Factors affecting the porridge-making quality in South African sorghums

Abstract

Research was undertaken to facilitate the breeding and selection of sorghums with both good milling and good porridge-making characteristics. Twenty seven cultivars were grown in the same locality under rainfed and supplementary irrigation conditions. The two measures of milling quality, abrasive hardness index and Brabender hardness (BH) were significantly correlated (P less than or equal to 0.001) in all sample sets; i.e. all data, rainfed samples and supplementary irrigation samples. The genetic basis of kernel hardness was confirmed as the hardest and softest cultivars were the same under both cultivation conditions. For all three sample sets there was a significant negative correlation (P less than or equal to 0.05) between kernel hardness according to BH and pasting peak viscosity (PPV). PPV is of importance as consumers prefer stiff porridges. The negative correlation between BH and PPV indicates that to select sorghum cultivars with good milling and good porridge-making quality, both kernel hardness and PPV need to be assessed. The sorghums produced under supplementary irrigation were softer according to BH, had higher PPV and set-back viscosity, and the starch contained a higher proportion of amylose than those produced under rainfed conditions. Thus, cultivation environment as well as genetics has a major effect on sorghum milling and porridge-making quality.