Abstract
Storage of raw milk under refrigeration makes it possible to reduce operating costs for production and prevents losses of this raw material by the acidifying activity of mesophilic bacteria. Meantime, storage for prolonged periods may result in decreased quality of dairy products, due to the growth and enzymatic activity of psychrotrophic bacteria. Thus, in this study, we evaluated the presence of psychrotrophic microorganisms, Pseudomonas spp. and Pseudomonasaeruginosa tracing sources of microbiological contamination in the milking process as well as the level of proteolysis of the milk in the expansion tank. The highest contamination (P <0.05) occurred with the psychrotrophic count, with maximum values of 5.11 log CFU•mL-1a value that has hydrolytic potential for K-casein. Some dairy farms were found to have a maximum caseinomacropeptide value of 142.93 mg•L-1, representing loss of quality for the industry and a raw material that is not suitable for human consumption. The points of greatest contamination were udder surface, insufflator, milking bucket and colling system. According to principal component analysis, the values obtained for the microbiological counts were not determinants of the release of caseinomacropeptide.
Highlights
Cold storage in expansion tanks selects for the growth of Pseudomonas (De Jongheet al., 2011) since these bacteria are able to outgrow the other bacteria present in the raw milk microbiota becoming predominant
In view of the production systems and agro-industrial chain of milk, it is of paramount importance to analyse the critical points that can lead to contamination with psychrotrophic microorganisms, establishing a relationship between refrigeration and good manufacturing and hygiene practices during milking, storage, and transportation (Zeniet al., 2013)
The level of serum added to milk due to fraud is determined by caseinomacropeptide analysis (CMP), which quantifies the free CMP in milk (Brasil 2006)
Summary
Cold storage in expansion tanks selects for the growth of Pseudomonas (De Jongheet al., 2011) since these bacteria are able to outgrow the other bacteria present in the raw milk microbiota becoming predominant (von Neubeck et al, 2015). In view of the production systems and agro-industrial chain of milk, it is of paramount importance to analyse the critical points that can lead to contamination with psychrotrophic microorganisms, establishing a relationship between refrigeration and good manufacturing and hygiene practices during milking, storage, and transportation (Zeniet al., 2013). To chymosin (rennet), the psychrotrophic microorganisms present in raw milk, carry out the hydrolysis of casein, which may cause an increase in the level of caseinomacropeptide (Magalhães, 2008). Sources of psychrotrophic contamination and proteolysis indices in raw milk determine the points of contamination in the milking process and raw milk by evaluating the counts of psychrotrophic microorganisms, Pseudomonas spp., and Pseudomonas aeruginosa, as well as the level of proteolysis in milk by quantifying CMP in dairy farms in Paraná, Brazil
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
