Home Winemaking Installment #2

⁰Brix – Ready or Not? - Determining Ripeness
How does a winemaker, viticulturalist, harvest intern, or wine enthusiast know when to pick the grapes? It boils down to four main categories: sweetness, acidity, pH, & flavor.

Here is our (Jen & Lindsey) first test of the Viognier: Jen picking and Lindsey squishing our Viognier sample.

Sweetness:The sweetness or sugar content of the grapes is measured in degrees ⁰Brix. Through the process of fermentation the sugar is converted to alcohol. The ideal level for Brix is different for each wine, whether red, white or dessert. The higher the sugar content, the higher the final alcohol content can be. For white wines, the ideal is between 21 and 23 ⁰Brix, for Red 23-25⁰Brix and as high as possible for dessert wines.Here, Jen is looking through a refractometer to measure the Brix. Our Viognier is at 20.5, which is not quite high enough.

pH:pH is both a microbial and chemical importance. It drives reaction toward or against the designated goal. The level of pH is incredibly important in producing a quality wine, and it is important to always monitor. The appropriate range for white is 3.2-3.5 and for reds 3.3 to 3.6.

Lucky for us, Nicolas, our new harvest intern, was in the lab and willing to help with our TA and pH testing. Our pH was at 3.31.

Acidity:The acidity in grapes is mostly Tartaric and Malic acids and some Citric, Acetic, and Suscinic acids. The acidity determines how tart the finished wine is and contributes to overall quality. Acidity is measure in g/L and at Harvest, should be between 7-9 g/L for whites and 6-8 g/L for reds.

Our TA was at 15, signaling our Viognier is not ripe enough.

Flavor: Flavors progress through the ripening process. The white wine grapes go from bean, veggie, and grassy flavors to citrus and then to honey and raisin. The red grapes start with a green pepper or olive flavor and transition to berries, fruit, and spice then ending with flavors of jam and raisin. All that said, each varietal has its own unique flavor profile.

The overall appearance and condition of the grape is also important to consider. There can be damage from birds, mold, or sunburn. If the grapes are not ripening or are falling apart, it is time to process. The weather also highly influences the schedule of picking. Cool, dry weather is ideal as cold fruit is the best.

The Viognier was quite tart. All measurements indicated that we need to wait to pick our viognier. We are looking forward to harvesting some fruit but will just have to keep watching and waiting.

SOURCE: Donovan, Linda, 2010 Home Winemaking Class, September 8 & 9, 2010