From Off-Flavors to Contamination: How to Prevent Common Problems in Home Brewing

Home brewing can be a rewarding and fun hobby, but it is not without its challenges. From infections to off-flavors, there are many potential issues that can arise during the brewing process.

Understanding the science behind these problems and taking preventative measures and avoiding mistakes can help you produce great-tasting beer every brew day.

In this list, we will cover 25 things that can go wrong during home brewing, including the problem, its causes, and potential remedies.

1. Infections: Infections can occur when bacteria or wild yeast contaminate the wort or beer. This can be caused by using improperly sanitized equipment or not properly cleaning equipment between batches. To prevent infections, use proper sanitation practices and clean equipment thoroughly between batches.
2. Oxidation: Oxidation occurs when beer is exposed to too much oxygen, causing it to taste stale or cardboard-like. This can be caused by improper bottling techniques or using equipment that is not airtight. To prevent oxidation, use proper bottling techniques and ensure all equipment is airtight.
3. Chlorophenols: Chlorophenols can cause beer to taste like band-aids or medicine. They are often caused by using chlorine-based sanitizers or using tap water that contains chlorine. To prevent chlorophenols, use non-chlorine-based sanitizers and consider using filtered or distilled water.
4. Diacetyl: Diacetyl is a buttery or butterscotch-like flavor that can be caused by bacterial contamination or a yeast strain that produces high levels of diacetyl. To prevent diacetyl, use appropriate yeast strains and ensure equipment is properly sanitized.
5. Acetaldehyde: Acetaldehyde can cause beer to taste like green apples or freshly cut pumpkins. It is often caused by not allowing the beer to properly ferment or by using an inappropriate yeast strain.
6. Esters: Esters can cause beer to taste fruity or like banana. They are often caused by using an inappropriate yeast strain or by fermenting at too high of a temperature. To prevent esters and monitor fermentation temperature.
7. Fusel alcohols: Fusel alcohols can cause beer to taste harsh or solvent-like. They are often caused by fermenting at too high of a temperature or by using an inappropriate yeast strain. To prevent fusel alcohols, monitor fermentation temperature and use appropriate yeast strains.
8. Metallic off-flavors: Metallic off-flavors can cause beer to taste like metal or pennies. They are often caused by using equipment that is not properly cleaned or by using metal equipment that is not stainless steel. To prevent metallic off-flavors, properly clean and sanitize all equipment and use stainless steel equipment.
9. Phenols: Phenols can cause beer to taste like band-aids or smoke. They are often caused by bacterial contamination or using an inappropriate yeast strain. To prevent phenols, ensure equipment is properly sanitized.
10. Skunked beer: Skunked beer has a distinct skunky odor and taste, similar to that of a skunk. It is often caused by exposing beer to light, especially UV light. To prevent skunked beer, store beer in a dark place and avoid exposing it to light.
11. Too sweet: Beer that is too sweet can be caused by using too much unfermentable sugar or by not allowing the beer to properly ferment. To prevent beer from being too sweet, use appropriate amounts of fermentable sugar and ensure the beer is fully fermented.
12. Vegetal off-flavors: Vegetal off-flavors can cause beer to taste like cooked vegetables or grass. They are often caused by using an inappropriate amount or type of hops, or by not properly storing hops. To prevent vegetal off-flavors, use appropriate amounts and types of hops and store them properly in a cool, dry place.
13. Haze: Haze in beer can be caused by a variety of factors, including using improper ingredients, not allowing the beer to fully ferment, or not properly clarifying the beer before bottling. To prevent haze, use appropriate ingredients, allow the beer to fully ferment, and clarify the beer before bottling.
14. Low carbonation: Beer that is low in carbonation can be caused by not adding enough priming sugar or by not properly carbonating the beer before bottling. To prevent low carbonation, ensure the proper amount of priming sugar is added and properly carbonate the beer before bottling.
15. High carbonation: Beer that is over-carbonated can be caused by adding too much priming sugar or by over-carbonating the beer before bottling. To prevent high carbonation, use the proper amount of priming sugar and properly carbonate the beer before bottling.
16. Gushing beer: Gushing beer occurs when the beer over-foams and spills out of the bottle. This can be caused by over-carbonation or bacterial contamination. To prevent gushing beer, properly carbonate the beer and ensure equipment is properly sanitized.
17. Sour beer: Sour beer can be caused by bacterial contamination or by using an inappropriate yeast strain. To prevent sour beer, ensure equipment is properly sanitized and use appropriate yeast strains.
18. Cloudy beer: Cloudy beer can be caused by a variety of factors, including using improper ingredients, not allowing the beer to fully ferment, or not properly clarifying the beer before bottling. To prevent cloudy beer, use appropriate ingredients, allow the beer to fully ferment, and clarify the beer before bottling.
19. Bitter beer: Beer that is too bitter can be caused by using too many bittering hops or by allowing the beer to ferment too long. To prevent beer from being too bitter, use appropriate amounts of bittering hops and monitor fermentation time.
20. Weak beer: Beer that is too weak can be caused by using too little malt or not allowing the beer to fully ferment. To prevent weak beer, use appropriate amounts of malt and ensure the beer is fully fermented.
21. Hot alcohol flavors: Hot alcohol flavors can cause beer to taste boozy or like rubbing alcohol. They are often caused by using an inappropriate yeast strain or by fermenting at too high of a temperature. To prevent hot alcohol flavors you need to regulate fermentation temperature.
22. Contamination from wild yeast: Contamination from wild yeast can cause beer to taste sour or funky. It is often caused by using equipment that is not properly sanitized or by not properly cleaning equipment between batches. To prevent contamination from wild yeast, use proper sanitation practices and clean equipment thoroughly between batches.
23. Inconsistent carbonation: Inconsistent carbonation can occur when different bottles of beer have different levels of carbonation. This can be caused by uneven distribution of priming sugar or uneven carbonation. To prevent inconsistent carbonation, ensure even distribution of priming sugar and properly carbonate the beer before bottling.
24. Inconsistent flavor: Inconsistent flavor can occur when different bottles of beer have different flavors. This can be caused by uneven fermentation or uneven bottling practices. To prevent inconsistent flavor, ensure even fermentation and bottling practices.
25. Cider-like flavors: Cider-like flavors can cause beer to taste like apple cider or vinegar. They are often caused by bacterial contamination or by using an inappropriate yeast strain. To prevent cider-like flavors, ensure equipment is properly sanitized and use appropriate yeast strains.

In conclusion, there are many potential problems that can arise when home brewing beer.

These problems can range from off-flavors to contamination and can be caused by a variety of factors such as improper ingredients, poor sanitation, and incorrect fermentation times. While these issues can be frustrating, they are a normal part of the home brewing process, and even the most experienced brewers will encounter them from time to time.

However, the best brewers take these challenges in stride and learn from their experiences.

By properly preparing equipment, using appropriate ingredients, and maintaining proper sanitation practices, home brewers can minimize the risk of encountering these problems and create delicious, high-quality beer.

With a lil bit of patience and practice, any home brewer can become a master of their craft and create beer that is both delicious and satisfying.

Leave a Comment acetaldehyde, isoamyl acetate, problem solving

↣ How long can beer be left in the primary fermenter?

Is there a risk of leaving beer in the primary fermenter too long?

As a general rule of thumb, one can leave the beer in the primary fermenter as long as one needs.

There is no set maximum time limit, though there are a couple of slight risks to keep in mind.

Many brewers simply follow the beer recipe or instructions on the malt kit and leave their wort to ferment for around a week to ten days. This usually allows enough time for the first stage of fermentation to have completed.

And technically that's OK, and it's time to bottle.

But the mystery and muscle of brewing beer are that there is a whole range of chemical processes happening in that wort you're fermenting.

Sure the yeast may have produced enough alcohol to make a good drop of beer but there are still a few things that happen.

The longer you leave your beer, the more chance the yeast has to get rid of smells and other leftovers from the fermentation process.

A great example of this is the presence of acetaldehyde in the wort. This chemical forms at the beginning of the fermentation process. It tastes like sour green apple and is not really conducive to a good brew. Giving your beer batch time to work through this will mean a better tasting beer.

Wort left for a long time is harder to carbonate when bottled, is this true?

It possibly could be, depends on your circumstances.

If the beer has been left in the fermenter over winter, for example, the yeast could have become quite dormant so the bottled beer will need to be warmed for the yeast to come 'back to life'.

A trick some brewers have found is that when it comes time to bottling a long-settled wort, give it a small stir up 2 days before you bottle. It causes the yeast to mix back into the beer (it will have settled at the bottom of the fermenter). If you move the fermenter into a warmer place, then your bottled beer with have a shorter carbonation time.

What's the best way to get rid of  'apple taste' from brewed beer?

Let the yeast take the time to convert it into ethanol (alcohol).

So leaving your beer for longer than the recommended instructions on the tin of the beer kit is pretty much a smart move. Frankly, given the benefit to the beer and thus the kit manufacturer's reputation, I do not know why they don't frame the time as a minimum.

That said, when I followed Te Aro's brewing instructions for their Obligatory ale, I made damn good beer.

Exceptions aside, the longer you condition your beer, the greater reduction in acetaldehyde that will occur and the beer your beer will take.

Stout beers have even more to work through so they can happily take longer in the primary.

Another benefit of leaving the beer in the primary for longer is that there is a greater chance that your beer will clear more sediment, thus giving you clear beer. 

Many-a-brewer likes to see their lager look like a lager - that classic light yellow / orange combo. Sure, some wheat beers can be a bit hazy.

At the end of the day this comes down to personal preference as the beer taste is not generally affected.

It's also important to consider the role temperature can play in brewing. If you want a short fermentation period but it's cold, then you may have to simply allow more time because the yeast slows down the alcohol production process when chilled. 

What about leaving beer in for extra long times like 3 - 6 months?

Many brewers have reported leaving batches for months and suffered no issues.

I'd reason though that the beer was stored in a cool place - a beer wort left in a hot environment is sure to fail as the yeast would probably get cooked.

The lid was probably screwed on very tightly as well and the beer must be kept out of the light. Put a sheet over it!

My mate Julian did a beer after 8 months once (a chilli one, go figure) - it tasted fine after bottling. 

There is an issue that can happen called 'autolysis'

This is when the yeast cells die, giving off some potentially 'off flavors'. These could be hydrolytic enzymes, lipids, and metal cations that can contribute to off flavor.

If you've made a healthy batch with a quality yeast, pitched at a good temperature and brewed in a stable environment, then the risks of autolysis are quite low. 

If you are quite concerned about this, you could counter by racking your beer to a secondary, thus removing the yeast cake from the equation.

It's important to note, the same process begins again when the beer is bottle conditioned - more sugar is added to the beer for the yeast to eat - this is because CO2 is the by-product of fermentation and is trapped in the beer.

Most beers strongly benefit from being bottle conditioned for three weeks before consumption and even then they usually start to become pretty drinkable at the 5 week mark.

If you have placed a lot of hops in your beer, remember that their effect reduces over time so once a well hopped beer has reached optimal drinking time, you may as well drink them!

Extra for experts: How to increase the alcohol level in homebrew - amylase can help with attenuation.

1 comment acetaldehyde, autolysis, ethanol, fermentation, temperature