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PubMed2006

Transformation of isoflavone phytoestrogens during the fermentation of soymilk with lactic acid bacteria and bifidobacteria.

In the present study, soymilk is fermented with lactic acid bacteria (Streptococcus thermophilus BCRC 14085, Lactobacillus acidophilus BCRC 14079) and bifidobacteria (Bifidobacterium infantis BCRC 14633, B. longum B6) individually, and in combination. The change in the content of various isoflavones (aglycones, glucoside, acetyl- and malonyl-glucosides) and the beta-glucosidase activity in soymilk during fermentation is investigated. It is observed that fermented soymilk contains a lower total isoflavone content (81.94-86.61 microg/ml) than soymilk without fermentation (87.61 microg/ml). Regardless of starter organism employed, fermentation causes a major reduction in the contents of glucoside, malonylglucoside and acetylglucoside isoflavones along with a significant increase of aglycone isoflavones content. The level of change in the content of various isoflavones and beta-glucosidase activity after fermentation varies with the starter organism. Among all the fermented soymilks tested, soymilk fermented with S. thermophilus showed the highest beta-glucosidase activity and the greatest increase in the contents of aglycones. The percentage of daidzein, genistein and glycitein to total isoflavone content in S. thermophilus-fermented soymilk increases from an initial 14.24%, 6.89% and 2.45%, respectively, to 36.20%, 28.80% and 12.44% after 24h of fermentation. Finally, the increase of aglycones and decrease of glucoside isoflavones during fermentation coincides with the increase of beta-glucosidase activity observed in fermented soymilk.

Bifidobacterium↗
PubMed2002

Production of carboxylic acids from hydrolyzed corn meal by immobilized cell fermentation in a fibrous-bed bioreactor.

Corn meal hydrolyzed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via anaerobic fermentations. In this study, corn meal, containing 75% (w/w) starch, 20% (w/w) fibers, and 1.5% (w/w) protein, was first hydrolyzed using amylases at 60 degrees C. The hydrolysis yielded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactococcus lactis and Clostridium formicoaceticum was used to produce acetic acid from glucose. Propionibacterium acidipropionici was used for propionic acid fermentation, and Clostridium tyrobutylicum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirred-tank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37 degrees C and 7.6, respectively, for acetic acid fermentation, 32 degrees C and 6.0, respectively, for propionic acid fermentation, and 37 degrees C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(1 h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(1 h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(1 h). These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fiber present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized cell bioreactor systems. It is concluded that the FBB technology is suitable for producing value-added biochemicals directly from agricultural residues or commodities such as corn meal.

Acetic Acid↗
PubMed2006

A lactic acid-fermented oat gruel increases non-haem iron absorption from a phytate-rich meal in healthy women of childbearing age.

Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, and formation of soluble complexes of Fe and organic acids. We tested the effect of an oat gruel fermented with Lactobacillus plantarum 299v on non-haem Fe absorption from a low-Fe bioavailability meal compared with a pasteurised, fermented oat gruel and non-fermented oat gruels. In a cross-over trial twenty-four healthy women with a mean age of 25 (sd 4) years were served (A) fermented gruel, (B) pasteurised fermented gruel, (C) pH-adjusted non-fermented gruel, and (D) non-fermented gruel with added organic acids. The meals were extrinsically labelled with 55Fe or 59Fe and consumed on 4 consecutive days, for example, in the order ABBA or BAAB followed by CDDC or DCCD in a second period. Fe absorption was determined from isotope activities in blood samples. The fermented gruel with live L. plantarum 299v increased Fe absorption significantly (P < 0.0001) compared with the pasteurised and non-fermented gruels. The lactic acid concentration in the fermented gruel was 19 % higher than in the pasteurised gruel, but the Fe absorption was increased by 50 %. In the gruel with organic acids, the lactic acid concentration was 52 % lower than in the pasteurised gruel, with no difference in Fe absorption. The fermented gruel increased non-haem Fe absorption from a phytate-rich meal in young women, indicating a specific effect of live L. plantarum 299v and not only an effect of the organic acids.

Acute-Phase Reaction↗
PubMed1995

Colonic protein fermentation and promotion of colon carcinogenesis by thermolyzed casein.

Thermolyzed casein is known to promote the growth of aberrant crypt foci (ACF) and colon cancer when it is fed to rats that have been initiated with azoxymethane. We speculated that the promotion was a consequence of increased colonic protein fermentation (i.e., that the thermolysis of the casein decreases its digestibility, increases the amount of protein reaching the colon, and increases colonic protein fermentation and that the potentially toxic products of this fermentation promote colon carcinogenesis). We found that the thermolysis of casein reduces its digestibility and increases colonic protein fermentation, as assessed by fecal ammonium and urinary phenol, cresol, and indol-3-ol. Thermolysis of two other proteins, soy and egg white protein, also increases colonic protein fermentation with increased fecal ammonia and urinary phenols, and thermolysis of all three proteins increases the levels of ammonia and butyric, valeric, and i-valeric acids in the cecal contents. We found, however, that the increased protein fermentation observed with thermolysis is not associated with promotion of colon carcinogenesis. With casein, the kinetics of protein fermentation with increasing thermolysis time are clearly different from the kinetics of promotion of ACF growth. The formation of the fermentation products was highest when the protein was thermolyzed for one hour, whereas promotion was highest for protein that had been thermolyzed for two or more hours. With soy and egg white, thermolysis increased colonic protein fermentation but did not promote colon carcinogenesis. Thus, although thermolysis of dietary casein increases colonic protein fermentation, products of this fermentation do not appear to be responsible for the promotion of colon carcinogenesis. Indeed, the results suggest that protein fermentation products do not play an important role in colon cancer promotion.

Animals↗
PubMed2001

Comparison of fermentation of selected fructooligosaccharides and other fiber substrates by canine colonic microflora.

OBJECTIVE: To compare fermentation characteristics of fructooligosaccharides (FOS) and other fiber substrates that are commonly found in canine diets. SAMPLE POPULATION: Fecal samples from 3 adult dogs. PROCEDURE: The ability of fiber substrates to be used in microbial fermentation reactions was assessed by use of an in vitro fermentation system. Dogs were fed a commercially available food, and feces were collected for use as the microbial inoculum. Substrates used were beet pulp, cellulose, soy fiber, mannanoligosaccharides (MOS), FOS, and 4 inulin products (inulin 1, 2, 3, and 4). Each substrate was incubated anaerobically with fecal inoculum and growth media for 6, 12, and 24 hours, and production of short-chain fatty acids (SCFA) was measured. RESULTS: Total production of SCFA was higher for fermentation of the 4 inulin products and FOS, whereas fermentation of beet pulp, MOS, and soy fiber resulted in moderate concentrations of SCFA. Fermentation of cellulose produced the lowest concentrations of total SCFA without detection of butyrate or lactate. Butyrate production was greatest for fermentation of the 4 inulin products and FOS. Total lactate production was greatest for FOS and inulin 4. As expected, production of SCFA increased for all substrates as fermentation time increased. CONCLUSIONS AND CLINICAL RELEVANCE: Canine fecal microflora ferment FOS-containing substrates in a similar manner, with little fermentation of cellulose-based carbohydrates. Furthermore, results of an in vitro fermentation system indicate that fiber type affects the metabolic activity of microorganisms, thus influencing the amount and nature of the end products of fermentation.

Animals↗
PubMed2006

Use of the in vitro cumulative gas production technique for pigs: an examination of alterations in fermentation products and substrate losses at various time points.

An experiment was conducted to examine changes in VFA and ammonia concentrations at different time points using 4 fermentable carbohydrate-rich feed ingredients as substrates and feces of unweaned piglets as inoculum. Fecal inoculum was collected, pooled, and mixed from 9 specially raised (no creep feed or antibiotics) crossbred piglets at 3 wk of age. Inulin, lactulose, molasses-free sugar beet pulp, and wheat starch were used as substrates and were fermented in vitro for 72 h (3 replicates per substrate). Cumulative gas production was measured as an indicator of the kinetics of fermentation. In addition, 3 bottles of substrate per time point with similar contents (amounts of substrate, inoculum, and media) were incubated but were allowed to release their gas throughout incubation. For these latter bottles, fermentation fluid was sampled at incubation time points including every hour between 1 and 24 h and at 48 h, and fermentation end products (VFA, lactate, and ammonia) and OM disappearance were measured. Dry matter and ash were analyzed from the postfermentative samples. The pH of the contents from these bottles was also recorded. The correlation in time between fermentation end products and cumulative gas produced was determined. The results showed that the prolongation of fermentation to 72 h, especially in the case of fast-fermenting inulin and lactulose, may lead to a different end product profile (P < 0.001) compared with the profile observed at the time at which most of the substrate has disappeared. Therefore, we concluded that the fermentation product profile at the end of in vitro fermentation at a specific time point cannot be used to compare fermentability of carbohydrate sources with different fermentation kinetics in terms of gas production.

Ammonia↗
PubMed1996

Effect of glucose fermentation on fiber digestion by ruminal microorganisms in vitro.

Two in vitro digestion trials were performed to determine whether the negative effect on fiber digestion when pH was maintained at > 6.2 was attributable to glucose alone or to end products of glucose fermentation. In some treatments, glucose was depleted by a previous 6-h incubation; the supernatant from this incubation was used as the buffer source for treatments using the fermented glucose medium. In trial 1, mixed cultures were grown on cellulose, soybean hulls, and corn bran in fresh media with 0 (control) or 25 mM glucose, in media previously fermented for 6 h with 0 (control) or 25 mM glucose, or in fermented control medium plus 25 mM lactic acid. The rate of NDF digestion was decreased with fermented glucose medium but not with fresh glucose medium or lactic acid medium. Concentrations of lactate, propionate, and butyrate did not appear to affect NDF digestion directly. In trial 2, six treatment media were used: control and glucose media that were either fresh or previously fermented for 6 h and fermented control and glucose media treated with a protease. Rate of NDF digestion was slower in cultures with fermented glucose medium that was treated with protease than in fermented control medium without protease. When treated with protease, rate of NDF digestion was not different between the fermented control medium and the fermented glucose medium. Thus, the negative effect on fiber digestion appeared to be attributable partially to a proteinaceous inhibitor that was produced in culture media containing a rapidly fermented sugar.

Animals↗
PubMed2002

Botulism among Alaska natives in the Bristol Bay area of southwest Alaska: a survey of knowledge, attitudes, and practices related to fermented foods known to cause botulism.

OBJECTIVES: Botulism cases due to traditional Alaska Native fermented foods occur periodically in Southwest Alaska. In this population, we conducted a survey on knowledge, attitudes, and practices related to botulism and fermented foods. METHODS: We interviewed 140 adults randomly chosen from nine villages. Data collected included fermented food consumption frequency; knowledge about the cause and symptoms of botulism; and fermented food preparation methods. RESULTS: Most respondents (81%) had eaten Alaska Native fermented foods at least once. Over 70% identified botulism as a foodborne illness, and over 87% believed eating certain Native fermented foods could cause botulism. One-third of fermented food preparers used plastic containers for fermentation. To prevent botulism, 45% vwould consider boiling fermented foods, and 65% would not eat foods fermented in plastic or glass containers. CONCLUSIONS: Despite high awareness of botulism in this population, one-third of fermented food preparers use plastic containers, a practice which may increase the risk of botulism. Misconceptions and acceptable prevention messages about botulism, such as using traditional nonplastic fermentation methods, were identified and included in an educational video.

Adolescent↗
PubMed2005

Late-onset anaphylaxis to fermented soybeans: the first confirmation of food-induced, late-onset anaphylaxis by provocation test.

BACKGROUND: Late-onset anaphylactic reactions without early-phase reactions are rarely reported. The hypothesized mechanism of late-onset anaphylaxis to fermented soybeans is delayed absorption or release into the bowel rather than an immunologic phenomenon. OBJECTIVES: To investigate the mechanisms of late-onset anaphylaxis to fermented soybeans in 2 patients and to characterize the allergens involved in anaphylaxis caused by fermented soybeans. METHODS: Two patients underwent skin prick-by-prick tests with fermented soybeans as is. We used an open challenge for the provocation test of anaphylaxis and measured changes in plasma histamine, plasma tryptase, serum eosinophil cationic protein, and plasma leukotriene B4 levels in 1 patient. In addition, specific IgE against fermented soybeans and the allergens of fermented soybeans were detected by enzyme-linked immunosorbent assay and immunoblotting, respectively. RESULTS: The results of the prick-by-prick tests with fermented soybeans as is were positive in both patients and negative in control subjects. The challenge with 50 g of fermented soybeans caused generalized urticaria and dyspnea 13 hours after ingestion of fermented soybeans in 1 patient. In addition, his plasma histamine and tryptase levels transiently elevated during the anaphylactic event. In enzyme-linked immunosorbent assay, the patients showed elevated IgE levels to the proteins of fermented soybeans. Serum IgE antibodies of patients 1 and 2 were bound to approximately 5- and 26-kDa proteins in immunoblotting of fermented soybeans, respectively. CONCLUSION: To our knowledge, this is the first report of late-onset anaphylaxis provoked by the challenge test half a day after ingestion of fermented soybeans.

Adult↗
PubMed2002

Effect of pre-fermentation on the production of cutinase by a recombinant Saccharomyces cerevisiae.

The importance of controlling the expression of heterologous cutinase in a recombinant Saccharomyces cerevisiae SU50 strain was investigated. Maximum specific growth rate and the biomass yield increased 1.91 and 1.16 fold, respectively, when cutinase production was induced by galactose in a pre-fermentation step. However, only 19% of specific cell activity was obtained in comparison to other fermentations following a pre-fermentation step without induction of cutinase expression. Thus, the pre-fermentation step was performed using a selective medium not containing galactose, and the fermentation was performed with a cheaper and complex non-selective medium containing galactose. Under these conditions, and with the aim of maximising the specific cutinase activity, a pre-fermentation with low volume and high density of viable cells must be used. However, due to the low pre-fermentation volume, low yeast cell concentrations and low specific cell activities were obtained after 96 h of fermentation. Otherwise, when the aim was to maximise cutinase yield and productivity, a pre-fermentation volume of 10% (v/v) in relation to fermentation and in the exponential growth phase with a cell concentration between 1.1 and 1.8 g dcw/l should be used. A higher pre-fermentation volume, such as 20% (v/v), would still be economical in the case of a pre-fermentation with low cell density or low cell viability.

Journal Article↗
PubMed2005

Yeast populations associated with Ghanaian cocoa fermentations analysed using denaturing gradient gel electrophoresis (DGGE).

The yeast populations associated with the fermentation of Ghanaian cocoa were investigated using denaturing gradient gel electrophoresis (DGGE). Samples were collected at 12-24 h intervals from heap and tray fermentations, at three different fermentation sites and different periods during the season. Eukaryotic universal primers were used to amplify a fragment of the 26S rRNA gene. The DGGE profiles were relatively complex, underlining that the fermentation of cocoa is a complex microbial process. The identities of selected fragments in the denaturing gels were revealed by sequencing. Hanseniaspora guilliermondii, Candida krusei and Pichia membranifaciens were detected from most fermentations, indicating their possible important role in the fermentation of Ghanaian cocoa. Saccharomyces cerevisiae and Candida zemplinina were almost exclusively detected during tray fermentations. The developed DGGE protocol was compared with traditional culture-based isolations. The results were comparable but slightly different, as one yeast species (C. zemplinina) was only detected using DGGE. On the other hand, Trichosporon asahii yielded only faint bands in the denaturing gels, despite the fact that it was detected using culture-based methods. Analysis of pure cultures showed that the targeted region of the 26S rRNA gene was poorly amplified in T. asahii, whereas all other investigated isolates were amplified efficiently using the chosen PCR approach. Cluster analysis revealed that the DGGE profiles clustered according to fermentation method and fermentation site. Furthermore, clustering according to progress in the fermentation was observed. The DGGE technique therefore seems to offer a relatively fast and reliable method for studying yeast population dynamics during cocoa fermentations.

Base Sequence↗
PubMed2004

Xylose fermentation by genetically modified Saccharomyces cerevisiae 259ST in spent sulfite liquor.

Spent sulfite pulping liquor (SSL) is a high-organic content byproduct of acid bisulfite pulp manufacture which is fermented to make industrial ethanol. SSL is typically concentrated to 240 g/l (22% w/w) total solids prior to fermentation, and contains up to 24 g/l xylose and 30 g/l hexose sugars, depending upon the wood species used. The xylose present in SSL is difficult to ferment using natural xylose-fermenting yeast strains due to the presence of inhibitory compounds, such as organic acids. Using sequential batch shake flask experiments, Saccharomyces cerevisiae 259ST, which had been genetically modified to ferment xylose, was compared with the parent strain, 259A, and an SSL adapted strain, T2, for ethanol production during SSL fermentation. With an initial SSL pH of 6, without nutrient addition or SSL pretreatment, the ethanol yield ranged from 0.32 to 0.42 g ethanol/g total sugar for 259ST, compared to 0.15-0.32 g ethanol/g total sugar for non-xylose fermenting strains. For most fermentations, minimal amounts of xylitol (<1 g/l) were produced, and glycerol yields were approximately 0.12 g glycerol/g sugar consumed. By using 259ST for SSL fermentation up to 130% more ethanol can be produced compared to fermentations using non-xylose fermenting yeast.

Biomass↗
PubMed2006

Bran fermentation as a means to enhance technological properties and bioactivity of rye.

Response surface methodology was applied to study the effects of fermentation on the levels of phytochemicals (folates, phenolic compounds, alkylresorcinols) and on the solubilization of pentosans in rye bran from native and peeled grains. Furthermore, the microbial composition of the brans before and after fermentation was studied. Peeling reduced the microbial load and lower microbial counts were detected in the fermentation experiments carried out with the bran from peeled grains. High temperature and long fermentation time favoured the growth of indigenous lactic acid bacteria (LAB), and a diverse microbial community was detected. The brans contained low levels of aerobic spore-forming bacteria, but their number was not increased during the fermentations. Fermentation of both brans increased the levels of folates, easily extractable total phenolics and free ferulic acid. During fermentation of bran from native grains, the levels of alkylresorcinols slightly increased but during fermentation of bran from peeled grains they decreased. Significant increase in soluble pentosans was established in both types of rye bran fermentations. Enhanced bioactivity and solubilization of pentosans with limited microbial growth were obtained after 12-14 h fermentation at 25 degrees C. The results suggest that fermentation is a potential bioprocessing technology for improved technological properties and bioactivity of rye bran.

Bread↗
PubMed1998

The effects of fermentation acids on bacterial growth.

Anaerobic habitats often have low pH and high concentrations of fermentation acids, and these conditions can inhibit the growth of many bacteria. The toxicity of fermentation acids at low pH was traditionally explained by an uncoupling mechanism. Undissociated fermentation acids can pass across the cell membrane and dissociate in the more alkaline interior, but there is little evidence that they can act in a cyclic manner to dissipate protonmotive force. Fermentation acid dissociation in the more alkaline interior causes an accumulation of the anionic species, and this accumulation is dependent on the pH gradient (delta pH) across the membrane. Fermentation acid-resistant bacteria have low delta pH and are able to generate ATP and grow with a low intracellular pH. Escherichia coli O157:H7 is able to decrease its intracellular pH to 6.1 before growth ceases, but this modest decrease in delta pH can only partially counteract the toxic effect of fermentation anion accumulation. Fermentation acid-resistant bacteria are in most cases Gram-positive bacteria with a high intracellular potassium concentration, and even acid-sensitive bacteria like E. coli K-12 have increased potassium levels when fermentation acids are present. Intracellular potassium provides a counteraction for fermentation acid anions, and allows bacteria to tolerate even greater amounts of fermentation anions. The delta pH-mediated anion accumulation provides a mechanistic explanation for the effect of fermentation acids on microbial ecology and metabolism.

Acetic Acid↗
PubMed2002

Impact of small scale fermentation technology on food safety in developing countries.

Fermentation is one of the oldest technologies used for food preservation. Over the centuries, it has evolved and been refined and diversified. Today, a variety of food products is derived from this technology in households, small-scale food industries as well as in large enterprises. Furthermore, fermentation is an affordable food preservation technology and of economic importance to developing countries. In the report of an FAO/WHO Workshop (FAO/WHO, 1996), fermentation was reviewed and the nutritional and safety aspects of fermentation technologies and their products were assessed. Fermentation enhances the nutritional quality of foods and contributes to food safety particularly under conditions where refrigeration or other foods processing facilities are not available. Hazard Analysis and Critical Control Point (HACCP) studies of some fermented products have demonstrated that depending on the process and the hygienic conditions observed during preparation, some fermented foods, e.g. togwa prepared in Tanzania, may pose a safety risk. Fermented foods must therefore be studied following HACCP principles and small-scale food industries and households must be advised on the critical control points of fermentation processes and the control measures to be applied at these points. This paper reviews the risks and benefits of fermentation and demonstrates the application of the HACCP system to some fermented foods in developing countries.

Consumer Product Safety↗
PubMed2004

Fermentation of seeds of Teff (Eragrostis teff), grass-pea (Lathyrus sativus), and their mixtures: aspects of nutrition and food safety.

Fermentation of pure teff (Eragrostis teff), pure grass-pea (Lathyrus sativus), and their mixtures, 9:1 and 8:2 (teff/grass-pea) has been done at two temperatures (room temperature and 35 degrees C) in duplicate using the strains of Lactobacillus plantarum, for bacterial fermentation, and Aspergillus oryzae and Rhizopus oligosporus in succession for solid-state fungal fermentation as inocula. In addition, the natural or spontaneous and back-slopping methods of bacterial fermentation have been done on the above four substrate groups. The pH and essential amino acid profiles of the different fermentation processes were compared. The back-slopping in teff at a temperature of 35 degrees C gave the sharpest pH drop. All fermentations done at 35 degrees C showed a steeper slope in their pH versus time plot compared to their room temperature counterpart. Fungal fermentation gave an improved amino acid profile for the essential ones in all of the substrate groups, except in pure grass-pea. Fermented teff/grass-pea (8:2) in this fungal fermentation has been found to be quite comparable in essential amino acid profile to an ideal reference protein recommended for children of 2-5 years of age. None of the bacterial fermentations produced a net change in their essential amino acid profile in any of the substrate groups investigated. Solid state fungal fermentation on pure grass-pea using the fungal strains R. oligosporous and A. oryzae in succession has shown that the neurotoxin beta-N-oxalyl-alpha,beta-diaminopropionic acid (beta-ODAP) in grass-pea has been removed by 80% on average for the high-toxin variety and by up to 97% for the low-toxin variety as determined by an improved chromatographic method with bioelectrochemical detection coupled on-line with refractive index detection.

Amino Acids↗
PubMed2001

Some microbiological and biochemical studies on the fermentation of 'awaze' and 'datta', traditional Ethiopian condiments.

The microbial and some biochemical changes during the fermentation of two Ethiopian condiments were studied. The aerobic mesophilic microflora of the ingredients of 'awaze' were dominated by Bacillus species (1.1 x 10(6) cfu/g) and lactic acid bacteria (4.5 x 10(4) cfu/g). The counts of aerobic mesophilic bacteria declined during the fermentation period. Lactic acid bacteria (LAB) reached the maximum count of 5.9 x 10(9) cfu/g at day 4 and the count remained > 10(8) cfu/g throughout the fermentation. The heterofermentative LAB dominated until day 3; thereafter the homolactics dominated the fermentation. Yeasts appeared at day 6 and increased to 2.5 x 10(6) cfu/g. In 'datta' fermentation, the count of aerobic mesophilic bacteria remained unchanged during the fermentation. LAB initiated the fermentation at a level of 7.1 x 10(4) cfu/g and reached 1.2 x 10(9) cfu/g at day 7. The homolactic LAB initiated and dominated the fermentation for the first 2 days and the heterolactics took over thereafter. Both fermentations were accompanied by declining pH and increasing titratable acidity. Salmonella typhimurium was inhibited during both fermentations within 48 h. Both 'awaze' and 'datta' had low initial contents of available protein and reducing sugars and these did not show marked differences throughout the fermentation.

Bacillus↗
PubMed1998

Fermentation products of sugar-beet fiber by cecal bacteria lower plasma cholesterol concentration in rats.

Plasma cholesterol concentration is reduced by feeding some dietary fibers but the mechanism is not fully understood. We examined whether cecal fermentation products are involved in lowering plasma cholesterol by feeding rats a highly fermentable sugar-beet fiber (SBF) in four separate experiments. These were designed to investigate the effects on plasma cholesterol of oral ingestion of fermentation products on plasma cholesterol, the effects of the products in comparison with that of a short-chain fatty acid (SCFA) mixture, effects of individual SCFA and effects of alteration of energy and nitrogen ratio in the diet by the addition of the SCFA mixture. Cecal contents of rats were cultured with SBF by using a jar fermenter under anaerobic conditions, and the supernatant from the culture medium, containing fermentation products of SBF, was collected and freeze-dried before feeding to rats. Yield of fermentation products as dry weight from the fiber was 80-90%. In rats fed a diet containing fermentation products (80 g/kg diet), plasma cholesterol concentrations were lower than in rats of the fiber-free group 3, 7 and 14 d after feeding the test diet. Major SCFA in the fermentation products were sodium salts of acetic, propionic and butyric acids. Plasma cholesterol concentration in rats fed the diet containing a mixture of equal amounts of the three SCFA salts (66 g/kg diet) as the fermentation products diet was also lower than that in the fiber-free group and was not different from those in rats fed SBF (100 g/kg diet) and the fermentation products. In rats fed an acetate-containing diet but not in rats fed diets without acetate, plasma cholesterol was significantly lower than in the fiber-free group. In conclusion, absorption of SCFA from cecal fermentation products lowers plasma cholesterol. Acetate, and not propionate, may be responsible for lowering plasma cholesterol concentration.

Animals↗