Distribution of thiamin (Vitamin B1) and fat in wheat grain

Authors

• L. H. Pulkki OTK Flour Mills, Helsinki
• K. Puutula OTK Flour Mills, Helsinki

DOI: https://doi.org/10.23986/afsci.71186

Abstract

The chief purpose of the experiments has been to find out the thiamin content of the different parts of wheat grain. Special attention has been paid to the relation of the thiamin and fat content in germ, in the outer bran tissues, and in flours of different grades. On comparing the yeast fermentation method and thiochrome method with each other the former gave 45 to 85 per cent higher values for thiamin than the latter. The results presented in this paper were obtained by using the thiochrome method. All thiamin, as well as crude fat, ash, and fiber contents are given on dry basis. 70 to 80 per cent of the thiamin contained in wheat is concentrated in the germ end of the kernel. In analysis there were obtained the following contents for the germ preparations separated in a special way; ash 5.6 & 5.7 %; thiamin 35.1 & 35.0 μg/g; fat 18.8 & 15.8 % (the corresponding figures of whole kernel; 1.8 & 2.0 %; 3.9 & 3.5 μg/g; and 2.0 & 2.0 %). The thiamin content of the germ preparation was accordingly 9 to 10 times and the fat content 8 to 10 times greater than that on whole kernel so that the relation of the thiamin and fat contents in the germ preparation was about the same as in whole kernel. The content of ash, on the contrary, vas comparatively much lower in germ. The thiamin content of the outer bran tissues of wheat is very low. A small quantity of bran containing thiamin only about a quarter (0.9 μg/g) of the amount contained in whole kernel (3.8 μg/g) was separated with a scouring apparatus of simple construction. It was further possible to separate material about 7 per cent of the weight of grain from its surface without more than 7 per cent decrease in the thiamin content; while the decrease in the fiber content was greater by far (about 40 per cent). The relation crude fat/thiamin is greater in bran tissues than in whole kernel. Analytical data are given of milling products and a series of flours of a commercial mill which was obtained by mixing mill streams in an order according to the ascending ash content. The possibility to control the amount of thiamin in commercial flour and its physiological value on the ground of the ash and fat contents is discussed. On the ground of the fat analysis it is to some extent possible to decide whether the vitamin or mineral substances found in flour has come into it »in a natural way» i.e. as a result of a high rate of extraction, or if a remarkable part of the nutrient in question has been added into it.