Precision cooling is an integral part of the brewing and distilling process. The quality and integrity of the finished products are reliant on accurate temperature control and reduction during key stages of brewing operations. Key aspects of production include:
Wort cooling and cooling requirements
During the initial stages of brewing, grain kernels are milled to form grist. The grist is transferred to the mash tun and heated water is added. During mash conversion, natural enzymes in the grist break down the malt starch into fermentable sugars. The mash is then pumped into the lauter tun where a sweet liquor (wort) is separated from the grist.
The wort is transferred to a kettle and heated to a controlled boil temperature of approximately 60°C before hops are introduced. After the boiling phase, residual malt and hop particles are removed.
Whilst the wort is still hot it is rapidly cooled for the following reasons:
- The wort is susceptible to oxidative damage if left to cool slowly. Rapid cooling lessens oxidative damage minimising unwanted flavours in the product.
- Trace quantities of dimethyl sulphide (DMS) evolve from the wort during the heating stage. DMS has a low boiling point and evaporates out of the hot wort. As the wort is cooled, DMS is still produced. Slow cooling allows DMS to accumulate due to limited boil off in the brew. High DMS levels in beer and lager can add off-flavours and taint the brew. Rapid cooling of the wort to about 25 °C minimises oxidation and DMS levels improving the flavour profile of the final beverage.
- Rapid cooling achieves a cold break. Proteins are thermally shocked and precipitated from the wort. A lack of rapid chilling can result in a chill haze in the finished product. Residual proteins can precipitate as the product is cooled before consumption. This is often considered undesirable especially if the product should be clear.
The diagram below shows key aspects of the brewing process (click to enlarge).
How is wort cooling achieved?
Most breweries pass the wort through a single or double stage plate heat exchanger to achieve cooling. The application is demanding; a significant heat load must be removed quickly form the process. A glycol water mix on the water circuit is common to provide enhanced cooling capacity. A double-walled food grade heat exchanger is generally selected to prevent contamination issues between the wort and cooling fluid.
When sizing a chiller for wart cooling, consider the following:
- Overall volume of the wort to be cooled (often quoted in BBL / barrel volumes).
- Desired knock out time (cooling time required to optimise the process).
- Initial wort temperature and the desired final wort temperature.
- Will the chiller also be providing cooling capacity for other brewing processes?
Fermentation temperature control
The provision of cooling capacity from a precision chiller is important throughout fermentation. The chiller must regulate the fermentation temperature to prevent product spoiling. In some instances, the brew is also rapidly cooled at the end of fermentation to assist yeast flocculation.
During the fermentation stage, the wort is generally transferred into stainless steel cylindroconical vessels (CCV). Brewer’s yeast is added to the sugary wort when the vessel is filled to begin fermentation. Sugars in the wort are converted to alcohol and CO2 along with other flavour adding compounds.
Fermentation is an exothermic process and can liberate significant heat. This heat must be controlled to protect the integrity of the brew. Temperature control is important for the following reasons:
- Different yeast varieties possess an optimum fermentation temperature range that needs to be maintained to optimise fermentation.
- Exposure to too much heat results in the formation of fusel alcohol and esters that can adversely affect the product flavour.
- Excess heat in the later fermentation stages increases yeast sensitivity to acetic and lactic acid resulting in reduced alcohol yield.
- Rapid cooling at the end of fermentation is used in some processes. The brew is cold crashed through rapid cooling to assist the flocculation of yeast resulting in a clear product prior to conditioning.
When sizing a chiller for fermentation, the following points should be considered:
- The volume of the brew/fermentation vessel (total kW heat load).
- Optimum temperature band required for fermentation.
- Will a cold crash be employed at the end of fermentation?
- Will other processes also be cooled, e.g., wort cooling?
Bottling and filling
In certain processes, beer and lager are cooled in the latter stages of conditioning and filtering. This is often done to improve product clarity and stability. In larger breweries, the temperature is often monitored and controlled during bottle and keg filling. Excess heat from bottling machines may need to be controlled to protect the integrity of the final product.
Cooling in the distillation process
Precision water coolers are vital in the production of high-quality consumer spirits. Several steps in the production of spirits are reliant on maintaining a consistent temperature and removing excess heat. Initial production stages for whiskey and spirits mirror those in the brewing process. Additional distillation and conditioning stages follow fermentation to produce the final product.
A typical process for producing whiskey is shown in the diagram below (click to enlarge):
Precision water coolers are often employed in the following processes during the production of whiskey and other spirits:
- Wort cooling prior to fermentation.
- Control of the fermentation temperature and crash cooling.
- Chill filtration prior to bottling.
Chill filtration
Non-filtered whisky with an ABV of 46% or lower can often form sediment in the bottle when stored in a cool place. The drink can also take on a cloudy appearance when water or ice are added before consumption. These cosmetic factors are considered undesirable in quality products. Natural fatty acids, esters and proteins in the whiskey form during distillation in addition to being imparted from the cask during maturation. These components flocculate and precipitate out of the whiskey when it is chilled.
Chill filtration is employed to prevent the above issues. The process involves dropping the whiskey temperature to 0 °C for malts (-4 °C for blends). Once chilled, the whiskey is passed through a series of tightly knit metallic meshes or paper filters under pressure. During this process, the precipitate and any other sediment or impurities from the cask (coals) are removed.
As with other brewing processes, food-grade heat exchanger is employed to manage the cooling.
Why Parker?
Parker Hyperchill and Hyperchill Plus chillers deliver safe and reliable operation under varied working conditions like those typically found in the brewery and distillation industry, helping owners and operators maintain the integrity of the final product and reduce cost of ownership.
Design features on the Parker product can deliver significant benefits to the end-users in the brewing and distillation industry.
Key features and benefits include:
- Configuration of generously sized water tank coupled with oversized condenser/evaporator allows the chiller to maintain cooling capacity even during rapid load and water temperature changes.
- High reliability, with energy management, to reduce total cost of ownership.
- Low water temperature options (down to -10°C) available for enhanced cooling.
- Stainless steel panel and high IP rating enable ease of operation in wet and humid brewing environments.
- Chillers fully compatible with the use of glycol / water mixture for demanding applications such as wort cooling.
This post was contributed by James Brown, compressed air and gas treatment/analytical gas sales manager and Filippo Turra, product manager, Parker Gas Separation and Filtration Division EMEA
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