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[Microbiological studies of Mladost sour milk]
Abstract:
Studied were a total of 239 productional batches of Mladost sour milk to establish the occasional contamination with coliform bacteria. It was found that 97.9 per cent of the batches had coli titers of 0.1 and over 0.1, and 2.1 per cent of the batches--over 0.01. Fourteen productional experiments were carried out to ascertain the sources of contamination with coli forms, yeasts, and moulds. It was found that the productional starter used for this type of sour milk did not contain coliforms and moulds in 0.1 cm3 but in about 43 per cent of the batches it contained 20 to 470 cm3 yeasts. It was also established that both yeasts and moulds that have found their way to the product multiplied in it to a various extent, depending on the activity of the cultures and the temperature of storage. Some of the stored batches deteriorated in terms of their organoleptic indices. At 11,000 cm3 yeasts the deterioration becomes stronger following the cummulation of greater amounts of biomass.
Insights
Mladost sour milk often shows contamination with coliform bacteria, with yeasts and molds contributing to spoilage. This study investigated contamination sources to improve product quality and safety.
Area of Science:
- Food Microbiology
- Dairy Science
Context:
- Coliform bacteria, yeasts, and molds can contaminate dairy products, affecting quality and safety.
- Mladost sour milk production batches were analyzed for microbial contamination.
Purpose:
- To identify the sources of coliform, yeast, and mold contamination in Mladost sour milk.
- To assess the impact of microbial contamination on the organoleptic properties of sour milk.
Summary:
- Analysis of 239 batches revealed high coli titers (97.9% with 0.1 and over 0.1).
- Production starter cultures contained yeasts (20-470 cm3 in 43% of batches) but not coliforms or molds.
- Yeasts and molds multiplied in the product, leading to organoleptic deterioration, especially at high yeast concentrations.
Impact:
- Identified starter cultures as a primary source of yeast contamination.
- Highlighted the role of storage temperature and culture activity in microbial growth and spoilage.
- Provides insights for improving microbial control in sour milk production to ensure product quality.