Plant Protein Extraction Guide

Overview

The extraction process governs the yield, purity, and functionality of plant proteins. Broadly classified as wet and dry fractionation depending on the water requirement, the protein extraction methods can also be categorised based on environmental and energy sustainability. Green extraction techniques are preferred over conventional approaches due to lower energy consumption,  a solvent-free process or usage of green solvents, and their ability to produce high-quality, clean-label protein with superior functionality. Different extraction methods vary with their working principle, factors influencing the extraction efficiency, advantages, and limitations. Isolation of protein from other macromolecules (fibre, starch, and fat) in plant materials is achieved based on the differences in solubility, polarity, particle size, charge and density, and the influence of enzyme/green solvent on the cellular structure to promote mass transfer and facilitate the extractability of protein. 

Environmental and health-related reasons are the major driving factors behind the popularity of plant proteins among food producers and consumers. In addition to achieving nutritional and functional parity with animal-derived proteins, it is imperative to ascertain the sustainability metrics of plant proteins. It is essential to comprehend the environmental implications of various protein fractionation methodologies.

Key insights from the report

  • Air classification and alkaline extraction followed by isoelectric precipitation are well-known methods of dry and wet fractionation, respectively.
  • The wet methods of protein extraction are known for their high protein yield, economic sustainability, and continuous operation.
  • Energy and environmental sustainability are the advantages of air classification over wet fractionation methods.
  • Plant proteins obtained using protease-assisted extraction have enhanced nutritional digestibility and techno-functional properties.
  • Microwave-assisted extraction and high-pressure-assisted extraction are efficient in inactivating the antinutritional factors and improving the functionality and digestibility of plant proteins.
  • Deep eutectic solvents are effective alternatives to ionic liquids and other corrosive solvents that are conventionally used for plant protein extraction.
  • Generally, mild aqueous extraction processes that do not use chemicals have a lower environmental impact than conventional wet fractionation methods.
  • Relative to wet extraction processes, dry fractionation methods reduce the environmental impact by up to 99% for most plant protein sources.

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