Identification and Capture of Phenolic Compounds from a Rapeseed Meal Protein Isolate Production Process By-Product by Macroporous Resin and Valorization Their Antioxidant Properties.

Tuong Thi Le,Armelle Ropars,Romain Kapel,Arnaud Aymes,Xavier Framboisier,Jean-Pol Frippiat

doi:10.3390/molecules26195853

Abstract

In this study, phenolic compounds from an aqueous protein by-product from rapeseed meal (RSM) were identified by HPLC-DAD and HPLC-ESI-MS, including sinapine, sinapic acid, sinapoyl glucose, and 1,2-di-sinapoyl gentibiose. The main phenolic compound in this by-product was sinapine. We also performed acid hydrolysis to convert sinapine, and sinapic acid derivatives present in the permeate, to sinapic acid. The adsorption of phenolic compounds was investigated using five macroporous resins, including XAD4, XAD7, XAD16, XAD1180, and HP20. Among them, XAD16 showed the highest total phenolic contents adsorption capacities. The adsorption behavior of phenolic compounds was described by pseudo-second-order and Langmuir models. Moreover, thermodynamics tests demonstrated that the adsorption process of phenolic compounds was exothermic and spontaneous. The highest desorption ratio was obtained with 30% (v/v) and 70% (v/v) ethanol for sinapine and sinapic acid, respectively, with a desorption ratio of 63.19 ± 0.03% and 94.68 ± 0.013%. DPPH and ABTS tests revealed that the antioxidant activity of the hydrolyzed fraction was higher than the non-hydrolyzed fraction and higher than the one of vitamin C. Antioxidant tests demonstrated that these phenolic compounds could be used as natural antioxidants, which can be applied in the food industry.

Highlights

Rapeseed (Brassica napus L.) is an oilseed cultivated worldwide, in Europe and China (11.684 and 11.760 tons/year, respectively) [1]
Values less than 0.12 and 1.9 for the retention time and peak area, respectively. These results revealed the good performance of the developed analytical method for quantification of phenolic compounds such as sinapine and sinapic acid within the permeate with and without hydrolysis
These results indicate that the desorption ratio was influenced by the ethanol concentration and the solubility of phenolic compounds in the desorption phase

Summary

Introduction

Rapeseed (Brassica napus L.) is an oilseed cultivated worldwide, in Europe and China (11.684 and 11.760 tons/year, respectively) [1]. This resource shows phenolic compound content as high as 1.705 g of sinapic acid equivalent (SAE)/100 g of dry matter [2]. Rapeseed phenolic compounds are mainly composed of sinapic acid esters. The most abundant rapeseed phenolic compound is an ester of sinapic acid and choline called sinapine [5,6]. Rapeseed contains minor phenolic compounds such as free sinapic acid, ferulic acid, vanillic acid, or syringic acid [3,10]

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