Protein of the Day #16: Maltase (plus a beer recipe)

I just bottled a batch of my Chocolate Cake Stout, which is:

• 1 lb of Simpon's roasted barley
  
• 1 lb of crisp amber malt
  
• 6 lbs gold malt syrup (from Northern Brewer)
  
• 1 oz Yakima Magnum hops (13.5 % Alpha acid)
  
• Safale S-04 yeast
  
• 8 oz Dutch process cocoa (from Penzey's Spices)
  
• 1 lb lactose sugar
  
• 1 whole vanilla bean (also from Penzey's).
  

Good stuff.





Maltase (alpha-D-glucosidase) is a crucial enzyme in beer making, and its regulation in response to other sugars is important to understand if you really want to grok brewing. Maltose is a disaccharide of two units of glucose; in most organisms it needs to be broken down to glucose before being used in other biochemical processes. The presence of glucose inhibits the production of maltase and maltose transporter proteins, so the glucose in a wort has to be mostly used up before the yeast will switch to consuming the maltose.