It’s Grape harvesting season again and I’ve started to measure the BRIX of our crop on a daily basis now. The day you pick determines the quality of wine. The usual timetable for our vineyard is sometime between now and November. Typically its been mid September but many of the vinyards in Napa Valley are already picking.. Todays BRIX reading was averaging around 22. If funny how different parts of the vineyard have different BRIX reading. Some were as high as 28 and others as low as 18. The sugar in the grapes varies because the Veraison (ripening) is a function of sun exposure. The plants are getting stressed from the drought but from what I have been told, this makes the plants concentrate sugar in the grapes and is a good thing. Also, I stopped watering them for about two weeks also while I was attempting to find a leak in the vineyard irrigation system. As the vines start to turn brown entering into a stage called Phloem Transport Arrest, the plants stop accumulating water and sugar and the end of growing season and the plant shuts down . The stems turn brown and the seeds go from green to brown. The flavor continues to develop after PTA,. The final stage is dehydration. The berries can lose 10% of there water which concentrates the sugar and acidity is reduced. Flavor synthesis ends and its time to pick for sure.
Determining the Phenolic maturity of the grape is the trick. Things like skin thickness, berry texture, seed color and texture and whether the stems have turned brown. Grapes can be picked successfully on the basis of appearance. Biologically, a grape is finished ripening when the phloem (water, sugars) stops moving from the leaves to the grapes. People can tell when a grape is ripe just by looking at and touching it. There is full and distinctive color, the grapes are soft, and the the stem is brown. Picking the grapes by hand involves picking the ripe, non rotten, non broken grapes. Its best to harvest when the temperature is cool like early morning or night. Once we pick into the bins, we sort the good from bad grapes clusters and destem them to the must container, crush and add yeast.
Things to look for:
Rich color, not green. A ripe grape crushes easily but not shrivled. A ripe grape is plump and juice, balanced between sweet and tart. It should taste like a ZIN. Sweet and not too tart, herbaceous vs vegetal, is the aftertaste chemical or bitter. Not Vinigery. A brix level of 20-24 for our Zin
As the grapes ripen, the PH rises. Grape juice natural acids effect taste. As BRIX goes up Acid levels goes down. To test Brix, the bigger a sample, the better, pick one grape from multiple clusters. Note taste and texture etc…test Brix, the bigger a sample, the better, pick one grape from multiple clusters. Note taste and texture etc…