Rapid Fermentation Research Articles

Exploring the core functional microbiota related with flavor compounds in fermented soy sauce from different sources

Flavor, the most important quality index of soy sauce, is mostly influenced by the microbiota in fermented food ecosystem, however, the association between microorganisms and soy sauce flavor is still poorly understood. Therefore, the bacterial and fungal profiles, physicochemical parameters, and flavor compounds (9 organic acids, 17 free amino acids and 97 volatile flavor compounds) of 5 different source soy sauce were investigated using high-throughput sequencing, HPLC, amino acid analyzer and SPME/LLE-GC–MS, and their correlations were explored. A total of 3 fungal genera and 12 bacterial genera were identified as potential flavor-producing microorganisms by multivariate data and correlation analysis. Notably, Lactobacillus and Tetragenococcus were strongly positively correlated with succinic acid and lactic acid, respectively. Moreover, not only fungi, but also bacteria were found to be closely correlated with volatiles. Finally, 5 screened potential flavor-producing microorganisms were validated using a rapid fermentation model, with multiple strains showing the potential to improve the soy sauce flavor, with Lactobacillus fermentum being the most significant. Our research will provide a theoretical basis for the regulation and enhancement of soy sauce flavor.

Fermentation characteristics of different sources of dietary fiber in vitro and impacts on growth performance, nutrient digestibility and blood para-meters of piglets

This study aimed to assess the effect of various source of high-fiber ingredients on growth performance, apparent digestibility of nutrients, and blood para- meters of piglets by investigating their in vitro fermentation characteristics. A total of 300 healthy crossbred piglets were randomly allocated to one of five diets including corn-soybean meal basal diet (CON), sugar beet pulp (SBP), soybean hull (SBH), fermented distillers’ grains (FDG), and kelp powder (KP). In vitro fermentation analysis revealed that the predominant short-chain fatty acids produced were acetate and valerate. Sugar beet pulp and kelp powder exhibited rapid fermentation rates, in contrast to SBH, oat bran, and FDG. The apparent total tract digestibility of dry matter (P < 0.05), gross energy (P < 0.05), and crude protein were decreased (P < 0.001) in different fiber diets than the CON diet. The serum concentration of threonine was increased by feeding fibers diets (P < 0.05). In conclusion, a diet containing 3% SBP (with a soluble-to-insoluble dietary fiber ratio of 17.04%) showed the best effects on increasing nutrients digestibility and serum amino acid concentrations. These findings may inform future applications of SBP in piglet nutrition.

Enhanced bacillomycin D yield by cyclic fermentation with diatomaceous earth immobilized Bacillus amyloliquefaciens fmbJ

Bacillus amyloliquefaciens fmbJ belongs to Gram-positive bacteria, which can secrete a series of antimicrobial substances, including lipopeptides. Among them, bacillomycin D (BD) has strong antifungal activity for wide range of applications. However, the current yield of BD cannot meet the requirements of industrial production. In this study, Plackett-Burman and Box-Behnken were used to optimize diatomaceous earth (DE) immobilized fmbJ for BD production. And the optimal conditions were obtained as 50 mL of fermentation medium (250-mL shake flask) with an inoculum of 6.38 %, fermentation at 33 °C 180 rpm for 72 h, and addition of 0.31 g DE at 15.48 h. The model predicted a yield of 947.01 mg/L and obtained 942.33 ± 5.46 mg/L after validation. The optimal condition was used for cyclic fermentation, and the results of three fermentations were 1101.31 mg/L, 1047.83 mg/L and 662.72 mg/L, which were higher than the free fmbJ. The results of fermentation parameters, intracellular amino acids and genes expression showed that immobilized fmbJ could accumulate amino acids related to BD synthesis, especially Glu, faster still have better stability, longevity and use time at rapid fermentation. Therefore, the index parameters of this study could provide a reference for the subsequent industrial production of BD.

Effects of partially hydrolyzed guar gums of different molecular weights on a human intestinal in vitro fermentation model

Partially hydrolyzed guar gums (PHGGs) are prebiotic soluble dietary fibers. High molecular-weight PHGGs have rapid fermentation and high short-chain fatty acid (SCFA) productivity rates, compared to low molecular-weight PHGGs. Therefore, low molecular-weight PHGGs may have less pronounced prebiotic effects than high molecular-weight PHGGs. However, the effects of PHGGs of different molecular weights on the human intestinal microbiota, as well as their fermentation ability and prebiotic effects, have not been investigated. The aim of this study was to evaluate the effects of two PHGGs of different molecular weights, Sunfiber-R (SF-R; 20kDa) and Sunfiber-V (SF-V; 5kDa), on human colonic microbiota and SCFA production. A human intestinal invitro fermentation model was operated by fecal samples with and without the PHGGs. The addition of 0.2% SF-R or SF-V increased the relative abundance of Bacteroides spp., especially that of Bacteroides uniformis. This increase corresponded to a significant (p=0.030) and non-significant (p=0.073) increase in propionate production in response to SF-R and SF-V addition, respectively. Both fibers increased the relative abundance of Faecalibacterium and stimulated an increase in the abundance of unclassified Lachnospiraceae and Bifidobacterium. In conclusion, the low molecular-weight PHGG exerted prebiotic effects on human colonic microbiota to increase SCFA production and bacteria that are beneficial to human health in a manner similar to that of the high molecular-weight forms of PHGG.

Effects of characteristics of douchi during rapid fermentation and antioxidant activity using different starter cultures.

As a traditional Chinese condiment, douchi has attracted attention in Asian and European countries because of its high nutrient content and unique flavors. Douchi is currently produced mostly by natural fermentation. The quality of douchi produced in this way is affected by microbial species, temperature, humidity, and season, so the physical and chemical properties of the product, the content of flavor substances, and its safety vary. In this study, four safe strains with high protease activity, screened previously, namely Bacillus velezensis, Bacillus amyloliquefaciens, Lichtheimia ramosa, and Lichtheimia corymbifera, were used as starter cultures for douchi fermentation. After 35 days, the results showed that the pH, titratable acids, free amino-type nitrogen, amino acids, the total number of colonies, and neutral protease activity of all samples had reached an average level. Through gas chromatography-mass spectrometry (GC-MS), the content of key aroma substances aldehydes and esters was higher than in commercial douchi and the free amino acid content of douchi fermented by the four strains was three to five times that of commercial douchi. Douchi fermented by Bacillus amyloliquefaciens had more flavor substances and the highest 2, 2-diphenyl-1-(2, 4, 6-trinitrophenyl) hydrazyl (DPPH) free radical scavenging rates of 92.4%. Four samples yielded total phenolic content and soy isoflavones in the range of 0.98-1.93 g kg-1 and 0.58-0.89 g kg-1 , respectively. These findings indicate that the use of a high-protease activity starter to produce douchi can improve the quality of douchi to a certain extent. The douchi obtained using Bacillus amyloliquefaciens not only has a good flavor but also has a high level of antioxidant activity. © 2023 Society of Chemical Industry.

Differential expression analysis of sugar accumulation-related genes during chestnut nut development

The chestnuts of Castanea mollissima Bl. are an important food crop in China, and have high nutritional content. To understand the pattern of sugar accumulation during chestnut nut development, the related enzyme gene regulatory pathways, and the molecular regulatory mechanisms of chestnut sugar biosynthesis metabolism, two chestnut varieties with different sugar content, namely Chengbu Youzhu (hereinafter referred to as CBYZ) and AnYou No. 1 (hereinafter referred to as AY01), were selected for investigation. Total sugar and starch content, and the activity of enzymes related to sugar accumulation, were measured in the nuts of the two chestnut varieties 10 days after flowering (DAF), 20 DAF, 30 DAF, 40 DAF, 50 DAF, 60 DAF, 70 DAF, 80 DAF, and 90 DAF. Changes in starch, straight-chain starch, and branched-chain starch content, and sucrose-phosphate synthase, soluble starch synthase, and granule-bound starch synthase enzyme activities were consistent with one-another. A total of 24 differentially expressed genes between the two varieties were associated with sugar biosynthesis and metabolism at three key stages (30, 60, and 90 DAF) of sugar accumulation. Further analysis showing upregulation of the expression of starch-related genes, such as β-amylase, GYS, and INV indicated that these genes were not actively expressed in AY01, resulting in slow accumulation of starch and reduced sugar content. By contrast, the downregulation of the expression of genes, such as PGK and MDH1, indicated that these genes were actively expressed in low-sugar chestnuts, resulting in the rapid fermentation of sugars. A link between gene up- or down-regulation during different developmental stages of chestnut and the effect of their expression on sugar content were established by KEGG pathway enrichment analysis. These findings provide further insights into the mechanism of sugar biosynthesis in chestnuts.

Insights into organic matter evolution during food waste stabilization induced by 14-hour high-temperature fermentation.

Large amounts of secondary pollutants are released during traditional composting, and rapid fermentation is desirable for the stabilization of food wastes. Food wastes were mixed with rice husk, placed in a bioreactor, and stirred continuously to achieve high-temperature fermentation for 14h. The transformations of the mixtures were analyzed using elemental and spectral analysis combined with kinetic equations and two-dimensional correlation spectroscopy. The carbohydrates, proteins, and aliphatic compounds of food waste were degraded after 4h of fermentation. Transformations of dissolved organic and sulfur- and nitrogen-containing substances followed first-order kinetic equations with reaction rate constants of 0.142h-1, 0.098h-1, and 0.016h-1, respectively. Organic matter conversion was in the following order: aliphatic → protein → carbohydrate and followed the order, acrylamide C → O-alkyl C → anomeric C at the molecular level. The fermentation process was characterized by the increase in protein- and fulvic-like compounds. Fulvic acid substances gradually accumulated during the late fermentation period. Thus, dissolved organic matter components were gradually transformed into humic substances with increasing fermentation time. The sequence of transformation during the fermentation process was, tyrosine-like → tryptophan-like → fulvic-like substances. Humification mainly occurred in the mature stage of composting; therefore, it was verified that the food waste was stabilized by a 14-h fermentation.

The influence of fermentation activity and ester producing capacity of yeast strains on the chemical composition and organoleptic characteristics of Gamza wines

The influence of the two technological parameters, temperature (20 °C, 24 °C, 28 °C) and the inoculum amount of the yeast culture (2%, 3%, 4%) on the duration of the alcoholic fermentation and the ester-producing capacity of the Badachoni and the 24-6 strains of Saccharomyces cerevisiae species was studied. The yeast exhibited high fermentation activity. The intensity with which it initiated the process and the time for its completion was in correlation with the studied factors. The strains showed the best activity at 28 °C/4%. Neural networks were applied and mathematical models were derived, properly describing the fermentation process and the change in the total amount of esters in the course of the process, depending on the technological conditions. The rate in the dynamic of the esters during the process was monitored in 4 stages - onset, rapid fermentation, quiet fermentation, and after malolactic fermentation. The maximum quantity of esters was synthesized in the middle of the process. During alcoholic fermentation, the esters followed a tendency to increase with decreasing the temperature, increasing the amount of yeast culture and the time of the process. The Badachoni and the 24-6 strains demonstrated the highest ester-producing capacity under the temperature of 20 °C and with the 4% inoculum of the yeast culture. The Badachoni strain quantitatively produced more esters than the 24-6 strain. No strict correlation was found between the amount of esters and the organoleptic properties of the wines. The sample containing the most esters had the highest tasting score only in the variants of the 24-6 strain.

Effect of co-inoculation of different halophilic bacteria and yeast on the flavor of fermented soy sauce

The flavor of soy sauce is closely related to the succession and interaction of the microbial community during fermentation. In this study, the selected potential flavor-producing microorganisms (7 species of bacteria and 4 species of yeast) were applied in the co-culture rapid fermentation model and their growth, physicochemical changes, volatile flavor compounds (VFCs), and sensory characteristics were investigated. Results showed that yeast promoted the growth of bacteria, while bacteria inhibited the growth of yeast in the co-culture model. Based on the results of VFCs and sensory evaluation, the combined fermentation of Zygosaccharomyces rouxii and Lactobacillus fermentum was the best strategy out of the 40 combinations. The effect of this combination was also validated in a 20 L fermentation application of soy sauce, which indeed enhanced the intensity of sauce-like, fruity, smoky, and caramel-like notes, as well as umami and kokumi tastes. These results provide a theoretical basis for the exploration and industrial application of flavor-producing microorganisms in soy sauce fermentation.

PSVII-2 Effects of Feeding a Starch or Pectin Supplement on Ruminal Parameters and gas Production of Grazing Young Bulls

Abstract The study aimed to investigate the effects of two feeding times and two sources of energy supplementation on pH, short-chain fatty acids (SCFA), and in vitro gas production (IVGP) of beef cattle reared in Urochloa brizantha cv. Marandu pastures. We used eight rumen-cannulated ½ Aberdeen Angus x ½ Nellore young bulls (280±7 kg) distributed in a double 4x4 Latin square design. Treatments consisted of supplementation at 0.3% of body weight with corn or citrus pulp, supplied at 0900 or 1700. Ruminal fluid pH was measured with a digital pH analyzer and SCFA was analyzed on a Shimadzu HPLC. The IVGP was determined using a transducer and a data logger for 48 h after incubation of samples combining forage and supplement in real intake proportion (88% forage, 12% supplement). Considering the rapid fermentation of sugars, animals supplemented with pectin maintained higher pH (P = 0.021) due to changes in bacterial populations to digest the pectic substances (Table 1). Lactate production after starch digestion caused lower pH. Despite the differences in evaluated energy substrates, there was no effect on the primary SCFA concentration (P &amp;gt; 0.05). Citrus pulp provided greater formic (P = 0.005) and valeric (P = 0.042) acids concentrations compared with corn, but there was no influence of formic acid in lactic acid production (Table 1). The greater IVGP by citrus pulp (P = 0.0140; Figure 1) may be related to its greater carbohydrate fraction A, soluble with a rapid rate of rumen degradation, and also because its ruminal fermentation results in greater acetic acid production, which provides more ruminal H2 and CO2, favoring the CH4 production. The citrus pulp can be used as an alternative source to corn because it might prevent acidosis, does not affect the main SCFA production, and is a non-human edible feed.

240 Nutritional Intervention to Improve Carbohydrate Utilization and gut Health in Pigs

Abstract In swine production, using feed antibiotics as antimicrobial growth promotants has been reduced; thus, feed alternatives to manage gut health are required. Dietary fiber, resistant starch, oligosaccharides, and exopolysaccharides are carbohydrate structures and are nutritional tools that may enhance gut health in pigs. Dietary carbohydrates may have a role to alleviate diarrheal diseases including in pigs post-weaning but also reduce constipation in sows. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. Dietary fiber sources differ in 2 key properties: fermentability and solubility. Rapid fermentation of fiber and oligosaccharides is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and combined output of metabolites should be the focus. Fiber properties may also manipulate retention time and physico-chemical properties of the undigested residue; hence, non-fermentable insoluble fiber may prevent constipation in sows. Starch is mostly digested and absorbed as glucose. However, resistant starch is not digested and acts as insoluble but fermentable fiber and has unique properties, because it specifically increases intestinal abundance of bifidobacteria, which are associated with improved gut health. Using crop breeding, feed processing, and feed additives, the structure of fiber and starch can be altered thereby changing its degradation kinetics and affecting its utilization as energy source and its prebiotic activity. Finally, exopolysaccharides from Limosilactobacillus reuteri and unique oligosaccharides may serve as receptor analogues for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC). These receptor analogues block lectin domains of bacterial adhesins and thus prevent adherence of pathogens to the gut wall, thereby avoiding initiation of post-weaning diarrhea. In conclusion, dietary carbohydrates are important energy sources but may also provide important solutions to maintain gut health in pigs.

A new and efficient method for producing food ingredients high in l-ornithine using unused parts of white cabbage (Brassica oleracea var. capitata).

A surplus of unused parts of vegetables (e.g., white cabbage [cabbage] cores and outer leaves) is generated daily by factories of fresh-cut vegetables. These parts are difficult to effectively utilize and are often discarded as biodegradable industrial waste. This study aimed to develop an efficient method for producing l-ornithine from cabbage residues. First, we added protease (Sumizyme FP) to the cores and outer leaves of sterile cabbages. After 8 days, the amount of l-arginine released was approximately fivefold the amount in the initial content. As l-arginine is a precursor of l-ornithine, the addition of protease combined with Pediococcus pentosaceus produced l-ornithine. However, the rapid lactic acid fermentation suppressed the metabolism of l-arginine to l-ornithine, which we overcame by adjusting the pH by adding eggshell. The anaerobic fermentation of the cores and outer leaves of sterile cabbages with 5% eggshell for 8 days produced 184 ± 2μmol of l-ornithine/100 g cabbage. PRACTICAL APPLICATIONS: This level of l-ornithine production is higher than that observed in freshwater clams (81-116 μmol/100 g), which are considered to be high in l-ornithine. This method can be applied to the production of inexpensive and safe l-ornithine-containing food materials derived from vegetables. Furthermore, ingestions of vegetables fermented by this method would provide a variety of health benefits of l-ornithine. The widespread adoption of this method will not only reduce the amount of waste generated daily from fresh-cut vegetable factories, but will also enable upcycling as a higher value-added food material.

Ensiling and thermic treatment effects on nutrient content, protein solubility, and in vitro fermentation of partial crop faba beans

Legumes such as faba beans have a great potential to create local, independent, and high-quality protein resources for ruminant nutrition. Suitable methods for cost- and energy-effective preservation and protein stabilization against rapid fermentation in the rumen play an important role. Partial crop faba beans harvested with 500 or 708 g dry matter (DM)/kg were ensiled, toasted (160 °C, 60 min), or ensiled and toasted and it was investigated how this affects nutrient composition, protein solubility, carbohydrate fermentation, and in vitro organic matter digestibility (IVOMD). Non-protein nitrogen (NPN) concentrations increased and true protein (TP) concentrations decreased after ensiling, depending strongly on DM concentration of the plant (i.e., on maturity) – in NPN, from 15% to 35% (P < 0.001) and from 16% to 21% of crude protein (CP) (P > 0.05), and in TP, from 85% to 65% and from 83% to 79% of CP with 500 and 708 g DM/kg, respectively (P > 0.05) – whereas concentrations of soluble protein did not increase as much as expected. Toasting reduced soluble protein concentration in native faba beans from 56% to 29% and from 54% to 40% of CP with 500 and 708 g DM/kg, respectively (P < 0.001) and in ensiled faba beans from 58% to 38% and from 60% to 34% of CP with 500 and 708 g DM/kg, respectively, compared to the native material (P < 0.001). Ensiling and toasting slightly affected other crude nutrient or metabolizable energy concentrations, carbohydrate fermentation, and IVOMD.

The hunt for the “holy grail”: Condensed tannins in the perennial forage legume white clover (Trifolium repens L.)

AbstractForage legumes such as white and red clover improve the nutritional quality of grazed pasture but can cause bloat. Their rapid fermentation in the rumen also contributes to environmental issues through higher methane emissions and urinary nitrogen losses. Condensed tannins are known to reduce urinary nitrogen and methane production from grazing animals, reduce bloat, reduce internal parasite burden, and improve animal productivity. Several forage legumes including birdsfoot trefoil and sainfoin do have good levels of condensed tannins but unfortunately these species fail to persist in intensively grazed pasture systems. Conventional breeding approaches including mutagenesis and phenotypic selection have failed to deliver condensed tannins in legumes, such as white clover, red clover or lucerne, that do persist under grazing. A recent advance using a molecular biology approach has identified a transcription factor or master switch that can 'turn on' the condensed tannin pathway present in white clover allowing biologically significant levels of condensed tannin expression in leaf tissue. In vitro tests have demonstrated that the condensed tannins produced in white clover leaves can bind protein at a pH 6.5, as found in the rumen, and then release them at pH 2.5, the pH in the abomasum, before entering the small intestine for amino acid absorption. Additional tests have demonstrated that these condensed tannins can reduce methane production by up to 15.7% in the first 6 h of incubation. The journey to this point, and the challenges ahead to deliver white clover cultivars with condensed tannin expression, is described.

29 Nutritional Interventions for Intestinal Health of Nursery Pigs: Carbohydrates

Abstract In swine production, using feed antibiotics as antimicrobial growth promotants has been reduced; thus, feed alternatives to manage gut health are required to prevent post-weaning diarrhea. Dietary fiber, resistant starch, oligosaccharides, and exopolysaccharides are carbohydrates that together with glycoproteins are nutritional tools that may be part of managing gut health in pigs. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. Dietary fiber is an alternative, but its sources differ in at least 2 key properties: fermentability and viscosity. Rapid fermentation of fiber and oligosaccharides is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and combined output of metabolites should be the focus. Increased viscosity has been associated with increased gut content of virulence factors that are linked with diarrhea. Fiber properties may also manipulate retention time and physico-chemical properties of the undigested residue. Starch is mostly digested and absorbed as glucose. However, resistant starch is not digested and acts as fermentable fiber but has unique properties, because it specifically increases intestinal abundance of bifidobacteria that are associated with improved gut health. Feed ingredients and some feed additives influence kinetics of fermentation and have prebiotic activity. Their kinetics of fermentation should be quantified so that it can be considered in feed formulation. Finally, exopolysaccharides from Limosilactobacillus reuteri and unique oligosaccharides and glycoprotein may serve as receptor analogues for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC). These receptor analogues block lectin domains of bacterial adhesins and thus prevent adherence of pathogens to the gut wall, thereby avoiding initiation of post-weaning diarrhea. In conclusion, dietary fiber and other carbohydrates may be important solutions to maintain gut health when antibiotics are removed as growth promotants from swine feeds.

A Novel Public Opinion Polarization Model Based on BA Network

At present, the polarization of online public opinion is becoming more frequent, and individuals actively participate in attitude interactions more and more frequently. Thus, online views have become the dominant force in current public opinion. However, the rapid fermentation of polarized public opinion makes it very easy for actual topic views to go to extremes. Significantly, negative information seriously affects the healthy development of the social opinion ecology. Therefore, it is beneficial to maintain national credibility, social peace, and stability by exploring the communication structure of online public opinions, analyzing the logical model of extreme public attitudes, and guiding the communication of public opinions in a timely and reasonable manner. Starting from the J–A model and BA network, this paper explores the specific attributes of individuals and opinion network nodes. By incorporating parameters such as individual conformity and the strength of individual online relationships, we established a model of online group attitude polarization, then conducted simulation experiments on the phenomenon of online opinion polarization. Through simulations, we found that individual conformity and the difference in environmental attitude greatly influence the direction of opinion polarization events. In addition, crowd mentality makes individuals spontaneously choose the side of a particular, extreme view, which makes it easier for polarization to form and reach its peak.

Technological Improvements on FML in the Chianti Classico Wine Production: Co-Inoculation or Sequential Inoculation?

Winemaking variables and techniques are known to affect the composition of wines. To obtain a rapid and safe fermentation course, with a reduced risk of proliferation of unwanted microbial species, frequent recourse is made to the use of selected microorganisms, which can greatly simplify the complex management of the fermentation process. In particular, selected strains of lactic acid bacteria are used, which are much more sensitive than yeasts to the operating conditions of the medium. In this regard, the overall aim of this research was to verify whether the early inoculation of homolactic acid bacteria for hexoses (Lactobacillus plantarum) carried out after 24 h, compared with that of saccharomycetes operating alcoholic fermentation, could be advantageous compared with a traditional innoculation with a different heterolactic bacterial strain for hexoses (Oenococcus oeni) operated at the end of alcoholic fermentation. The grape variety chosen was Sangiovese, the protagonist of Tuscan oenology. The evaluation focused on different aspects such as the management of winery operations, and the quality and longevity of the product; was carried out in all phases of winemaking; and analysed both from a chemical and sensory point of view.

Fractional order time-delay multivariable discrete grey model for short-term online public opinion prediction

Aiming at the rapid fermentation characteristics of the online public opinion, this paper established the fractional order multivariable time-delayed discrete grey model to predict the trend of short-term online public opinion. Considering the dynamic time-varying delays of each driving factor in online public opinion, the time-delay parameters are introduced, and the lag time are determined by the maximum grey correlation theory. In order to reduce the influence of uncertainty between short-term public opinion data, the integer order accumulation is extended to the fractional order one, and the parameters are calculated by optimization model. Furthermore, the model is applied to forecast real event on microblog, and the results show that the new grey model has higher prediction accuracy compared with related grey models.

Long-term population dynamics of viable microbes in a closed ecosystem of fermented vegetables

This study was performed to investigate the succession of various microorganisms naturally present in raw ingredients and the changes in metabolites following long-term fermentation of kimchi. Kimchi was stored at 4 °C for 500 days, and the composition of the microbial community and the nature of metabolites were analyzed using metataxonomics and metabolomics. We confirmed that the taxa belonging to Leuconostoc and Weissella were dominant in the early stages of fermentation, while Latilactobacillus and Levilactobacillus were dominant in the middle and late fermentation stages, respectively. In the eukaryotic community, Cladosporium was dominant in the early stages, while Pichia and Hanseniaspora tended to increase in the middle and late fermentation stages. The longitudinal metabolite profile demonstrated that about half (55.7%) of the metabolites present in kimchi after 500 days of fermentation were produced within 15 days of fermentation due to rapid fermentation in the initial stage. These results revealed that even in a closed environment, the viable microbiota in fermented vegetables are not static but dynamic, and the composition of metabolites evolves accordingly during long-term fermentation.

Prebiotic effect of porang oligo-glucomannan using fecal batch culture fermentation

Porang glucomannan is a polysaccharide extracted from Amorphophallus oncophylus and its degradation product is porang oligo-glucomannan (POG). It contains glucomannan, which has been used as an emulsifier, thickener, or as a nutritional supplement to counter many diseases. While it is believed to have health benefits, there are only limited studies exploring this aspect of porang glucomannnan (PGM). It was hydrolyzed using β-mannanase to obtain POG under optimal conditions: reaction temperature of 37 °C, reaction time of 4 h, pH 5.5 and E/S of 1:1,000 (w/w). The study aimed to evaluate the fermented POG, which might also generate short-chain fatty acids (SCFA) and to estimate the prebiotic activity score of POG fermented in vitro. The results show that SCFA profiles of POG fermentation gave a high acetic acid concentration (32.64 mM) and butyric acid (6.68 mM) at 12 h, having butyrogenic effects after a rapid fermentation. Mostly the beneficial bacteria grew faster on POG and KOG (konjac oligo-glucomannan) than on PGM or control at the beginning of incubation. Among the substrates screened, POG showed a highly positive prebiotic index of 10.29, increasing bifidobacteria and lactobacilli but reducing bacteroides population. So, POG is a candidate prebiotic since it has bifidogenic, butyrogenicity, and fermentability.