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A New Approach to the Production of Cheese Starter - Some Preliminary Investigations

Authors: E.G. Pont and Gwenda L. Holloway


A scheme for the production of frozen bulk starter concentrate, based on the continuous culture of lactic streptococci, the centrifugal separation of the bacterial cells, and their freezing in liquid nitrogen, is outlined. Experiments have shown that a concentrated fluid suspension of Streptococcus lactis cells, equivalent to 20 gal. of bulk starter, would contain 3 x 1014 cells and would occupy a volume of about 400 ml. About 130,000 such cultures per year would be required to replace conventional bulk starters in Australian cheese factories.

pH-controlled fermentations in milk and whey have provided information on some of the factors which would affect the growth of lactic streptococci in continuous culture. The pH for maximum growth rate and population density was 6.3 and the optimum temperature 30°C. At pH 6.3 maximum direct microscopic counts of about 5 x 108 per ml were obtained in whey and 1 x 1010 in milk. The highest counts, exceeding 5 x 1010 per mil were obtained in cheese whey fortified with yeast extract and tryptone. At this level of count the concentration of sodium lactate is an important factor in limiting population density. It is estimated that with unfortified whey a fermentation volume of 420 gallons using 8,000 to 9,000 gallons of whey per day would be required for the continuous production of concentrated starters at the rate of 130,000 per year. With fortified whey the fermentation volume could be as low as 25 gallons and the rate of whey utilization 800 gallons per day.

$15.00 (inc. GST)

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