Winter temperatures on grain storage
Can anyone tell me how they deal with varying temperatures of grain? Doesn't using hotter strike liquor change the enzyme profile (and fermentation/flavor) even if the resulting mash is the same temperature? Do you use a specific heat of 0.4 for correction figures?
As you have pointed out, you simply cahnge the mashing in temperature, especially critical if using infusion mash and not a mash mixing vessel. The degree of temperature change (admittedly based on UK experience - not perhaps extremes of say minus 20 or 30 which could be experienced in some parts of the world) does not affect the enzymes dramatically enough to affect overall wort extraction. one ot two degrees C is normally sufficient bearing in mind my previous comments re UK winter / summer temperatures.
I have to say that temperature changes were based on watching the mash temperature in the steeles masher, and tweaking the flow rates of the hot and cold water at point of use, not using any empirical formula to obtain a hot liquor tank at the specific required temperature.
Try the guys in Alaska - I guess they know what cold is !!
Varying Grain Temperatures
Common practice for smaller scale brewing is to do just what Mr. Murton does - to change mash water temperature as you go using trial and error to hit your desired conversion temperature. Larger breweries have the option of using vessel steam to assist in the event that the malt is colder than expected.
These changes should not have a significant effect on your fermentability so long as your mash water temperature does not get high enough to denature amylase enzymes. If your malt is very cold and you are converting at a high temperature (say 160 F or 71 C) you may run into difficulty as your mash water will have to be very hot - hot enough to denature said enzymes. I have seen this happen in the past and the fermentation profile was affected dramatically. Since there is no way to predict the extent of enzyme danaturation the effect is not only negative, it's very unpredictable. You will only know the extent of the problem after fermentation. Since this particular brewery had steam on the mash tun the solution was to mash-in in the mid 150's F and use steam and mixing to get the the desired conversion temperature.