Physicochemical
and Functional Properties of Rapeseed
Protein Isolate: Influence of Antinutrient Removal with Acidified
Organic Solvents from Rapeseed Meal
- Publication date
- Publisher
Abstract
The presence of antinutritional constituents
in rapeseed protein
products (RPI), such as polyphenols, phytates, allyl isothiocyanates,
and glucosinolates, is a formidable constraint. The effect of antinutrient
removal from rapeseed meal with an organic solvent mixture (methanol/acetone,
1:1 v/v, combined with an acid (hydrochloric, acetic, perchloric,
trichloroacetic, phosphoric)) on the physicochemical and functional
properties of RPI was investigated. The extraction resulted in a substantial
reduction of antinutrients from RPI, especially polyphenols and phytates,
with concomitant decreases in protein yield and solubility. Treatment
harbored significant improvement in the degree of whiteness, which
was highest in the perchloric acid case. Surface hydrophobicity and
free sulfhydryl group of RPI changed considerably, with perchloric
acid-treated samples showing higher values, whereas the disulfide
content remarkably increased in trichloroacetic acid- and phosphoric
acid-treated samples, signifying aggregation. Intrinsic emission fluorescence
and FTIR spectra showed significant changes in proteins’ tertiary
and secondary conformations, and the changes were more pronounced
in samples treated with higher concentrations of acids. No appreciable
alteration appeared among the electrophoretic profiles of proteins
from pristine meal and those treated with lower levels of acids. Interfacial
surface properties of proteins were variably improved by the solvent
extraction, whereas the converse was true for their extent of denaturation.
The results suggest that the physicochemical and conformational properties
of RPI are closely related to its functional properties