Potential of Leucaena leucocephala (white leadtree) seed flour as a functional food with umami taste

Abstract

Leucaena leucocephala (White leadtree) legume seed is promoted in several countries of Southeast Asia. The young pods are edible and occasionally eaten by Indonesians because of their unique combination taste of savory, sweet and slightly bitter. This study investigated the processing effects of steam blanching on the protein profile (total amino acids) and the taste components of L. leucocephala seed flour. A 5-minute steam blanching on seeds increased the soluble sugar components from 10.59±1.091 to 14.78±1.590 mg/g (dry basis) and free amino acids content from 39.25±2.260 to 49.66±2.070 mg/g on the seed flour. On the other hand, steam blanching could decrease the content of the organic acid (167.78±4.800 mg/g to 149.29±10.420 mg/g) and the value of total amino acids from 23.86±1.293 (%w/w) to 24.43±1.411 (%w/w). Leucaena leucocephala seed flour had an essential amino acids ratio (E/T) value of 37.09±2.340– 37.94± 1.130, predicted protein efficiency ratio (P-PER) of 0.27±0.002–0.30±1.668. In addition to the umami taste contributor component, a nucleotide compound was detected in fresh and steamed seed flour namely inosine-monophosphate (IMP). Equivalent umami concentration (EUC) showed that L. leucocephala seed flour contains high MSG-like components (425.92±4.76 to 540.12±13.05 mg MSG/100 g). Glutamic acid and aspartic acid, in line with Inosine Monophosphate (IMP), are MSG-like components providing a savory taste, known as ‘umami’ by receptors in humans. Steam blanching for five minutes prevented the degradation of sweet and savory compounds. Thus, the seed flour of L. leucocephala is notably marked to be utilized as an alternative to functional food with an umami taste.