Strange Smell in Beer
Whether you are a novice brewer or have been brewing for some time, you may have encountered different aromas in your beer at some point in your brewing journey. We understand that this can be disappointing, which is why we want to share with you some of the most common smells, their causes, and how to avoid them in your future brews.
Being able to recognize and address these common odors is essential for becoming a skilled brewer. However, before we dive in, there are some general practices you can follow to ensure consistent excellent results in your beer:
1. Clean and sanitize everything! Maintaining cleanliness is crucial for brewing high-quality beer.
2. Always use healthy yeast and an adequate amount of it. If you’re using liquid yeast, make sure to create a proper yeast starter. If you’re using dry yeast, check the expiration date and rehydrate it accordingly. You can find more information about making yeast starters here.
3. Oxygenate your wort properly. Whether through aeration or using dedicated oxygenation equipment, ensuring proper oxygen levels is important.
4. Ferment at the appropriate temperature for the yeast strain you’re using. You can learn more about fermentation here.
So, what smells should you look out for?
Acetaldehyde – sour green apples, cider, and sometimes rotten apples.
Acetaldehyde is one of the most common aromas found in beer and is produced by yeast during the primary fermentation process. It is usually converted into ethanol alcohol. However, if the beer lacks sufficient fermentation time, has a very high specific gravity, or is brewed at too high or low temperatures, acetaldehyde can be present.
How to avoid this smell
Avoiding the rotten apple flavor is crucial in homebrewing and is often a result of bacterial infection. The easiest way to prevent infection is by thoroughly sanitizing all your brewing equipment!
You can also prevent apple or cider-like smells by:
– Properly aerating the beer before adding the yeast.
– Avoiding exposure to oxygen during the fermentation process (resist the temptation to open the fermenter lid and check on your brew, as airborne pathogens can cause contamination).
– Not bottling or kegging the beer prematurely.
Diacetyl – butter, buttered popcorn, or butterscotch
Diacetyl may not sound as unpleasant as cider or rotten apple, but it’s another chemical naturally produced by yeast that is usually reabsorbed by yeast cells. This buttery flavor can be caused by weak yeast, excessive or inadequate oxidation, prolonged low fermentation temperature (common in lagers), or weak or short boiling.
How to avoid this smell
Treat your yeast well and provide it with the necessary nutrients for a healthy fermentation.
Avoid subjecting the yeast to extreme temperatures.
Ensure proper ventilation and allow sufficient time during the fermentation process.
Estery – bananas, pears, anise, and even rose petals/bubble gum
Again, these off-flavors may not seem undesirable, but unless you’re brewing specific styles like English or Belgian ales, they shouldn’t suddenly appear in your beer. Esters are produced during fermentation and contribute fruity flavors to your beer.
How to avoid this smell
While these flavors are not the worst on the list, you can avoid them by:
– Fermenting at a lower temperature.
– Ensuring an appropriate yeast pitch rate.
– Aerating your wort properly.
Note:
If you encounter these flavors when using a particular English yeast strain, you can try using an American yeast strain instead.
Phenolic – spicy, clove, cinnamon, nutmeg, or smoky aroma
Let’s get a bit more scientific here… Phenolic compounds contain hydroxyl and carbon molecules, which are responsible for the many delightful flavors in food and even some beers. However, if your beer doesn’t aim for these flavor profiles, you may end up with a plastic or smoky taste.
This smell can be caused by excessive chlorine in the water or the particular yeast strain used.
How to avoid this smell
Consider using bottled water next time to see if the situation improves. You can also try using American or British yeast strains instead.
Fusel Alcohol
It may sound strange, but sometimes beer can have an alcohol-like smell, often described as “hot.” This occurs when there are issues during the fermentation process, causing the beer to have higher-than-desired levels of alcohol.
We need ethanol in beer, which is produced by yeast when it converts maltose sugar. However, sometimes other alcohols, such as propanol, isobutanol, butyraldehyde, and isoamyl alcohol (also known as fusel alcohol), can be produced during fermentation.
How to avoid this smell
If your beer tastes like paint thinner or nail polish, it may contain undesirable alcohols from the fermentation process. Ensure that you maintain the recommended temperature range for the yeast during fermentation.
Dimethyl Sulfide (DMS) – creamed corn or cooked vegetables
This aroma can be a bit complicated, but we’ll keep it simple. DMS is derived from the breakdown of S-methylmethionine (SMM), which is formed during the malt germination stage. It is a common aroma found in light beers, and here’s why:
Nowadays, except for the lightest malts, most malts have their SMM eliminated during the kilning process. SMM is heat-sensitive, so during mashing, it breaks down into dimethyl sulfide (DMS). Most of the DMS then evaporates during the boiling phase of your brew.
How to avoid this smell
If your freshly brewed beer tastes like buttered corn, you likely have a DMS issue. Here are some ways to avoid this aroma:
– Focus on a vigorous boil and avoid covering your equipment during this process, as it prevents DMS evaporation. Any condensation formed on the lid will be filled with DMS and fall directly back into your brew. Boil vigorously!
– Minimize the time your hot wort stays at high temperatures, as prolonged exposure leads to more DMS production. Cool the wort quickly after boiling.
Sour – vinegar or tart
Unless you’re intentionally brewing sour beer, you should strive to avoid this aroma. It is usually caused by bacterial contamination or the presence of wild yeast strains, resulting in a strong vinegar taste in your brew.
How to avoid this smell
Unfortunately, once this occurs, there’s no saving your homebrew. Thorough sanitization is the easiest way to prevent this issue. The more beer you brew and the more equipment you use, the more critical disinfection becomes! Also, resist the temptation to open the fermenter lid and check on your brew, as it increases the risk of infection.
These are some of the most common aromas, but there are many others. The key takeaway is that proper sanitation and brewing techniques are crucial to avoiding off-flavors.
Copper Beer Brewing Equipment
Have you ever encountered unpleasant odors in your beer, or are you interested in beer brewing equipment? Please feel free to email us at info@ace-chn.com.
