Wednesday, October 11, 2006

Brewers lingo, explanation of some terms

If you are new to brewing I have probably confused you by using technical brewing terminology in earlier posts. I have been asked to explain some of them, so here you go.

EBC (European Brewing Convention) - a unit for measuring beer color. This scale is mostly used in Europe, while in the US the SRM (Standard Reference Method) unit is used. Higher values indicate a darker beer.

IBU (International Bittering Unit) - a unit for measuring the hop bitterness in a beer as contributed by the alpha acids in hops. IBUs of between 15 (less bitter) and 70 (bitter) are common.

OG, SG and FG (Original Gravity, Specific Gravity and Final Gravity respectively) - describe the concentration of sugars in the beer/wort. The value is a factor indicating the relative gravity (weight) to water. OG is the gravity before fermentation. SG is the gravity as measured at an arbitrary point during fermentation. FG is the gravity after fermentation, i.e. when all the sugars have been eaten by the yeast. Note that not all sugars will be depleted as yeast strains have relative merits for eating complex sugars. This means that the final gravity will rarely fall below 1.000, but usually end up in the 1.006-1.025 range. Higher values indicate a sweeter beer. Sugar is heavier than water. Alcohol is lighter than water, hence the possibility of the final gravity falling below 1.000.

Mash efficiency - a measure given in percentage indicating the efficiency of the mash relative to the amount of sugars than can theoretically be extracted from the malts. It is a goal for the brewer to achieve a high mash efficiency as it will lower costs, i.e. use less malts to achieve a higher original gravity.

Gelatinizing - grains/cereals that have not been malted have to be gelatinized to expose the starch, so that enzymes can break them down into simpler sugars. Boiling them will usually do this. They will not provide any enzymes themselves, so the enzymes will have to come from malts. In other words, the cereals will have to be mixed with malts so that enzymes can break down the starch.

Please let me know if you'd like to have other aspects of brewing or brewing terminology explained.

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