Impact of Hydrothermal Techniques on the Chemical Components of Mallotus subulatus

Abstract

Background and Objective: Mallotus subulatus is an underutilised hard-to-cook legume in South West Nigeria. The aim of this study was to investigate the effects of four hydrothermal techniques (atmospheric boiling, atmospheric steaming, pressure boiling and pressure steaming) on the cooking time and chemical components of the seed after soaking to varying hydration levels. Materials and Methods: The seeds were soaked at varying hydration levels and then subjected to thermal processing to determine the effect of four hydrothermal techniques, on mineral elements present in the Mallotus subulatus seeds. The data were analyzed by using SAS (ver. 15). All data were subjected to Analysis of Variance [ANOVA] and the significant differences were determined at p<0.05. The means were separated using Duncan’s Multiple Range Tests.Results: Soaking of the seed prior to thermal processing decreased cooking time. Highest reduction of 80.18% in cooking time was observed when the seed was processed by pressure boiling. Hydrothermal processing methods caused significant reduction in the nutrients. Boiling at elevated pressure had better retention of nutrients. Increase in hydration level resulted in better conservation of nutrients. Crude protein content of the raw sample (20.97%) decreased by 4.63% at 100% hydration level when the seed was boiled at elevated pressure. The processing methods caused significant decreases in phytic acid, saponin and tannin, however, trypsin inhibitor was eliminated. Conclusion: The results showed that processing of the seeds at high hydration levels followed by boiling at elevated pressure caused the lowest reduction in cooking time and better retention of nutrients. The study will encourage adaptation of this lesser known legume and hence solve the problem of protein energy malnutrition.