“Red red wine, you make me feel so fine
You keep me rockin’ all of the time.”
—Neil Diamond
Lovers of wine may know of sulfur dioxide (SO2). This widely used, effective preservative helps wine maintain its quality and color. That said, the sulfur in wine can trigger headaches, hives, diarrhea, stomach pain, and allergic asthma. Talk about a buzz kill. With this in mind, a group of researchers recently looked at replacing SO2 in wine with the monoterpene α-pinene. [1]
They made their own white wine with Golden Muscat grapes, sucrose, and yeast (Saccharomyces cerevisiae). After a little filtration, they meted out the preservatives: on the one hand, SO2 at 40 ppm according to “commercial practice,” and on the other hand, α-pinene at concentrations of 0.03125 g/100 mL, 0.0625 g/100 mL, and 0.125 g/100 mL. A control without any preservative rounded out the lineup. They aged the wine for 1, 30, and 180 days. Analytical tests included:
- Microbes
- Physicochemical: soluble solids, pH, acidity, and transmittance
- Pectin content and esterification (major determinants of transmittance)
- Ethanol
- Color
- Phenolic acids
- Antioxidant activity
- Phenolic compounds
- Sensory properties: color, aroma, flavor, long-lasting taste, sweetness, acidity, bitterness, complexity, and overall quality
The natural terpene α-pinene outperformed the control and held its own against SO2 across all tests.
Both SO2 and α-pinene inhibited microbes and browning. Antioxidants were actually higher for the control due to microbes producing phenolic compounds; differences in this regard were considered null.
At 0.3125 g/100 mL and 0.0625 g/100 mL α-pinene, transmittance trumped other conditions, including SO2. Transmittance is a “major parameter of winemaking,” reflecting contamination and quality.
The highest amount of α-pinene (0.125 g/100) lowered ethanol content significantly, suggesting that at too-high concentrations, the terpene may interfere with yeast growth.
Flavor intensity, flavor, and aroma were superior with 0.0625 g/100 mL α-pinene. Thus, the low amounts of α-pinene enhanced the wine’s flavor profile compared to SO2. Too much pinene was negative, however; 0.125 g/100 α-pinene affected taste and aroma by adding “intense citrus aroma” that conflicted with the wine’s grape aroma.
α-Pinene exhibited less browning intensity in terms of color compared to SO2, and this may have contributed to its superior transmittance. Its ability to reduce pectin (which affects viscosity) may also have played a role.
Overall, the researchers conclude, “These findings indicated that α-pinene possessed an excellent antibacterial ability and could be a viable alternative for SO2 in winemaking.” [1]
Reference
- Shih M-K, et al. A novel application of terpene compound α-pinene for alternative use of sulfur dioxide-free white wine. International Journal of Food Properties. 2020;23(1):520-532. [Impact Factor: 2.775; Times Cited: 3 (Semantic Scholar)]
