Protein Fractions of Jackfruit Leaf Flour and Protein Concentrate: Amino Acid Profile, Functional Properties and Thermal Analysis

This study aims to obtain protein fractions, such as albumin, globulin, prolamin, and glutelin, from jackfruit leaf flour and protein concentrate (LPC). The protein fractions were characterised based on their protein content, amino acid profile, hydrosolubility, emulsifying, foaming, and thermal properties. The flour and LPC are mainly composed of prolamin and glutelin, respectively. The glutelin fractions presented a higher protein content and amino acid profile, featuring elevated leucine, valine, and glutamic acid levels. The glutelin fraction of LPC exhibited the highest hydrosolubility (27.7–88.6%), while globulin fractions displayed the lowest values (0.0–25.9%). The prolamin fraction of LPC showed higher foaming capacity (113.3%) and foaming stability (95.55%). The better emulsifying activity index (53.2 m2/g) and emulsion stability index (82 min) were observed in the glutelin fraction (LPC). The globulin (flour and LPC) and prolamin (flour) fractions had the highest glass transition, denaturation temperatures, and low enthalpy values. Therefore, the functional and thermal properties depend on amino acid composition and protein content. The glutelin and prolamin fractions of LPC could be used as emulsifying and foaming (respectively) agents based on vegetable proteins. LPC protein fractionation proved instrumental in obtaining proteins with superior functional properties compared to flour ones.