Composition and properties of oat grain and straw

Abstract

1. In the comparatively humid climate, of the west of Scotland, the water content of oat grain, threshed soon after harvest, amounting, as a rule to between 16 and 18 %, fell, during storage, to between 12·0 and 14·5 %. Grain grown in the drier climate of the south of England and Wales contained on an average 12·2 % compared with 14·4 %. The weight of stored grain varied to a certain extent according to the hygrometric condition of the atmosphere. The maximum variation amounted to between 4 and 5 % of the initial weight of the grain.In addition to the usual analytical data, it was found to be of great advantage, in connection with each sample of grain examined to keep a record of, date of threshing and date of analysis, proportion of whole grain, weed seeds, husk, etc., average weight of 1000 grains, height above sea-level, type of soil, length of growing period, rainfall, previous cropping and manuring, condition of the crop.2. Between 11 and 12 % of the fatty substances in the oat kernel is present in the germ (embryo), the remainder is principally in the aleurone layer. The amount of extractable substances varied according to the solvent employed, ether and petroleum ether yielded the smallest and alcohol the largest extract. From 88 to 96 % of the total, was dissolved out by different solvents, in a five hour extraction. With repeated five hour extractions, ether still gave a small residue in the sixth extract. All the extracts contained finely divided solid matter in suspension, which could be made to separate out as a yellow residue and it amounted to between 0·25 and 6 % of the ether extract.The extracts were found to be slightly higher from “air dry” meal and ordinary ether compared with “dry” meal and dry ether.Free fatty acids were almost absent in the oil from freshly ground kernel, but afterwards they rapidly increased and in 24 days, calculated as oleic acid, they formed over 55 % of the extract. Drying the grain such as is done in the manufacture of oatmeal, had the effect of slowing down the rate of hydrolysis of the fat, but the amount of acid finally liberated was the same.