To be honest, I don’t know. There are many variables in the brewing process and it is very difficult to determine why a brew has off-flavors. Having been meticulous ourselves and taking copious notes, we still have had some unexplained results. Having said that, there are some common mistakes that are known to cause problems in a brew. Let’s take a look at some of them.
The number one cause of poor results of a homebrew is sanitizing of all of the equipment used in the process. Unwanted bacteria and wild yeasts are the primary contributors to off-flavors. Sanitizing must be meticulous especially after the boil when the wort is most susceptible to the introduction of unwanted micro-organisms.
Have you followed the recommended cleansing and sanitizing procedure through-out your brew? Did you use appropriate sanitizers at the recommended concentration and more importantly, the recommended contact time? Different sanitizers require different times to be in contact with your equipment to effectively kill the unwanted micro-organisms.
Is your equipment in good condition? Plastic equipment over time can develop scratches that can harbor bacteria that is difficult for sanitizers to reach. Most experienced homebrewers replace their heavily used plastic equipment once a year.
Most homebrewers in the Lowcountry will be using water direct from a municipal water supply. Generally speaking, if you are happy with your tap water, it should be fine for your home brewing needs. However, some regions do have different water chemical/mineral profiles that could effect your homebrew. Water from wells are also known to have distinctive profiles that can cause adverse flavors in your beer. Sulfur, mineral hardness and PH levels can influence your brew’s flavor. Most municipal water companies can provide a detailed analysis of their water profile. The internet can provide further advice on dealing with more specific water components.
There are many advanced homebrewers who, in order to replicate a beer from a specific region, will ‘make their own water’. They will remove all trace elements from their water source through reverse osmosis filtering or distilling – leaving only pure water. They will then ‘build’ their water by adding minerals, acids and other elements to recreate the natural water profile of the beer they are trying to reproduce.
Virtually all municipal water supplies utilize chlorine as a disinfectant. Becoming more popular is a chlorine and ammonia compound called chloramine. Both can be linked to off flavors usually described as medicinal or ‘plastic flavor’. Chlorine usually not the problem as it is generally removed during the boil. Simply letting your water sit for an hour will allow the chlorine to dissipate. Chloramine is more difficult to remove from your water and requires either carbon filtering or the addition of Camden Tablets (Potassium Metasulfite). If you suspect the chloramine content of your water could be causing off-flavors, take a look at this site for a more in-depth discussion of chloramines.
Are your ingredients fresh, stored properly and added in the appropriate amounts? Hops, especially whole hops lose their flavoring oils very rapidly unless stored at a cool temperature. If your grains have been milled, they are very susceptible to oxidation which can cause off-flavors. Be sure to store your milled grains in an airtight container, away from sunlight and preferably refrigerated.
Exposing Your Brew To Air
After the boil, when you have pitched the yeast, introducing oxygen into the must with a vigorous aeration of the wort is recommended. After that point, fresh air is the enemy that needs to be kept out of your brewing beer. An airlock with sanitized water is essential and while racking or bottling your beer, minimal disturbance and aeration is the goal! Any air at this point can contain bacteria and wild yeast and once below 160 degrees F., your must/beer is susceptible to contamination.
SPECIFIC OFF-FLAVORS AND POSSIBLE CAUSES
Excessive Fruity Flavors
Usually caused by high fermentation temperatures. It is difficult in the Lowcountry summers to maintain the ideal temperatures for fermentation even in an air conditioned home. Ale yeast work best at temps in the upper 60s to low 70s degrees F, while lager yeast needs cooler temps between 48 and 55 degrees F.