Abstract
This study aimed at quantifying the occurrence of proteolytic psychotropic microorganisms and total coliforms in refrigerated raw milk, in addition to assessing the quality through its physical-chemical composition. The samples were collected in 10 dairy farms in the municipality of Santa Helena – Western Paraná. Two collections were made, one during the spring and the other during the summer. Samples of refrigerated raw milk were carried out directly from the cooling tank, aseptically, packed in sterile bottles and transported under isothermal conditions (± 4 ºC) to the laboratory where the physical-chemical composition and microbial populations were determined. The levels of fat had great amplitude between the seasons, being higher in the summer, while there was no variation for the contents of protein, lactose, minerals, and non-fat solids. The total coliform count did not differ between seasons. The values obtained for proteolytic psychotropic counts were higher in the summer. A significant positive correlation was found between the total coliform counts, the proteolytic psychotropic counts (r=0.73), the levels of protein (r=0.45), non-fat solids (r=0.45), and minerals (r=0.46). Also, the proteolytic psychotropic counts showed a positive correlation with the cryoscopic index. The milk components met the requirements of NI76. The quality of refrigerated raw milk in the municipality of Santa Helena, Western Paraná was not satisfactory for total coliforms, due to its high incidence, indicating the need for good practices in milking management. Proteolytic psychotropic bacteria presented low proliferation, thus not affecting milk quality.
Highlights
Material and MethodsMilk is considered a complete food because it contains proteins, fats, carbohydrate minerals, vitamins, and water, but the quality of milk can be affected due to physical and chemical factors (KUMAR et al, 2018)
Bacterial contamination can come from udder dirt, the hands of the milker, milking equipment, and poorly sanitized drums and buckets (JAMAS et al, 2018)
The groups of microorganisms most commonly used as indicators of hygiene in milk are mesophilic, psychrotrophic, and coliform aerobes (PERIN et al, 2019)
Summary
Material and MethodsMilk is considered a complete food because it contains proteins, fats, carbohydrate minerals, vitamins, and water, but the quality of milk can be affected due to physical and chemical factors (KUMAR et al, 2018). The present study aimed to quantify the occurrence of proteolytic psychrotrophic microorganisms and coliforms and to evaluate the quality of milk through the physical-chemical composition.
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