Compositional Changes in African Oil Bean (Pentaclethra macrophylla Benth) Seeds During Thermal Processing

Abstract

The effect of thermal processing as a preservation technique on the nutritional, anti-nutritional and functional characteristics of African oil bean seeds (Pentaclethra macrophylla Benth) was investigated. Samples were drawn from the different stages during the processing (namely; cooked, fermented and canned) along with the raw seeds, and examined for proximate chemical composition, elemental concentrations, anti-nutritional content and functional properties. The results show that processing reduced the protein content from 22.32% dry wt. in the raw seeds to 19.00% dry wt. in the canned product; while oil content increased from 53.98% to 60.11% respectively. Also, fermentation and canning significantly (P<0.05) reduced the phosphorus and iron contents of the seeds while processing generally raised the calcium and magnesium contents. Each processing step brought about a decrease in levels of anti-nutritional factors analyzed. Oxalates, tannins and phytic acid were reduced from 2.79mg/g, 0.38g/100g and 2.11g/100g in the raw seeds to 0.81mg/g, 0.22g/100g and 1.16g/100g in the canned product, respectively. Water and oil absorption capacities were not significantly (P>0.05) affected by the processing operations. However, the capacity to gel and foam reduced with successive processing steps. Overall, thermal processing of the African oil bean seeds raised nutrient bioavailability, digestibility and functionality.