In order to meet world demand for protein, food manufacturers need flexibility in choosing protein ingredients, including those from plant proteins. Factors to consider when selecting a plant protein include nutritional quality, functional attributes and sensory properties. While some protein sources are “well-established” and have been consumed for generations, new ones are also emerging, noted Laurice Pouvreau, Ph.D., Senior Scientist, NIZO food research, in her 2016 Protein Trends & Technologies Seminar titled “Unlocking the Potential of Alternative Proteins for Use in New Applications.”
A few years back, NIZO analyzed the solubility of a number of commercially available proteins at pHs 4, 6.8 and 8 and found they were low. It determined that efforts to improve protein solubility would be a worthwhile goal. [For larger PDF of chart, click on image.]
Through advances in ingredient technology, new sources of protein ingredients will come from efforts to extract proteins from a broad range of pulses, such as chickpeas, fava beans (broad beans), beans and lentils, and from by-products of oilseeds. One example is the high-in-protein sunflower cake that is left over when oil is extracted from sunflower seed.
Pouvreau added that there has been much research on the extraction of protein from green leaves, duckweed/Asian watermeal (from the genus Wolffia) and microalgae. [NOTE: Some of these are already commercially available and were presented at this event’s Protein Sampling Station.]
However, “Plant proteins can be deficient in essential amino acids; so it is necessary to mix proteins in appropriate ratios to deliver the target amino acid profile. Protein blends allow novel source proteins to compete with animal proteins in nutritional quality,” said Pouvreau. Understanding protein blends also allows for texture customization and cost optimization. Research at NIZO has created blends of sodium caseinate with soy or pea protein that yield stable emulsions.
Protein digestibility is also important. There are two primary methods for measuring protein quality: PDCAAS and DIAAS. Both require digestibility testing in animals, which can be expensive. The industry is researching analytical methods that avoid these challenges. For example, NIZO has been working on a new technology, SIMPHYD (SIMulation of PHYsiological Digestion) that mimics in vitro digestion in the mouth, stomach and duodenum.
Solubility is a key property of protein ingredients and impacts a wide range of food and beverage applications. Plant proteins exhibit great variation in solubility, and that solubility is affected by pH. (See chart “Plant Protein Solubility.”)
NIZO has worked on protein processing, such as a mild fractionation process, in order to optimize functional properties. Factors impacting solubility include crop composition, downstream processing and storage conditions, among others. Solubility, in turn, impacts functionalities—such as color, digestibility, emulsification, heat stability, flavor, viscosity and gelling properties.
One important functional property is foaming. Traditional commercial pea protein foams are grainy with an undesirable mouthfeel, but work at NIZO produced pea proteins that maintained 95% solubility and which formed fine, stable foams.
There has been much interest in RuBisCO, which, as the main protein in green plants, is the most abundant protein in the world. A traditional plant protein extraction yields a product that is dark green and highly insoluble. NIZO has developed a mild extraction method, combined with a decoloration method, that yields a plant protein with 70-90% protein, off-white color and high functionality.
Pouvreau noted that it is better to optimize an ingredient’s flavor during its processing than to try to mask or modify flavor in the final product. Plant proteins often have flavors that are described as beany, cardboard, bitter or astringent. Volatile organic compounds, generated by the oxidation of unsaturated fatty acids, also generate off-flavors. Here, too, NIZO has worked on modifying the extraction process to create a pea protein low in oxidation flavors and has used fermentation by co-starter cultures to reduce beany off-flavor.
Astringency, which is defined as a dry, puckering mouthfeel, is a result of the interaction of proteins or polyphenols with saliva and is directly related to the molecular properties of the protein, rather than the extraction method. One area of research aiming to minimize astringent mouthfeel involves controlling the interaction of proteins and saliva components.
These exciting new technologies will allow plant proteins to supplement and compete with animal proteins to serve a hungry planet, concluded Pouvreau.
“Unlocking the Potential of Alternative Proteins for Use in New Applications,” Laurice Pouvreau, Ph.D., Senior Scientist, NIZO food research BV
