Beer Odor Guide: Infection

What Is An Infection?

Infection refers to the introduction or presence of undesirable microorganisms in beer or raw materials, When these undesirable microorganisms are made into beer and start to compete for sugar with cultured yeast, infection will occur. Bacteria or undesirable microorganisms in wild yeast can destroy beer. For both novice brewers and professional brewers, infection is the most feared situation. The severity of the infection may be difficult to judge from the appearance. In extreme cases, the infection can cause the beer to become cloudy, sour or smelly, and may make the beer look unsightly or undrinkable. Although beer infection is not dangerous to human health, allowing infected beer to reach consumers is very harmful to the reputation and business of any brewery.

Life essentially depends on sugar, and many organisms can destroy the flavor of the beer. The term “wort breaker” is sometimes applied to spoilage organisms that tolerate oxygen and grow best before fermentation lowers the pH of the wort and produces ethanol. Of course, there are some bacteria called “beer destroyers”, they tend to prefer anaerobic conditions and can survive well in a lower pH environment and an environment containing alcohol. Most brewers believe that the most common beer-destroying organisms are Lactobacillus, Pediococcus, and wild yeast, including Brettanomyces. Each type of bacteria has its own favorite nutrients, temperature range, pH range, and growth rate.

Infection is a very scary situation in the eyes of winemakers and consumers. But, certain beer styles are completely needed or encouraged, including Berlin Weiss beer, Lambik beer, and Belgian-style sour beer. An infection in the eyes of one brewer may be the taste complexity required by another brewer, especially in the field of sour beer styles. But, in most beers, the brewer only needs to add the required raw materials to the brewhouse equipment and hopes to exclude all other biological factors.

How Does The Infection Develop In Beer?

When the wort is boiled in a kettle, the wort should be non-toxic. Because in the subsequent wort cooling, fermentation, cold transfer, and packaging process, the infection may occur. This situation is generally caused by improper cleaning of brewery equipment. In addition, it is also possible that bacteria or microorganisms were accidentally introduced into the beer when ingredients were added before fermentation. In addition, the infection may also occur during cold transfer or packaging.

How To Find Out If Beer Is Infected?

It has an oily gloss on the top of the beer and looks like a thin white ice cap with jagged edges, which is a sign of the beginning of the infection. This infection is usually caused by wild yeasts such as Brettanomyces or wild bacteria such as Lactobacillus. In more severe infections, this layer of biofilm called a “film,” may look wavy, or it may look like a bubble with a belt. Although they look like different types of infections, they are caused by similar strains of bacteria or yeast.

Films only form when there are aerobic conditions and are a way for wild yeast/bacteria to protect themselves from oxygen because they prefer an anaerobic environment. So, if your beer is not exposed to oxygen during the fermentation process, you may still be infected even if there is no skin formation. In this case, the only way to know if it is infected is to taste it.

Don’t worry about getting sick while tasting beer, because these wild bacteria, yeasts, or molds will not harm you. If the beer tastes bad or stinks, you may want to throw it away. But in some cases, the infection may cause the beer to taste better. Remember, the popular sour beer is brewed using these wild yeasts and bacteria.

How To Solve The Problem Of Beer Infection?

The best way for brewers to combat harmful microorganisms in finished beer is proper sanitation of fermentation tanks, bright tanks, and filling equipment. You need to stick to a good cleaning and disinfection program. If you are using stainless steel brewing equipment, try not to use detergent to disinfect the equipment, because the detergent will cause irreversible damage to the stainless steel.

In addition, the use of sterile bottles and barrels is also a good way. In breweries, especially large industrial breweries, the beer is sent to the bottling line for aseptic filtration or pasteurization after packaging. These steps are to extend the shelf life of beer by removing or killing potentially infectious microorganisms so that drinkable beer is more likely to reach consumers’ tables. Although pasteurization kills microorganisms, it can produce a stale or “cooked” taste and aroma if it is not handled properly. Sterile filtration can remove bacteria, but it also removes the taste, aroma, body, and even color of beer.