Nutrients in Milk
Posted by in Milk on July 13, 2011
Lactose
It is the principal and typical carbohydrate of milk, known as milk sugar. Glucose, galactose and other sugars such as oligosaccharides are also present in traces. Lactose exists in true solution in milk. It is a disaccharide, composed of two molecules of monosacharides; glucose, and galactose. Lactose is readily fermented by the lactic acid fermenting bacteria producing lactic acid and has significance in milk and milk products. It exists in two isomeric forms, designated as α and β forms of which the β form is more soluble than the alpha form in water. Lactose content of cow milk is 4.9 percent. The lactose content of milk is inversely proportional to the ash content of the milk. Udder infection promotes an increased level of chloride in the milk and depresses the secretion of lactose.
Proteins
Milk protein is a rich source of essential amino acids. Whey proteins are proteins that are passed along with the whey portion after the coagulation of milk. They contain 51% essential amino acids when compared to 45% in casein. The sulphur containing amino acids, which are considered essential and important, are found in higher concentration in whey protein than in casein. Usually the quality of egg proteins are regarded as very high. But the net protein utilization, biological value and the protein efficiency ratio of milk protein come neck in neck with the quality of egg protein. Lactalbumin, a whey protein , whose biological value, net protein utilization and protein efficiency ratio is considered superior when compared to the major milk protein, casein. Normally double the quantum of vegetable protein is required to meet the daily requirement of essential amino acids when compared to that obtained from the milk proteins.
Casein
May be defined as the major protein, which is precipitated at pH 4.6 and is exclusive to milk. It is present in spherical bodies as micelles, which vary in size with negative surface charge. The caseins of milk may be sub-divided into five main classes, αs1, αs2, β, gamma and k-caseins. In milk, casein is present in combination with calcium in the form of calcium caseinate or more precisely calcium hyhdrogen caseinate.
Whey proteins
Are those in the whey fraction, after the precipitation of casein at pH 4.6. These are the alpha-lactalbumin, beta-lactoglobulin, immunoglobulins, lactoferrin, transferrin, proteose-peptone fractions etc. Most of these are globular proteins subject to heat denaturation. α-lactalbumin exists in variants A and B forms and is susceptible to denaturation by unfolding of the tertiary structure. β-lactoglobulin is identical to blood globulin and insoluble in water and is responsible for the transfer of antibodies. Normal milk contains 0.1%, whereas colostrum contains 6 %. Read the rest of this entry »
Cow’s Milk and Constipation in Children
Posted by in Milk on July 13, 2011
Cow’s Milk: Cause Of Constipation?
I did not associate cow’s milk consumption with constipation until this week. My daughter started complaining of stomach cramps and this went on for four days. She would crumple up in agony. It was very strange because there was no vomiting or diarrhea and she hadn’t eaten anything unusual or that she was allergic to. Or so I thought.
I drink milk myself, and it tends to have a laxative effect on me. It was only after a trip to the local GP and another to the hospital that I learned the cause of her trouble might be cow’s milk. Apparently, cow’s milk may cause constipation in young children.
The connection never occurred to me because I thought milk would have a laxative effect rather than the reverse. After all, this is what happens with me. I thought if my daughter was at all intolerant to milk, it should manifest as diarrhea instead of constipation.
Evidence Of Link Between Cow’s Milk And Constipation
I researched the subject and came across an interesting study done at a university in Italy in 1998. It involved 65 children with chronic constipation who had been prescribed laxatives after dietary changes had failed to cure the constipation. Each child received either cow’s milk or soy milk for two weeks, had a rest week, then for the next two weeks had the other milk that they didn’t get the first time. When the results were analyzed, it was discovered that while they were on soy milk, 68% of the children were no longer constipated. In contrast, their conditions remained the same when they were on cow’s milk.
Dr Alan Greene of DrGreene.com suggests that it could be the protein in cow’s milk that is at the root of the problem, and that switching to soy milk can dramatically improve the quality of life of a child suffering chronic constipation. Read the rest of this entry »