Pasteurisation: A Summary

Pasteurisation:

A Summary

Everyone has to start somewhere.

What is Pasteurisation?

Pasteurisation is the process of killing bacteria and other microbes from drink produce. This is important because of the various stages in the juice, cider and beer making processes where the produce can be contaminated, and if those microbes reach the end consumer they could cause some serious harm. In cider and beer the fermentation process needs to be stopped by killing all remaining yeasts, else the packaging may explode. Another reason to pasteurise your drinks is to give them a longer shelf life. Typically, only juice and cider are pasteurised, but beer can be pasteurised by the larger manufacturers in order to reduce the risk of consumption of microbes by their large consumer base, where the alternative (filtration techniques) can be high-risk to the taste of the produce.

There are various types of pasteurising equipment on the market which all give the same end result but vary in suitability for the sort of business they are used for, mainly in terms of efficiency and capacity. We explore the technicalities of each type of pasteuriser below, along with the pros and cons and a couple of examples of which type of drinks manufacture business benefits most from each variant.

It is worth noting that there are two initial categories of pasteurisation; in-bottle pasteurisation and flash pasteurisation. If considering in-bottle pasteurisation, please note that it is best to fill each bottle as much as possible. The more oxygen there is in the bottle, the higher the risk of micro-organisms surviving the pasteurisation process. Inside the bottle, pasteurising is done through the transfer of heat from the surrounding water to the hot liquid inside the bottle, which then carries the heat to every part of the inside of the bottle, killing any micro-organisms not just in the liquid itself, but inside the bottle, the cap and the air trapped inside. Therefore the more of the inside of the bottle touched by the liquid, the more effective pasteurisation is.

Bath Pasteurisers

A Bath pasteuriser is designed to pasteurise relatively small amounts of product in-bottle. Bath pasteurisers are usually used by smaller companies who are looking for a very low-maintenance, simple piece of equipment to pasteurise up to 400 1L bottles per hour depending on the capacity of the pasteuriser chosen.

How does a bath pasteuriser work?

A bath pasteuriser heats a bath of water until it reaches the desired temperature, and regulates the water to keep it at this temperature until the set time is up. The heat from the water transfers to the juice / cider / beer and kills any micro-organisms inside it, but also kills microbes from the cap and the bottle.

How to use a bath pasteuriser

Fill the tub with clean water, set the temperature and time required, and place the bottles to be pasteurised in the machine. The machine will heat the water to the desired temperature and will regulate the temperature of the water to ensure it does not get too hot or too cold, ensuring in efficient, effective pasteurisation of the bottled product. A light should either come on or go out (depending on the specific equipment) once the time is up, and the next batch of bottles can be placed into the now-heated water.

Common problems and how these can be resolved:

Whole plant non-functional

The mains plug issue may be having issues – ask an electrician to fix the plug
The heating boiler may have malfunctioned – press the dejam button
The pasteuriser may be out of fuel – replenish the fuel supply
This could be because the safety temperature limiter has switched off – reset the safety temperature limiter

Temperature control non-functional

Switch for Magnet value could be in ‘MAN’ or ‘OFF’ position – switch to “AUTO”
Bypass valve could be closed – open the bypass valve to 45 degrees

Product too cold

The Magnet valve may not be working – disconnect from power, check, remove and clean the membrane
The pasteuriser may have low fuel – replenish the fuel supply

Product too hot

The regulating valve may be closed too much – open the valve
The set temperature may be too high – check the set temperature is right and adjust
Product discharge may be blocked – restore the product discharge or cease the heat

Summary: Ideal for cold-filled bottles within the juice, cider or brewing industries, bath pasteurisers are low maintenance and easy to use, but are more suitable for small quantities of bottles.

Chamber Pasteurisers

Another form of in-bottle pasteurisation, chamber / cabinet pasteurisers are similar to bath pasteurisers in that the process is batch-based rather than continuous. This usually meets the needs of most brewers. Chamber pasteurisers are available in a larger range of capacities to bath pasteurisers, capable of pasteurising between 720 bottles and 2,880 (240 crates) of bottles per hour depending which size pasteuriser is used.

How does a chamber pasteuriser work?

A chamber pasteuriser showers bottles within the chamber with hot water at the specified pasteurisation temperature until the specified time is complete. The larger chamber pasteurisers use steam in order to ensure that the heat energy pasteurises every bottle in the chamber, as steam is far easier to circulate than showered water.

How to use a chamber pasteuriser

Load filled and capped bottles requiring pasteurisation onto a crate / trolley which is then wheeled into the chamber. Close the chamber door from the outside and set the temperature and time required. A light will go out once the time has expired, so the bottles can be removed and another crate wheeled in.

Summary: Ideal for cold-filled bottles within the juice, cider or brewing industries, a chamber pasteuriser is available in many different sizes in order to meet the needs of almost all breweries.

Tunnel Pasteurisers

The final mainstream form of in-bottle pasteurisation is a tunnel pasteuriser, which is different to the previous pasteurisers discussed as these are designed for large scale production due to the continuous process. Tunnel pasteurisers traditionally took up a lot of space due to the linear design of the pasteurising and cooling process. However, Hermis tunnel pasteurisers are looped in design to ensure minimal floor space is used whilst maximum processing efficiency is achieved. There are still varying sizes of tunnel pasteurisers available to meet the needs of varying brewery sizes, but tunnel pasteurisers are rarely necessary for anything smaller than a commercial brewery.

How does a tunnel pasteuriser work?

A tunnel pasteuriser showers bottles being conveyed through the tunnel with different stages of hot water. This means that when each bottle first enters the tunnel, it is showered with warm water, which gets steadily warmer throughout the tunnel, and then cools down again at the end. This prevents thermal shock to the bottles and the cooling process is a safer way to ensure the micro-organisms killed by pasteurisation are definitely dead.

How to use a tunnel pasteuriser

Depending on the level of automation within your brewery, you may design a conveyor straight from the filling and capping machine to the pasteuriser, or you may manually load the tunnel pasteuriser’s conveyor your bottles. This is the only maintenance which needs to be done. At the end of the pasteurisation process, again depending on the brewery size, the bottles may be manually or automatically conveyed ready for labelling.

Summary: Ideal for cold-filled bottles within the juice, cider or brewing industries, tunnel pasteurisers are almost entirely automated and continuous, which is fantastic for drink manufacturers who need to pasteurise a large amount of product in-bottle in a continuous fashion.

Flash Pasteurisers

Flash pasteurisers are another good solution to continually pasteurise products of varying quantities. Frequently used by juice and cider manufacturers, flash pasteurisers are available in a range of sizes to meet the needs of any juice or cider maker, capable of pasteurising between 250L and 3,000L an hour depending on the model used.

How does a flash pasteuriser work?

A flash pasteuriser uses what is sometimes called “coil-in-coil”, “tube-in-tube” or “coil-in-tube” technology in which the juice or cider is pumped through a coil which is heated by a coiled heating element, instantly pasteurising the product as it travels through the coil.

How to use a flash pasteuriser

The flash pasteuriser takes a little more preparation than the previous pasteurisers discussed. A 30-40L tank of water must be kept nearby and pumped through the pasteuriser using the valve control and pump until the air is removed from the heat exchanger. Once this is done, heat the pasteuriser to 45 degrees, check gradation and try to get the temperature as consistent as possible. Continue to run the plant with water until the operating temperature has been reached, then run the plant with the product to be pasteurised. The pasteuriser can be connected to a bottling machine or a tank, so the pasteurised product can be pumped off to wherever it needs to go.

Summary: Ideal for large-scale pasteurisation primarily in the juice or cider industries

Further Advice

Whether you know exactly which equipment you need or you have no idea at all, please remember that we offer a free consultative service whereby we will recommend the best equipment to suit the capacities you are working with, the way you are packaging, the other equipment you already have or are purchasing, and of course, the product which you are making and pasteurising.