jims beer kit - i have a problem

[beesley121]

i may have a problem guys

ive put a hob goblin clone on today and my mash tun doesnt seem to be holding the temperature

it has dropped from 69 celcius (a per instructions) to 66 celius in approx 45 mins

ive read somewhere that a mash should not go lower than 65 celcius so im getting worried

ive got another 45 mins to go, should i add a couple of litres of approx 80 celius water to help bump up the temp??

[arturobandini]

Don't sweat it Beesley. Just keep it wrapped up and give it the full 90 without checking it and you will be fine. 66c is optimum temperature for a mash and even if it falls out to 63c after the remaining 45 minutes it's no disaster. First AG's need to be relaxed affairs to an extent and topping up your mash could raise all kinds of panic induced problems.

[Graham]

it has dropped from 69 celcius (a per instructions) to 66 Celsius in approx 45 mins

Your average over 45mins is 67.5°C; so it is not as bad as you think. 65-66°C is the typical mash temperature anyway. It is the average that matters (but it doesn't matter that much). If you begin your mash at 69°C, and it ends up after 90 minutes at 63°C, your average is 66°C which is fine. It is not true that the temperature should not drop below 65°C - that is middle of the range.

To be realistic, too much panic ensues with many home brewers if mash temperature drops. The enzymes responsible do not suddenly switch off if the temperature drops below a certain figure. They continue working right down to room temperature, albeit an awful lot slower. Indeed, at lower temperatures than typical mash temperatures, the activity of the two enzymes merge back together again, being the equivalent of 65°C in sugar-balance terms- but not the equivalent in time.

If your mash temperature drops over the mash period, don't skimp on mash time. The typical 90 minutes' mash time is supposed to give a safety-margin for these sort of occurrences, so it would be unwise to go below it. Indeed, if your mash temperature drops significantly, extend the mash time to compensate.

Of course, if you keep taking the lid off your mash tun to measure the temperature, the temperature is bound to drop. Really then, after doing your initial measurements after mashing in, it is best to fit the lid and forget about it for 90 minutes, and leave the outcome to the powers of darkness.