In their research, scientists focused, for example, on grapevine wood, which contains the well-known antioxidant resveratrol. “Grapevine wood, specifically vine shoots, contains up to a thousand times more of this antioxidant than wine, and it is precisely this that is pruned as part of vineyard maintenance. However, it is possible to extract this antioxidant from the wood,” explained Ivo Soural from the Institute of Post-Harvest Technology of Horticultural Products at MENDELU. They also focused their attention on spruce knots and oak and acacia wood. “Knots in wood are considered waste material in wood processing. However, spruce knots are rich in lignans, which are antioxidants that can be used to enrich food,” Soural described.

The substances cannot be analyzed directly in the wood material; they must be converted into a solution, so extracts are prepared from the wood and then analyzed. The values obtained for individual or total antioxidants are converted to the amount in the wood material. “Antioxidants also often act as phytoalexins, i.e., substances that protect plants from attack. This is partly confirmed by our measurements, where the amount of stilbenes increases over several months in slowly dried plant material, whereas in material quickly dried by lyophilization, these substances are practically absent,” the scientist outlined.

Antioxidants may therefore not only be useful in the food industry, but can also be used for plant protection. “An interesting fact is our patent for an antifungal spray based on liquid extract from vine waste, where extracts from grapevine wood protect vines in vineyards against fungal pathogens that cause powdery mildew and downy mildew,” said Soural.

Antioxidants can also be found in oak or acacia extracts. “We can also look at commonly used cinnamon, which contains cinnamaldehyde, giving cinnamon its characteristic aroma and taste while also acting as an antioxidant. After all, wood contains lignin, a structural polymer composed of various phenolic compounds that exhibit antioxidant properties,” explained Soural.

Although the use of wood extract for food purposes may sound strange, the opposite is true. “In general, it is possible in the food industry. It depends on what solvent is used. If alcohol is used, there is usually no problem, but if methanol or another toxic solvent is used, then there would be a problem. Of course, it depends on the dosage and quantity. Another aspect is legislation, as there is an effort to put something that is not food into food. However, if we stick to wood, such as oak, in which wine is commonly aged, there is no problem,” the scientist explained.