Characterizing Plant Proteins to Predict Optimal Food Matrix Use

Originally Published: June 24, 2017
Last Updated: June 24, 2021
Characterizing Plant Proteins to Predict Optimal Food Matrix Use.Flour silos at a large industrial flour mill. Milling techniques can be optimized to produce high-yield protein fractions.

Both wet- or dry-process pathways are used to industrially concentrate and purify (“refine”) proteins to desired-quality parameters. In characterizing plant proteins to predict optimal food matrix use, the ideal is to provide the highest degree of purity and quality for the lowest possible cost. The tradeoff is that the purer and more undenatured a protein, the more expensive it is.

Denis Chéreau, Ph.D., CEO of IMPROVE SAS (Dury, France), reviewed emergent technologies that promise to significantly improve the purity, quality and economics of protein processing in his presentation titled “Disruptive Ingredient Technologies: Characterizing Plant Proteins to Predict Optimal Food Matrix Use.” IMPROVE SAS is a private R&D laboratory focused on food, feed, cosmetic and agro-material technologies.

“There are four key elements whereby to characterize proteins,” said Chéreau, “nutritional value, functional properties, organoleptic quality, and labeling and health-claims compliance.” Nutritional value depends upon the presence, integrity and bio-availability of amino acids. Functional properties depend upon the interfacial properties of native protein structures. Organoleptic properties rely on the matrix surrounding the protein and the raw material. Health claims and labeling compliance provide the interface whereby a protein meets consumer expectations and stays aligned with regulation.

Characterizing Plant Proteins to Predict Optimal Food Matrix Use. This chart compares solubility of soy, rape seed (canola) and wheat protein at various pH.

Nutritional value, functional properties, organoleptic quality, and labeling and health-claims compliance are the four key elements by which to characterize proteins. For example, solubility is an important functional property. [Click on image for downloadable PDF].

In today’s consumer market, “one has to consider protein allergenicity, anti-nutritional factors, peptide bioactivity, clean label perceptions, GMO status, ‘organic’ compliance, plant origin and protein purity,” said Chéreau. All of these factors enter into processing considerations.

Chéreau catalogued some potentially “disruptive” technologies that promise to further enhance protein quality, consumer expectations and processing efficiencies. Some examples:

Dry refining. An advantage to dry processing is its compatibility with clean and organic labeling expectations, explained Chéreau. “It also helps to preserve a protein’s native nutritional value and functional properties.” Milling techniques optimized to yield ultra-fine seed flours, when combined with high-speed air classification, yield high-protein fractions. “Using an air classifier at 16,000rpm, we have been able to yield faba bean fractions with up to 70% purity,” said Chéreau. There is a tradeoff, however, between purity and yield. One promising method being investigated to enhance yield is to apply a “coronal discharge” to the flour and then separate the high-protein fractions based on their surface electrical charges.

Wet refining. Ultra-fine, milled dry plant-protein fractions can be further solubilized and purified through heat coagulation, isoelectric precipitation or membrane filtration. Efficient protein solubilization begins with very fine-milled particles. “We have been able to achieve close to 100% protein solubility in faba beans at pH 9-10, using 300 micrometer (micron)-sized particles, with 88.3% extraction efficiency,” said Chéreau.

The structures of the dry particles are also important. Each technique can yield protein isolates in the 80-92% concentration range with 70% yields. However, both heat coagulation and isoelectric precipitation can yield protein denaturation or organoleptic shortcomings, while conventional membrane filtration remains expensive.
Chéreau reviewed a number of “disruptive” technologies that could enhance the economic efficiencies of these processes.

A few examples:
Forward osmosis uses semi-permeable membranes and a proprietary draw solution comprised of a “food-grade GRAS liquid” that can “easily be regenerated at very low cost.” The operating temperatures for this step are between 10-50°C, optimizing protein integrity. However, work is still underway to identify membranes able to operate at the pH 9-10 range for optimum solubilization. “The process requires very little energy; is easy to scale-up; and integrates easily into existing processing lines,” said Chéreau.

Dynamic cross-flow filtration uses rotating ceramic disks to generate turbulent flow across membranes, resulting in significant energy savings… “as much as five times less than conventional systems,” claimed Chéreau. “This system works well with high viscosity fluids.” The researchers are still working to resolve issues with high-viscosity by-product stream utilizations.

Electrostatic spray-drying shows promise for highly sensitive proteins, such as egg or milk proteins. The process electrically charges solvent particles, causing them to migrate to the exterior of the particles in a nitrogen environment, yielding enhanced drying efficiencies while minimizing energy costs. Drying temperatures for this process are 80°C vs. 180°C for more conventional spray-drying.

In sum, the presentation offered an encouraging and creative view of how next-generation, “disruptive” protein technologies could be mixed and matched to enhance quality and functionality with significant cost-savings.

“Disruptive Ingredient Technologies: Characterizing Plant Proteins to Predict Optimal Food Matrix Use,” Denis Chéreau Ph.D., General Manager, IMPROVE SAS, denis.chereau@improve-innov.com

This presentation was given at the 2017 Protein Trends & Technologies Seminar — Technical Program: Formulating with Proteins.

Click here for access to the PowerPoint presentation of Disruptive Protein Technologies by Denis Chéreau Ph.D., General Manager, IMPROVE SAS.

Click to see the list of past and future Protein Trends & Technologies Seminars.

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