DEAR DR. BLONZ: Is there any nutritional advantage to goat's milk over cow's milk? What about those who are allergic to cow's milk, or who are lactose-intolerant? -- T.R., La Jolla, California
DEAR T.R.: All things considered, it is a bit of a wash. Goat's milk has a bit more protein, fat, potassium, calcium and magnesium than cow's milk, and even a small amount of vitamin C. But there is less vitamin B12, folate, selenium and riboflavin.
There are differences in taste, but most people are able to digest cow's milk and goat's milk with equal ease. A few may find the softer curd of goat's milk easier on the stomach. Both milks have comparable levels of lactose, but because they are from different animals, their proteins will not be identical.
If you are thinking of trying goat's milk because you're allergic to cow's milk, start with a small amount. There have been cases, especially in young children, of cross-reactions among different types of milk. In other words, a child with an allergy to cow's milk may also react to goat's milk, even without any previous exposure to it.
DEAR DR. BLONZ: When you fry or scramble your eggs, do you destroy more protein than if you were to poach them? I have heard this and wonder if it is true. Also, what goes on during the cooking of the egg white? -- G.G., Berkeley, California
DEAR G.G.: Bottom line first: As long as you do not overcook your eggs, there is no evidence that frying or scrambling will destroy significantly more protein than poaching.
As for egg whites: They are a great source of high-quality protein. Think of individual protein molecules as long chains of amino acids; when viewed three-dimensionally, those in an egg are folded among themselves like crumpled strips of paper. Raw egg white is almost 90 percent water by weight, and the proteins are suspended in the clear, viscous liquid.
When heated, protein globules tend to uncoil a bit. This step helps our digestive process, as it makes it easier for our protein-digesting enzymes to get at the protein and break it into individual amino acids -- a necessary step prior to absorption. Heated egg proteins begin to interconnect, and when this happens, the egg white becomes solid and opaque. Water remains at first, but as more and more heat is applied, the water eventually gets squeezed out and the egg white takes on a harder, eventually rubbery, texture.
The idea, of course, is to cook the egg without overdoing it. Poaching takes place at or below 212 degrees F, the boiling point of water. Frying takes place at higher temperatures: at or slightly above 250 degrees F. Excessive heat from overcooking can destroy any protein. It makes sense that there would be a greater risk of overdoing it with frying or scrambling than with poaching, but the temperatures at which eggs are normally prepared would not be high enough to cause any significant protein destruction.
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