| Abstrakt: |
Sixteen wheat cultivars originating from different countries and genotypes and characterised by different technological properties were analysed for the amount and proportion of ω- and α-type and γ-type gliadin subgroups. The optimal extraction of gliadin from flour was achieved with 60% (v/v) aqueous ethanol after pre-extraction with a salt solution. The separation and quantitative determination was performed by reversed-phase high-performance liquid chromatography on C18 silica gel. The amount of both total gliadin and subgroups revealed distinct inter-cultivar differences. Within the subgroups, the α-type gliadins were generally present in greatest amount, followed by the γ-type gliadins, whereas the ω-gliadins were present at lower levels. A strong statistical relationship was found between the protein content of the flours and the amounts of total gliadin, α-type and γ-type gliadins. Other flour properties (baking volume, SDS-sedimentation volume, dough resistance and extensibility) were correlated only weakly with gliadin contents, with only ω1,2-gliadins and γA-gliadins showing moderate negative and positive effects, respectively. The proportions of ω- and α-type and γ-type gliadins found within the total gliadin fraction covered broad ranges (α: 43·9-59·9%, γ: 30·5-45·6%, ω: 6·2-20·0%). The proportions of the gliadin subgroups were to some extent related to the genotype of the cultivar. Thus, high proportions of ω-gliadins (17-20%) were typical for wheat/rye hybrids. In view of the inter-cultivar variation observed, the value of immunochemical assays developed for the analysis of total gliadin in food is restricted if the reactivity of the antibodies used is not directed to all types of gliadin components but to the minor subgroups of ω-gliadins. Copyright 1994, 1999 Academic Press |
