Abstract:
The objective of the study was to investigate the effect of fractionation on properties of flour from whole and dehulled Jack bean (Canavalia ensiformis L.). Dehulled- and whole Jack bean were dry-milled into flour and sieved through meshes having the opening of 300 µm, 150 µm, 125 µm, 75 µm, and 45 µm. The result showed that flour from dehulled-Jack bean contained 55.2% carbohydrates, 35.2% protein, 4.7% fat, 1.7% crude fiber, and 3.3% ash while that from whole Jack bean contained 56.3% carbohydrates, 30.7% protein, 3.4% fat, 6.6% crude fiber, and 3.0% ash. The hull contained 36.2% carbohydrates, 4.4% protein, 0.9% fat, 55.0% crude fiber, and 3.6% ash. The dehulled flour passing 45 µm opening mesh had the highest carbohydrate content (64.2% db) while that passing the 300 µm mesh had the highest protein content (40.7% db) The flour from whole bean passing 300 µm mesh was found to possess the highest fat content (4.7% db). The amylose content of the flour samples ranged between 21.9-33.9% of dry starch. The amylose content was the highest in the flour with smallest particle size. Jack bean starch granules were oval and round in shape. The granules had rough surfaces and presented distinctive birefringence. All flour particles displayed the characteristic of CA type of diffraction pattern. The dehulled flour had an average size of 57.8 µm while the whole bean flour had an average size of 78.8 µm, and was decreased with decreasing mesh opening size. Both of flour samples contained eight essential amino acids. The dehulled and whole bean flour was found to have low methionine and high glutamic acid. The total phenolic contents measured by Folin-Cioculteu reagent method of dehulled and whole bean flour varied from 1043.5-4266.0 µg/g and 946.9-3773.3 µg/g, respectively. Decrease in particle size resulted in an increase in total phenolic compounds in hull. RS2 and RS₃ contents of flours with different particle sizes differd (p≤0.05). The RS2 contents of dehulled and whole bean flour fell within the 9.1-17.3 and 0.8-2.8% ranges and RS3 varied from 8.8-10.6 and 0.7-4.5 %, respectively. Lightness and red color were found to increase as the flour particle size decreased, while yellow color decreased with particle size reduction. The water binding capacity (WBC) and oil holding capacity (OHC) of dehulled and whole bean flours and hull having different particle sizes fell within the range of 1.1-1.6, 1.2-2.0 and 5.5-7.7 g water/g (db) and 8.3-8.5, 8.1-8.6 and 7.6-7.9 g oil/g (db), respectively. The WBC of dehulled and whole bean flour was not correlated with the flour particle size whereas the OHC increased as the particle size decreased. An increase in temperature caused better swelling power and solubility of dehulled and whole bean flour. The dehulled flour was found to possess higher swelling power and lower solubility than whole bean flour. The gelatinization temperatures (using DSC) of dehulled and whole bean flour were in the range of 81.7-88.8°C and 78.4-88.3°C, respectively. The flour with the smallest particle size had the highest gelatinization enthalpy. There was no significant difference (p>0.05) among pasting temperature of the flour samples. However, increase in peak viscosity and final viscosity of dehulled and whole bean flours were found with particle size reduction.