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In the general framework of a program to improve the local production of common wheat by the Lebanese State, we have characterized the rheology of different bread wheat cultivars selected for their adaptation to semi-arid weather conditions. After a biochemical characterization [i.e. synthesis and accumulation of the major constituents of the grains (mainly storage proteins and starch)] of the plant material selected in a previous work, the main technological behavior of the flour that resulted from these grains and associated with bread-making properties was evaluated in the present study. Despite the selection of the plant material used in this study, the results demonstrate that environmental conditions inducing limitations in reserve accumulation [i.e. high gliadin content, very high level of polymerization/aggregation of polymeric prolamins, significant increase in the amylopectin/amylose ratio, modifications in the distribution of starch granules (A-type vs. B-type)] during grain filling affected the rheological behavior. The studied flours showed high wet and dry gluten contents, high Zeleny values, and a low gluten index value. They also showed high extensibility on the alveograph and extensograph and elevated dough strength on the farinograph, as well as great water absorption. Furthermore, flours of the studied cultivars did not express their optimal rheological potential in spite of their favorable glutenin subunit composition.

To support the introduction of local soft wheat varieties, the Lebanese state has implemented, during recent years, an improvement program to select plant material with good productivity in semi-arid conditions that can lead to national production that can, at the same time, meet quality needs expressed by Lebanese processors. In the present study, the main biochemical components of grains conventionally associated with bread-making properties (storage proteins, starch polysaccharides) were physiochemically characterized for a panel of local soft wheat varieties selected. During the two consecutive years of cultivation, the post-flowering thermal constraints significantly modified the kinetics of accumulation of the major constituents by mainly limiting the grain filling time. The level of polymerization/aggregation (i.e., gliadin/glutenin ratio, unextractable polymeric protein (UPP) amount, molecular weight average of glutenins) of prolamins was very high. The reduction in the amount of starch was accompanied by a significant change in the amylopectin/amylose ratio. Finally, the genotypes studied were characterized by significantly different distributions of starch granules; the percentage of the volume occupied by A-type and B-type starch granules varied between genotypes for the two cropping years. All these observations must be considered because of their determining role in the technological aptitude of the flours generated.