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Einhorn-Stoll, U., Archut, A., Eichhorn, M., & Kastner, H. (2021). Pectin - plant protein systems and their

application. Food Hydrocolloids, 106783. https://doi.org/10.1016/j.foodhyd.2021.106783

Ulrike Einhorn-Stoll, Artwin Archut, Marina Eichhorn, Hanna Kastner

Pectin - Plant protein systems and their

mainly due to denaturation during extraction. They require improvement for easier

incorporation into food products, and combinations with pectin were tested for this purpose.

Coacervates, formed mainly by electrostatic interactions, and conjugates, formed by covalent

binding, improved protein solubility around the isoelectric point, surface activity and

emulsion and foam stability. Active (often hydrophobic) ingredients were encapsulated by

conjugates or bilayers or within nanoparticles to stabilise them in a hydrophilic environment

and to control their release. Coacervates were also able to mask the bitter taste of plant

characterised pectin samples, is required for a better understanding of the interactions, aimed

at an extended plant protein application for human nutrition.

Contents

1. Introduction

2. Theoretical aspects of pectin – plant protein interactions

3.4 Other studied pectin – plant protein systems

4. Summary and outlook

food products enhanced the interest in the utilisation of plant proteins as food ingredients

within the last decade (Sá et al., 2020). Proteins are a main component in different terrestrial

plants such as legumes, grains, seeds, pseudocereals, almonds and nuts. The protein content

may vary from about 10% in rice to about 45% in soy beans (Sá et al., 2020). Initially, protein

concentrates and isolates were by-products of the extraction of oil (e.g. from soy and rapeseed)

or starch (e.g. from corn, wheat and potato), but nowadays, the production of plant protein

cause at least partial denaturation. In particular, protein solubility is often reduced, which is

a key factor for protein functionality (Li & de Vries, 2018; Ebert et al., 2020; Mota da Silva et

al., 2021). The limited techno-functional properties may complicate the incorporation of plant

proteins into food products, which is widely determined by the “interaction capacity” and

depends in particular on protein conformation and surface properties. Techno-functional

properties of plant proteins may be additionally affected by processing conditions during food

production (Qamar et al., 2020).

Independent of the extraction process, isolated plant proteins are a mixture of different

protein fractions with varying properties. For instance, protein products with a high share of

prolamins and glutelins are less water-soluble than those containing mainly globulins and

consequence, their solubility is strongly reduced and is minimum around pH 4 - 5, in the range

consist of two major fractions, a globulin fraction with 65 - 80% and an albumin fraction of 20

- 35% of the total protein content (Schroeder, 1982). The pI of pea protein isolates is around

pH 4.5, and the solubility is low in this pH-range. Corn contains about 8% protein (Shukla &

Cheryan, 2001), the main fractions are zein and glutelin, with each about 40%. Zein includes

a high proportion of non-polar amino acids, this makes it hardly soluble in water below pH 11

but well soluble in aqueous solutions containing e.g. urea or anionic detergents or in apolar

solvents like ethanol. The pI of zein is around pH 6. Another protein that should be mentioned

lentils), grain (rice, wheat) and potato (Fig. 1, Table 1).