Effects of environmental factors on protein content and composition in buckwheat flour

Abstract

The effects of environmental conditions (year, growing site) on protein compounds in buckwheat (Fagopyrum esculentum Moench) were studied. Small-plot experiments with four buckwheat cultivars (tetraploid Emka and diploid Kora, Pyra, and Krupinka) were established in two growing sites in 1999 and 2000. Crude and pure protein content, proportion of protein solubility fractions, SDS-PAGE of protein fractions, and immunoassay of gluten-like proteins were determined in buckwheat flour. The growing site had the most significant effect on variability of crude protein content. On the contrary, pure protein content was most of all affected by year. Apparently a higher occurrence of later developed buckwheat seeds in 1999 harvest (as a consequence of weather abnormalities) could generally cause lower content of pure protein in this year (7.32 %) than in 2000 (9.10 %). Alcohol-soluble protein fraction (prolamins like proteins, PLP), considered as inconvenient for gluten-free diet, was generally found at low level, but at the average of experiment, signifícant differences (P < 0.05) between years 1999 and 2000 were recorded, 2.12 and 5.37 % of crude protein, respectively. On the other hand, specific determination of harmful gluten-like proteins (GLP) by immunochemical assay (ELISA) revealed, that in the all tested samples their contents were below the detection limit of the method 12.5 mg.kg^-1. Obtained SDS-PAGE subunit profile of AGLP was divided into four groups with range of molecular weight 5-51 kDa. PLP profile was only represented by a double-band with 17 kDa and by a band with molecular weight of about 8 kDa.