The Egg-Replacement Value of the Proteins of Cereal Breakfast Foods, with a Consideration of Heat Injury

Abstract

A 10-week diet experiment on ten young men was carried out in 5-day periods in order to compare the nutritional value of the proteins of seven cereal breakfast foods with egg protein. Diets contained 5% of the calories in the form of protein, approximately 45% in the form of carbohydrate and 50% in the form of fat. Egg or cereal protein supplied 78% of the total nitrogen, cream and butter 11% and fruit and other accessory foods such as lettuce and a vitamin B complex tablet the remaining 11%. Cereal protein alternated every 5 days with egg protein. One half of the diet squad ate the cereals in a certain order, the other half in reverse order. This served to balance whatever progressive change in the tendency to retain nitrogen might result from long-continued sustenance on low protein. The average level of nitrogen intake for all subjects was 5.92 gm., the egg period always equalling the following cereal period. Replacement of egg protein by cereal protein is calculated by dividing the difference in nitrogen balance on the two diets by the amount of egg nitrogen fed. This difference expressed as a percentage is then subtracted from 100 to find the extent (in percentage) to which cereal replaces egg. ‘Biological value’ also was calculated taking egg as standard. The difference between fecal nitrogen on cereal and egg is subtracted from food nitrogen to give ‘absorbed nitrogen.’ The difference between cereal and egg urinary nitrogen then is found and expressed as a percentage of the absorbed nitrogen. This value subtracted from100 gives (as a percentage) the extent to which the cereal protein absorbed replaces egg protein in the metabolism of the body. A whole grain oats had the highest replacement and ‘biological’ values, 87 and 98, respectively. A wheat endosperm product gave the next highest R.V. (72) followed by a granulated ‘whole wheat’ supplemented with wheat germ (70), torn (shredded) whole wheat (68), toasted ‘whole’ wheat (64), flaked whole wheat (63) and inflated (‘puffed’) wheat (57). In the B.V. scale, oats was followed by the torn wheat (92.8), toasted ‘whole’ wheat (90), granulated wheat (88.7), flaked wheat (82.1), inflated wheat (79.8) and wheat endosperum (79.7). The lower rank of the flaked and inflated whole wheats in both scales is believed to be accounted for by the high heat to which they are subjected in the process of manufacture. Digestibility was not diminished.