Heat-induced nanoparticles from pumpkin leaf protein for potential application as β-carotene carriers

Abstract

Nanoparticles prepared by heat treatment of protein from pumpkin leaves were evaluated as potential carriers of β-carotene. White protein fraction was recovered from green juice produced by pressing the leaves, with the step of enzyme-assisted extraction (green protocol) or without it (conventional protocol). Heat treatment of white protein fractions from conventional and green protocols at 90 °C and pH 9.3 during 20 min induced formation of nanoparticles with peak diameter 18 nm and 21 nm, respectively. Due to heating, portion of β-sheets in nanoparticles from both native protein fractions decreased by approximately 15 %, associated with an increase in surface hydrophobicity-to-area ratio. Quenching constant of β-carotene for nanoparticles was increased nearly 100 times by heating the white protein fraction recovered in green protocol. Native white protein fraction from conventional protocol and corresponding nanoparticles exhibited high ability to bind β-carotene, with quenching constant 3 × 105 L/mol and 3.3 × 105 L/mol, respectively. White protein fraction from pumpkin leaves appeared to be a suitable substrate for the fabrication of nanoparticles by heat treatment, with potential application as β-carotene nanocarriers in food matrices.

Keywords

• Leaf protein
• Enzyme-assisted extraction
• Secondary structure
• β-Carotene
• Surface hydrophobicity
• Quenching constant