Couscous quality and agronomic performances in relation to phenotypic recurrent selection in sorghum improvement

Abstract

Parameters affecting couscous quality were evaluated. Considering sorghum and millets, significant differences were found for milling ability, product color and chemical analysis. Millet products exhibited a higher degree of starch gelatinization than sorghum products. Couscous yields were similar for both species but millet flour tended to cook more uniformly than sorghum flour. Milling procedures were a pertinent source of variation. Traditional milling produced finer flour giving more couscous with lighter color. This result was confirmed by using different flour fractions of the same cultivar. Fine flours absorbed more water and yielded more couscous than coarse flours. Traditional milling did not damage starch more than mechanical milling. But finer flours (over sieve #80 and PAN), produced greater values for enzyme susceptible starch and also amount of overs. Non-normal endosperm types, waxy and heterowaxy, were not suitable for couscous preparation. Endosperm texture was the most critical variable among normal type cultivars. Environmental effect was significant on milling yield but did not affect couscous yield among cultivars when cooking was made with the same amount of flour. Relationships between couscous quality parameters and agronomic performances were mainly explained in terms of kernel characteristics: milling yield, test weight, and kernel hardness. Phenotypic recurrent selection was effective on milling yield. Successful breeding for couscous quality and grain yield can be achieved only at intermediate levels of selection.