As you may have known, lager and ale are two big categories for beer. In general, lager is pale in color, light in body and tend to be more refreshing; while ale is darker, fuller, giving sort of slightly cooked fruit aromas.
Lager is easy to find as they are almost everywhere in supermarkets and stores, which share up to 90% of beer sales. Most people take their first step into the beer world through lager.
The name “lager” comes from German “lagern” which means cellar. The name suggests the several-month maturation process it undergoes at freezing point. With the current technology, this process takes about 20 days! The residue and colloidal is settled and then filtered, making it clear. At the same time, the yeast will also remove any off flavors (such as green apple, cream, etc.) produced during the fermentation. Therefore this step is very important for lager! In the ancient times when there was no refrigeration, brewers used to put the beer in the cave, the cellar, and collect ice from freezing lakes or rivers to keep the temperature low.
In addition to the above steps, yeast is crucial to the production of lager. Different from Ale in which the yeast floats at the top of the juice, the sugary liquid undergoes bottom fermentation instead. The temperature is maintained at 6-13 degrees Celsius (Ale yeast strike to work at this temperature!), so it produced very little ester, and therefore the final flavor is clean and fresh!
Compared to the history of beer, the nowadays popular lager has a shorter history of several hundreds years only. Ale was the mainstream thousand years ago and now it is time for Ale to come back. History repeats itself.
拉格（lager）名字來自德文 lagern，解釋為窖藏。因為釀造拉格時經過一個熟成( maturation) 過程，啤酒發酵後需要在接近冰點的溫度保存數個月！以現時的技術，這個過程也需要大概20天！經過低溫熟成，殘留在啤酒的膠質沉降，令啤酒清澈。同一時間，酵母也會把發酵時產生的雜味（例如青蘋果、奶油味等）清除，令味道變得潔淨！所以，這個步驟對拉格非常重要！以前並沒有製冷技術，釀酒師會把啤酒放在山洞、地窖，並在河或湖收集冰塊來保溫！
除了上述步驟外，拉格還有一樣重要材料：酵母。拉格選用的酵母品種跟艾爾的不同，它是底層發酵（bottom fermentation)，不會像艾爾酵母般在發酵時飄浮在麥汁頂層。另外，它的發酵溫度低，為攝氏 6-13 度（艾爾酵母會在這溫度罷工！），正因這樣，他所產生的酯類（ester）很少，味道也較乾淨清新！