The effect of softness genes on the biscuit-making quality of soft wheat

English: The purpose of this study was firstly to determine the segregation ratios of softness genes in this particular genetic background. * Secondly, the effect of these softness genes on bisquit-making quality had to be determined. * A soft, white wheat cultivar was crossed with a hard red wheat cultivar. * The soft white wheat cultivar had the ability to produce biscuits with an acceptable diameter while the hard red wheat cultivar had agronomic qualities that rendered it suitable for production in the Northern Cape irrigation area of Southern Africa. * Soft wheat kernels were selected from the progeny using a microtome and micron settings as an indication of kernel softness. * Micron settings were used as an indication of kernel softness. Soft textured kernels had a setting of seven micron or higher. Hard textured kernels had a setting of between one and six micron. * The selected soft kernels were agronomically reconstructed to the hard red wheat cultivar for three generations, using the backcross method. Results showed that kernel softness is determined by a single locus and two alleles, with the dominant gene determining kernel softness. The two near-isogenic lines that differed with regard to kernel texture, were evaluated for milling and baking qualities. * The genes for kernel softness had no effect on dough strength as measured by the mixogram. * The stability and dough strength as measured by the alveogram were significantly influenced by the genes for kernel softness. The AWRC was significantly lower in soft wheats. * The genes for kernel softness significantly increased biscuit diameter. * Break flour yield was highly correlated with biscuit diameter (r = 0.835), while the percentage flour protein (r = -0.797) and mixing time (r = -0.695) were significantly negatively correlated with biscuit diameter in the soft group. * In the group with hard kernels, alveograph strength (r = -0.795) and AWRC (r = -0.713) showed a significantly negative correlation with biscuit diameter. * The stepwise regression on biscuit diameter within the soft group showed high variances for flour extraction, break flour and alveograph strength. Within the hard group, high variances were found for flour protein, flour extraction, break flour and mixing time.