Physicochemical and Functional Properties of Rapeseed Protein Isolate: Influence of Antinutrient Removal with Acidified Organic Solvents from Rapeseed Meal

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.

Enhanced Solubility of Rapeseed Meal Protein Isolates Prepared by Sequential Isoelectric Precipitation

“…Among them, rapeseed meal proteins are considered prospective nutritive and functional ingredients for the food industry [ 4 , 5 ]. The most common approach to prepare protein-rich ingredients, namely protein isolates (PI), is by isoelectric precipitation after extraction with NaOH [ 6 , 7 , 8 , 9 ]. The precipitation occurs at a single pH where the solubility of the proteins is the lowest which, however, diminishes their potential practical application.…”

In Vitro Digestibility of Rapeseed and Bovine Whey Protein Mixtures

“…Rapeseed ( Brassica napus L.) is a promising alternative source of plant protein due to its widespread cultivation for rapeseed oil production and abundant availability . However, exploitation of rapeseed protein has been limited by its high dietary fiber content and presence of antinutritional compounds such as glucosinolates, phenolics, and phytates. − In addition, three distinct classes of rapeseed trypsin inhibitors (RTIs) have been identified in B. napus seeds. − These compounds greatly affect the physicochemical, functional, and nutritional properties of purified rapeseed protein products if not removed during processing . Nevertheless, the proteins in rapeseed have high contents of sulfur-containing amino acids (AAs) ranging from 3 to 4%, which is more than any other vegetable protein source .…”

Multifunctionality of Rapeseed Meal Protein Isolates Prepared by Sequential Isoelectric Precipitation

“…However, they possess desired nutritional and functional characteristics that are highly dependent on raw material characteristics, seed processing, and protein isolate preparation mode [ 15 , 16 ]. Most protein isolates are prepared by isoelectric precipitation in the acidic pH area, where they exhibit the lowest solubility [ 17 , 18 , 19 , 20 ]. A low solubility limits protein isolate functionality and subsequent application.…”