Fermentation In Order Research Articles

Mineral requirements for methane fermentation

Mineral deficiency appears to pose a more critical problem in the anaerobic treatment process than in the aerobic treatment process. Furthermore, the methane fermentation step of anaerobic treatment appears to be the stage most sensitive to mineral deficiency. Commonly the mineral deficiency is a trace metal, and, since the fermentation step is the terminal stage in the treatment process, a build‐up of these reactants (mainly acetate, propionate, butyrate and hydrogen) can adversely affect the overall process. A review of the literature follows concerning the mineral requirements of methane fermentation in order to facilitate a proper understanding of the anaerobic process, especially in its application to treatment of industrial waste waters that are prone to be deficient in certain minerals. Types of limiting nutrients are considered with specific attention given to nitrogen, sulfur, phosphorus and the trace metals, and the physiological role and intracellular concentration of minerals is discussed. An ...

Ergebnisse zur Aufbereitung von schweinegülle als substrat für biotechnologische Stoffwandlungsprozesse

Summary Pure and mixed cultures of Clostridium Spec, were tested in sterile and nonsterile batch fermentations in order to increase the content of short chain fatty acid in different liquid swine manure substrates. Fatty acid concentrations of 15 g/l were reached by a thermochemical pretreatment of the substrates and the application of a mixed culture of Cl. acetobutylicum, Cl. butyricum and Cl. paraputrificum . The distributions of C 2 −C5 fatty acids were determined. The results represent the basis to intensify the process of the biotechnological conversion of liquid swine manure.

Optimization of fermentation conditions for alcohol production

The quantitative effects of carbohydrate levels, degree of initial saccharification, glucoamylase dosage, temperature, and fermentation time were investigated using a Box-Wilson central composite design protocol. With Saccharomyces cerevisiae ATCC 4126, it was found that the use of a partially saccharified starch substrate markedly increased yields and attainable alcohol levels. Balancing the degree of initial saccharification with the level of glucoamylase used to complete hydrolysis was found necessary to obtain optimum yields. The temperature optimum was found to be 36 degrees C. The regression equations obtained were used to model the fermentation in order to determine optimum fermentation conditions.

Submerged Production of Edible Mushroom Mycelium

The edible mushroom Morchella esculenta, previously adapted to a peat extract culture medium, has been grown using acid Sphagnum peat extracts as the only substrate source. Extracts obtained by autoclaving peat mixed with 1.5% (v/v) H2S04 for 2h at 121°C were utilized in shaker flask fermentations in order to evaluate the incidence of different factors on the growth. Sets of different conditions for inoculum ratio, temperature, initial pH, fermentation time and agitation speed were tested. The results are expressed as mycelial yield (g of dry mycelium produced per g of carbohydrate consumed). The best combination of operating variables in the range of values investigated, were: 7% (v/v) inoculum ratio, 26°C, pH 6.0, 6 days and 150RPM.

Autolysis of Yeasts in Champagne

The evolution of amino acids in champagne has been studied over a period of several years from the start of the bottle fermentation to aging for 4 to 5 years in contact with the yeast. After the excretion of amino acids by yeasts at the end of the bottle fermentation the concentration of amino acids remains stable for several months. Then it begins to rise again slowly but continuously. This second phase of enrichment with amino acids corresponds to the autolysis of the yeast cells. This phenomenon has also been studied with active dry yeasts after rehydration. It depends on some parameters such as the pH, the ethanol concentration, and the temperature. For champagne the age of the yeast sediment also plays a role. Autolysis proceeds only if the wine is aged for several months in contact with the yeast. Indeed, the yeasts are the seat of intracellular proteolytic activity which causes the degradation of cytoplasmic constituents and the enrichment of the wine in amino acids. Autolysis has truly a great influence on the organoleptic properties of champagne, particularly on its aromatic properties. Investigations are now underway for the production of yeast autolysates in fermenters for the purpose of addition to the wine at the time of the bottle fermentation in order to accelerate the aging process.

Aerobic vs. anaerobic fermentation for recycling swine waste in tropical farmlands

Aerobic and anaerobic fermentation systems have been proposed as an attractive solution for waste recycle and a way for overcoming the lack of protein in tropical feedstuffs such as cassava meal, but little attention has been paid to the problem of increasing land productivity, measured as kg of liveweight/ha-year, within farms where plant and animal production are integrated. Comparison is made of present production system of hogs in Mexico, using sorghum and soy bean meals, with a potential system, using cassava meal blended with roasted (full fat) soy beans. It is found that land productivities are, 500 and 881 kg/ha-year, respectively. This seems to indicate that introduction of cassava meal in swine production systems might increase by 76% land productivity of integrated farms as compared to the use of sorghum in tropical regions. Substitution of soy beans by aerobic fermentation of cassava, increases land productivity only 1% as compared to cassava:soy beans alternative. Partial recycling of swine waste using lactic fermentation in order to improve sanitary conditions, increases land productivity by 13% as compared to cassava:soy bean alternative. It is concluded that fermentation procedures do not increase land productivity in order to compensate for capital and labour costs of those procedures but they could be an attractive way to waste management. Anaerobic fermentation would be a more efficient process for such a purpose and a cheaper one to implement in rural areas of the Third World.

Influence of engineering variables upon the morphology of filamentous molds

AbstractA modal has been described for the influence of growth rate and shear stresses in the fermentor upon the morphology of filamentous molds. The main concept of this model is the dynamic equilibrium between growth and breakup of the hyphae. The latter has been approached according to well‐known engineering theories for dispersion of physical systems. Experiments to verify the model with a strain of Penicillium chrysogenum in batch and continuous culture revealed that the length of the mycelial particles increased with increasing growth rate and decreased with increasing power input her unit mass in the fermentor. Although this was qualitatively in agreement with the presented model, quantitatively the model had to be rejected. Variation of the tensile strength of the hyphae with age and culturing conditions could have been one of the causes of disagreement. Oxygen tension, varied independently from stirrer speed, in the range of 12–300 mm Hg was shown to have no influence upon the morphology. With respect to the question of possibly using high‐energy inputs in industrial mold fermentation in order to decrease hyphal length and suspension viscosity, it was concluded that this is of little practical value. A substantial decrease in hyphal length requires an enormous increase in energy input.

Formaldehyde as a silage additive. II. The chemical composition and nutritive value of lucerne hay, lucerne silage, and formaldehyde and formic acid-treated lucerne silages

Formaldehyde-treated silage, formic acid-treated silage, formaldehyde-formic acid-treated silage, untreated silage, and lucerne hay were made from a lucerne sward and offered to Merino wethers. The formaldehyde was applied at a rate of 0.9 % of the weight of the dry matter and formic acid at 0.5 % of the fresh weight of the lucerne. Formaldehyde-treated silage and formaldehyde-formic acid-treated silage had significantly lower concentrations of ammonia nitrogen and total and individual organic acids than untreated silage. Formic acid-treated silage had a similar degree of fermentation to untreated silage, but more acetic acid and less lactic acid were produced than in untreated silage. However, when formic acid was applied in combination with formaldehyde, the ensiling fermentation was inhibited more than when formaldehyde was applied alone. There was some apparent protection of protein by the formaldehyde treatment. Treatment with formic acid significantly increased the in vivo digestibility of both nitrogen and dry matter, but did not increase ad libitum intake or wool growth by sheep offered this silage. Compared to untreated silage, treatment with formaldehyde significantly reduced the in vivo digestibility of nitrogen, produced a non-significant increase in intake, and significantly increased wool growth. The treatment of lucerne with both formaldehyde and formic acid significantly increased in vivo digestibility of dry matter, ad libitum intake, and wool growth compared with untreated silage. The treatment of lucerne with a mixture of formaldehyde (0.9% of the dry matter) and formic acid (0.5% of the fresh weight) was a suitable method of controlling the ensiling fermentation in order to increase the ad libitum intake of lucerne silage by sheep and their subsequent wool production. However, the intake and wool production of sheep offered such silage was still significantly less than that of sheep offered lucerne hay.

Studies on the Fluorescent Compounds in Fermented Foods

As a basic experiment for the study of aflatoxin degradation during fermentation of miso, the effect of hydrogen-ion concentration to the degradation of aflatoxin was examined. It was found that the pH value for the most effectiVe degradation of aflatoxin was over 9 and contrary the most stable pH values for aflatoxin were 4-5. The pH values of 95 samples of the commercial miso from all of the prefectures in Japan were mostly between 4.6-5.4. As the result of this survey, it was shown that there was no effect of pH value of the miso as regard to aflatoxin degradation.A certain amount of aflatoxin was added to green miso before fermentation in order to investigate the degradation of the toxin during miso fermentation. There was some degradation of aflatoxin B1 and G1 in miso in the early stage of the fermentation, but in the later the velocity was remarkably reduced. As the result, above 50 percent of aflatoxin B1 and G1 remained in miso after 1 month fermentation. With regard to aflatoxin B2 and G2, no degradation was detected during miso fermentation.