Oxidative stability and quality of raw Saanen and Alpine goats milk

Abstract

The milk composition and concentration of thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) activity in fresh and refrigerated raw goat milk of Saanen and Alpine breed at the breeding period were investigated. Low average milk fat, SNF and lactose content were determined in both breeds with no significant differences between breeds regarding the milk yield and milk composition. The significantly higher somatic cell count (SCC) was detected in Saanen goats. The SOD activity and TBARS concentration were significantly higher 14 h after the collection and cold storage in both breeds of dairy goats with no difference between the breeds. In the Alpine goats the TBARS concentration was negatively correlated with urea concentration, and in the milk of the Saanen goats the TBARS was positively correlated with proteins and SCC. The higher SCC in the Saanen goats may have caused higher production of secondary oxidative products catalysed by the enzyme superoxide dismutase from polymorphonuclear granulocytes present in the udder, or by some other enzymes that participate in oxidation of the milk constituents. The energy shortage and protein surplus in the diet of the dairy goats may have induced the higher degree of lipid mobilisation and a consequent increase of polyunsaturated fatty acids (PUFA) that are easily prone to oxidation and formation of the secondary oxidative products.Keywords: goat, raw milk, milk components, peroxidation, quality Zusammenfassung Oxidative Stabilität und Qualität der Rohmilch von Saanen-und AlpenziegenUntersucht wurde die Milchzusammensetzung, die TBARS-Konzentration (Thiobarbitursäurereaktive Substanzen) und die SOD-Aktivität (Superoxiddismutase) in frischer und gekühlter Rohmilch von Saanen-und Alpenziegen während der Fortpflanzungszeit. Zwischen beiden Rassen bestanden keine signifikanten Unterschiede bei der Milchleistung und der Milchzusammensetzung, wobei ein relativ niedriger Fett-, Laktosegehalt und ein niedriger Wert für die Trockensubstanz nachgewiesen wurden. Bei den Saanenziegen ergab sich ein höherer somatischer Zellgehalt (SCC). 14 Stunden nach der Milchgewinnung und Kühlhaltung waren in der Milch die TBARS-Konzentration und die SOD-Aktivität signifikant höher, wobei zwischen den Rassen keine Unterschiede ermittelt wurden. Eine negative Beziehung fand sich zwischen dem TBARS-Wert und dem Harnstoffgehalt bei den MARENJAK et al.: Oxidative stability and quality of raw Saanen and Alpine goats milk 638 Alpenziegen, positiv war bei den Saanenziegen die Beziehung zwischen dem TBARS-Wert und dem Eiweiß-sowie SCC-Gehalt. Der höhere SCC-Gehalt war möglicherweise die Ursache für eine höhere Erzeugung von sekundären Oxidationsprodukten verursacht durch die Superoxiddismutase und den im Euter vorhandenen polymorphkernigen Granulozyten oder anderen Enzymen die an der Oxidation der Milchinhaltstoffe teilnehmen. Energiemangel und Eiweißüberschuss in der Ernährung von Milchziegen verursacht möglicherweise die höhere Lipidmobilisation und folglich die Erhöhun...

Nitrite and catalase levels rule oxidative stability and safety properties of milk: a review

“…59 However, in this review we provided evidence that formation of oxidatively modied products in milk could also result from the formation of NO 2 c during udder inammation, and thus it is more likely an explanation for the formation of rancid avor in large volumes of bulk milk. This conclusion is based on research carried out mainly in one laboratory, but it is substantiated by certain publications: the study of Marenjak et al 60 showed that low-quality milk (i.e., with high somatic cell count) contains more Lpx than high-quality milk and in the study of Mannello et al 61 it was found that nipple-aspirated uid collected from breast cancer women contains increased content of carbonyls on proteins, which suggests that oxidative stress in the mammary gland is involved in the etiology of the disease. The study of Bhat et al 62 sustains our ndings 21 that the content of Lpx and carbonyls may increase during milk storage.…”

Changes in superoxide dismutase activity postpartum from Laoshan goat milk and factors influencing its stability during processing

“…Kiyosawa et al (2014) have reported that the SOD activity in milk during storage in the refrigerator (at <5 C) decreased rapidly with storage time and fell to 40% of that of fresh skim milk after 5 days. And, it is also reported that the SOD activity were significantly higher 14 h after the collection and cold storage in both breeds of dairy goats with no difference between the breeds (Marenjak et al 2009). In the milk kept in the freezer (À80 C) for 10 days, the SOD activity did not change in comparison with that of fresh skim milk (Nagasawa et al 1972).…”

Milk urea concentration as a tool for optimising crude protein content in dairy goat diets: a path to sustainable milk production

“…MU concentration is influenced by numerous environmental factors such as stage of lactation, parity, season, productivity, and milking time (Schepers and Meijer, 1998;Giaccone et al, 2007;Abdouli et al, 2008), but the most important factors affecting urea formation remain the amount of crude protein intake from the diet and the ratio of crude protein intake to energy, as well as the ratio of degradable and non-degradable proteins in the rumen (Marenjak et al, 2004;Bonanno et al, 2008).…”