Evaluation of physico-chemical characteristics of fresh, refrigerated and frozen Lacaune ewes' milk

Abstract

The production of ewe milk is seasonal and milk yield per animal is low, even in specialized animals. This study aimed to verify the possibility of preserving bulk tank milk for seven days under cooling (5°C) and freezing (-5°C), verify the influence of cooling treatments and of the months of the year on the physical and chemical characteristics of the product. The chemical composition of milk, including the fat, protein, lactose and total solids contents, was not altered by cooling and freezing. Protein and lactose contents varied according to the months of the year. The average percentage and standard deviation of fat, protein, lactose and total solids was 8.10±1.30, 5.22±0.37, 4.43±0.23 and 19.34±1.54, respectively. The density, pH, titratable acidity, as well as alcohol and heat stability tests were significantly influenced by the treatments used (P < 0.05), but no differences were found between fresh and frozen milk. Prolonged refrigeration caused an increase in acidity and decrease in pH, with a consequent reduction in the stability of milk. These results demonstrated that freezing does not affect the chemical composition and physical characteristics of milk in nature and it could be a solution for the producer and the sheep milk industry. de 8,10±1,30, 5,22±0,37, 4,43±0,23 e 19,34±1,54, respectivamente. A densidade, o pH, a

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

“…At a natural pH value, the average ES for red deer's milk closely resembles that of sheep's milk (62 and 63%, v/v, respectively), both being slightly but significantly higher than that of goats' milk (50%, v/v) but far lower compared with bovine milk (83%, v/v), which proved to be the most stable to high ethanol concentrations of the four species discussed. These data are consistent with previous studies carried out on sheep and goat milk (Fava et al, 2014;Guo et al, 1998) while, for bovine milk, values obtained were intermediate to those reported by other authors (Chavez et al, 2004;Chen, Lewis, & Grandison, 2014;Davies & White, 1958).…”

Why are most physicochemical parameters not useful in predicting the quality of sheep milk?

“…The assessment of the results indicated that the acidity was the best way to indirectly evaluate the quality of sheep milk. However, this parameter is only valid when the initial milk acidity is well known, since the natural acidity of sheep milk varies significantly, mainly due to oscillations in the protein content at the different stages of lactation and also to variations in the feed and animal breed (Todaro et al ; Fava et al ).…”

Characterization of casein and alpha lactalbumin of African elephant (Loxodonta africana) milk

“…The above results imply that the CN micelles in African elephant milk would consist mainly of β-CN. Milk of the African elephant was destabilized by 62% ethanol, which is comparable to that of ewe (Fava et al, 2014), goat (Guo et al, 1998), and buffalo (Unnikrishnan et al, 1988), and therefore deemed less stable than cow milk, which is destabilized by 75% ethanol. The milk of ewe and goat also has a much lower content of α S1and κ-CN, which is given as a reason why these milks are less stable to ethanol and heat (Horne and Muir, 1990;Horne 2008).…”

“…A down-scaled procedure of the ethanol stability test (Fava et al, 2014) was performed by mixing 200 μL of ethanol (in different concentrations) and 200 μL of milk in an Eppendorf tube. After standing for 20 min at room temperature, the mixtures were centrifuged at 20 × g for 5 min at room temperature.…”

“…Heat and ethanol stability has been studied for milk from several species, and it seems as if the α S1 -and κ-CN play the major role. Cow milk contains the highest amounts of these 2 and has the highest stability, compared with other species (Unnikrishnan et al, 1988;Horne and Muir, 1990;Guo et al, 1998;Horne, 2008;Fava et al, 2014).…”