Effect of heat-treatment and defatting on the proximate composition of some Nigerian local soup thickeners

A comparative study of the effect of heat-treatment and defatting on the proximate composition of melon seeds (Colocynthis citrullus Linn.), dikanut seeds (Irvingia gabonensis) and cocoyam tuber (Colocasia esculenta), mostly used now as conventional soup thickeners in southern Nigeria, was carried out. There was generally no significant difference in proximate composition between raw and heat-processed samples at the 5% level (P = 0.05). In raw and defatted samples, the level of protein in melon seeds was 59.4% higher than in dikanut seeds and 90.3% higher than in cocoyam tuber; but in heat-processed and defatted samples, the protein level in melon seeds was 56.9% higher than in dikanut seeds and 87.5% higher than in cocoyam tuber. Similar trends were observed in the ash contents and ether extracts for both raw and heat-processed samples. r, the level of carbohydrate in raw defatted cocoyam tuber was 29.7% higher than in dikanut seeds and 75.1% higher than in melon seeds, but in heat-processed and defatted samples, carbohydrate level in cocoyam tuber was 36.9% higher than in dikanut seeds and 76.3% higher than in melon seeds. In the undefatted raw and heat-processed samples, the calorific values determined using Atwater factors were highest in dikanut seeds and lowest in cocoyam tubers.