Removal of phenolic compounds from de-oiled sunflower kernels by aqueous ethanol washing

Wanqing Jia,Konstantina Kyriakopoulou,Bente Roelofs,Mbalo Ndiaye,Jean-Paul Vincken,Julia K Keppler,Atze Jan Van Der Goot

doi:10.1016/j.foodchem.2021.130204

Wanqing Jia, Konstantina Kyriakopoulou + Show 5 more

Open Access

https://doi.org/10.1016/j.foodchem.2021.130204

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Journal: Food chemistry	Publication Date: May 25, 2021
Citations: 16	License type: cc-by

Affiliation: Wageningen University & Research

Abstract

Selective removal of phenolic compounds (PCs) from de-oiled sunflower kernel is generally considered a key step for food applications, but this often leads to protein loss. PC removal yield and protein loss were assessed during an aqueous or aqueous ethanol washing process with different temperatures, pH-values and ethanol contents. PC yield and protein loss increased when the ethanol content was < 60% or when a higher temperature was applied. Our main finding is that preventing protein loss should be the key objective when selecting process conditions. This can be achieved using solvents with high ethanol content. Simulation of the multi-step exhaustive process showed that process optimization is possible with additional washing steps. PC yield of 95% can be achieved with only 1% protein loss using 9 steps and 80% ethanol content at 25℃. The functional properties of the resulting concentrates were hardly altered with the use of high ethanol solvents.

Highlights

Sunflower (Helianthus annuus L.) is the third most cultivated oilseed crop in the world after soy bean and rapeseed (USDA, 2020)
We present the results: (1) analysis of the extract regarding removal of phenolic compound (PC) and protein loss under different process conditions; (2) PC removal and protein loss with multi-step washing by simulations; (3) evaluation of the functionality of the washed concentrates with respect to microstructure, protein nativity, water holding capacity (WHC) and nitrogen solubility index (NSI)
The difference between the results for the two methods could be explained by the use of chlorogenic acid (CGA) as a marker component in the high-performance liquid chromatography (HPLC) analysis, whereas in the F-C method, total phenol content (TPC) was calculated on the basis of gallic acid equivalents

Summary

Introduction

Sunflower (Helianthus annuus L.) is the third most cultivated oilseed crop in the world after soy bean and rapeseed (USDA, 2020). Because of its high protein content (25%–55% w/w), sunflower meal is often sug gested for food applications, but it is still mainly used for animal feed (Laguna et al, 2019; Pickardt, Eisner, Kammerer, & Carle, 2015). The high content of phenolic compounds (PCs) (1%–4% on a dry basis) re stricts its use in the food industry, because the presence of chlorogenic acid (CGA) in sunflower meal. This can lead to dark green and brown colouring under alkaline conditions or during aqueous processing through the formation of protein and PC complexes (Ozdal, Capanoglu, & Altay, 2013; Pedrosa et al, 2000). The formation of these complexes can lower the nutritional value of the protein by altering its digestibility and bioavailability (Karefyllakis, Salakou, Bitter, Van der Goot, & Nikiforidis, 2018), and the functionality of the protein is changed (Keppler et al, 2020; Rawel, Meidtner, & Kroll, 2005)

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