Bamboo Leaf Protein Concentrate: Wet Fractionation, Protein Secondary Structure, Digestibility, Trypsin Inhibition

The protein that is separated from the fibrous leafy portions of plant materials is called leaf protein concentrate (LPC). In this study, fermentation of green juice of fresh bamboo leaves resulted in LPC with the highest crude protein content. Osborne fractionation revealed that nearly 60% of soluble proteins in bamboo LPC are alkali-soluble (glutelin). In all cases of precipitation methods employed, bamboo LPCs had the highest percentage of glutelins in them, followed by prolamins, albumins, and globulins. Protein in vitro digestibility showed a positive correlation with α-helix:β-sheets ratio of bamboo LPCs. Overall protein in vitro digestibility study indicated that acid-precipitated LPC was most digestible. Trypsin inhibition activity (TIA)% was evaluated through the Kunitz method and FTIR. Results revealed that acid-precipitated bamboo LPC had the lowest degree of TIA%. A higher degree of TIA% reduction was achieved at 121 °C than at 100 °C. In the case of adsorption by activated carbon, activation energy was observed to decrease with increasing initial TIA% in bamboo LPCs. Correlation analysis of various quality attributes of bamboo LPC obtained from different precipitation methods revealed the importance of Osborne fractionation in the initial selection procedure of leaf sources and concentration methods.