Quillaja, which is derived from the native Chilean Mapuche word ‘quillean’ that means ‘to wash’, is not a novel ingredient.
Food manufacturers have been using extracts of the Quillaja Saponaria tree, also known as soapbark, as a foaming agent in beverages like root beer where some foaming is desired and as an emulsifier in food. It also has some applications in cholesterol-reduction in dairy and flavor enhancement.
However, according to Dr. Ricardo San Martin from the Alt. Meat Program, a research hub at UC Berkeley in the US, said interest in using quillaja extracts has “spiked” in the past years.
“Due to their unique chemical structure, they perform better than traditional emulsifiers such as soy lecithin. Soy lecithin faces increasing scrutiny for health and environmental concerns and alternatives are becoming more appealing," said San Martin, who won a research grant from plant-based advocacy group, the Good Food Institute (GFI), to investigate how quillaja extract could mimic fat in plant-based products.
“For our project, nano-structures produced with quillaja are extremely resistant to shear stress and oxidation. These properties are key for formulating novel plant-based foods," he told GFI.
Quillaja, or quillaia, extract contains over 100 triterpenoid saponins as well as polyphenols and tannins, according to a paper by the United Nations’ Food and Agriculture Organization (FAO).
It also notes that quillaja bark can be collected sustainably by pruning branches, which improves the quality of existing forests.
Nano-scale, healthy oleogels
The results of the research will be open-access to allow plant-based food manufacturers improve the quality of products on the market and get one step closer to imitating the real thing.
“We are preparing gels containing nano-scale globules of healthy vegetable oils called oleogels," he said. "These structures have properties that resemble solid fatty products and can be incorporated in plant-based extruded products. We will improve the sensory experience of present products that lack enough fat or incorporate unsaturated oils that do not retain well during cooking.”
San Martin has been trialing different vegetable oils, including canola and sunflower, to find the one that bests adapts to the structures it is trying to create.
According to San Martin, who is based at the Alt. Meat Program at the University of California Berkeley, the biggest challenge is creating structured oleogels.
“The oleogels must exhibit strong molecular interactions with plant-based matrices. They are important to plant-based meats because the surface properties of oleogels allow their retention during the process of cooking and mastication (chewing),” he said.
GFI: Adding fat to plant proteins has been 'a real challenge'
Dr. Erin Rees Clayton, who was head of GFI’s competitive grants program last year, said that taste and texture are two characteristics of plant-based meat that often don't meet consumer expectations, and San Martin’s research could address both of these issues.
“To really mimic animal meat, plant-based meat needs to create a ‘juicy’ eating experience. But figuring out how to incorporate fats (oils) into plant-based meat has been a challenge,” she told FoodNavigator-LATAM.
“Fats are ‘slippery’ and can interfere with the formation of the final plant-based meat product if they are added too early in the production process, particularly if extrusion is used. Additionally, if the fats leak out of the plant-based meat during the cooking process, the consumer will still not have a satisfactory eating experience.”
The Good Food Institute is currently carrying out several analysis projects with external experts that will help inform the specific scientific and technical challenges it chooses to address in its next call for research proposals, Rees Clayton said.
General topics include improving the sensory characteristics of plant-based products and cultivated meat, as well as scaling up production and bringing down cost.