Nutritional value and functional properties of moringa oleifera leaf protein concentrate

Abstract

Moringa oleifera leaf is considered an inexpensive source of protein. As leaf protein concentrate (LPC), protein content offered is higher and easier for use than in leaf. Therefore, this study aimed to prepare moringa leaf protein concentrate (MoLPC) from dried moringa leaves, compare their physico-chemical and functional properties and determine enhanced nutritional value of pancakes fortified with MoLPC compared to unfortified pancake. Using two varieties (Thai (TMo) and Indian (IMo) moringa from Nan area), LPC from each variety was prepared by alkali solubilization (pH 9) followed by acid-precipitation at pH 4.5. Effects of heat on the protein precipitation was studied by pI precipitation undergoing an additional heating period (550C, 20min) or regular precipitation at room temperature. MoLPC pellet was then adjusted to pH 7.0 before subjected to freeze drying. ThaiLPC-Heat showed significantly higher protein content (61.48 ± 1.04%) and yield of mass MoLPC extraction (4.50 ± 0.13%). Heating significantly influences proximate compositions of MoLPC whereas variety influences yield of mass MoLPC extraction and crude protein content only. Solubility showed pH 3.5 to give minimum solubility for all MoLPC. At pH of 6 and higher, higher protein solubility for all MoLPC occurred. Heat had significant influence on the decreased solubility of MoLPC. IndianLPC-RT showed significant high emulsifying properties across pH 6, 7 and 8 whereas ThaiLPC was found to have improved emulsifying properties when heated at precipitation step. Results of surface hydrophobicity correlated with emulsifying properties of MoLPC. ThaiLPC-Heat was chosen to replace 5% to 15% of pancake mix. The MoLPC substitution showed nutritional enhancement of protein content increasing compared to the control. Increased crude protein content (18.7 ± 1.2%), increased crude fiber (12.6 ± 1.3%) and decreased carbohydrate (48.1 ± 3.8%) significantly occurred at MP15%. Texture profile analysis of the pancakes showed that springiness and cohesiveness of pancakes are maintained even with substitution of MoLPC at 15%. However, the hardness of the pancake textures was significantly influenced with replacement of pancake-mix with MoLPC even at 15%. Data obtained from this study is important for the development and implementation of Moringa oleifera leaf protein concentrate for its potential use in food.