Journal article

Publication year: 1979

Pages: 165-187

Journal: Zeitschrift für Acker- und Pflanzenbau

Volume number: 148

Issue number: 3

ISSN: 0044-2151

Publisher: Parey

Abstract: 
There is a clear increase in crude protein in germinating wheat grain. This is analogous to the respiration losses in N-free substances. The absolute crude protein amounts scarcely change. After 84 h germination the crude protein in the total grain dry weight (grain residue + germ) was raised relatively to 110; after 132 h raised the relatively to 124 (as compared with ungerminated 11.2%, dry matter = 100). After 132 h of germination the residue of the grain still made up 51% and the germ 28% of the original grain dry weight. The crude protein content was then 9% of the dry weight in the grain residue, 22.8% in the germ and 13.9% of the total grain dry weight. As germination progressed the absolute values of total sol N (water sol + salt sol + alcohol sol + alkali sol fraction) per 10 g grain dry weight did not increase despite the increased crude protein content. Relative to total protein, it clearly decreased because the nonsoluble fraction of the total crude protein increased. With increasing time of germination the proportions of the reserve protein fractions of total soluble N decreased strongly. The prolamine fraction decreased from 24% at 0 h germination time to 13% at 84 h to 5% at 132 h. The glutenin fraction fell from 39 to 25 to 21% over the same period. At the same time the water soluble fractions (albumins + non precipitable N compounds) increased greatly from 24 to 49 to 64%. The increase in the non precipitable fraction (free amino acids and amides, etc.) was considerably greater than this. The salt soluble globulin fraction altered in the early germination stages but only slightly in absolute and relative terms to the other fractions. The newly formed enzyme globuline was only slightly observable in quantitative terms. With progressing germination the amino acid fractions of the protein of the total grain changed greatly as well as the amino acid in the individual protein fraction. A consistant amino acid composition during germination was not found. Not only did the proportion of the individual fractions change but so also did the amino acid distribution within the fraction, especially in the more rapidly broken down reserve proteins. With increasing germination time the amino acids glutamic acid and proline decreased strongly in the total grain protein hydrolysates by corresponding changes in the germ and the residual grain, and in their relations to one another. Histidine, serine and methionine did not change greatly. The contents of aspartic acid, lysine, threonine, valine, isoleucine, phenylalanine and glycine were all greatly increased. The changes in the amino acid fractions after 84 h germination expressed in total grain protein and in the individual protein fractions are given as well as the contents in the residual grain and in the grain germ after 132 h germination. An increase in the lysine content in the total protein of the wheat grain after 84 h germination to a relative value of 138 (ungerminated = 100) was established. This is stressed in relation to the lysine conditioned limitation of the biological value of wheat protein (marked new formation of lysine in the course of the germination process).

Harvard Citation style: JAHNDEESBACH, W. and SCHIPPER, A. (1979) CHANGES IN THE PROTEIN-COMPOSITION OF WHEAT GRAINS DURING GERMINATION, ZEITSCHRIFT FUR ACKER UND PFLANZENBAU-JOURNAL OF AGRONOMY AND CROP SCIENCE, 148(3), pp. 165-187

APA Citation style: JAHNDEESBACH, W., & SCHIPPER, A. (1979). CHANGES IN THE PROTEIN-COMPOSITION OF WHEAT GRAINS DURING GERMINATION. ZEITSCHRIFT FUR ACKER UND PFLANZENBAU-JOURNAL OF AGRONOMY AND CROP SCIENCE. 148(3), 165-187.