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  • 1
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The scale-up of a whey fermentation byKluyveromyces fragilis was carried out in order to reproduce on a larger scale (100-l fermenter) the results obtained on a smaller scale (15-l fermenter). Using a standard procedure for inoculum development and medium pasteurization, the effects of mixing and lactose concentration on yeast growth, lactose consumption, COD reduction and dissolved oxygen have been studied. The most successful operation for this fermentation was found to be associated with high stirring rates and low lactose concentrations, since the process was controlled by both oxygen and lactose concentrations.
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The fermentation of grape must by Candida utilis ISS 28 was studied at different substrate concentrations, pH values, and nutrient supplementation in a shaken-flask fermenter, by using a composite design experiment. The experimental biomass yields were fitted to the only statistically significant factors with a mean standard error less than 8%, by using multiple regression analysis. Optimal conditions for maximum cell yield were established by plotting a series of loci at constant biomass yield and then verified experimentally, thus confirming the remarkable accuracy of the model
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The growth behaviour of Fusarium avenaceum (Sect. Roseum Wr.) in slurry fermentation systems using untreated orange peel as substrate was studied in a laboratory-fermenter scale to reproduce the results obtained in a shakenflask fermenter. The eventual effect of impeller speed on mechanical disruption of mycelial hyphae was then assessed by determining mycelial growth, total reducing sugars consumption, TOC reduction, carbon dioxide evolution and oxygen absorption rates. In particular, the main biomass yield coefficient, as well as the apparent specific growth rate, appeared to be independent of the impeller speed, at least within the experimental range of 450 and 900 min−1 (equivalent to peripheral impeller speeds of 3.8–7.5 m sec−1.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The fermentation of whey by Kluyveromyces fragilis IMAT 1872 was studied in a 15-l jar fermenter to assess the influence of temperature, lactose concentration, aeration and agitation on the biomass yield. Optimization of the operating parameters resulted in a 57.2% yield. The observations were analyzed in a ‘composite’ design. Canonical analysis and an F-test showed that only the first two principal axes (i.e., “oxygen transfer coefficient’ and ‘lactose inhibition’ factors) of the system under study were significant. Therefore, the observations were fitted to a quadratic expression, by using only these factors: 86% of the data fall within a 10% deviation band. This empirical model allowed the formulation of an operating strategy to select the set of conditions yielding the maximum value of biomass.
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  • 5
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The efficiency of Chemical Oxygen Demand (COD) reduction η in the fermentation of whey by Kluyveromyces fragilis IMAT 1872 was studied at various temperatures, lactose concentrations, air dilution ratios and stirring speeds. Their effects on the biomass yield (y) has been determined previously (Moresi et al. in press). Two different optimal sets of these variables were found according to whether the objective was the production of cell mass or the reduction of COD. The two sets were then compared to establish a strategy for the industrial development of this fermentation process. The experimental efficiencies of COD removal were submitted to analysis in a composite design. Only the first two principal axes (i.e., the ‘oxygen transfer coefficient’ factor and the ‘stripping’ factor) of canonical analysis were found to be significant by an F-test. Therefore, the observations were fitted with a quadratic expression by using only these factors: the mean standard error was less than 6%. The yield of cells, expressed as g of dried cells/g of COD removed, varied in this fermentation, but this parameter may be particularly useful for analyzing and optimizing any fermentation process when the culture medium is a mixture of carbohydrates or the main substrate is fully utilized during the initial stages of fermentation.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Factor analysis was applied to fermentation of whey by Kluyveromyces fragilis IMAT 1872 allowing a screening of the experimental variables (temperature, pH, ammonium sulphate, potassium phosphate, yeast extract and lactose concentration and fractional filling of the flasks). The lactose level and the ratio of the solution and flask volumes have a marked effect on the biomass yield, as they control the oxygenation level of the culture media. Nutritional supplementation and environmental conditions have only a marginal effect on yield in this fermentation process. The best fit obtained by regression analysis between the biomass yield and the first principal component of factor analysis (oxygenation factor) showed a linear relationship: 64% of the data fall within a 25% deviation band.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A composite design technique was used to optimize the fermentation of whey by Kluyveromyces fragilis IMAT 1872. The experimental variables (temperature T, salts NP, yeast-extract YE and lactose level L), but not pH, were found to be significant at a level of 5%. The optimal operating conditions were determined (T=36.4°C, pH=5.1, NP=0.47% w/v, YE=0.114% w/v, and L=24.75 g/l). Temperature and lactose level exhibited a great influence on the biomass yield about the stationary point. Canonical analysis showed that these variables are not mutually independent. The optimal conditions will be used as starting point for a factorial design on a jar fermenter.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The biomass yields (y) and COD reduction efficiencies (η) of a whey fermentation by Kluyveromyces fragilis were studied in a 100-1 fermenter at various stirrer speeds and lactose concentrations, and compared to those obtained in 10-1 and 15-1 fermenters at constant values of the oxygen transfer coefficient (kLa) and air velocity. The empirical models previously constructed by using the 15-1 fermenter data could be used to predict the yields on the other scales by calculating for each run the 15-1 fermenter which would provide the same oxygen transfer coefficient measured by the sulphite method on each fermenter under study. To make this model independent of stirrer speeds used in each generic fermenter, the effect of aeration and mixing was incorporated into an overall parameter (kLa) and the values of y and η were correlated only with temperature, lactose level and kL a, since these variables were approximately orthogonal. The validity of this model was finally checked against the yields reported by Wasserman et al. (1961) in a 6-m3 fermenter, thus confirming the capability of the model to provide a reliable basis for further scale-up on the production scale.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The fermentation of potato starch by Schwanniomyces castellii IMAT 3754 was studied at differentsubstrate concentrations, pH values, and nutrient supplementation in a shaken-flask fermenter in a composite design experiment. The experimental biomass yields were fitted to the only two significant factors (“substrate inhibition” and “nutritional” factors) with a mean percentage error smaller than 10% by means of multiple regression analysis. The optimal conditions for maximum cell yield were first established experimentally, and then applied to other starchy materials, such as soluble maize starch, maize starch, tapioca and rice flour. They were then scaled-up in a laboratory fermenter, thus allowing a preliminary kinetic analysis of this fermentation process to be performed.
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The growth behaviour of Memnoniella echinata and Fusarium roseum was examined in slurry fermentation systems using untreated orange peel as substrate. A composite experiment was then designed to study the effect of orange peel initial concentration and the effect of the nitrogen: peel ratio on crude protein yidld (Y p ) and protein enrichment (Z p ) of the final biomass. The more concentrated the peel slurry, the greater the substrate inhibitory effect on microbial growth becomes. Finally, multiple regression technique allowed both the experimental values of Y p and Z p to be reconstructed with mean percentage errors smaller than 4% and 8%, respectively, and the optimal operating strategy for such SCP production process to be determined.
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