Source I
Bacteria - rods
Lactobacillus type

Source II
Bacteria - round
Pediococcus type

I. DMS - Dimethyl Sulphide originates in malt and malt extract and has an odor/taste of creamed corn-corn.

To minimize a rolling kettle boil of 75 minutes minimum with a quick wort chilling is required. Also see mfgs. specifications.

II. Bacterial Off Tastes - The off tastes result from either a high concentration of bacteria present in wort or on equipment and from normal (low) levels allowed to grow under favorable conditions - higher pH and warmer temperatures, high nutrient levels.

In order to prevent bacterial off tastes, the following procedures should be followed:

1- Ensure that all aeration equipment, wort chiller, lines, fittings and gaskets and hoses are clean, sanitized and rinsed before wort transfer.

2- Ensure that the fermenter is sanitized with the proper strength (not too concentrated) solution. Iodophor should be allowed to dry and not be rinsed off. Chlorine bleach sanitizer 1 liq. oz. in 10 gals. should be rinsed off with hot water.

3- All yeast pitching vessels and tools should be sanitary.

4- Thoroughly aerate the wort with sterile breathing air.

5- Pitch a sufficient quantity of viable yeast slurry in a uniform manner to ensure proper intermixing with wort being transferred. A rapid fermentation will lead to the desired lower pH and anaerobic conditions which aid in preventing some bacterial growth.

6- Do not brew beer until it is needed as excess standing time will allow more time for bacteria to grow and yeast to die producing other off flavors.

7- As soon as fermentation is complete and beer taste is satisfactory, chill beer to 32-36^oF. Do not let beer stand for extended periods of time above 40^oF.

8- Do not reduce the temperature of beers brewed with ale yeast until fermentation is complete. On fermenters with uninsulated bottoms it is important to move the beer off the settled yeast within one week after fermentation is complete.

A sterile filter on the output of standard D.E. or sheet filters will remove all bacteria before entering serving tanks or kegs. This provides extended shelf life if kegs and serving tanks are properly sanitized. We can provide such a filter.

Return to Home Page

Send us e-mail