However, its effect as a bacteriostatic mechanism in milk is probably negligible lactoferrin- an iron bind ing protein that sequesters iron from microorganisms, thus taking away one of their growth factors. Its effect as a bacteriostatic mechanism in lactoperoxidase- an enzy me naturally present in raw milk that catalyzes the conversion of hydrogen peroxide to water. When hydrogen peroxide and thiocyanate are added to raw milk, the thiocyanate is oxid ized by the enzyme/ hydrogen peroxide complex producing bacteriostatic compounds that inhibit Gram negative bacteria, E coli, Salmonella spp, and streptococci. This technique is being used in many parts means of increasing the shelf life of raw mif r raw milk is not readily available, as a of the world, especially where refrigeration fo Milk biosynthesis Milk is synthesized in the mammary gland. Within the mammary gland is the milk producing unit, the alveolus. It contains a single layer of epithelial secretory cell surrounding a central storage area called the lumen, which is connected to a duct system The secretory cells are, in turn, surrounded by a layer of myoepithelial cells and blood The raw materials for milk production are transported via the bloodstream to the secretory cells. It takes 400-800 L of blood to deliver components for 1 L of milk Proteins: build ing blocks are amino acids in the blood Casein submicelles may gin aggregation in golgi vesicles within the secretory cell Lipids o C4-C14 fatty acids are synthesized in the cells o C16 and greater fatty acids are preformed as a result of rumen hydrogenation and are transported directly in the blood Lactose: milk is in osmotic equilibrium with the blood and is controlled by lactose K, Na, Cl; lactose synthesis regulates the volume of milk secreted The milk components are synthesized within the cells, mainly by the endoplasmic reticulum(ER) and its attached ribosomes. The energy for the er is supplied by the mitochondria. The components are then passed along to the golgi apparatus, which is responsible for their eventual movement out of the cell in the form of vesicles. Both vesicles containing aqueous non-fat components, as well as liquid droplets(synthesized by the er) must pass through the cytoplasm and the apical plasma membrane to be deposited in the lumen. It is thought that the milk fat globule membrane is comprised of the apical plasma membrane of the secretory cell Milking stimuli, such as a sucking calf, a warm wash cloth, the regime of parlour etc causes the release of a hormone called oxytocin. Oxytocin is relased from the pituitary gland, below the brain, to begin the process of milk let-down. As a result of this hormone stimulation, the muscles begin to compress the alveoli, causing a pressure in the udder 88 However, its effect as a bacteriostatic mechanism in milk is probably negligible. • lactoferrin - an iron binding protein that sequesters iron from microorganisms, thus taking away one of their growth factors. Its effect as a bacteriostatic mechanism in milk is also probably negligible. • lactoperoxidase - an enzyme naturally present in raw milk that catalyzes the conversion of hydrogen peroxide to water. When hydrogen peroxide and thiocyanate are added to raw milk, the thiocyanate is oxidized by the enzyme/ hydrogen peroxide complex producing bacteriostatic compounds that inhibit Gram negative bacteria, E. coli , Salmonella spp , and streptococci. This technique is being used in many parts of the world, especially where refrigeration for raw milk is not readily available, as a means of increasing the shelf life of raw milk. Milk Biosynthesis Milk is synthesized in the mammary gland. Within the mammary gland is the milk producing unit, the alveolus. It contains a single layer of epithelial secretory cells surrounding a central storage area called the lumen, which is connected to a duct system. The secretory cells are, in turn, surrounded by a layer of myoepithelial cells and blood capillaries. The raw materials for milk production are transported via the bloodstream to the secretory cells. It takes 400-800 L of blood to deliver components for 1 L of milk. • Proteins: building blocks are amino acids in the blood. Casein submicelles may begin aggregation in Golgi vesicles within the secretory cell. • Lipids: o C4-C14 fatty acids are synthesized in the cells o C16 and greater fatty acids are preformed as a result of rumen hydrogenation and are transported directly in the blood • Lactose: milk is in osmotic equilibrium with the blood and is controlled by lactose, K, Na, Cl; lactose synthesis regulates the volume of milk secreted The milk components are synthesized within the cells, mainly by the endoplasmic reticulum (ER) and its attached ribosomes. The energy for the ER is supplied by the mitochondria. The components are then passed along to the Golgi apparatus, which is responsible for their eventual movement out of the cell in the form of vesicles. Both vesicles containing aqueous non-fat components, as well as liquid droplets (synthesized by the ER) must pass through the cytoplasm and the apical plasma membrane to be deposited in the lumen. It is thought that the milk fat globule membrane is comprised of the apical plasma membrane of the secretory cell. Milking stimuli, such as a sucking calf, a warm wash cloth, the regime of parlour etc., causes the release of a hormone called oxytocin. Oxytocin is relased from the pituitary gland, below the brain, to begin the process of milk let-down. As a result of this hormone stimulation, the muscles begin to compress the alveoli, causing a pressure in the udder