Bovine Mastitis: Safety and Quality Issues in Cheese Production

Abstract

Bovine mastitis is a common hygiene-related issue in milk production. It increases the somatic cell count in milk. Somatic cell count is an important indirect indicator of milk quality. Somatic cells include those of udder and blood. Normally, one healthy udder lobe secretes ≤ 500,000 somatic cells per 1 cm3 milk. In the presence of pathogenic bacteria, the same amount indicates a latent infection. Inflammatory processes in the udder include impaired secretion and mastitis. They increase the number of leukocytes and other blood cells in the total somatic cell count, which means that the milk came from sick cows. Raw milk for cheese production must contain ≤ 4×105 cells per 1 cm3. Mastitis, or garget milk is not suitable for cheese production. Staphylococcus aureus is the most common causative agent of staphylococcal mastitis in cows. Coagulase-positive staphylococci are responsible for 30-50% cases of infectious mastitis. They pose great risks for bulk-formed cheeses. Mastitis affects milk processing, taste, and storage capacity. It is high in chlorides and low in lactose, which gives it a flat and salty-bitter taste. If somatic cell count exceeds 5×105 cells per 1 cm3, the resulting milk has poor thermal stability. As the content of somatic cells in milk increases, so does the rennet coagulation time: fat goes into whey and moisture in curd increases, which eventually reduces cheese yield.