FOOD VALUE OF BREAD

Waikato Times, Volume 126, Issue 21043, 20 February 1940, Page 16

FOOD VALUE OF BREAD

DISCOVERIES OF RESEARCH RESULTS OF FLOUR MILLING Not everything is gold that glitters, and not everything is the staff of life that is labelled “Bread.” During the past thirty years many investigations have been made into the nutritive value of bread. As a consequence of the recent rapid development of chemical and biological work in food values, vitally important information has been published. The Division of Nutrition, Lister Institute, London, has probably said the last word on the subject in the article “The Nutritive Value of Wheaten Flour and Bread,” published in the Nutrition Abstracts and Reviews, Volume 8. Bread made from wheaten flour, states the Lister Institute, is one of the most widely distributed forms of food in existence, over a great part of the earth. Ever since the latter part of the eighteenth century, wheaten bread has been the staple food of the British people. Among the poorer people in particular, because of its high food value and relatively low cost, it has become the chief constituent of the diet. On the other hand, in a well-balanced diet containing ample milk, green vegetables and raw fruit, the food-value of the type of bread eaten is not of quite so much importance as in the poorer diets in which bread, with very little of the other essential foodstuffs, makes up the daily ration. What Milling Does In the process of flour-milling, the germ and the outer layers of the wheat berry are removed, and the endosperm is then ground down to a fine flour. From most wheats it is impossible to obtain a white flour containing more than 75 per cent of the finer elements; and the usual extraction of flour is 70 to 72 per cent. This type of flour, termed “standard grade” flour, is treated by various bleaching and other “refining” processes, and constitutes the greater part of the flour used by bakers in bread-making. By further milling, finer flours of lower extraction can be obtained, of approximately 60 to 42 per cent extraction. Some figures of the composition of wheat and flour are given in the following table:—

The process of milling does not affect the protein content of the flour to a very serious extent, or the carbohydrate content; but it does reduce the fat content, and the mineralash content falls very greatly. Although the proportion of protein in wheat is not seriously altered in flours prepared from it by various degrees of milling, experimental studies of the nutritive or biological value of the protein of whole wheat, as compared with that of various flours milled from it, show that the protein of white flours is to some extent inferior for growth and maintenance of the animal organism. The nitrogen balance of the organism is controlled by its nitrogen intake. A perfect protein should, of course, approach a biological value of 100. In 1932 and 1934, experiments showed a biological value of 68 for whole wheat, and a value of 61 for white flours.

Percentages of Whole Standard Wheat Grade Carbohydrate 74.7 72 Protein 12.6 14 Fat 2.3 2 Mineral Ash 1.8 0.5 Water 8.5 15