Fermentation Tank Research Articles

Understanding the Effects of Self-Induced Anaerobic Fermentation on Coffee Beans Quality: Microbiological, Metabolic, and Sensory Studies.

In this study, an investigation of the microbial community structure and chemical changes in different layers of a static coffee beans fermentation tank (named self-induced anaerobic fermentation-SIAF) was conducted at different times (24, 48, and 72 h). The microbial taxonomic composition comprised a high prevalence of Enterobacteriaceae and Nectriaceae and low prevalence of lactic acid bacteria and yeast, which greatly differs from the traditional process performed in open tanks. No major variation in bacterial and fungal diversity was observed between the bottom, middle, and top layers of the fermentation tank. On the other hand, the metabolism of these microorganisms varied significantly, showing a higher consumption of pulp sugar and production of metabolites in the bottom and middle layers compared to the top part of the fermentation tank. Extended processes (48 and 72 h) allowed a higher production of key-metabolites during fermentation (e.g., 3-octanol, ethyl acetate, and amyl acetate), accumulation in roasted coffee beans (acetic acid, pyrazine, methyl, 2-propanone, 1-hydroxy), and diversification of sensory profiles of coffee beverages compared to 24 h of fermentation process. In summary, this study demonstrated that SIAF harbored radically different dominant microbial groups compared to traditional coffee processing, and diversification of fermentation time could be an important tool to provide coffee beverages with novel and desirable flavor profiles.

Development of Virgin Coconut Oil Fermented Tank Using Teak Wood Powder Insulator

One of the processed products derived from coconut that has great demand in the world of health and beauty industry is virgin coconut oil or known as VCO. Most VCO is processed manually using conventional methods with unhygienic plastic containers and placement in open spaces by the home industries. This research is to develop a VCO-fermented tank that was able to maintain hygiene and low temperature during the fermentation process by using SS403 and teak wood insulation as the main materials. This research carries on by comparing the fermentation process and results between the conventional method and the new VCO tank. 41% VCO is produced from raw coconut milk using a new VCO tank which is 5% higher than the conventional method. The VCO fermented tank produced more VCO and was able to maintain lower temperatures compared to the conventional method and also can be operated with less procedure order. Keywords: Fermentation Tank, Temperature Retaine, VCO, Virgin Coconut Oil

Extremely halophilic strains of Halobacterium salinarum as a potential starter culture for fish sauce fermentation.

Proteinase-producing halophilic archaea were isolated from Thai fish sauce collected from industrial fermentation tanks at various periods of fermentation. Five isolates namely, J-1-S4, J-1-S13, J-1-S22, 2m-40-15-R2, and P-1-S8, were identified as Halobacterium salinarum with slightly different colony and morphological characteristics among isolates. Starters of five isolates were prepared and added to the anchovy mixed with 25% solar salt and fermented for 180days at 30-35°C. Halophilic bacteria/archaea counts of inoculated samples were decreased and undetected after 120days of fermentation. At 180days of fermentation, α-amino group contents of inoculated fish sauce samples (856-1010mM) and total nitrogen content (2.2%-2.5%) were higher than the control without archaea inoculation (p<0.05). All samples contained low amounts of biogenic amines, suggesting that all starters were not biogenic amine formers. The major volatile compound found in samples inoculated with H. salinarum P-1-S8 and H. salinarum 2m-40-15-R2 was 3-methylbutanal, which contributes to the meaty note. Dimethyl disulfide, a compound that contributes to fecal note, was detected in all inoculated samples in a lower amount than in the commercial fish sauce (p<0.05). Thus, H. salinarum accelerated protein hydrolysis and produced desirable volatile compounds during fish sauce fermentation in a strain-specific manner.

Metagenomic insights into microorganisms and antibiotic resistance genes of waste antibiotic fermentation residues along production, storage and treatment processes

Antibiotic fermentation residue (AFR) is nutrient-rich solid waste generated from fermentative antibiotic production process. It is demonstrated that AFR contains high-concentration of remaining antibiotics, and thus may promote antibiotic resistance development in receiving environment or feeding farmed animals. However, the dominate microorganisms and antibiotic resistance genes (ARGs) in AFRs have not been adequately explored, hampering understanding on the potential antibiotic resistance risk development caused by AFRs. Herein, seven kinds of representative AFRs along their production, storage, and treatment processes were collected, and multiple methods including amplicon sequencing, metagenomic sequencing, and bioinformatic approaches were adopted to explore the biological characteristics of AFRs. As expected, antibiotic fermentation producer was found as the predominant species in raw AFRs, which were collected at the outlet of fermentation tanks. However, except for producer species, more environment-derived species persisted in stored AFRs, which were temporarily stored at a semi-open space. Lactobacillus genus, classified as Firmicutes phylum and Bacilli class, became predominant bacterial taxa in stored AFRs, which might attribute to its tolerance to high concentration of antibiotics. Results from metagenomic sequencing together with assembly and binning approaches showed that these newly-colonizing species (e.g., Lactobacillus genus) tended to carry ARGs conferring resistance to the remaining antibiotic. However, after thermal treatment, remaining antibiotic could be efficiently removed from AFRs, and microorganisms together with DNA could be strongly destroyed. In sum, the main risk from the AFRs was the remaining antibiotic, while environment-derived bacteria which tolerate extreme environment, survived in ARFs with high content antibiotics, and may carry ARGs. Thus, hydrothermal or other harmless treatment technologies are recommended to remove antibiotic content and inactivate bacteria before recycling of AFRs in pharmaceutical industry.

Determination of the variations in the metabolic profile and sensory quality of Liupao tea during fermentation through UHPLC–HR–MS metabolomics

Liupao tea is a dark tea with unique quality. Semi-finished Liupao tea with two different fermentation processes (traditional/tank) was analyzed to explain the chemical characteristics and taste quality. The content change rate of polyphenols, flavonoids, and theabrownin in traditional fermentation was approximately twice that in tank fermentation. Electronic tongue revealed that bitterness and astringency increased, whereas aftertaste-astringency decreased after fermentation. 36 compounds were identified as the biomarkers responsible for the metabolic changes caused by fermentation with significant decrements in catechins, catechin gallate, and α, α-trehalose, and significant increments in gallic acid content (VIP > 3; P < 0.05). In addition, 26 metabolites were identified to distinguish between tank and traditional fermentation, with correlation analysis indicating that catechin gallate, epicatechin and gallic acid accounting for the differences in taste between the two processes. This study provides a comprehensive insight into the chemical composition and sensory quality of different Liupao tea fermentations.

Formulation of a glycolipid:lipopeptide mixture as biosurfactant-based dispersant and development of a low-cost glycolipid production process

Biosurfactant-based dispersants were formulated by mixing glycolipids from Weissella cibaria PN3 and lipopeptides from Bacillus subtilis GY19 to enhance the synergistic effect and thereby achieve hydrophilic-lipophilic balance. The proportions of each biosurfactant and dispersant-to-oil ratios (DORs) were varied to obtain the appropriated formulations. The most efficient glycolipid:lipopeptide mixtures (F1 and F2) had oil displacement activities of 81–88% for fuel and crude oils. The baffled flask test of these formulations showed 77–79% dispersion effectiveness at a DOR of 1:25. To reduce the cost of the dispersant, this study optimized the glycolipid production process by using immobilized cells in a stirred tank fermenter. Semicontinuous glycolipid production was carried out conveniently for 3 cycles. Moreover, food wastes, including waste coconut water and waste frying oil, were found to promote glycolipid production. Glycolipids from the optimized process and substrates had similar characteristics but 20–50% lower cost than those produced from basal medium with soybean oil in shaking flasks. The lowest cost dispersant formulation (F2*) contained 10 g/L waste-derived cell-bound glycolipid and 10 g/L lipopeptide and showed high dispersion efficiency with various oils. Therefore, this biosurfactant-based dispersant could be produced on a larger scale for further application.

Evaluation of the Components Released by Wine Yeast Strains on Protein Haze Formation in White Wine

Cultures of 23 indigenous yeast strains (22 Saccharomyces cerevisiae and a non-Saccharomyces, Torulaspora delbrueckii), isolated from fermentation tanks at wineries in Castilla-La Mancha (Spain), and were performed under winemaking conditions using a synthetic must. Polysaccharide analysis and turbidity assays were conducted so as to observe the capacity of the released mannoproteins against protein haze formation in white wine, and 3 strains (2 Saccharomyces cerevisiae and T. delbrueckii) were chosen for further experiments. The action of a commercial b-glucanolytic enzyme preparation (Lallzyme BETA®), and a β-(1→3)-glucanase preparation from Trichoderma harzianum Rifai were evaluated to release polysaccharides from the different yeast strains’ cell walls. Protection against protein haze formation was strain dependent, and only two strains (Sc2 and Sc4) presented &gt;50% stabilization in comparison to controls. Addition of β-glucanases did not increase the concentrations of polysaccharides in the fermentation musts; however, a significant increase of polymeric mannose (mannoproteins) was detected using an enzymatic assay following total acid hydrolysis of the soluble polysaccharides. Enzymatic treatment presented positive effects and decreased protein haze formation in white wine.&#x0D; DOI http://dx.doi.org/10.17807/orbital.v8i6.869

Antibacterial Activity of Aureonuclemycin Produced by Streptomyces aureus Strain SPRI-371.

Actinomycetes play a vital role as one of the most important natural resources for both pharmaceutical and agricultural applications. The actinomycete strain SPRI-371, isolated from soil collected in Jiangsu province, China, was classified as Streptomyces aureus based on its morphological, physiological, biochemical and molecular biological characteristics. Its bacterial activity metabolites were identified as aureonuclemycin (ANM), belonging to adenosine derivatives with the molecular formula C16H19N5O9 for ANM A and C10H13N5O3 for ANM B. Simultaneously, the industrial fermentation process of a mutated S. aureus strain SPRI-371 was optimized in a 20 m3 fermentation tank, featuring a rotation speed of 170 rpm, a pressure of 0.05 MPa, an inoculum age of 36–40 h and a dissolved oxygen level maintained at 1–30% within 40–80 h and at >60% in the later period, resulting in an ANM yield of >3700 mg/L. In the industrial separation of fermentation broth, the sulfuric acid solution was selected to adjust pH and 4# resin was used for adsorption. Then, it was resolved with 20% ethanol solution and concentrated in a vacuum (60–65 °C), with excellent results. Antibacterial experiments showed that ANM was less active or inactive against Xanthomonas oryzae pv. oryzae, Xanthomonas citri subsp. citri and Xanthomonas oryzae pv. oryzicola and most bacteria, yeast and fungi in vitro. However, in vivo experiments showed that ANM exhibited extremely significant protective and therapeutic activity against diseases caused by X. oryzae pv. oryzae and X. oryzae pv. oryzicola in rice and X. citri in oranges and lemons. In field trials, ANM A 150 gai/ha + ANM B 75 gai/ha exhibited excellent therapeutic activity against rice bacterial leaf blight, citrus canker and rice bacterial leaf streak. Furthermore, as the dosage and production cost of ANM are lower than those of commercial drugs, it has good application prospects.

Bioreactor as the root cause of the "manganese effect" during Aspergillus niger citric acid fermentations.

High-yield citric acid production by the filamentous Ascomycete fungus Aspergillus niger requires a combination of extreme nutritional conditions, of which maintaining a low manganese (II) ion concentration (<5 μg L−1) is a key feature. Technical-scale production of citric acid predominantly uses stainless-steel tank fermenters, but glass bioreactors used for strain improvement and manufacturing process development also contain stainless steel components, in which manganese is an essential alloying element. We show here that during citric acid fermentations manganese (II) ions were leaching from the bioreactor into the growth media, resulting in altered fungal physiology and morphology, and significant reduction of citric acid yields. The leaching of manganese (II) ions was dependent on the fermentation time, the acidity of the culture broth and the sterilization protocol applied. Manganese (II) ion leaching was partially mitigated by electrochemical polishing of stainless steel components of the bioreactor. High concentrations of manganese (II) ions during early cultivation led to a reduction in citric acid yield. However, the effect of manganese (II) ions on the reduction of citric acid yield diminished towards the second half of the fermentation. Since maintaining low concentrations of manganese (II) ions is costly, the results of this study can potentially be used to modify protocols to reduce the cost of citric acid production.

Removal of a mixture of formaldehyde and methanol vapors in biotrickling filters under mesophilic and thermophilic conditions: Potential application in ethanol production

ABSTRACT Ethanol is a significant source of energy as a biofuel; however, its production using corn involves the generation of harmful emissions from both fermentation tanks and dryers. Scrubbers control the emissions from fermentation tanks, while the emissions from the dryers are controlled by regenerative thermal oxidizers. Potential alternatives to these energy- and water-intensive technologies are biotrickling filters (BTFs). In this study, two BTFs were operated in parallel to treat formaldehyde and methanol emissions in a volumetric ratio of 4:1, one at 25°C (mesophilic), and the other at 60°C (thermophilic). The mesophilic BTF simulated emissions from fermentation tanks, while the thermophilic BTF simulated emissions from dryers. Both beds were operated at an empty bed residence time of ~30 s and influent formaldehyde concentrations of 20, 50, and 100 parts per million per volume (ppmv). Formaldehyde polymerization was reduced in this study by adding NaOH to pH levels of 7.0–7.4 and heating the solution to a temperature of 60°C. BTFs have successfully removed formaldehyde at typical ethanol plants emissions ~21 ppmv. The BTF technology have the potential in replacing the conventional air treatment methods used at ethanol plants. Implications: Currently, ethanol plants remove and treat hazardous air pollutants (HAPs) using wet scrubbers from the fermenter off-gasses and using thermal oxidizers to combust off-gasses. The utilization of biotrickling filters (BTFs) for HAP removal generally and formaldehyde particularly has wide implication in the field of renewable energy. Utilizing BTFs in the 200+ ethanol plants in USA will save cost and reduce water and energy needs significantly. BTFs can reduce an ethanol plant’s carbon intensity (CI) by 1 to 3 g CO2/MJ. This can result in roughly $50 million per year in additional revenue in Nebraska for instance.

Enhancing the capability of Klebsiella pneumoniae to produce 1, 3-propanediol by overexpression and regulation through CRISPR-dCas9.

Summary Klebsiella pneumoniae is a common strain of bacterial fermentation to produce 1, 3‐propanediol (1, 3‐PDO). In general, the production of 1, 3‐PDO by wild‐type K. pneumoniae is relatively low. Therefore, a new gene manipulation of K. pneumoniae was developed to improve the production of 1, 3‐PDO by overexpressing in the reduction pathway and attenuating the by‐products in the oxidation pathway. Firstly, dhaB and/or dhaT were overexpressed in the reduction pathway. Considering the cost of IPTG, the constitutive promoter P32 was selected to express the key gene. By comparing K.P. pET28a‐P32‐dhaT with the original strain, the production of 1, 3‐PDO was increased by 19.7%, from 12.97 to 15.53 g l−1 (in a 250 ml shaker flask). Secondly, three lldD and budC regulatory sites were selected in the by‐product pathway, respectively, using the CRISPR‐dCas9 system, and the optimal regulatory sites were selected following the 1, 3‐PDO production. As a result, the 1, 3‐PDO production by K.P. L1‐pRH2521 and K.P. B3‐pRH2521 reached up to 19.16 and 18.74 g l−1, which was increased by 47.7% and 44.5% respectively. Overexpressing dhaT and inhibiting expression of lldD and budC were combined to further enhance the ability of K. pneumoniae to produce 1, 3‐PDO. The 1, 3‐PDO production by K.P. L1‐B3‐PRH2521‐P32‐dhaT reached 57.85 g l−1 in a 7.5 l fermentation tank (with Na+ neutralizer), which is higher than that of the original strain. This is the first time that the 1, 3‐PDO production was improved in K. pneumoniae by overexpressing the key gene and attenuating by‐product synthesis in the CRISPR‐dCas9 system. This study reports an efficient approach to regulate the expression of genes in K. pneumoniae to increase the 1, 3‐PDO production, and such a strategy may be useful to modify other strains to produce valuable chemicals.

The Potential of Pig Sludge Fertilizer for Some Pasture Agricultural Lands’ Improvement: Case Study in Timiș County, Romania

In the context of the current energy crisis, pig sludge may be a more accessible fertilizer resource for different categories of farmers and agro-ecosystems, in order to support soil fertility and agricultural production. The present study presents results regarding the influence of pig sludge on soil quality and the spatial and temporal variability of a pasture agro-ecosystem, in the area of Ciacova locality, Timiș County, Romania. The pig sludge was fermented for a period of 6 months in fermentation tanks and was applied at a rate of 80 m3 ha−1 y−1 between 2013 and 2019, on two pasture plots (P808, P816). In the study period (2013–2019), the agrochemical indices studied presented the values: pH = 5.90 ± 0.09 (P816-6-13) and pH = 6.90 ± 0.06 (P808-7-18); P = 10.20 ± 2.26 ppm (P808-4-13) and P = 69.10 ± 3.04 ppm (P808-5-19); K = 176.00 ± 7.44 ppm (P816-4-13) and K = 429.00 ± 7.33 ppm (P816-3-19); NI = 2.45% ± 0.08% (P816-6-13) and NI = 3.87% ± 0.06% (P816-6-19). The variability of the land, i.e., the pasture category, evaluated based on the NDVI index (seven NDVI classes were generated, C1 to C7) decreased under the influence of pig sludge, the values of the variation coefficients being CVNDVI = 17.5098 in 2019 compared to CVNDVI = 41.5402 in 2013 for P808 and CVNDVI = 32.0685 in 2019, compared to CVNDVI = 52.2031 in 2013 for P816. It was found that the land area decreased (2019 compared to 2013) from classes C1 to C4 NDVI (low NDVI values, NDVI &lt; 0.5) and the area increased within classes C6 and C7 NDVI (high NDVI values, NDVI &gt; 0.5).

Energy-Positive Disintegration of Waste Activated Sludge—Full Scale Study

This study aimed to evaluate the effects of mechanical disintegration of waste activated sludge (WAS) on full scale anaerobic digestion, considering the possibility of obtaining a positive energy balance. The results showed that an increase in energy density (εL) used in disintegration was accompanied by an increase in the release of organic compounds from sludge (SCOD increased from 211 ± 125 mg O2/L for εL = 0 kJ/L to 6292 ± 2860 mgO2/L for εL = 180 kJ/L). Some of them were volatile fatty acids. The percentage share of WAS subject to disintegration was also documented as a crucial parameter affecting the efficiency of biogas production. An increase in the value of this parameter from 25% to 100%, even at much lower εL used in disintegration (therefore with much smaller amounts of organic compounds released from sludge flocs) resulted in an increase in biogas production. Conducting disintegration of the entire stream of WAS directed to the fermentation tank at εL 30 kJ/L resulted in an increase in biogas production by 14.1%. Such a surplus would allow production of approximately 360 kWh/d net electricity. Mechanical disintegration of thickened WAS therefore may be an economically justifiable strategy for the intensification of anaerobic sludge stabilisation.

Online prediction of total sugar content and optimal control of glucose feed rate during chlortetracycline fermentation based on soft sensor modeling.

In the process of chlortetracycline (CTC) fermentation, no instrument can be used to measure the total sugar content of the fermentation broth online due to its high viscosity and large amount of impurities, so it is difficult to realize the optimal control of glucose feed rate in the fermentation process. In order to solve this intractable problem, the relationship between on-line measurable parameters and total sugar content (One of the parameters that are difficult to measure online) in fermentation tank is deeply analyzed, and a new soft sensor model of total sugar content in fermentation tank and a new optimal control method of glucose feed rate are proposed in this paper. By selecting measurable variables of fermentation tank, determining different fermentation stages, constructing recursive fuzzy neural network (RFNN) and applying network rolling training method, an online soft sensor model of total sugar content is established. Based on the field multi-batch data, the change trend of the amount of glucose feed required at each fermentation stage is divided, and the online prediction of total sugar content and the optimal control strategy of glucose feed rate are realized by using the inference algorithm of expert experience regulation rules and soft sensor model of total sugar content. The experiment results in the real field demonstrate that the proposed scheme can effectively predict the total sugar content of fermentation broth online, optimize the control of glucose feed rate during fermentation process, reduce production cost and meet the requirements of production technology.

Development of the Manure Distributing Machine

HighlightsIn this study, a compact, mobile manure distributor capable of operating effectively on narrow farm roads and applying undiluted, highly concentrated manure on fields was developed.The inclusion of three manure distribution functions is expected to reduce manure transport and application costs.The use of this machine can reduce livestock waste disposal costs, increase soil fertility, enhance the physical and chemical properties of soil, reduce the use of commercial fertilizers when planting crops, upgrade the technology employed for recycling domestic livestock resources, and assist with animal husbandry by facilitating the planting of forage and high-energy crops.Abstract. In this study, the aim has been developed a manure collecting, processing, and distributing processor (machine) that is suitable for farming in Taiwan’s agricultural lands. The designed machine is composed of a stirring and draw unit, a manure containing barrel, a manure output mechanism, a ditch excavator, and a soil covering device or filling pipes set with pan-breakers. A tractor both carries and supplies power to the machine. Undiluted manure is pumped from an anaerobic fermentation tank into the manure containing barrel within which the stirring and draw unit is set, and after the manure is thoroughly mixed and stirred, it well the manure is delivered to the manure output mechanism through a 2-in. round pipe. The processing and spreading units developed here are soil-surface-spreading type, soil-stratum-setting type, and deep-soil-setting type. The soil-surface spreading type unit output manure on land surface directly then mixes the manure into soil by tillage, the soil-stratum-setting-type unit uses the ditch excavator to first dig a ditch, and after manure is pumped into the ditch, the soil covering device covers the ditch with the excavated soil. The deep soil setting enables manure to be deposited 30~40 cm below the soil surface, with the loose soil being spread back over the manure after filling. In field tests, manure was spread over the soil surface, incorporated into the soil, or deep filled into subsoil at three test sites, namely Yilan County riverside land, the Tainan County Livestock Research Institute, and a sweet potato field and cornfield in Tainan County. The results revealed that the 3-ton capacity of soil-stratum-setting method field capacity reached 0.58 ha/h at a speed of 2.92 ± 0.07 km/h, and the average cultivation depth was 17.5 ± 0.3 cm. The 5-ton capacity of soil-surface-spreading method working capacity was 1.02 ha/h at a speed of 3.49 ± 0.23 km/h. The 5-ton capacity of soil-stratum-setting method working capacity was 0.61 ha/h at a speed of 2.52 ± 0.32 km/h, and the average cultivation depth was 21.29 ± 1.31 cm. For the 5-ton capacity barrel of the deep-soil-setting type manure spreading machine field capacity was 0.62 ha/h at a speed of 2.8 ± 0.43 km/h. By using the soil-surface-spreading method can fast to handle livestock wastewater and/or manure spray-on land, and using the soil-stratum-setting method or deep-soil-setting method can reduce odor dissipation and fill it directly. Thus, this study successfully developed the compact, mobile, and domestically made manure-distributing processor that can suitably operate in Taiwan farm roads and apply undiluted, highly concentrated manure on fields. The three manure-distributing methods are expected to lower manure transport and application costs. Keywords: Fertilizer spreading, Reuse, Swine manure, Waste reduction.

Antioxidant, Nutritional, and Physicochemical Quality of Yoghurt Produced from a Milk-Based Fermentation Mix Enhanced with Food Spices

Utilization of natural additives, which could meet the growing need for ‘clean label’ and value addition with respect to disease prevention and health promotion in humans, is a current interest in the yoghurt industry. In this study, yoghurt recipes derived from a standard milk-based fermentation mix enhanced with African black pepper (ABP), turmeric, or cloves extracts were evaluated for antioxidant, nutritional and physicochemical qualities. Each fermentation mix was pasteurized, inoculated with 0.5% industrial starter culture containing Streptococcus thermophillus and Lactobacillus delbrueckii subsp. bulgaricus (1:1), and then allowed to ferment in a fermentation tank for 9 hours at 40 °C. The results revealed that the clove-enriched yoghurt recipe exhibits the strongest antioxidant capacity, as indicated by a significant increase (p &amp;lt; 0.05) in total phenolics, total flavonoids, total antioxidant capacity (TAC), DPPH radical scavenging activity, nitric oxide radical scavenging activity, ferric ion reducing power (FRAP), and inhibition of lipid peroxidation, but it also exhibits reduced apparent viscosity and organoleptic properties. Similarly, ABP increased the antioxidant characteristics, with increased protein content and gel viscosity. Turmeric extracts significantly increased (p &amp;lt; 0.05) the calcium content and reduced syneresis. In conclusion, the fermentation of a milk-based mix containing ABP extract resulted in yoghurt which combines improved antioxidant characteristics with increased protein and enhanced techno-functionality.

ASPECTS REGARDING THE ENERGITICAL VALORIFICATION OF URBAN SLUDGE TREATMENT

This paper highlights through the issues addressed, the application aspects regarding the approach of the concept of recovery of sewage sludge from an urban wastewater treatment plant (SEAU), which is in a stage of technological expansion and modernization. Thus, it is considered the need to process the potential of biological mass generated by anaerobic stabilization in the SEAU, with a population of about 10,000 equivalent inhabitants, which requires on one hand, the technological design of activated sludge basins and on the other hand, the design of a sewage sludge fermentation tank, in order to produce biogas, necessary for its recovery for energy purposes.

Influence of Environmental Microbiota on the Activity and Metabolism of Starter Cultures Used in Coffee Beans Fermentation

Microbial activity is an integral part of agricultural ecosystems and can influence the quality of food commodities. During on-farm processing, coffee growers use a traditional method of fermentation to remove the cherry pulp surrounding the beans. Here, we investigated the influence of the coffee farm microbiome and the resulting fermentation process conducted with selected starter cultures (Pichia fermentans YC5.2 and Pediococcus acidilactici LPBC161). The microbiota of the coffee farm (coffee fruits and leaves, over-ripe fruits, cherries before de-pulping, depulped beans, and water used for de-pulping beans) was dominated by Enterobacteriaceae and Saccharomycetales, as determined by llumina-based amplicon sequencing. In addition, 299 prokaryotes and 189 eukaryotes were identified. Following the fermentation process, Pichia and the family Lactobacillaceae (which includes P. acidilactici) represented more than 70% of the total microbial community. The positive interaction between the starters resulted in the formation of primary metabolites (such as ethanol and lactic acid) and important aroma-impacting compounds (ethyl acetate, isoamyl acetate, and ethyl isobutyrate). The success competitiveness of the starters towards the wild microbiota indicated that coffee farm microbiota has little influence on starter culture-added coffee fermentation. However, hygiene requirements in the fermentation process should be indicated to prevent the high microbial loads present in coffee farm soil, leaves, fruits collected on the ground, and over-ripe fruits from having access to the fermentation tank and transferring undesirable aromas to coffee beans.

Effects of ultra-long fermentation time on the microbial community and flavor components of light-flavor Xiaoqu Baijiu based on fermentation tanks.

Microbial structure and succession of fermented grains play a significant role in Baijiu’s flavor and quality. In this study, high-throughput sequencing (HTS) coupled with headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the microbial community structures and flavor components in the fermented grains at the end of fermentation from different fermentation time of light-flavor Xiaoqu Baijiu. HTS results showed that Lactobacillus acetotolerans, Lactobacillus helveticus, Lactobacillus buchneri, Wickerhamomyces, Saccharomyces, and Condenascus were identified as the dominant microbes, but Lactobacillus (96.28%) exhibited obvious advantages at the end of ultra-long fermentation time (day 98). HS-SPME-GC-MS analysis revealed that esters and alcohols had the most abundance in fermented grains of day 98, containing high concentrations of ethyl acetate, diethyl succinate, phenylethyl alcohol, isoamyl alcohol, and n-propanol, which were related to the succession of Lactobacillus and yeast communities. Interestingly, the content of n-propanol in the ultra-long fermentation time samples (day 98) was 6 times of that in normal fermented grains (day 14), which may be caused by higher abundance of Lactobacillus in day 98 samples. Monte Carlo permutation test showed residual starch, acidity, and amino nitrogen (p < 0.05) were important factors affecting the microbial community. Together, these results shed light on the physicochemical changes, microbial dynamics, and key flavor components of fermented grains at the end of fermentation from different fermentation time and provide a strategy for further improvement of Baijiu quality.

The heat and mass transfer of a fermenting multiphase flow using acoustic measurement technology and numerical methods

This experimental research was performed for the measurement-based detection and numerical simulation of a biological multiphase flow in a fermentation tank. The difficulties of an investigation are the many complex interactions between the different three phases (yeast as solid, carbon dioxide as gas, wort as liquid). One of the main difficulties is, that the natural convection processes are superimposed by rising gas bubbles in a high turbid fluid. Due to the various problems in optical measurement (e.g. PIV, LDA) the measurement is realised with acoustic sensors, so-called transducers. For a detailed understanding of the results of the acoustic measurement and the associated interpretation of the heat and mass transfer, high demands are on the acoustic measurement technology and the subsequent evaluation due to the real multiphase flow. These requirements are further complicated by the combination of several transducers and the targeted conversion of the measurement technology from a 1D acoustic measurement method to a 2D flow field measurement system. Furthermore, it is shown how problems of the acoustic measurement technology, caused by the multiphase flow, can be solved. The systematic investigation and improvement of the measurement technique allows the direct correlation of the measured temperature fields with the flow fields of the acoustic measurement technique. This combination of temperature and velocity allows the heat transfer of the yeast from the inside to the liquid and the cooling from the outside to the liquid to be analysed and investigated in detail. Finally, the influence of the different phases (yeast as solid, carbon dioxide as gas, wort as liquid) is evaluated, visualised and the complex interactions of the phases on heat and mass transfer are explained. In addition to acoustic measurements in the fermentation fluid, numerical simulations are used to provide additional insights into the processes in a fermenter. • Measurement of a biological multiphase flow with an acoustic measurement technique. • Temperature field measurement during fermentation in a cylindro-conical fermenter. • Simulation of natural convection during fermentation in a fermenter. • Simulation of gas bubbles and their interaction during fermentation in a fermenter. • Simulation of yeast with the Kinetic Theory of Granular Flow model.