Biological value measures protein quality by calculating the nitrogen used for tissue formation divided by the nitrogen absorbed from food. This product is multiplied by 100 and expressed as a percentage of nitrogen utilized. The biological value provides a measurement of how efficient the body utilizes protein consumed in the diet. A food with a high value correlates to a high supply of the essential amino acids. Animal sources typically possess a higher biological value than vegetable sources due to the vegetable source’s lack of one or more of the essential amino acids. There are, however, some inherent problems with this rating system. The biological value does not take into consideration several key factors that influence the digestion of protein and interaction with other foods before absorption. The biological value also measures a protein’s maximal potential quality and not its estimate at requirement levels.
Here is a great review of BV and other measures of protein.
*disregard parts of paper saying ketosis and protein is bad I was more interested in the measures of quality protein.
wo substances in raw eggs have been shown to block nutrient availability. Conalbumin is a protein that can bind together with iron and block its availability. Avidin is a second egg protein that can bind together with biotin (a B-vitamin) and make it unavailable.
The cooking of eggs helps denature both of these proteins, and can increase the availability of both iron and biotin from eggs. Of course, another reason for cooking eggs involves health safety. The U.S. Centers for Disease Control and Prevention estimate that 1 of every 20,000 eggs may be contaminated with the bacterium Salmonella, which is actually passed from the infected hen to the egg before the shell is formed.
The nutritional and healing properties of vegetables are in special need of your help when it comes to proper cooking technique! Here are our six cardinal rules for preserving the power of vegetables:
Don’t pre-soak vegetables to make them tender. REASON: nutrients that dissolve in water can be lost by pre-soaking.
Cook vegetables in as little water as possible. REASON: nutrients that dissolve in water are less likely to be lost.
Leave vegetables in contact with water for as little time as possible. REASON: nutrients that dissolve in water are less likely to be lost.
Balance heat and water contact. If you use high heat, keep water contact at a minimum, either by steaming, or baking in a dry oven. If you use low heat, you can allow more water contact. For example, simmering is okay because you bring the water to a boil and then turn down the temperature. But never boil on high heat with direct water contact for more than a few minutes. REASON: nutrients that dissolve in water are less likely to be lost.
Use the Color Power test: when vegetables become more vivid in their colors, with brighter greens and yellows and reds, the power of the vegetables is being enhanced. When the colors begin to pale or become lost, the power is also being lost.
Think tender, not soft. Tender is what your digestive system needs with several types of vegetables, especially those with tough stems and stalks. But soft almost always means less healing power.
Protein and mineral content is relatively stable in red meat, regardless of how you cook it. Vitamins, however, are often affected by cooking methods. Water-soluble vitamins, such as the B vitamins, tend to be the most affected by cooking methods, but fat-soluble vitamins, including vitamin E, can sometimes be affected.
Water-soluble vitamins can drop due to high temperatures, long cooking times, cooking in an alkaline solution or cooking in water. Fat-soluble vitamins can leach out of your red meat if you cook the meat in large amounts of fat. Choosing cooking methods that minimize these conditions will result in meat with the most nutrients.
One of the best cooking methods for red meat if you want to minimize vitamin losses is stir frying, according to the European Food Information Council. Stir frying uses only small amounts of oil and liquid and involves short cooking times, although sometimes the temperatures used are a bit high.
Understanding how microwaves work can help clarify the answer to this common question. Microwave ovens cook food with waves of oscillating electromagnetic energy that are similar to radio waves but move back and forth at a much faster rate. These quicker waves are remarkably selective, primarily affecting molecules that are electrically asymmetrical — one end positively charged and the other negatively so. Chemists refer to that as a polarity. Water is a polar molecule, so when a microwave oven cooks or heats up food, it does so mainly by energizing — which is to say, heating up — water molecules, and the water energizes its molecular neighbors.
In addition to being more selective, microwave-oven energy is also more penetrating than heat that emanates from an oven or stovetop. It immediately reaches molecules about an inch or so below the surface. In contrast, regular cooking heat goes through food rather slowly, moving inward from the outside by process of conduction.
Some nutrients do break down when exposed to heat, whether it is from a microwave or a regular oven. Vitamin C is perhaps the clearest example. So, as a general proposition, cooking with a microwave probably does a better job of preserving the nutrient content of foods because the cooking times are shorter.
As far as vegetables go, it’s cooking them in water that robs them of some of their nutritional value because the nutrients leach out into the cooking water. For example, boiled broccoli loses glucosinolate, the sulfur-containing compound that may give the vegetable its cancer-fighting properties as well as the taste that many find distinctive and some, disgusting. The nutrient-rich water from boiled vegetables can be salvaged and incorporated into sauces or soups.
Is steaming vegetables better? In some respects, yes. For example, steamed broccoli holds on to more glucosinolate than boiled or fried broccoli.