To produce quality products, distillers need quality inputs. Unfortunately, that’s not always an easy task. Despite suppliers’ best efforts, it’s not uncommon to receive subpar or defective raw materials that can have a major impact on the quality of your spirits.
That’s why it’s important to establish testing protocols for your raw materials. Such protocols can ensure that those materials meet quality standards and thus help safeguard against inconsistency in your product.
Here are a few simple quality tests for raw materials that you can easily incorporate into your daily processes.
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Grain
Grain is central to products such as whiskey, and it’s one of the most-used raw materials among distillers. Many grain suppliers work closely with both farmers and distillers to perform analytical testing, and they’ll happily provide distillers with detailed certificates of analysis ensuring the quality of their grain.
Nonetheless, grain is inherently unstable, and problems with shipping, storage, and pests can only exacerbate that instability. When receiving new shipments of grain, distillers should implement a few basic quality tests to ensure the quality of incoming lots.
The first test, always recommended when receiving a new grain, is the sniff test. Anyone who works with grain can tell you that moldy or dirty grain has a particular, and often unpleasant, smell. Having your team members who receive the newly delivered grain smell it is an easy way to identify possible problems. If a new lot of grain smells off, or not like it normally does, that’s a sure sign that something may be wrong and that you might have to reject the grain.
If you’re unsure about the smell, one way you can enhance the aroma is by placing the grain in a microwave for a few seconds. Microwaving the grain volatilizes any aromas, good or bad. (Beyond checking for faults, this is also useful a way to determine the sensory characteristics of a new grain.)
After your grain passes the smell test, the next test you can conduct is to make a grain tea. Simply coarse-grind a set amount of grain, add hot water (~180°F/82°C), and steep for about five minutes. After steeping, filter out the grain solids and perform sensory evaluation on the resulting tea. This is a fast and easy way to further evaluate the quality of your grain, and it should quickly reveal any problems that were not readily identified with the smell test. Note that the grain-tea method is best for raw grains. For malted grains, there’s a similar test known as the hot-steep method, also known as Sensory Analysis 14 among the American Society of Brewing Chemists.
Finally, a third trial you can conduct on incoming grain is known as a gelatinization test. Suppliers do a lot of testing of their grains, and sometimes all the information on a COA can be overwhelming to a distiller. Yet there’s always room for improvement, and something that’s not commonly listed on a grain COA is the grain’s specific gelatinization temperature.
Gelatinization is the process by which starch granules break apart in the presence of water and heat, allowing enzymes to act upon them. Each grain has its own optimal gelatinization temperature that can vary greatly among different varieties—or even among different lots—of the same grain. For distillers, that means that a mashing regimen that works for one type of grain may not be as effective on another. However, a gelatinization test can help you determine the optimal temperatures at which to mash the grains.
The most accurate way to conduct a gelatinization test is with a piece of lab equipment known as a rapid visco analyzer, or RVA. RVAs determine the gelatinization temperature of grain based on the viscosity of a mixture of the grain and water at increasing temperatures. RVAs are effective—unfortunately, they’re also expensive, ranging from perhaps $2,000 used to as much as $50,000 for new and top-of-the-line. If an RVA isn’t in your distillery’s budget, you can conduct a simpler version of the test by heating milled grain in the presence of temperature-stable enzymes until the mixture passes an iodine test. This method isn’t as accurate or effective as an RVA, but it can still be useful in determining whether it makes sense to adjust your mashing regimen.
Water
Water is without a doubt one of the most important ingredients used in distilling. From mashing to cleaning to proofing, water is critical to almost every aspect of the distillery. That means that water quality is incredibly important to monitor for quality.
Luckily, most distillers already have well-funded and built-in water-quality testing in the form of municipal water departments. Municipal water companies perform many tests that help to ensure the quality of water they supply, and these reports are generally readily accessible online.
However, just because a water is safe to drink doesn’t always mean it’s good for distilling, and many municipalities don’t provide all the information a distiller may want. Therefore, it’s always important to regularly do your own testing to confirm the water’s quality.
Water testing can take many forms, the bulk of which are best performed by specialized third-party companies. However, there’s one test you can easily execute to ensure that incoming water is suitable. The taste and odor acceptance test, or TOA, is a simple go/no-go test that you can quickly incorporate into the distillery’s process methodology. To conduct a TOA, just open a spigot to the water intended for use, take a small sample, and then smell and taste it. If it tastes as expected, then you can proceed; if not, then you may need to either get other testers involved, try to figure out what’s wrong, or use a different water source.
At first glance, a TOA sounds like simple common sense—and it is. Regardless, a surprising number of distillers don’t even think about tasting their water before use, and this leads to all sorts of preventable mistakes. By instituting a required TOA test in all distillery processes that involve water—and many that don’t—you can avoid costly blunders and create a more consistent, quality product.
Yeast
Yeast is one raw material that only rarely seems to be an issue for distillers. Indeed, during my 10-plus years as a distiller, I can count on one hand the number of times I’ve had to deal with bad yeast—and in all those cases, suppliers quickly rectified the situation.
Cultivating and selling pitchable amounts of yeast is a technically complicated task, and the distilling industry is blessed with many suppliers that accomplish this task well. Yet mistakes do happen, and because there’s no alcohol without healthy yeast, it’s wise for distillers to perform a few basic quality checks to ensure the yeast’s quality.
The first thing to do when receiving an order of yeast—either dried or liquid—is check the seals of each container. Pure pitches of yeast are easily contaminated, and even the slightest opening may mean that the yeast has been spoiled. If there’s any damage to a container, isolate the enclosed yeast and ask your supplier to send a replacement. Most suppliers will happily oblige.
Once you’re satisfied that the yeast are intact, the next step is to determine whether there’s any contamination intrinsic to the yeast sample. Despite the yeast labs’ best efforts, there are many ways for microbes to contaminate the process. Therefore, it’s important to confirm that the yeast is free from infection. There are several ways to do this, but the two most common are QPCR and diagnostic plate testing. The details on these two methods are best reserved for a future article, but it’s worth noting that QPCR requires specialized equipment and knowhow, and it’s mainly only large companies or third-party testers that perform it. On the other hand, diagnostic plate testing is relatively cheap and requires only basic equipment. However, it’s slower and sometimes inaccurate.
Finally, the last quality test that is useful to perform on incoming yeast is to check for viability. Viability is how we describe yeast’s ability to grow and reproduce in a specific medium. As with contamination testing, there are many ways to assess viability, and they all vary in complexity, cost, and accuracy. The most basic way is to simply add a small portion of your yeast to a known fermentable medium and measure how quickly it attenuates. You can do this with either dried or liquid yeast, and while it’s not always accurate, it can at least show you whether the yeast are alive or dead.
Notably, most distillers reserve contamination and viability testing only for liquid pitches because liquid yeasts are much more vulnerable to infection and heat shock during transport than dried yeast. However, personally, I find it important to check all yeast regardless of origin. Besides, there’s little harm in taking a few grams of dried yeast and adding it to a stir plate of wash to ensure it begins fermenting efficiently and without any off-flavors. As the saying goes, an ounce of prevention is worth a pound of cure.
Quality Requires Care
There are dozens if not hundreds of simple tests and methods you can undertake to ensure the quality and consistency of your products. The above tests are just a few of the most common and easily instituted ones.
Take nothing for granted. Examine your raw materials intake and processing closely. Establishing good intake methods for raw materials will help you achieve the consistency and quality for which all distillers strive.
