Fractionation and characterization of heat-stable basil seed protein isolates and their utilization in high protein gluten-free bread

Abstract

Basil (Ocimum basilicum L.) is an annual plant known for its essential oil and phenolic content. The aim of this study was to isolate and characterize proteins from basil seeds and evaluate their potential in food fortification. The mucilage was removed from the seed by aqueous extraction and thermal hydration, whereas oil was removed via cold pressing. Basil seed protein isolate (BSPI) was obtained by an alkali extraction-isoelectric precipitation method and con tained approximately 95% protein. Once BSPI was fractionated, the samples were characterized by albumin (13.5%), globulin (16.7%), glutelin (39.5%), and prolamin (30.2%) fractions. The denaturation temperature of BSPI and its frac tions ranged between 93 and 142 C. Through the analysis of Fourier transform infrared spectra, β-sheet and β-turn elements were found to be dominant sec ondary structures accounting for 89.4% in BSPI, which in turn lead to enhanced thermal stability. Since aqueous dispersibility and water holding capacity (WHC) values were acceptable, BSPI was further utilized in the manufacture of gluten-free bread. The textural parameters of bread supplemented with 2%, or 10% basil seed protein were mostly comparable to the controls rendering basil protein fortification possible in a staple food, especially for countries where basil is produced in high quantities and is reasonably affordable.