The Quinhydrone Electrode for pH Determinations in Milk and Dairy Products

Steinsholt, K.; Calbert, H. E.

doi:10.3168/jds.s0022-0302(60)90167-3

Cited by 2 publications

(3 citation statements)

References 5 publications

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“…The values were converted to cell dry weight (CDW) from a predetermined standard curve. The concentration of sucrose and lactic acid in the broth were measured using the Roe method and a rapid colorimetric method [8], respectively. Nisin titer was determined by a modified agar diffusion assay [9].…”

Section: Methodsmentioning

confidence: 99%

“…Samples were withdrawn aseptically from the broth at regular time intervals and analyzed for biomass and nisin titer. For VVCF, sucrose solution (190 g l −1 ) was added to the broth at invariable rates (8,9,10, and 12.5 ml h −1 ) after 3-h (determined by pre-experiments) fermentation. For VVIF, the sucrose solution (190 g l −1 ) was added in batches to keep the concentration of sucrose in an appropriate range (5-10 g l −1 in the main experiments, determined by pre-experiments).…”

Section: Batch and Fed-batch Fermentationmentioning

confidence: 99%

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Variable Volume Fed-Batch Fermentation for Nisin Production by Lactococcus lactis subsp. lactis W28

Wang

Jing

et al. 2008

Appl Biochem Biotechnol

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A feeding technology that was suitable for improving the nisin production by Lactococcus lactis subsp. lactis W28 was established. The effects of initial sucrose concentration (ISC) in the fermentation broth, feeding time, and feeding rate on the fermentation were studied. It was observed that a fed-batch culture (ISC = 10 g l(-1)) with 100 ml sucrose solution (190 g l(-1)) being evenly fed (9-10 ml h(-1)) into the fermenter after 3-h fermentation gave the best performance in terms of biomass and nisin yield. Under these conditions, the total biomass and the total nisin yield were approximately 23% and 51% higher than those in batch fermentation, respectively. When the sucrose concentration was controlled at 5-10 g l(-1) in variable volume intermittent fed-batch fermentation (VVIF) with ISC = 10 g l(-1), the total biomass and the total nisin yield were 29% and 60% above those in batch fermentation, respectively. The VVIF proved to be effective to eliminate the substrate inhibition by maintaining sucrose at appropriate levels. It is also easy to be scaled up, since various parameters involved in industrial production were taken into account.

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Section: Methodsmentioning

confidence: 99%

Section: Batch and Fed-batch Fermentationmentioning

confidence: 99%

Variable Volume Fed-Batch Fermentation for Nisin Production by Lactococcus lactis subsp. lactis W28

Wang

Jing

et al. 2008

Appl Biochem Biotechnol

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“…The concentration of lactic acid in continuously growing cultures at 30 °C was determined colorimetrically by the method of Steinsholt & Calbert (1960). The deproteinized test solutions were stored at -20 °C until required for analysis.…”

Section: Lactic Acid Determinationmentioning

confidence: 99%

Growth studies on the lactic streptococci: IV. Some observations on redox potential

Keen¹

1972

Journal of Dairy Research

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Redox potential changes at 30 °C in anaerobic reconstituted skim-milk cultures of Streptococcus cremoris AM^ and AM 2 and Streptococcus lactis ML 8 have been investigated in batch cultures and continuous cultures maintained at constant pH by the addition of fresh medium. Str. lactis ML 8 was more strongly reducing than either Str. cremoris AM X or AM a . The positive E h values which can arise in dense continuous cultures of lactic streptococci are not likely to affect either the lactic acid formation or proteolytic activity of the resultant bacterial concentrate. An electrolytic reduction cell is described which allows variations in redox potential in cultures to be controlled simply and effectively.Oxidation-reduction potentials constitute one of a number of environmental factors which affect the growth of bacteria (Tabatabai & Walker, 1970). For many years investigations into this factor were primarily concerned with measuring the potentials achieved in culture medium during the growth cycle of microbial cells under anaerobic or aerobic conditions. It has been established that changes in the redox potential not only indicate the level of dissolved O 2 present in the culture medium (Tengerdy, 1961a; Wimpenny 1969a; Jacobs, 1970) but also cause varaitions in cell regulation by different groups of enzymes (Wimpenny, 19696) and alter the production of a number of fermentation products (Tengerdy, 19616).The purpose of the present investigation was to observe redox potential changes in batch cultures and in continuous cultures with controlled pH of single strains of lactic streptococci. Preliminary investigations indicated that for some strains of lactic streptococci, positive redox potentials were obtained under continuous culture conditions at optimum pH values for growth. It was necessary, therefore, to determine whether these redox potentials which may arise in continuous cultures of the lactic streptococci affect their ability to form lactic acid and to degrade protein, both of which activities are important in the manufacture and ripening of cheese. In addition, a simple method is described for the control of redox potential in continuous cultures.

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The Quinhydrone Electrode for pH Determinations in Milk and Dairy Products

Cited by 2 publications

References 5 publications

Variable Volume Fed-Batch Fermentation for Nisin Production by Lactococcus lactis subsp. lactis W28

Variable Volume Fed-Batch Fermentation for Nisin Production by Lactococcus lactis subsp. lactis W28

Growth studies on the lactic streptococci: IV. Some observations on redox potential

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