But as a preview (especially for you!) a bit more research has shown that normal (12 fl oz) bottles tend to be batch tested during production to something like 200-250psi. I plan to update the information with some stuff that I have found about what pressure bottles can handle. as you can see, heat pasteurisation isn't all that scary once you know "the rules". This gives the option of short times in the waterbath which in turn minimizes the time the bottles are exposed to high pressure. the bottles and bath reach the same temperature), so bottles don’t reach the initial bath temperature and don’t go above equilibrium.Īs pasteurizsation level is significantly influenced by both temperature and time, optional pre-heating of the bottles allows them to reach pasteurizing temperature quickly. Generally, equilibrium is reached around 70C (i.e. When the bottles are put in the bath, they heat up and the water cools down. This is the approach outlined by Pappers (see the sticky at the top of the forum) and JimRausch (see a post on 16 April 2018) where bottles are put in a waterbath which has been heated to 80C or more, then the heat source is removed. Two similar approaches are commonly used for waterbath heat pasteurizing. Achieving well above 50 PUs doesn’t appear to cause flavor changes or pressure problems if excessive temperature isn’t involved. Substantial pasteurization takes place during cooldown as the bottles drop in temperature towards 60C after they have been heated to the pasteurization temperature. Increasing heating time increases total PUs. Effective pasteurization can be achieved at temperatures below 70C with a bottle heating time in the order of 10 minutes. Bottle pressure generated during pasteurization returns to “normal” (20 psi-40 psi) at room temperature. “Standard” bottles in good condition should handle over 160 psi for the short period of time involved in heat pasteurization. Depending on the carbonation level, pasteurization temperatures between 65C and 70C can generate bottle pressure in the range 100-160 psi. Higher temperatures also produce higher bottle pressure which increases exponentially with temperature as CO2 is driven out of solution. The number of PUs generated per minute increases exponentially with temperature so pasteurizing above 65C will produce high levels of pasteurization per minute, resulting in the target of 50 PUs being reached or exceeded in a short period of time. There are opinions that 30 PUs are sufficient to pasteurize cider so in practice, achieving something approaching 50 PUs should result in effective pasteurization. So, lower temperature for a longer time produces similar results to a higher temperature for a shorter time. Pasteurization results from temperature x time. The target for other beverages depends on their pathogen and yeast load. The recommended target for heat pasteurizing cider is 50 PUs. So, two minutes exposure will result in twice the PUs. One PU is the level of pathogens, yeast, etc, destroyed in one minute at 60C for the beverage being pasteurized. Pasteurization occurs at temperatures above 60C and is measured in Pasteurization Units (PUs).
Heat pasteurize bottled cider which is carbonated to no more than 3 Volumes of CO2ĭo this at no more than 65C-70C for 10-12 minutes then let the bottles cool down The short version of how to heat pasteurize reasonably safely is… None of the approaches are new as they are based on previous work by Pappers, JimRausch, Bembel and others, but they each give a different insight into the process.įor craft cidermakers without access to special equipment such as low micron filters or “flash pasteurizers”, heat pasteurizing of bottled cider in a heated waterbath is the easiest and a very effective method of producing sweet, carbonated cider. It was an interesting exercise, so I thought it worthwhile posting what I have found out even though it repeats some stuff that I have posted before. So, thanks to plenty of Covid restriction spare time, and following yet another post asking about heat pasteurization I set up some experimental trials looking at different approaches to heat pasteurizing and recorded what, when and how things happen. The aim is to bottle cider well above SG 1.000, allow fermentation to continue and generate carbonation to a desired level, then stop fermentation at a point where residual sugar remains… all without creating bottle bombs! Regular readers of the forum will know that I have had a “bee in my bonnet” about heat pasteurizing for sweetness and carbonation control as an alternative to chemical pasteurization.