Saturday, 30 March 2013

Cider101 - Pasteurisation

In this latest Cider101 series of blog posts I have blabbed on about several practices of cider making and now want to turn my attention to pasteurisation; or the cooking of cider:-)

Pasteurisation is simply the process of heating the cider up to a certain temperature (around 67 degrees or so) and holding it for a time at that temperature in order to kill the yeast cells. There are a couple of reasons for doing this. Firstly because the cider is sweetened with juice or fermentable sugars – to prevent fermentation starting again.  Secondly, it is often done for cider that is going into storage; sold to a wholesaler or so that the best before date is lengthened.

Courtesy of Cider Workshop/Andrew Lea
Done well, pasteurisation may give the cider a slightly cooked taste - not apple sauce but there is a difference in taste that can be detected. Also, because all development and maturation of a cider ceases at the point of pasteurisation, often more complex flavour profiles are lost.

Stopping a minute, let me go over those two reasons for pasteurising in a little more detail. Both are valid and it ought be made perfectly clear that, as with one or two other practices, pasteurising cider is not a crime - nor does it make a cider 'not real' or mystically 'not full juice'

1. Pasteurising for sweetening.

Cider yeast will consume all fermentable sugar, whether naturally found in the fruit or added by the maker. This is a bit of a problem when trying to use natural sweeteners such as sugar or apple juice... both are fermentable. Generally, the only way to stop this is either to pasteurise in bottle or 'hot fill' a bag in box. Don't forget that not only the cider has to be pasteurised but the container too!

I guess the question is simply this - is pasteurisation any worse than using artificial sweetener?

2. Pasteurising for storage.

This is much more a problem for bag in boxes than bottles. These are essentially a plastic bag (well its a little more complex than that as often there will be multiple layers) which is stored inside a cardboard box that provides a structure and form to make things easily dispensable.

As already mentioned, yeast consumes any fermentable sugar. This creates carbon dioxide. This leads to bags expanding and potentially exploding. For a small producer, this is not an issue - the bag in box can be left and watched and vented if required. For those who fill quite a few, or where cider is delivered some time before use (i.e. to a distributor) this is not going to happen. So, by pasteurising the cider the issue of exploding bag in boxes becomes less of a problem.


There are alternatives to pasteurising cider... not least of which is simply not to do it! Dry, still cider shouldn't need to be pasteurised - as long as it is fully fermented. OK, it may prevent some degrading of the cider over time - though ultimately the cost of changes to flavour doesn't outweigh the convenience of having cider stored in bags. I realise that some prefer to do it, but if I am honest it fails me as to why!

Using artificial sweeteners instead of natural ingredients is another alternative - though this must be personal preference to the producer... like a piece of art, cider must be a product of the choices of its maker. So whilst it's an alternative, its up for grabs as to whether its any better. Putting my cards on the table, personally, I use artificial sweetener (sucralose). I think juice makes a cider too 'juicy' but would use sugar if the process of pasteurising and hot filling weren't so damn expensive!

I do know of one or two producers who will sweeten with juice/sugar just prior to bagging a cider and then hope it is used quickly... I have also seen the results of such practice when it goes wrong!

Keeving, or stopping a fermentation to leave residual sugar is surely the most elegant way of producing sweeter cider. Drawbacks are that it is neither easy or guaranteed to work and should be held in heavy glass sparkling drink bottles for safety. Done well, this style of cider commands the best prices, but I cannot see festivals or pubs selling sweet cider from champagne bottles!

An alternative to the storage problem, CAMRA may say, is to use polypins (rigid containers fitted with a one way vent). Well, perhaps this is true while the cider is in storage or if the contents are to be used very quickly. However, once the polypin is breached and air meets the cider the quality of the diminishes surprisingly quickly (due to oxidisation and any bugs in the air). Air doesn't get in to a bag in box as it is collapses as cider is drawn. There is also the problem of cleanliness. How many producers have has polypins returned damaged or filthy - or not even their own polypins but some 90 year old version (especially from CAMRA festivals?!). At between £30 - £40 per container, they are not a cheap alternative to bag in box - and with the questionable benefits it isn't that practical or cost effective.


In summary, pasteurisation is necessary for any sweet cider created to only contain natural ingredients, or if bagged before it is fully mature. Cider yeast is powerful stuff and it is not easy to stop fermentation without it. The alternatives are either debatable or flawed. The negative is that there is some pay off in terms of alteration to flavour.

Oddly, supermarkets generally insist on pasteurisation... even where ciders are either artificially sweetened or dry. This probably has more to do with Elf and Safety overkill than anything else... and I suspect that protest from a cider maker would fall on deaf ears.

Additional note

For large companies, they no longer need to pasteurise. This is where this blog post cross threads with the next Cider101 planned – filtration. Cider can be sweetened, filtered finely to remove all yeast and bottled without risk of renewed fermentation, as long as it is done in ‘clean room’ environment (i.e. absolutely sterile). This is an expensive way of doing things, and is only really available to larger producers, or smaller producers who pay for the privilege of 'clean room' and micro filtration processes. I will cover the filtration side of this next time, but I would say that there is a pay off – after all, which is larger – yeast cells or other cells that make up the flavour/body etc? OK – lets not get too technical eh, but (borrowing from the knowledge of Andrew Lea) flavour is lost this way in a much more pronounced way than for pasteurising alone.

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