Page 11 - Grapevine JanFeb 2022

In The Winery

FREE SULFUR DIOXIDE

Aeration Oxidation Test (Tried & True)

By: Tom Payette, Winemaking Consultant
A precise test for a winery to measure the is not inexpensive, the chemistry somewhat daunt-

free Sulfur Dioxide in juices, musts, wines
ing, and the glass apparatus has the appearance of
and at bottling is critical. Selecting the
proper test can be challenging due to cost and being overly fragile and complicated. The units are
expensive however, since we are seeking to mea-
expertise. Make certain to investigate the options sure a chemical in parts per million. A tool to do
of the many available tests to determine which just that is bound to be costly. The mechanics and
one gives reliable results when working with your chemistry are not complicated. Without drawing
wines. Having the precise number is imperative large chemical equations a summary follows: Free
to take proper action if needed. One of the tests, SO2 is drawn off of a sample of wine after a shift
aeration oxidation, is discussed below. It may seem in the pH brings the sample to a very low ph range
antiquated but many well established cellars still allowing all the free SO2 to be released and mea-
adhere to this testing system. sured. Once in the gaseous state, the gas is pulled
through a hydrogen peroxide reaction flask with an
The equipment to run the aeration oxidation test indictor in the flask’s solution. The hydrogen per-

877-892-5332 The Grapevine • January - February 2022 Page 9

Grapevine Main Pages GV111221_Layout 1-1 copy.indd 9 12/16/21 3:29 PM