The Effect of Different Processing Treatments on the Proximate Composition and Functional Properties of Maize-Mung bean Composite Flours

Three processing methods (fermentation, malting and toasting) were used in processing maize and mung bean seeds into flours. Composites of maize: mung bean (MA: MU) flours were produced using different ratios. Proximate composition and functional properties of the composite flours were determined. Proximate composition showed that moisture contents of the treated flours were generally low for all fermented flours (6.57 - 7.61 %), malted flours (5.78 - 8.98 %) and toasted flours (4.93 - 8.18 %). The processing methods gave appreciable protein content (10.10 - 21.50 % for fermented, 11.12 - 19.51 % for malted and 12.81 - 17.23 % for toasted respectively) and ash content (1.01 - 5.60 % for fermented, 2.10 - 4.75 % for malted and 3.20 - 6.60 % for toasted respectively) while the fibre content (0.17 - 0.07 % for fermented, 0.66 - 0.00 % for malted and 0.33 - 0.00 % for toasted respectively) and fat content (3.34 - 1.14 % for fermented, 2.84 - 1.91 % for malted and 3.96 - 1.83 % for toasted respectively) were low for all processing methods. Carbohydrate (CHO) and energy values were generally high for all processing steps. The results of functional properties showed that fermentation, malting and toasting processes resulted to flours with similar water absorption capacity, emulsion capacity and foam capacity values. Malting process resulted to flours with higher oil absorption capacity (1.81 - 3.19 g/mL), gelatinization temperature (64.50 - 95.00°C) and gelation capacity (81.50 - 102.50 %) compared to fermentation and toasting. Fermentation process resulted to flours with higher bulk density (0.68 - 0.76 g/cm) compared to malting (0.65 - 0.69 g/cm) and toasting (0.64 - 0.69 g/cm) processes. Conclusively, the studied processing methods could be employed towards producing flours with appreciable functional properties and improved protein, mineral and carbohydrate contents. Practical Applications : Processing this hard-to-boil and hard-to-dehull legume (mung bean) into flour and its use in supplementing cereals such as maize which has limited protein content would boost the nutritional profile of their composite flours when utilized in the food industry for breakfast cereal formulation and production, and possibly infant food formulation as well as in the production of baked foods and extruded snack products.