Seasonal variation, method of determination of bovine milk stability, and its relation with physical, chemical, and sanitary characteristics of raw milk

Abstract

-The objective of this research was to determine the variation of milk stability evaluated with ethanol, boiling, and coagulation time tests (CTT) to identify milk components related with stability and verify the correlation between the three methods. Bulk raw milk was collected monthly at 50 dairy farms from January 2007 to October 2009 and physicochemical attributes, somatic cell (SCC), and total bacterial counts (TBC) were determined. Milk samples were classified into low, medium, and high stability to ethanol test when coagulation occurred at 72 °GL, between 74 and 78 °GL, and above 78 °GL, respectively. Univariate analysis was performed considering the effects of year, months, and interaction in a completely randomized design. Principal factor analysis and logistic regression were done. There was an interaction between months and years for stability to the ethanol test and coagulation time. All samples were stable at the boiling test. Boiling test was not related to ethanol and coagulation time tests. Coagulation time was weakly but positively correlated with ethanol test. Broken line analysis revealed that milk stability measured with CTT and ethanol tests decreased sharply when SCC attained 790,000 or 106 cell/mL of milk, respectively. Milk stability measured with ethanol test decreased when TBC was higher than 250,000 cfu/mL, while there was no inflexion point between TBC and stability measured with CTT. Milk with high stability presented lower values for acidity, TBC, and SCC but higher values for pH, lactose, protein, and CTT compared with lowstability milk. Due to the execution easiness, single-point cut-off result and low cost, we do not recommend the replacement of ethanol test for boiling or coagulation time test.Key Words: milk composition, seasonality, somatic cell count Revista Brasileira de Zootecnia

Some aspects of the ethanol stability of red deer milk (Cervus elaphus hispanicus): A comparison with other dairy species

“…Acidity of red deer milk is comparable with that of sheep milk, both being much higher than those of goat and cow milk (P < 0.001). Previous studies with milk deer did not provide information about this parameter; however, the values obtained in the cow, goat and sheep species are in accordance with those suggested by other authors (Machado, Fischer, Stumpf, Stivanin, 2017;Mahmood & Usman, 2010;Park et al, 2007).…”

Field findings about milk ethanol stability: a first report of interrelationship between α‐lactalbumin and lactose

“…Prediction of milk stability increased with the input of milk ash content in the statistical model (Nagelkerke's R = 0.11). Findings presented here endorse the understanding that events leading to milk instability are often of a multifactorial nature and have high correlation with the salt balance ratio .…”

“…It is well known that minerals influencing the ionic strength of micelles, particularly Na, Cl and K, also promote ethanol destabilization. 3 Consequently, lactose usually appears in smaller amounts in unstable milk, 2,18 while the average levels of chloride, sodium and potassium are higher. 3 Wang et al 27 also stated that the lower milk osmolarity in response to reduced milk lactose concentration could be compensated by higher milk K + concentration.…”

“…On this basis, mixing a single volume of ethanol solution, usually 70 ml dL −1 , into an equal volume of milk is a simple technique useful for judging its quality and can quickly differentiate between fresh milk from acidic milk or colostrum. Therefore, the alcohol test has been largely applied by the dairy industry worldwide and is still an important subject in many countries that use the alcohol test to measure the quality of raw milk, such as Argentina, Brazil, Cuba, France, India and South Africa …”

“…Therefore, the alcohol test has been largely applied by the dairy industry worldwide and is still an important subject in many countries that use the alcohol test to measure the quality of raw milk, such as Argentina, Brazil, Cuba, France, India and South Africa. 2 However, solubility of milk components other than casein micelle -such as serum proteins, minerals, salts and lactose -can be modified by alcohol and other organic solvents. 3 Other researchers have linked milk ethanol stability with scour of calf, 4 -casein polymorphism, 5 feed restriction, 6 acid-base disturbances 7 and different molar ratios of lactose crystals, 8 making milk ethanol stability a phenomenon associated with many variables that influence the balance of soluble salts in the serum phase.…”