For those us of in the northern hemisphere it is time we start getting ready for harvest season!

WineMaker Magazine has a great Harvest Check List in their most recent edition, written by Bob Peak. It is wonderfully detailed and a must read for all our customers. It is an all encompassing check list whereas ours will just scratch the surface. Our checklist reflects only what we do here at our own winery. What you do during your own harvest is up to you.

We always use a checklist to prepare and to ensure we have everything we need for a successful harvest. Our winery, Little Oaks Winery, is a small operation with a limited about of employees and we have found that preparing for harvest is essential for producing award-winning, memorable wines. Our winery is about four to five weeks away from harvest time. It’s time to start preparing.

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Wine is an acidic substance, and there are ranges of acidity that are appropriate to each varietal.  In general a wine that is too acidic will taste sharp or sour, while one that is not acidic enough will taste flat and insipid. It’s no surprise to those of you on the quest for great achievements in winemaking that pH and acidity (TA) are important aspects that are key to know and control.  In a previous issue of The Wine Analyst’s Blog (April_pH_Blog), we discussed pH and how it’s measured. In this issue of The Wine Analyst’s Blog, we’ll learn more about pH, TA, and how to understand and manage them in winemaking.  We’ll also look at yeast assimilable nitrogen (YAN) which uses the TA system. Keep Reading More!

For years it has been said that the Ripper method for measuring sulfite (SO2) has one drawback: interference from “reductones”. These are substances that react with the iodine titrant as SO2 itself does, causing an overestimation of the true SO2 level. But as we’ll see below, this does not seem to be a huge problem with the Vinmetrica version of the Ripper method, and where encountered, it can usually be corrected for.
The Ripper method uses iodine or iodine-generating reagents to oxidize the SO2 in the test sample (primarily wine, but beer and cider are also examples). It relies on the quantitative reaction of iodine (I2) oxidizing the SO2 in the sample under acid conditions.

In this reaction, SO2 is acting as a “reductant” for the oxidant iodine. When all the SO2 is oxidized by iodine at the endpoint, excess iodine appears in solution. The Vinmetrica system detects this event as a sharp rise in electrochemical current with its SO2 electrode.
Anything in the sample that reacts like a reductant – called a “reductone” – in a Ripper titration will appear to be SO2, leading to an overestimation of the SO2 level. A well-known example of a reductone is ascorbic acid. Ascorbic acid (“AA”, also known as ascorbate or vitamin C) reacts with iodine just as SO2 does, that is

Ascorbic acid can be found in modest amounts in some vinifera varietals, and it can occur in high levels in a number of fruits, like citrus and some berries. When trying to measure SO2 levels in these samples, one must be careful not to get misled by ascorbate parading as SO2!
There are other things present in wines and juices that can act as reductones. In principle, reducing sugars (glucose, fructose) and various polyphenols could act as reductones.

How to correct for reductones:

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Vinmetrica Compares Well with Wine Testing Labs

Summary: Vinmetrica is participating in the CTS Wine Industry Interlaboratory Program this year. Along with 100 other labs, we tested two samples from CTS for up to 16 parameters. Using our products, we obtained results for free and total SO2, pH, TA, malic acid, and residual sugar that were in good agreement with those of the other participants.

We are pleased to report the first round of results from participating in Collaborative Testing Services’ (CTS) Wine Industry Interlaboratory Program for 2020. CTS (www.collaborativetesting.com) provides samples to, and analysis of the results from, participating laboratories in a wide variety of testing technologies. The Wine Industry Interlaboratory Program focuses on chemical and physical analysis of wine.

This last round of samples from CTS (“Cycle 065”) comprised two sweet red wines. About 100 labs across the US participated. The following parameters were available to be measured and compared: Total SO2, Free SO2, TA, pH, Residual Reducing Sugars, L-malic acid, %ABV, Specific Gravity, Glucose + Fructose, Copper, Potassium, A420, A520, L-lactic acid, Conductivity, and Methanol. We submitted results for all these except Copper, A420, and A520, the first because we don’t have the equipment for it, the latter two because we rarely perform them (though we can do so). Keep Reading More!

As many of you know, Winemaker Magazine (WMM) is a great source of information and techniques for the serious home winemaker. This weekend many of us planned to attend the annual WMM Conference that was to be held in San Luis Obispo amid one of our favorite wine regions, the California Central Coast. In the interest of public health and safety, the meeting has been postponed. As of this writing, it is to be held next year May 20-23 in the same location. So we’re looking forward to that!

Discount codes!
The Vinmetrica Team would have been at the WMM Conference to share information about our products and to learn more about your needs. We can’t all meet this year, but we can provide the same discount codes for a brief time as we do every year at the conference!

If you order anything on-line from Vinmetrica before midnight on Sunday, you can take 15% off your entire order by entering this discount code Keep Reading More!

I’m sure many of you are familiar with the technique of malolactic fermentation (MLF), typically carried out in most red wines and in some white varietals.  MLF plays an important role in the finished wine’s feel and taste. MLF reduces titratable acidity, increases pH, and produces flavors often characterized as “soft” or “buttery”.  In addition, carrying out MLF before bottling prevents an unintended development of carbon dioxide gas (CO₂) due to MLF starting up in the bottle, which can lead to fizzy wine, or worse, exploding bottles! Keep Reading More!