Non-alcoholic wine, typically containing less than 0.5% alcohol by volume (ABV), has grown in popularity as a health-conscious alternative. This has led to questions about the retention of beneficial compounds found in traditional wine. A compound of particular interest is resveratrol, a polyphenol associated with various health benefits, including cardiovascular support. The central question is whether the industrial process of removing ethanol also strips away this valuable antioxidant. The presence and concentration of resveratrol in the final non-alcoholic product is directly influenced by both the grape source and the specific dealcoholization technique employed.
Resveratrol’s Origin in Grapes
Resveratrol is a natural compound produced by plants, classified as a phytoalexin, synthesized in response to external stressors like fungal infections or injury. In grapes, this compound is concentrated almost exclusively in the skins and seeds. Because of this concentration, the winemaking process is a major determinant of the final resveratrol content.
Red wines naturally contain significantly higher levels of resveratrol than white wines. This difference occurs because red wine is fermented with the grape skins and seeds left in contact with the juice for an extended period, allowing the polyphenol to be extracted. White wines are typically fermented after the skins are quickly separated from the juice, resulting in a much lower baseline concentration. Therefore, non-alcoholic red wines start with a much richer source of the compound than their white counterparts.
The Impact of Dealcoholization Methods
The subsequent process of removing the alcohol from finished wine introduces a risk of losing heat-sensitive compounds like resveratrol. The three main commercial methods used for dealcoholization are vacuum distillation, reverse osmosis, and the spinning cone column. Each of these techniques affects the wine’s chemical profile differently.
Vacuum distillation involves heating the wine to a lower temperature than its normal boiling point to evaporate the ethanol. While this minimizes heat damage, higher temperatures can still cause some loss of volatile aromatic compounds and heat-sensitive polyphenols. The spinning cone column method is a gentler distillation technique that uses centrifugal force, often cited for better retention of volatile flavors and stable compounds like resveratrol.
Membrane techniques, such as reverse osmosis, separate the wine into a permeate (water and alcohol) and a concentrate (flavors and polyphenols) using pressure and semi-permeable membranes. These methods avoid high heat entirely, often leading to better retention of resveratrol and other heat-sensitive compounds. However, regardless of the method, any mechanical processing introduces a risk of physical loss or degradation to the compounds in the wine.
Comparing Resveratrol Levels
Variability in Concentration
Non-alcoholic wine does contain resveratrol, though the final concentration is highly variable compared to its alcoholic source. A typical glass of alcoholic red wine might contain anywhere from 0.24 to over 10 milligrams per liter (mg/L), depending on the grape variety and vintage. After dealcoholization, some studies show a reduction in resveratrol concentration, while others report little change or even an increase.
Factors Affecting Retention
The apparent increase in concentration is often a result of the alcohol removal process itself, which reduces the total volume of the liquid, effectively concentrating the non-volatile components like resveratrol. Furthermore, the removal of ethanol can reduce the precipitation of tartrate salts, which are known to absorb polyphenols, thus leaving more of the compound in the liquid. In the final product, the resveratrol concentration can be reduced significantly or remain comparable to the original, depending on the producer’s chosen dealcoholization method and its operating temperature.
Other Polyphenols in Non-Alcoholic Wine
The health profile of non-alcoholic wine extends far beyond just resveratrol, as it retains a broad spectrum of other beneficial compounds. Key among these are anthocyanins, which are responsible for the red and purple color of the wine, and catechins and quercetin, which are classified as flavonoids.
These compounds are generally less volatile and more stable than ethanol, meaning they are well-retained throughout the dealcoholization process. The presence of these retained compounds means that non-alcoholic wine maintains a high overall antioxidant capacity. Ultimately, even if the amount of resveratrol is diminished, the beverage still delivers many of the heart-healthy and antioxidant benefits associated with the original alcoholic wine.