Vanilla extract, a widely used flavoring compound in food and cosmetics, is derived from the chemical compound vanillin found in the seed pods of vanilla plants. The enzyme VpVAN in plants synthesizes vanillin from ferulic acid, but this method yields only limited amounts of vanillin, making it commercially impractical. Although chemically derived vanilla essences are available cheaply, they do not match the flavor of natural vanilla extract, leading to a high demand for the latter. Climatic limitations for vanilla plant cultivation and low yields per plant have contributed to a decrease in the supply and an increase in the price of natural vanilla extract.
In response to these challenges, Professor Toshiki Furuya and his graduate students at Tokyo University of Science developed an enzyme that can convert plant-derived ferulic acid into vanillin. Ferulic acid can be obtained in abundance from agricultural waste such as rice bran and wheat bran. The enzyme, created using genetic engineering techniques, converts ferulic acid into vanillin simply by mixing the two at room temperature, providing a sustainable method for producing flavor compounds. Their research, published in Applied and Environmental Microbiology, offers a simple and environmentally friendly approach to vanillin production that could address the rising demand for natural vanilla extract.
By modifying the molecular structure of an oxidase enzyme called Ado, the researchers were able to predict amino acid changes that would enable it to interact with ferulic acid for vanillin conversion. After replacing specific amino acid residues in Ado with others, they identified a mutant protein that efficiently converted ferulic acid into vanillin without requiring any cofactors. The engineered enzyme exhibited high catalytic efficiency and affinity for the substrate, producing vanillin on a gram scale per liter of reaction solution. This sustainable process only required mixing the enzyme, ferulic acid, and air at room temperature, offering a scalable method for vanillin production.
The newly developed enzyme has shown promise in enabling the commercial production of natural vanillin on an industrial scale, which has not been achieved by microbial or plant-derived enzymes before. The ability of the enzyme to convert ferulic acid from renewable plant-based sources into vanillin offers an environmentally friendly alternative to current methods of vanillin production. Professor Furuya emphasizes the potential of harnessing microorganisms and enzymes to derive valuable compounds from plant-based resources, leading to a more sustainable approach in minimizing the environmental impact. Their ongoing collaboration with a company focuses on implementing the production of vanillin using the newly developed enzyme for real-world applications.