Improving Product Consistency and Minimizing Off Flavors and Odors for Craft Brewers

Posted on: July 12, 2019

With the rapid expansion of new craft breweries across the country, it’s not surprising to see many of the new breweries take a minimalist approach to water treatment in order to keep initial capital costs down. Most new breweries are connecting to a municipal water supply system where the water has been chlorinated. They then remove the chlorine through the use of GAC (granular activated carbon). Some will make a few water chemistry adjustments, while others simply take the dechlorinated water and begin extracting the sugars from the grains through the mashing process.

Given that the incoming water is chlorinated and that the wort is boiled, many brewers make the false assumption that microbial contamination is not an issue immediately after boiling the wort. Although it’s true that properly chlorinated water should not contain elevated amounts of microbial contaminants, it’s been well documented that some organisms are resistant to chlorine. Those chlorine resistant organisms then multiply when exposed to favorable conditions and a food source. Unfortunately, GAC can provide that harborage which results in downstream contamination.

In addition, thermophiles can survive the boiling process. With no disinfection technology or treatment after GAC and before the mash, thermophiles and some chlorine resistant organisms can cause wort contamination. An old article published in The Institute of Brewing provides more details about common Enterobacteriaceae that have been documented in the wort. Below are some notes on their findings:

  • Citrobacter, Enterobacter, and Klebsiella are some of the common Enterobacteriaceae found in wort.
  • Enterobacteriaceae can slow the fermentation process and raise the pH.
  • If not addressed, this type of contamination results in inconsistencies in beer taste and flavor profiles especially in regards to fusel alcohols, esters, sulfur compounds, carbonyl compounds, and volatile phenols.

An article titled The Microbiology of Malting and Brewing, expands on this even further by noting the following key issues:

  • Bacillus and Clostridium may be in the mash or wort which could cause excessive acidification, nitrosamine formation, or contribute to the production of butyric acid.
  • Addressing contamination issues prior to mashing can improve filterability and extraction efficiency.
  • Commonly found microorganisms at various points in the brewing process can be found below.

Given the above issues, and the importance of quality and consistency in the final product, most larger breweries already use UV disinfection systems after GAC beds to counteract microbial contaminants such as chlorine resistant organisms, thermophiles, and other unwanted organisms that colonize within the GAC beds. For craft brewers, UV technology has often been viewed either as a luxury item (since most industrial UV systems are overengineered for their use) or as unnecessary (since most craft brewers are unaware of the pitfalls associated with GAC towers).

As a response to feedback from craft brewers, Aquionics developed a new line of UV systems branded as Pureline Craft. This new line of UV systems was designed with the following objectives:

  1. Reduce system cost and pricing but provide craft brewers with the same disinfection capabilities as large brewers who use UV.
  2. Identify the key organisms that can contribute to taste and odor issues in the ingredient water.
  3. Design the UV systems to inactivate those organisms that have been identified in GAC and those thermophiles that can survive the boiling process of the wort.
  4. Validate the systems for those organisms and provide a performance guarantee to eliminate those taste and odor issues from these water microbiology contaminants.

With this approach, Aquionics’ has now made UV technology more affordable and it is the only line of UV systems designed around the needs of craft brewers. By implementing Aquionics’ Pureline Craft UV system, craft brewers can be confident that unwanted organisms will not create off flavors and odors in their final product which will result in a more consistent beer.

For more information on microbial contaminants found in the mash, wort, and post-boil, please review the information in the links below.

http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1974.tb03629.x/abstract
http://mmbr.asm.org/content/77/2/157.full