Simple Tests You Can Perform at Home
One key to success for professional brewers is consistency. A commercial product must be consistent and consistently good (contamination free). Most professional brewers have access to a laboratory for testing their products at different stages of production.
Even if the lab is just a workbench in a closet away from the brewing area, it’s a place where they can get a good look at the ingredients or check for bacterial contamination. Professional testing includes analyzing ingredients and brewing processes to assure batch consistency and searching for bacterial contamination as part of a larger quality-control program.
As a homebrewer you will be consuming your product quickly, so defects have an abbreviated opportunity to appear, and who cares if one batch of your special stout is different from another? Some homebrewers don’t care. Really, the only requirement for homebrewing is to be happy with the product you create. But some brewers do care. Exploring the homebrewing hobby is fun, and when the exploring includes working toward a better beer, it’s also rewarding. You can use the professionals’ tests to create your own quality-control program. The simplest quality-control tests need no — or very little — special equipment.
The No-Lab Test:
The primary test for your at-home lab program is extremely simple and enjoyable. It doesn’t even require a lab. Form a taste panel — undoubtedly, you’ll have many volunteers. The taste panel should perform sensory evaluation with quantitative sheets or as near to quantitative as you can make them.
Typically, these sheets track three areas: aroma, flavor, and after-palate. Aroma is described with words such as estery/fruity, floral, yeasty, and hoppy. Flavor is described as floral, phenolic, sulfury, salty, astringent, warming, and full-bodied, among others. After-palate uses terms such as sweet, bitter, mouth-coating, and astringent. Each description is rated 1, absent; 2, barely detectable; 3, obviously present; 4, very strong; or 5, overwhelming.
The upshot of the tasting panels is to know your own beers. If you know how your beer tastes while it is fermenting, conditioning, or being served, this information will give you the ability to detect a flaw and rectify the error either during the brewing process or when you repeat the recipe.
Iodine Conversion and pH Tests:
An iodine test is a simple test that all-grain brewers can use to improve the quality (yield) and consistency of their batches. The test indicates the conversion of starches to brewing sugars in the mash. The iodine method produces distinct color reactions between an iodine solution and the different dextrins that accompany complete conversion.
The iodine test, also called the starch test, consists of adding a drop of tincture of iodine (found at any drugstore) to a drop of cold, clean wort on a white saucer. If the color remains iodine brown, the starch conversion is complete. A blue or purplish color shows the presence of starch, indicating conversion is not complete so the mash should continue. Do not return the sample to the mash, because iodine is toxic.
When you check for conversion, it’s also a good time to take a small sample of your mash and make a pH reading. The pH paper needed is readily available from any homebrew supplier. The optimal pH varies according to the beer you’re making. In general it should fall in the range of 5.5 plus or minus 0.4, so between 5.1 and 5.9.
As a rule of thumb, the pH of the finished beer should be approximately one point less than your mash pH. It should fall somewhere around 4.4, again plus or minus 0.4. This general rule works for most beer styles. Fruit beers usually have lower pH (more acidic) because of the citric acid present in the fruit.
Testing for Clean Beer:
The next test does not require a laboratory, but it does need equipment. You can conduct a forcing test with just a flask (or two) and an area in the house that does not change temperature too much (such as a cabinet or closet). A homemade incubator (see Building an Incubator, page 54) moves things along even faster.
The objective of this test is to discover whether the beer in your fermenter will be “clean.” Using unpitched wort, incubate a sample at 88° F for 48 hours. If no taste, aroma, or visible changes are noticed, your wort is in the clear. If haziness develops, you likely have a problem.
Be sure to collect the beer aseptically, so as not to introduce bacteria. To do this, sterilize a flask, cover the mouth of the flask with aluminum foil, and bake in a 325° F oven for two to three hours. Also, use a bucket of iodophor (two minutes of contact time) to sterilize your choice of collecting equipment. A turkey baster will work fine. Collect 100 milliliters of wort.
Allow the wort to run through the tap for a bit to cool the tap before you collect the sample. Then collect 100 milliliters of wort midstream. If you have bacteria, some off-flavors might not appear for a few days. If the beer tastes okay now, you might be able to salvage it all by drinking it quickly. Maybe you should throw a party. Off-flavors grow worse as the bacteria multiplies, so your time is short — perhaps only a few days. The bottom line is that the presence of bacteria tells you that you need to be more careful about sanitation practices.
Because the test is performed before pitching, clean wort can produce contaminated beer. If this happens, there is a good chance that the contamination occurred when you pitched the yeast. So focus on your sanitation practices at that point in the process.
These tests give you knowledge of your working materials. The tests are cheap, fast, and easy
to perform. Knowing what you are working with excites the mind into thinking of different ways to better the next batch which, coincidentally, betters you as a brewer.
