Abstract
Introduction. Microorganisms of dairy raw materials tend to adhere to the surfaces of processing equipment and form sustainable biofilms, which is a serious issue in the dairy industry. The goal of the present work was to investigate formation of biofilms on a glass surface in static model conditions, and removal of such biofilms by cleaning.
 Study objects and methods. The study objects were the permeates of skim milk, sweet whey and acid whey, as well as the biofilms formed and washings from glass slides. Biofilms were removed from the glass with detergents used in the dairy industry. Standard methods of determining microbiological and physicochemical properties were used to characterize the permeates. The biofilm structure and morphology of microorganisms participating in biofilm formation were investigated with a light spectroscopy. The efficiency of biofilm removal in a cleaning process was quantified with optical density of washings.
 Results and discussion. Biofilms in whey permeates formed slower compared to those in skimmed milk permeate during the first 24 h. Yeasts contributed significantly to the biofilm microflora in acid whey permeate throughout 5 days of biofilm growth. Well adhered biofilm layers were the most stable in skimmed milk permeate. The highest growth of both well and poorly adhered biofilm layers was observed in sweet whey permeate after 3–5 days. It was established that the primary attachment of microorganisms to a glass surface occurred within 8 h, mature multicultural biofilms formed within 48 h, and their partial destruction occurred within 72 h.
 Conclusion. The research results can be used to improve the cleaning equipment procedures in processing secondary dairy raw materials.
Highlights
Microorganisms of dairy raw materials tend to adhere to the surfaces of processing equipment and form sustainable biofilms, which is a serious issue in the dairy industry
It was established that the primary attachment of microorganisms to a glass surface occurred within 8 h, mature multicultural biofilms formed within 48 h, and their partial destruction occurred within 72 h
We found that biofilms in permeate samples formed rather quickly even on a smooth glass surface (Fig. 2)
Summary
Microorganisms of dairy raw materials tend to adhere to the surfaces of processing equipment and form sustainable biofilms, which is a serious issue in the dairy industry. The study objects were the permeates of skim milk, sweet whey and acid whey, as well as the biofilms formed and washings from glass slides. We propose using Jerusalem artichoke powder as a functional nutrient in the formulation of food products. We studied the influence of vacuum, vibration, and grinding on the kinetics of drying Jerusalem artichoke tubers of a “Skorospelka” variety in the laboratory vacuum vibromixing mill dryer (VVMD). Jerusalem artichoke powder obtained in the VVMD can be used in different branches of the food industry due to its long shelf life, low consolidation, and no caking, with residual moisture of 6.1%
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