sorghum as a world food grain. Research in the 1980s has demonstrated that the genes controlling tannin production can be reduced through crossbreeding. Tannins can be eliminated or at least reduced to negligible quantities. White-seeded, tannin-free types are known and are particularly promising for the future.
Removing tannins makes sorghum a far better food for humans, but in parts of Africa, unfortunately, it would seem also to be good for the birds. However, some white-seeded types that are both tannin free and shunned by birds are already available.
Two sorghums that are bird resistant and free of tannin were identified in 1989.6 These two genotypes (Ark 1097 and a Brazilian hybrid) were assayed and found to contain absolutely no tannin throughout the whole time their seeds were developing. In addition, both showed good bird resistance in trials in Indiana, USA. In Puerto Rico, where bird pressure is greater, each was damaged, but only in one of two replications; in the other, it remained untouched. All in all, these white-seeded, tannin-free genotypes appear to be slightly less bird resistant than the standard, strongly resistant, high-tannin types. Nonetheless, the level of resistance was enough that these sorghums can be very useful in areas where bird damage is normally severe.
The nutritional quality of these two is not yet fully determined, but all indications are that both are fully comparable to the low-tannin (bird-susceptible) sorghums. In a feeding trial, for example, laboratory rats grew much faster and showed more efficient feed utilization than the (high-tannin, bird-resistant) control. Remarkably, they were even better than the low-tannin types. Indeed, there were no apparent nutritional problems associated with consuming the grain.
Trials of these sorghums are under way in Kenya.
The starches in the grains of most sorghums have gelatinization temperatures around 70°C. They must reach that temperature to become cooked and edible. However, research has shown that some sorghums have starches whose gelatinization temperature is only about 55°C. This can reduce the cooking time required. These sorghums have waxy kernels (endosperm) rather than hard vitreous ones. Thus,