Microbial quality and safety of milk and milk products in the 21st century

Abstract

Milk and milk products have been utilized by humans for many thousands of years. With the advent of metagenomic studies, our knowledge on the microbiota of milk and milk products, especially as affected by the environment, production, and storage parameters, has increased. Milk quality depends on chemical parameters (fat and protein content and absence of inhibitory substances), as well as microbial and somatic cells counts, and affects the price of milk. The effects of hygiene and effective cooling on the spoilage microbiota have shown that proteolytic and lipolytic bacteria such as Pseudomonas or Acinetobacter spp. predominate the spoilage bacterial populations. These bacteria can produce heat‐stable proteases and lipases, which remain active after pasteurization and thus can spoil the milk during prolonged storage. Additionally, milk can become contaminated after pasteurization and therefore there is still a high demand on developing better cleaning and sanitation regimes and equipment, as well as test systems to (quantitatively) detect relevant pathogenic or spoilage microorganisms. Raw milk and raw milk cheese consumption is also increasing worldwide with the growing demand of minimally processed, sustainable, healthy, and local foods. In this context, emerging and re‐emerging pathogens once again represent a major food safety challenge. As a result of global warming, it is conceivable that not only microbiological risks but also chemical risks relating to presence of mycotoxins or plant toxins in milk will increase. Herein, we provide an overview of the major microbial hazards occurring in the 21st century.

Natural Agents against Bovine Mastitis Pathogens

“…Control of udder health is important for the dairy production chain in light of food safety issues, with control of udder pathogens being the most important in the reduction of foodborne illness and giving healthy dairy food [14,15]. Besides, development and spread of resistance to antibiotics as a consequence of mastitis treatment represent a public health threat to consumers as a global problem, influencing both human and animal health.…”

From Cheese-Making to Consumption: Exploring the Microbial Safety of Cheeses through Predictive Microbiology Models

“…S. aureus is one of the main pathogens found in cheeses produced with raw milk and is a common cause of bovine mastitis, being detected in bulk tank milk at high prevalence rates [48,49]. Since enterotoxin-producing S. aureus exhibits a high osmotolerance, it can grow or survive in cheeses with a w levels as low as 0.86 [50].…”

Growth interferences between bacterial strains from raw cow's milk and their impact on growth of Listeria monocytogenes and Staphylococcus aureus

“…Additionally, the strains Listeria monocytogenes DSM 20600 T , Staphylococcus aureus DSM 1104 T , Bacillus subtilis DSM 10 T and Micrococcus luteus DSM 20030 T were included in this Accepted Article study. L. monocytogenes and S. aureus are major human pathogens associated with the consumption of raw and unpasteurized milk and milk products (Fusco et al 2020). Strains of B. subtilis were frequently isolated from raw milk and are associated with spoilage by proteolysis or lipolysis (De Jonghe et al 2010;Ivy et al 2012).…”

“…and coagulase-positive Staphylococcus spp. (Fusco et al 2020). Pasteurisation of milk is considered effective to reduce pathogenic bacteria.…”

“…However, there is increasing interest in on-farm sale of raw milk and pathogens were even detected in pasteurised milk, either due to heat-resistance or post-pasteurisation contamination (Mullan 2019;Pannella et al 2019;Berge and Baars 2020). L. monocytogenes and Staphylococcus aureus are the major pathogens associated with consumption of raw milk and raw milk products and outbreaks occur regularly (Fusco et al 2020). L. monocytogenes is of particular importance in stored raw milk, since it is able to grow under refrigeration (Leclair et al 2019).…”