Hygiene indicators in a milk processing plant – a review

Milijana Sinđić; Marija Pajić; Aleksandra Nikolić; Tijana Ledina; Miloš Dimitrijević; Radoslava Savić Radovanović

doi:10.18485/meattech.2025.66.3.38

Milijana Sinđić University of Belgrade, Faculty of Veterinary Medicine, Department of Food Hygiene and Technology, Belgrade, Serbia https://orcid.org/0009-0006-0751-863X
Marija Pajić University of Novi Sad, Faculty of Agriculture, Novi Sad, Serbia https://orcid.org/0000-0001-9756-2461
Aleksandra Nikolić Institute of Meat Hygiene and Technology, Belgrade, Serbia https://orcid.org/0009-0009-0012-3418
Tijana Ledina University of Belgrade, Faculty of Veterinary Medicine, Department of Food Hygiene and Technology, Belgrade, Serbia https://orcid.org/0000-0002-9903-1477
Miloš Dimitrijević University of Novi Sad, Faculty of Agriculture, Novi Sad, Serbia https://orcid.org/0009-0008-0237-0546
Radoslava Savić Radovanović University of Belgrade, Faculty of Veterinary Medicine, Department of Food Hygiene and Technology, Belgrade, Serbia https://orcid.org/0000-0002-2419-5936

DOI: https://doi.org/10.18485/meattech.2025.66.3.38

Keywords: hygiene indicators, milk, processing plant

Abstract

This review paper focuses on the current microbiological parameters employed to evaluate the hygiene of raw milk and dairy products within processing plants. Key indicators of raw milk hygiene and overall quality include the total bacterial count (TBC) and somatic cell count (SCC). As the primary raw material in dairies for producing drinking milk and various dairy products, milk offers an ideal environment for the proliferation and spread of numerous microorganisms. In the dairy industry worldwide, contamination after pasteurization is commonly detected using indicator groups such as coliform bacteria, enterobacteria, total gram-negative bacteria, Pseudomonas, and gram-positive spore-forming bacteria. Enterobacteriaceae serve as hygiene indicators because they encompass a broad range of bacteria, including harmful species like Salmonella and Klebsiella pneumoniae. However, the standard coliform test depends on lactose fermentation, and since not all harmful enterobacteria—such as Salmonella, Shigella, or Yersinia—can ferment lactose, they may go undetected. Contamination of final dairy products can cause outbreaks of foodborne illnesses and incur additional expenses due to product recalls. Therefore, it is advisable to monitor hygiene indicators throughout milk production and processing to evaluate the effectiveness of the production process and decrease the necessity for repeated testing of final products.