Faculty of Natural and Agricultural Sciences
School of Agricultural and Food Sciences
Department of Food Science
Selected Highlights from Research Findings
One limitation to the use of sorghum as a food is that its proteins become less digestible when cooked wet. This is caused by the formation of disulphide-linked enzymatically resistant protein polymers. Research findings indicate that gamma-irradiation of sorghum flour before cooking can alleviate this reduction.
Gamma-irradiation cleaves disulphide and hydrogen bonds that stabilize kafirin protein structure to give a more open protein network. This exposes additional peptide bonds to proteolysis to give a better digestibility. Gamma-irradiation of sorghum flour at 10 kGy has the potential to produce safe, more digestible nutrient-dense weaning sorghum porridges. Prof A Minnaar
Food Science
+27 (0) 12 420 3239
amanda.minnaar@up.ac.za
Long cooking times is one of the most important factors limiting the utlisation of cowpeas. Micronisation is an infra-red heat treatment where moisture conditioned grains and legumes are exposed for a short time to electromagnetic radiation (1.8 to 3.4 um). Research findings indicate that micronisation of pre-conditioned cowpeas to a surface temperature of 153 °C significantly reduced their cooking time.
Micronisation physically produces fissures in the cowpea seed coats and cotyledons, which leads to improved water uptake properties, a softer texture and increased percentage of splits during cooking. The treatment also pre-gelatinises the starch and denatures the cowpea protein.
When whole seeds are required in the cooked product of course varieties that are susceptible to splitting during cooking would also not be appropriate for micronisation processing.
Prof A Minnaar
Food Science
+27 (0) 12 420 3239
amanda.minnaar@up.ac.za
|
