Comparison of Faba Bean Protein Ingredients Produced Using Dry Fractionation and Isoelectric Precipitation: Techno-Functional, Nutritional and Environmental Performance.

Martin Vogelsang-O’Dwyer,Emanuele Zannini,Elke K Arendt,Jens Christian Sørensen,Mirjam Busch,Iben Lykke Petersen,Juergen Bez,Andreas Detzel,Marcel Skejovic Joehnke,Martina Krueger,James A O’Mahony

doi:10.3390/foods9030322

Abstract

Dry fractionated faba bean protein-rich flour (FPR) produced by milling/air classification, and faba bean protein isolate (FPI) produced by acid extraction/isoelectric precipitation were compared in terms of composition, techno-functional properties, nutritional properties and environmental impacts. FPR had a lower protein content (64.1%, dry matter (DM)) compared to FPI (90.1%, DM), due to the inherent limitations of air classification. Of the two ingredients, FPR demonstrated superior functionality, including higher protein solubility (85%), compared to FPI (32%) at pH 7. Foaming capacity was higher for FPR, although foam stability was similar for both ingredients. FPR had greater gelling ability compared to FPI. The higher carbohydrate content of FPR may have contributed to this difference. An amino acid (AA) analysis revealed that both ingredients were low in sulfur-containing AAs, with FPR having a slightly higher level than FPI. The potential nutritional benefits of the aqueous process compared to the dry process used in this study were apparent in the higher in vitro protein digestibility (IVPD) and lower trypsin inhibitor activity (TIA) in FPI compared to FPR. Additionally, vicine/convicine were detected in FPR, but not in FPI. Furthermore, much lower levels of fermentable oligo-, di- and monosaccharides, and polyols (FODMAPs) were found in FPI compared to FPR. The life cycle assessment (LCA) revealed a lower environmental impact for FPR, partly due to the extra water and energy required for aqueous processing. However, in a comparison with cow’s milk protein, both FPR and FPI were shown to have considerably lower environmental impacts.

Highlights

The important role of plant proteins in human nutrition is becoming increasingly recognized.More sustainable options than animal protein are needed in order to guarantee food security, as the global population is projected to increase by two billion over the 30 years [1,2]
A higher protein content was measured for faba bean protein isolate (FPI) (90.1%, dry matter (DM)) compared to FPR (64.1%, DM)
Air classification of plant proteins results in lower protein purity than is obtained by aqueous extractions. This is due to the physical limitations of the process in separating protein bodies from starch granules and other seed material, and the protein content of the protein bodies is a limiting factor [12,31]

Summary

Introduction

The important role of plant proteins in human nutrition is becoming increasingly recognized.More sustainable options than animal protein are needed in order to guarantee food security, as the global population is projected to increase by two billion over the 30 years [1,2]. Foods 2020, 9, 322 of feed protein to animal proteins is inherently inefficient, and plant protein crops such as legumes, which are mainly used as feed, may be better utilized for direct human consumption [3]. Protein isolates may be produced using aqueous extraction methods; these include alkaline, neutral, or acid extraction, followed by isoelectric precipitation (IEP) or ultrafiltration (UF), as well as salt extraction followed by micellization [12,13]. Another option to produce protein ingredients is dry fractionation, where dried legumes are milled, and the particles are air classified based on size and density into protein-rich and starch-rich fractions [14]

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