edible product containing specific bioactive substances. However, the dynamic changes in the bioactive substances of organic acids, amino acids and polyphenols as well as the species and function of microorganisms in mulberry Jiaosu are still not clear. Herein, the whole fermentation process of mulberry Jiaosu was comprehensively researched by analyzing the microbial community structure and bioactive substances. The results showed that the change in physicochemical parameters mainly happened within 30 days of fermentation. The total organic acids and total polyphenols presented upward trends. Total amino acids were partly consumed during the fermentation. A total of 173 fungal genera and 295 bacterial genera were detected in mulberry Jiaosu, mainly including Torulaspora, Zygosaccharomyces and Lactobacillus, whose abundance can be influenced by changes in the fermentation environment. During the fermentation of mulberry Jiaosu, 8 organic acids, 17 amino acids and 9 polyphenols were observed, which could be regulated by the metabolism of microorganisms. Zygosaccharomyces exhibited positive correlations with the majority of the organic acids, amino acids and polyphenols, presenting a great influence on the formation of bioactive substances. Compared with fungi, bacteria contributed more to the synthesis of organic acids, free amino acids and polyphenols. This study revealed the bioactive substances and microbial diversity during the fermentation of mulberry Jiaosu, which are findings that will contribute to the precise regulation of the fermentation process and improvement of the product quality. Full article

Algae are capable of sequestering nutrients such as nitrates and phosphates from wastewater in the presence of sunlight and carbon dioxide (CO₂) to build up their body mass and help combat climate change. In the current study, we carried out different case studies to estimate the volume of algal biomass that could be produced annually using the rotating algal biofilm (RAB) method in three large-scale water resource recovery facilities (WRRFs) in Texas: Fort Worth, Dallas, and Houston. We calculated the total amount of lipids, carbohydrates, and proteins that could be fractionated from the algal biomass while using the hydrothermal flash hydrolysis process, followed by converting these biomolecules into commodity products via reported methods and yields. In the first case study, we estimated the amount of biogas and electricity produced in anaerobic digesters when the algal biomass and sludge generated in large-scale WRRFs are co-digested. Using this approach, electricity generation in a large-scale WRRF could be increased by 23% and CO₂ emissions could be further reduced when using biogas combustion exhaust gases as a carbon source for the RAB system. In the second case study, it was estimated that 988 MT mixed alcohol or 1144 MT non-isocyanate polyurethane could be produced annually from the protein fraction in the WRRF in Fort Worth, Texas. In the third case study, it was estimated that 702 MT bio-succinic acid or 520 MT bioethanol could be produced annually using the carbohydrate fraction. In the fourth case study, it was estimated that 1040 MT biodiesel or 528 MT biocrude could be produced annually using the lipid fraction. Producing renewable commodity fuels and chemicals using the algal biomass generated in a WRRF will help to displace fossil fuel-derived products, generate new jobs, and benefit the environment. Full article

Globally, greater than 30% of waste is disposed of in some form of landfill, and it is estimated that annual waste-related emissions will increase by up to 76% by 2050. Emissions arising from fossil fuel-derived products and waste disposal in landfills have prompted the development of alternative technologies that utilize renewable resources. Biomass feedstock is being investigated globally to produce renewable fuels and chemicals. Globally, crop-based biomass and waste biomass are the major feedstocks for chemical production, and the market value of crop-based biomass is expected to increase at the fastest rate. South America, Europe, and North America are currently the global leaders in renewable or bio-based chemical production. In South Africa (SA), the country is still heavily reliant on landfilling as a waste solution. Wastes from agricultural production processes in SA are considered promising feedstocks for beneficiation opportunities to produce bio-based chemicals. The second-generation (2G) agricultural feedstocks that can be used in SA include fruit waste; sugarcane by-products and waste; forestry, timber, pulp, and paper waste; and invasive alien plants. Fermentation, or “green chemistry” technologies, can be used to convert various feedstocks into bio-based chemicals. Bio-based chemicals may be used as drop-in substitutes for existing petrochemical products, for use in end-user industries such as automotive and transportation, textiles, pharmaceuticals, consumer and home appliances, healthcare, and food and beverages. Bioethanol, specifically, can be used in transport fuel, as feedstock for power generation, as an energy source for fuel cells along with hydrogen, and as feedstock in the chemicals industry. Bio-butanol, an olefin derivative, can be used as a drop-in replacement for petroleum-based butanol in all its applications. Different monomers of bio-based chemicals can be used to produce biopolymers, polyhydroxyalkanoates (PHAs), and polylactic acid (PLA), which are subsequently used to produce bioplastics. A total of 25 bio-based chemicals and the technology used to produce them are summarized in this paper. Overall, bioethanol remains the dominant sugar platform product globally. Drawing on global trends, the potential options for the South African market include bioethanol, n-butanol, acetic acid, and lactic acid. It is estimated that the conversion of 70% of the lignocellulosic biomass available in SA would meet 24% of the country’s liquid fuel requirement as a bioethanol equivalent. The most feasible sources of lignocellulosic biomass or waste for beneficiation in SA are generated by the agricultural sector, including sugarcane by-products and waste. Taking into consideration the abundance of lignocellulosic biomass, adequate market segment sizes, and socio-economic factors, it is apparent that there are potential opportunities to investigate the co-production of bioethanol with lactic acid or other bio-based chemicals on an industrial scale. Full article

By 2050, aviation-related carbon emissions are expected to quadruple to over 3000 million tonnes of carbon dioxide, so finding sustainable alternative solutions to minimise pollution is a key scientific challenge. Aviation gasoline and kerosene are currently used to power most jet engines. While battery-powered planes and planes that could utilise a cleaner fuel, such as hydrogen, are possible, the time scale required to improve and implement these technologies is distant, with air fleet turnover taking some 30 years. Existing jet engines could be modified to run on biodiesel, and considering the close similarity in fuel density to kerosene, could be a less disruptive approach to the industry. The sheer volume of biodiesel required remains a challenge, and certainly, using plant-derived oils grown on arable land is not acceptable, as it competes with food production. However, high-lipid-yielding microalgae (where productivity is an order of magnitude greater than oilseeds), grown on marginal land, such as desert or semi-desert areas of the world, could be possible. Indeed, to replace 30% of fossil fuel with algal-derived biodiesel would require 11,345 km² of land. Biodiesel preparation is well understood, but what is lacking is proven technology aimed at optimising microalgal production of oil at a much larger scale. Here, a synergic review of the current state-of-the-art in algal production, that includes strain selection, possible production sites, culturing costs, and harvesting to identify the bottlenecks in meeting the ASTM specifications for the aviation industry, is presented. Full article

Bioethanol is an important biofuel which can be produced from the abundant low-value lignocelluloses. However, the highly toxic inhibitory compounds formed in the hydrolysate and the ineffective utilization of xylose as a co-substrate are the primarily bottlenecks that hinder the commercialization of lignocellulosic bioethanol. In this study, aiming to properly solve the above obstacles, an engineered Saccharomyces cerevisiae strain was constructed by introducing the xylose reductase (XR)–xylitol dehydrogenase (XDH) pathway, overexpressing the non-oxidized pentose phosphate pathway, and deleting aldose reductase GRE3 and alkaline phosphatase PHO13 using a GTR-CRISPR system, followed by adaptive laboratory evolution (ALE). After screening, the isolated S. cerevisiae YL13-2 mutant was capable of robust xylose-utilizing, and exhibited high tolerance to the inhibitors in undetoxified steam-exploded corn stover hydrolysate (SECSH). An ethanol concentration of 22.96 g/L with a yield of 0.454 g/g can be obtained at the end of batch fermentation when using SECSH as substrate without nutrient supplementation. Moreover, aiming to simplify the downstream process and reduce the energy required in bioethanol production, fermentation using fed-batch hydrolyzed SECSH containing higher titer sugars with a YL13-2 strain was also investigated. As expect, a higher concentration of ethanol (51.12 g/L) was received, with an average productivity and yield of 0.71 g/L h and 0.436 g/g, respectively. The findings of this research provide an effective method for the production of bioethanol from lignocellulose, and could be used in large-scale applications in future works. Full article

Lactic acid is a versatile chemical with a wide range of industrial applications, including food additives as well as the production of biodegradable plastics, pharmaceuticals and cosmetics. LA can be produced through carbohydrate fermentation using various microorganisms, including lactic acid bacteria (LAB). However, the high production cost of commercial fermentation media for lactic acid raises concerns among researchers. Consequently, there is a demand for research to develop new, more affordable, and sustainable fermentation media. Utilizing underutilized agro-industrial wastes from Malaysia, particularly in the coconut, oil palm, rice, and sugarcane processing industries, offers several advantages. These include biomass reuse, cost-effective production of valuable chemicals, and agricultural waste reduction. This review discusses the potential of underutilized Malaysian agro-industrial waste from the coconut, oil palm, rice and sugarcane processing industries as sustainable carbon sources for LA production. The topics covered encompass the chemical and nutritional composition of the wastes, their potential for lactic acid fermentation with specific microorganisms, factors influencing lactic acid production, and potential applications. Additionally, this review also highlights the challenges and opportunities associated with reutilizing agricultural waste for lactic acid production. Full article

The influence of yeast assimilable nitrogen (YAN) and elemental sulfur (S⁰) on the formation of volatile sulfur compounds (VSCs) during fermentation was investigated. Pinot noir fermentations were performed using Saccharomyces cerevisiae strain UCD522 or P1Y2 with an addition of 0, 5, or 15 µg/g elemental sulfur. H₂S production during fermentation was measured using lead acetate tubes and additional VSCs measured by GC-PFPD. The addition of S⁰ resulted in H₂S formation during alcoholic fermentation regardless of which yeast strain was used. H₂S production was greater in fermentations performed by UCD522 with increasing amounts of S⁰ resulting in increased production of H₂S. Higher S⁰ resulted in wines containing higher concentrations of methyl thioacetate and glutathione disulfide. Additional experiments examined the impact of nitrogen composition and S⁰. The addition of diammonium phosphate (DAP) resulted in an increase in H₂S formation during fermentation whereas the addition of amino acids did not, whether S⁰ was added or not. Fermentations where DAP and S⁰ were both added produced a higher concentration of H₂S compared to fermentations where S⁰ or DAP additions were made individually. VSCs in the wine were also impacted by the addition of nitrogen and/or S⁰ with the addition of S⁰ and nitrogen (DAP or amino acids) resulting in elevated concentrations of methyl thioacetate in the wines. Full article

Sub-moderate temperature (ranging from low to moderate temperature) anaerobic digestion (AD) could balance fermentation efficiency and energy input. We investigated biogas production and the microbial community in wastewater AD at sub-moderate (15 °C, 20 °C, and 25 °C) and moderate (35 °C; control group) temperatures with the organic loading rate (OLR) incrementally increased over 200 days. The impact of temperature on biogas production was found to be minimal at a low OLR but became more significant at a high OLR. Notably, a temperature threshold ranging from 15 °C to 20 °C exerted a strong inhibitory effect on biogas production and disrupted the microbial community. And, SMT-AD is deemed by this study to be the optimal application strategy of wastewater with low temperature and low OLR. Bacterial richness was positively and linearly related to temperature. There is a relevance between methane production and archaeal diversity under the influence of temperature and OLR. Temperature and OLR shaped the ecological function of predominant bacteria. Anaerolineales, Thermotogales, and Lactobacillales were strongly influenced by temperature. Synergistales had a synergistic relationship with Desulfovibrionales. Clostridiales was responsible for acetate and butyrate production and closely related to Lactobacillales. Acetoclastic Methanosaetaceae was the predominant methanogen. Methanogens could survive and maintain their population even though methanogenesis was limited under high OLRs and low temperatures. Full article

Our study aimed to investigate the applicability of dielectric measurements across three key stages of plant-based biomass utilization: enzymatic hydrolysis of native and microwave pre-processed corn-cob residues, ethanol fermentation of the hydrolysates, and anaerobic co-digestion with meat-industry wastewater sludge. Our major findings reveal that microwave pre-treatment not only accelerates enzymatic hydrolysis but also improves sugar yield. A strong linear correlation (r = 0.987–0.979; R² = 0.974–0.978) was observed between the dielectric constant and sugar concentrations, offering a reliable monitoring mechanism. During ethanol fermentation, microwave pre-treated samples resulted in higher yields; however, the overall bioconversion efficiency was lower. Dielectric measurements also exhibited a strong linear correlation (r = 0.989–0.997; R² = 0.979–0.993) with ethanol concentration. Finally, anaerobic co-digestion could be effectively monitored through the measurement of the dielectric constants (r = 0.981–0.996; R² = 0.963–0.993), with microwave-treated samples showing higher biogas yields. These results demonstrate that dielectric measurements provide a promising alternative for monitoring and controlling biomass utilization processes. Full article

Recently, the industrial focus has shifted to renewable raw materials due to the exhaustion and rising pressures about environmental and political issues. Lignocellulosic biowaste can be derived from a range of sources, such as animal manure, forestry waste, and agricultural waste, and it can be transformed into lactic acid through a biochemical process. There are 942.63 million cattle in the world and annually generate 3.7 billion tons of manure, which could be used to produce lactic acid. The economic viability of a lactic acid plant from cow manure has not yet been determined and is, thus, considered in this study. Using the modeling program Aspen Plus data and other sources, as well as collecting all economic inputs, the feasibility analysis of a lactic acid plant handling cow manure is assessed in this paper. Three scenarios are calculated to check the feasibility depending on the plant size: scenario I handles 1,579,328 t·year⁻¹, scenario II handles 789,664 t·year⁻¹, and scenario III handles 315,865 t·year⁻¹. The results demonstrate that treating the tested lignocellulosic biomass for the manufacture of lactic acid is economically feasible because the economic analysis shows positive net present values for scenarios I, II, and III. The technoeconomic analysis reveals that the minimum lactic acid selling price for scenario I is 0.945 EUR·kg⁻¹, which is comparable to the cost of commercial lactic acid produced from starch feedstock. Scenario II achieves a minimum selling price of 1.070 EUR·kg⁻¹, and scenario III 1.289 EUR·kg⁻¹. The sensitivity analysis carried out reveals that the factor with the biggest impact on the NPV is the yield. Moreover, this study provides a model of industrial application and technoeconomic evaluation for lactic acid production from cow manure. Full article

Fermentation can increase the concentration of active ingredients and improve the effectiveness of Chinese herbal medicine. The purpose of this study was to investigate the effect of solid-state fermentation (SSF) on the polysaccharide content and color of Glycyrrhiza stems and leaves, as well as to explore the potential of computer vision-based analytical chemistry for the rapid, non-destructive, and accurate quality identification of fermented herbs. The effects of different inoculation rates on the polysaccharide content and color of fermented Glycyrrhiza stems and leaves were evaluated. Subsequently, dynamic changes in the viable counts of the probiotic strains, pH values, polysaccharide content, and color of Glycyrrhiza stems and leaves were explored during the entire fermentation process. The correlations of color variables that were extracted from the images with key quality indicators of the Glycyrrhiza stem and leaf samples were verified. The results showed that with an increase in inoculation amount, the polysaccharide content demonstrated a trend of first increasing and then decreasing, which was consistent with the color parameter behavior, and the optimal inoculation amount was 0.2%. During fermentation, R, G, B, S, V, L, a*, and B* were significantly correlated with the polysaccharide content (p < 0.01), while the correlation of H was weak. Principal component analysis (PCA) based on color variables can effectively distinguish between different stages of fermentation. This study provides a reference for the rapid and nondestructive analysis of fermented Glycyrrhiza stems and leaves, offering a new approach to process monitoring and quality control of fermented herbs. Full article

l-Lysine, an essential amino acid for humans and mammals, is widely used in the food, feed, medicine, and cosmetics industries. In this study, a lysine over-producing Escherichia coli mutant was isolated using a fluorescence-based screen and an E. coli strain lacking five of the six L-lysine tRNA-UUU genes. Firstly, an l-lysine codon-rich protein was fused with a green fluorescent protein (all AAG codons were replaced with AAA), yielding a rare codon-rich screening marker positively correlated with l-lysine content. After association and room temperature plasma (ARTP) mutagenesis and induced fluorescent protein expression culture, mutant strains with strong fluorescence were sorted using flow cytometry. The fermentation performance of the high-yielding l-lysine strains were evaluated, which resulted in 16 of the 29 mutant strains showing increased L-lysine yields compared with those of the wild-type strains and a screening efficiency of up to 55.2%. Following a 48 h fermentation, the production of l-lysine (14.8 g/L) and biomass by E. coli QD01ΔtRNA L2 were 12.1 and 4.5% higher than those of the wild-type strain. The screening strategy for high-yielding strains based on the artificial rare cryptosystem established in this study will provide an efficient, accurate, and simple method for screening other amino-acid-producing microorganisms. Full article

The fermentation of syngas is an attractive technology that can be integrated with gasification of lignocellulosic biomass. The coupling of these two technologies allows for treating a great variety of raw materials. Lignin usually hinders microbial fermentations; thus, the thermal decomposition of the whole material into small molecules allows for the production of fuels and other types of molecules using syngas as substrate, a process performed at mild conditions. Syngas contains mainly hydrogen, carbon monoxide, and carbon dioxide in varying proportions. These gases have a low volumetric energy density, resulting in a more interesting conversion into higher energy density molecules. Syngas can be transformed by microorganisms, thus avoiding the use of expensive catalysts, which may be subject to poisoning. However, the fermentation is not free of suffering from inhibitory problems. The presence of trace components in syngas may cause a decrease in fermentation yields or cause a complete cessation of bacteria growth. The presence of tar and hydrogen cyanide are just examples of this fermentation’s challenges. Syngas cleaning impairs significant restrictions in technology deployment. The technology may seem promising, but it is still far from large-scale application due to several aspects that still need to find a practical solution. Full article

Whey has applications in food, beverages, personal care products, pharmaceuticals, and the medical sector. However, it remains a massive dairy residue worldwide (160.7 million m³ year⁻¹), with high organic and nutrient loads. About 42% is used for low-value products such as animal feed and fertilizers or is even directly discharged into water streams, leading to ecosystem damage via eutrophication. We reviewed the uses and applications of cheese whey, along with associated environmental impacts and innovative ways to mitigate them using affordable and scalable technologies. Recycling and repurposing whey remain challenges for remote locations and poor communities with limited access to expensive technology. We propose a closed-loop biorefinery strategy to simultaneously mitigate environmental impacts and valorize whey resources. Anaerobic digestion utilizes whey to produce biogas and/or carboxylates. Alternative processes combining anaerobic digestion and low-cost open photobioprocesses can valorize whey and capture organic, nitrogenous, and phosphorous nutrients into microalgal biomass that can be used as food and crop supply or processed into biofuels, pigments, and antioxidants, among other value-added products. The complete valorization of cheese whey also depends on facilitating access to relevant information on whey production, identifying stakeholders, reducing technology gaps among countries, enforcing legislation and compliance, and creating subsidies and fostering partnerships with industries and between countries. Full article

The rapid and intelligent evaluation of black tea taste quality during the fermentation process is an unsolved problem because of the complexity and hysteretic of the current taste evaluation method. Common infrared spectroscopy and machine vision technologies can rapidly evaluate the taste quality of black tea, but they can not obtain comprehensive sample information. To obtain comprehensive sample information and achieve the rapid evaluation of the taste quality of black tea, the fusion data from hyperspectral images of fermentation samples were applied to predict the taste quality. The successive projection algorithm (SPA) and ant colony optimization (ACO) were used to select effective bands for spectral data. Subsequently, the color images were synthesized using three carefully selected effective bands obtained through the SPA and ACO. The 18 image features were extracted from each synthesized color image and fused with spectral effective bands. The fusion data and three different algorithms, such as partial least squares regression (PLSR), support vector machine regression (SVR), and extreme learning machine (ELM), were employed to establish the regression model for taste quality. Specifically, the fusion-SPA-PLSR model exhibited the best performance. This study provides a novel method for the intelligent evaluation of taste quality during black tea fermentation and lays a theoretical foundation for the intelligent processing and control of black tea. Full article

The objective of this research was to investigate the feasibility of integrating oat (1 → 3, 1 → 4)-β-D-glucan (β-glucan) dried by two different techniques (freeze drying and spray drying) into a synbiotic formulation with Akkermansia muciniphila. The study evaluated the impact of this synbiotic formulation on the growth of A. muciniphila and its effect on the fermentation process. The extracted oat β-glucans underwent freeze-drying (FD) and spray-drying (SD) processes before being introduced as supplementary carbon sources (1%) to brain heart infusion (BHI) medium containing A. muciniphila MSCL 1582. The BHI medium containing inulin, D-glucose, and BHI without added substrates served as the control. Bacterial growth and short-chain fatty acid (SCFA) production were measured before and after 72 h of fermentation. A light microscope and KOVA slides were used for the A. muciniphila count, and SCFA levels were measured via gas chromatography. Our findings revealed that oat β-glucans could effectively function as prebiotic substrates in complementary synbiotic composition with A. muciniphila, without inhibiting growth and causing metabolic impairment. Both FD and SD techniques demonstrated equivalent and favorable impacts on the fermentative capacity of A. muciniphila, rendering them suitable choices for the drying of β-glucans. Incorporating oat β-glucan into synbiotic formulations offers potential benefits, contributing to A. muciniphila growth and the fermentation process. Full article

The adverse effects of climate change, predominantly propelled by greenhouse gas emissions from fossil fuels, underscore the urgency of seeking sustainable alternatives to fossil fuel use. Amid growing concerns about climate change caused by fossil fuels and petrochemicals, this review focuses on sustainable solutions through the conversion of glycerol into value-added biochemicals. Glycerol, as the main byproduct of biodiesel production, is a particularly attractive chemical due to its potential to be upgraded into value-added building blocks and biochemicals. This review provides a detailed analysis of different thermochemical (catalytic) and synthetic biology (fermentative) pathways for the conversion of glycerol into 1,2-propanediol and 1,3-propanediol, which have proven industrial and commercial applications globally. The synthesis of propanediol from glycerol hydrogenolysis and other catalytic processes using different active metals and acidic oxides is reviewed. The reaction mechanism involved in hydrogenolysis reactions concerning the surface reaction mechanism is systematically discussed. The metabolic activities of promising microorganisms in fermenting glycerol, as the carbon source used to produce propanediol, are illustrated and elaborated. Combining these insights, this review is a comprehensive resource that can foster a better understanding of glycerol transformation into propanediol and its implications for sustainable chemistry and industrial practices. This exploration of alternative methods emphasizes the potential of sustainable approaches to reshape production practices and contribute to climate change mitigation. Full article

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the deposition of amyloid β-peptide (Aβ) and subsequent oxidative inflammatory response, leading to brain damage and memory loss. This study explores the potential of Antrodia cinnamomea (AC), a Taiwan-native fungus known for its anti-inflammatory and antioxidant properties. The metabolites of AC, including dehydroeburicoic acid (DEA), 4-acetylantroquinonol B (4-AAQB), dehydrosulphurenic acid (DSA), and polysaccharides, were of particular interest. In the experiment, deep ocean water (DOW) was used to facilitate the solid-state fermentation of Antrodia cinnamomea NTTU 206 (D-AC), aiming to enhance its functional components. The impact of D-AC on the modulation of AD-related risk factors and the augmentation of cognitive abilities was subsequently evaluated in an AD rat model. This model was established via consecutive infusions of Aβ40 into the brain over a 28-day period. The administration of D-AC resulted in remarkable improvements in the rats’ reference memory, spatial probe test, and working memory. Notably, it restored the hippocampal magnesium levels by upregulating the expression of the magnesium transporter MAGT1. Concurrently, D-AC significantly downregulated the expressions of β-secretase 1 (BACE1) and the phosphorylated tau protein (p-tau), which were both implicated in AD progression. Additionally, it mitigated inflammatory responses, as suggested by the decreased levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in the hippocampus and cerebral cortex. Ultimately, the ability of D-AC to restore the brain magnesium levels, attenuate inflammatory responses, and reduce hippocampal Aβ40 deposition led to significant improvements in the cognitive decline of AD rats. D-AC demonstrated a comparable efficacy with its counterpart, AC fruiting bodies (F-AC group), despite their componential differences. This study underscores the potential of D-AC, enriched through fermentation, as a novel dietary strategy for Alzheimer’s disease prevention. Full article