Accuvin tests

[PeterZ]

I just received a collection of Accuvin tests from George, covering free SO2, pH, malic acid, l-lactic acid, residual sugar, and titratable acidity. I have to say, I am impressed!!

In the past I have spoken about diluting red wines with distilled water for tests like TA, to make the end point easier to see. Not necessary with these tests, as the sample size is so small compared to the liquid it is mixed with that the color is unimportant. In the case of the free SO2 test, for example, the sample size is about 1/20th of the volume of liquid you put it into.

They also have developed a very accurate and easy way to measure very minute quantities of liquid. The SO2 test uses 53 microliters (.053 ml) of wine or must, and their sampling and measuring system looks to me to be within +/- 5% - more than adequate for us.

I'll be running some tests this weekend. Free SO2 is the only one I am equipped to test the accuracy of (and I'm not really sure of how good my technique will be in the kitchen), but I'll report here on my confidence in the rest of the tests.

BTW, those of you who are red/green colorblind probably will not be able to use these tests, as they all rely on color matching to printed standards.

 

[Wade E]

Great Peter as Im getting mine on Friday and will be starting a blueberry melomel that Im going to use these tests on.

 

[geocorn]

The color strips are easier to read than the other products, but you will have problems with any of the test if you are colorblind.

 

[sangwitch]

I'm looking forward to the test results. Please let everone know how easy the instructions are to follow. I purchased the other test kit and I had trouble working out what the instructions were saying. I don't have a chemistry background, but I do like to think of myself as well educated and able to follow directions.


[with a southern drawl] how y'all doing!

 

[Wade E]

Well if I can do it, y'all can do it. If Peter cant do it, no one can!

I picture his winemaking area with bubbling beakers and glass tubes running everywhere!

 

[Waldo]

A step by step pictoral of the tests being performed would be fantastic.

 

[grapeman]

I have looked the tests over(except Free So2) and they all are very easy to use. I haven't done the tests yet, but will this weekend at some point. I like the residual sugar test. That one could be very useful. I have a perfect wine I sweetened to test it out on. That one also has high acidity so it should be the one I use for the tests.

 

[Coaster]

I've been using these for a while. I even get my wife to help with reading the color charts. Make sure you wait the allocated time for each test, some can be as long as 5 mins IIRC. Also, follow the directions about shaking and not shaking so you get just the amount they want each time. Don't mix the pipettes (sample collectors), they are different volumes. I use these on my Welch's batched after my first one came out so high in acid I had to include "Biting" in the name.
Cost per test is kinda high compared to some other ways, but ease of use it really high.

 

[PeterZ]

I'm really not the person to judge ease of use or quality of directions. I looked at what came with thest kit, and realized immediately how the test was done. As long as you puzzle out how the pipettes that measure out the sample work the tests are a piece of cake. If I'd thought about it, I would have used AutoCAD at work today (I convinced my boss to let me have a copy - we have a concurrent-user license - and have been learning how to use it) to draw up one and annotate it. I can save it as a PDF and upload it. It's a really neat design, and it looks like a b!tch to injection mold.

 

[PeterZ]

OK, I ran some tests on my almost-ready-to-bottle merlot yesterday. I have good news and bad news.

First, the good news. The vial type tests (SO2 and TA) are fantastic. They are easy to read, and easy to do. The instructions work well, and are very understandable.

The SO2 test is great. The sampler is amost impossible to screw up, and I was looking for errors. You place the tip in the wine or must, release the upper bulb, and a precice amount of liquid is held in a capillary tube. A quick wipe with a tissue removes any wine/must from the outside of the tube without wicking any from the inside (I was looking for that due to the very tiny - 53 microliters - sample size), you inject it into the test vial. put the top back on, shake, and wait 5 minutes.

I evaluated the color comparison in my wine room (5' x10') with 2 60 watt bulbs, 2x40 watt fluorescents, direct afternoon sunlight, and held under a table lamp with a 100 watt bulb. The last was the easiest to read. Both my son and I got the same reading on a blind test. (Based on the results of the merlot test, I added 1/4 tsp of K-meta, and will test again at bottling next weekend.)

The TA test was also good. The reaction with this test is immediate. When you inject the sample into the vial the middle of the vial reacts with a massive collor change instantly. This reminded me how to agitate small vials. Don't shake. Invert until all liquid has drained to the bottom. Repeat 5 or 6 times, until the solution is uniform in color.

The problem with the strip tests is that they are effected by the color of the wine . The pH test wants you to read a color from blue to green. In two runs with the merlot, the only color on the spot was red. The color of the wine overwhelmed the indicator.

Based on the indications in the instructions, these tests were designed for the vintner, but they will work for us, under the following restrictions. The stick tests - l-lactic acid, malic acid, pH, and residual sugar - will only work with white and blush wines. The vial tests - SO2 and TA - are awesome and will work for anything.

 

[Wade E]

Great news Peter and thanks for sharing bas I cant get to any of my batches as of yet.

 

[PeterZ]

UPDATE!!!

I stabilized and fined the Strawberry White Merlot IM kit I am making for my daughter today. I ran some of the strip tests on it. It is a "strawberry red" wine, with about the color intensity of a rose. The strip tests that didn't work on my merlot worked fine on this wine.

In my opinion, the strip tests will work fine on any wine except:

A red kit, where the color from the skins is already in the must,
A red wine from grapes after it has been pressed,
A fruit wine that has very dark juice to begin with, but I'll leave that evaluation to the fruit wine makers.

All in all, I am impressed with the fidelity of the colors on the printed scales vs. the color that actually develops in the test. They are very easy to read, and it is very easy to perform the test.

 

[NorthernWinos]

Whatare the names of thetests used on this batch????

 

[Wade E]

Everything worked great for me on my blueberry batch except the PH
strip which either my PH was off the charts or like Peter said is just
to dark and turned purple instead of green or blue like the color
should have been.

 

[PeterZ]

I ran the pH and residual sugar, and both worked fine. The Free SO2 and Titrable Acidity vial tests will, IMHO, work on anything. The instructions are important, as the color fidelity is designed to work (and does) best under incandescent light. Flourescent light is the wrong color, as is direct sunlight. Overcast is OK, but I had my best results with a 100 wat bulb in a lamp, holding it in the direct light coming out under the shade, and with 60 watt frosted globes in my bathroom winery. Avoid the "daylight" bulbs (the ones that look blue in the package) as they are too cold (in color) and too hot (in degrees K).

Ever wonder what the color in degrees K means? Photographers know about this, because it was vital with film. Everybody with a digital camera is confronted with it.

K is the Kelvin scale. It has the same magnitude as the Celcius scale - i.e. the difference between where water freezes and water boils is 100 degrees. The difference is that the K scale has zero at the point where all molecular motion stops - absolute zero (about -273.something C, -450 F give or take). Incandescent lighting is about 2700K. That is the quality of light given off by the glow of platinum at that temperature, which is 4892F. Sunlight at high noon is about 5000K, much bluer.

If you have ever taken snapshots with daylight film indoors without a flash, you have seen that everything looks a little browner. That's because the film was designed for 5000K light and was being used with 2700K light.

I tell you that to tell you this: The Accuvin test people have gone to great lengths to make these tests easy to use and, more importantly, easy to read. I've used all too many tests that had to be read in direct sunlight, or that didn't specify the light required, making them very difficult to read.

 

[mufasha]

Hi peter, based on your knowledge of these tests, for the malic test would you say that it is crucial to read the color indicator for a sample exactly at the 4-6 minute mark? Can you read the color of the sample after this 4-6 minute mark? My issue is that many of the wines I tested showed no color change at the 4 minute mark, but after about 5 minutes displayed a different color, and this color was constant after a longer period of time. I'm worried that the time that they give the instructions is too short for how long it takes the indicator to show the true value of the malic acid present in the wine.

 

[Runningwolf]

Mufasha, first off welcome to the forum. This thread you are replying to is over five years old so I'm not sure you'll get a reply from Peter. I haven't seen him around for at least a year. What I can tell you about accuvin tests, are they are very cumbersome to use and inaccurate. With that said their customer service is awesome if you call them.