How delicate are the enyzmes in grain?

[yashicamat]

Reason for me asking is I've seen references to using boiling water to bring the temperature of the mash tun up etc. . . . but at the same time, a mashout halts all enzyme activity. This has left me a bit puzzled; if the higher temperatures of the mashout destroy the enzymes, surely the boiling water would too. Unless a) only the enzymes local to where the hot water enters are destroyed and when stirred, the remaining are redistributed, or b) the enzymes are not destroyed by the higher temperatures, they just don't function outside of the 60 to 70 degrees C range and the theory with a mashout is that the temperature won't ever drop back down again as it will then be sparged with hotter water, then boiled.

Thanks.

[mysterio]

There are plenty of enzymes in a mash to get the job done, when you add the boiling water it doesnt stay boiling for very long when you distribute it throughout the mash. When brewers are talking about infusing boiling water, they're usually talking about bringing it up from 50 - 55 to a saccharification rest temperature (say 63 - 70). If you bring the entirity of your mash up to 76 - 77C for the mash-out, then yes, you will tend to halt the majority of enzymatic activity.

Incidently, a single infusion without a mash-out for British ales is probably what the majority of HB'ers practice. The advantage of the optional mash-out is to 'lock' in a particular wort profile for repeatability. Step-mashes are useful when trying to replicate German lagers or Belgian ales, or if you're using a large majority of strange adjuncts i.e. in an American light lager or something.

[yashicamat]

Thanks for the reply. What I was stabbing at more was really how much of the process is the enzymes being exposed to temperatures they do not function in, as opposed to temperatures which actually damage / destroy them?