Hi I have just started doing step mashes to see what effect it has as i have been using a lot more Vienna and Munich malt in the grist. Now I know that it should not be really essential to do with modern malts but I have found that the first 2 brews I have done the BH Eff has gone up quite a bit from a average 75% to nothing less than 78% to 82%. I have 1 further brews which have not completed fermenting showing 85% which has lager malt munich and vienna in it at equal amounts so am I right in saying at the lower step of 62c and the higher step of 68c it is pulling more sugars combined from both steps hence the higher Eff
A lot of brewers use both temperatures to get both attenuation and body, I recently put up an Irish Extra Stout recipe where the mash is 60 minutes at 64 C followed by 30 minutes at 68 C.
I think it is important to get the dough in temperature right to protect the Beta Amylase, just from a few things I have read on other forums
From BYO
Mashing Enzymes from A to B
In a brewer’s mash we are concerned with the activity of two main enzymes, alpha and beta amylase.
Alpha amylase is the enzyme responsible for breaking large, complex, insoluble starch molecules into smaller,soluble molecules. It is stable in hot, watery mashes and will convert starch to soluble sugars in a temperature range from 145 to 158 °F (63 to 70 °C). It requires calcium as a co-factor.
Beta amylase is the other mash enzyme capable of degrading starch. Through its action, it is the enzyme largely responsible for creating large amounts of fermentable sugar. It breaks starch down systematically to produce maltose. Beta amylase is active between 131 and 149 °F (55 and 65 °C). But like all enzymes, its activity reaches a peak, declines, and then drops precipitously as temperature increases. The rate is also dependent on the amount of enzyme present. It takes time for all of the enzyme to be destroyed, but what is still intact works very quickly. So as the mash temperature approaches 149 °F (65 °C), beta amylase is operating at its fastest rate but it is also being denatured.
This may seem trivial, but at these higher temperatures the denaturation is so rapid that the enzyme is mostly gone in less than 5 minutes. Also, in a homebrewer’s mash tun, where the grain may be poured into very hot water, the exposure to very high heat for the few seconds before the mixture becomes homogenous may work to destroy the fragile enzymes.
This means that, in a practical sense, the manipulation of beta amylase activity can be utilized to control the fermentability of the wort. If the mash is allowed to “stand” at a temperature that favors the action of beta amylase, then agreater proportion of the sugars extracted from the malt will be maltose and hence the wort will prove more fermentable.
In my commercial breweries, I found that changing the mash temperature from 149 to 156 °F (65 to 69 °C) raised the beer’s terminal gravity from 1.008 to 1.014. This is a significant difference.
