Fruits in Craft Beer: A Study to Evaluate the Impact of Fruits on the pH in the Brewing Process and the Breweries Waste Water

Problems in the waste water treatment system of a local micro-brewery brought up the question whether fruits as additional ingredients can have a significant influence on the pH and the Chemical Oxygen Demand (COD) of the waste water. To reach an answer to this question, five batches of beer were brewed in August 2016 in the laboratory of the College of Environmental Science and Forestry in Syracuse, New York. Four of these different fruits (peaches, blueberries, banana and orange peel) were added for the secondary fermentation. Once the fermentation process was done, the beer was filtered and the retentate was diluted to simulate the cleaning process of the filter. The pH level was monitored in several steps during the brewing and the COD was measured for the simulated wash water. The latter is commonly used to express the amount of organic pollutants found in drinking or waste water. It is an indicator of the mass of oxygen consumed by a certain volume of solution and expressed in milligrams per liter.

The evaluation of the data showed that the pH of the beer after the secondary fermentation varied between 3.82 – 4.83 and 4.43 – 6.60 in the wash water. The COD turned out to be between 1937 mg/l and 2917 mg/l in the wash water.