Oxygen is essential for all living things. It’s role is to participate in various biochemical processes, but it is necessary to pay attention to the inhalation of pure oxygen. Short-term exposure is not harmful, but it should be borne in mind that prolonged inhalation can create major problems. Like other living things, yeast uses oxygen to maintain biochemical processes. Although fermentation is an anaerobic process (a process that takes place without the presence of oxygen), yeast needs oxygen to ensure cell growth and proliferation.
At the beginning of fermentation, the yeast will use molecular oxygen to synthesize sterols and unsaturated fatty acids (which are essential components in yeast cells). If the brewer decides to add sterols and unsaturated fatty acids directly to the wort, there is no need to add oxygen. If there is a lack of lipid components, there are undesirable consequences such as delayed fermentation, poor organoleptic properties, insufficient activity and the number of yeast cells. It should also be borne in mind that too high a concentration of oxygen will lead to undesirable consequences such as too rapid fermentation, unfavorable yeast growth, and higher ester content.
In beer production, it is important to assess the right moment to add oxygen.
It is most often added during the production process, during the transfer of wort from the clarification vessel, over the refrigerator to the fermenter, but before the yeast is added.
EXTRA TIP
This is usually done after the wort is cooled because numerous studies have shown that the oxygen solubility in wort is better at lower temperatures.
Due to the limited oxygen solubility in malt, measuring devices should be located away from the aeration site in order to read the oxygen values as accurately as possible. Oxygen needs vary from strain to yeast strain used in production as well as to the type of beer. Most often these values range between 6-8 ppm.
After the production of the finished product, it is necessary to control the concentration of dissolved oxygen. Beer ages naturally, even if it is microbiologically correct. One of the main causes of beer aging is oxidation. If the amount of oxygen is reduced, the duration of beer is extended. The preferred concentration of dissolved oxygen in the finished product should be 0.0-0.5 ppm. Oxidation of beer produces compounds that impair the organoleptic properties of beer and creates a product that is not desirable for end users. For this reason, it is necessary to measure and control the oxygen in the final product.
Hanna Instruments offers several options for monitoring and measuring oxygen during beer production.
Continuous monitoring of oxygen concentration in beer
HI8410
Dissolved oxygen controller
The HI8410 is a panel mounted dissolved oxygen controller that is used to maintain and monitor the concentration of DO in a wide range of industrial process applications. The HI8410 uses a Galvanic probe that typically requires less maintenance than a Polarographic style making it ideal for long term monitoring.
- Fail Safe Alarm System protects these meters against the pitfalls of process control.
- Low maintenance Galvanic probe.
HI76410/10
Galvanic DO Probe
The Oxygen that passes through the membrane causes an electric current flow, from which the oxygen concentration is determined.
Other features include:
- recorder output in 0-20 mA or 4-20 mA configuration;
- LED indicators which identify whether the controller is in operation mode or setup selection mode;
- overtime control function;
- hysteresis setting.
Portable DO meters
HI98198
Portable Optical DO (opdo) meter
This professional, waterproof meter complies with IP67 standards and measures:
- DO
- Barometric pressure
- BOD
- temperature
The HI98198 is supplied complete with all accessories including probe, smartcap sensor with built in RFID, and a rugged carrying case.
Advantages: HI98198 Dissolved Oxygen Meter has many advantages over other Galvanic and Polarographic Dissolved Oxygen Meters.
This meter uses HI764113 Rugged Optical Dissolved Oxygen Probe for Dissolved Oxygen measurement which has following benefits:
- No membranes
- No electrolytes
- No oxygen consumption
- No flow dependence or minimum flow rate
- Fast and stable readings
- Minimal maintenance
Author:
Tajana Mokrović, mag.nutr.
Stewart G. G. (2014.) : Encyclopedia of Food Microbiology, Volume 3, Cardiff, UK, str. 302-30
Marić V. (2009.) : Tehnologija piva, Karlovac, str. 15-20
The Brewer International magazine, (March 2002), str 45-47
