Sour  Beer  

By  Cris,an  A.  Sierra  

What  is  sour?  

•  Taste  percep,on  •  Vs  Bi9er,  Tart,  Astringent  

Why  is  beer  sour?  

•  Chemical  reac,ons  •  Metabolism  •  Op,mal  pH  and  temperature  

•  Bacteria  •  Bre9  

Sour  Mechanism  

Sour  Taste  Buds  

Ace,c  acid  

•  Same  acid  in  vinegar  •  Sharper  than  lac,c  acid  •  Produced  by  Acetobacter  and  Bre9anomyces  only  when  oxygen  is  present  

Funk  

•  Barnyard  •  Horse  blanket  •  Damp  basement  

Lac,c  acid  

•  SoK  tangy  flavor  •  Produced  by  lactobacillus  and  pediococcus  

Sour  

•  Tart  •  Acidic  •  Tangy  •  pH  of  about  3.0  to  3.9  

Enzymes  101  

Substrate  

Enzyme-­‐Substrate  Complex  

Transi,on  State  

Product  

Enzyma,c  Ac,vity  Grain  

Enzyma,c  ac,vity  is  Temp  &  pH  dependent  

Enzyma,c  ac,vity  is  Temp  &  pH  dependent  

Enzyma,c  ac,vity  is  Temp  &  pH  dependent  

Bre9anomyces  

Yeast  Pathways  

Bre9anomyces  •  Produces  esters,  like  brewers  yeast  •  Can  break  down  esters  (fruity)  •  Produces  ace,c  acid  with  O2  otherwise  no  sourness  only  

funky  •  More  interspecies  varia,ons  than  brewer’s  yeast  •  Pitch  100cells/mL  •  Pitch  into  already  fermented  beer  •  Alpha-­‐glucosidase:  dextrin  catabolism  •  Beta-­‐glucosidase:  glucose/simple  sugar  catabolism  •  Cellobiouse:  wood  sugar  •  Absorbs  nutrients  when  saccharomyces  autolysis  •  82  degrees  F  (growth)  about  68  for  flavor  

Lactobacillus  

Lactobacillus  

•  104  to  111  degrees  F    •  Homofermenta,ve:  only  lac,c  acid;  higher  nutri,onal  requirments  

•  Heterofermenta,ve:  lac,c  acid,  CO2,  ethanol  •  Lowers  pH  to  3.3  to  3.4  •  Consume  dextrins  

Lactobacillus  Pathways  

Hops  

•  An,microbial  •  Inhibits  lactobacillus  >20  IBUs,  aim  for  <  5  IBU’s  

•  Inhibits  ability  to  transport  sugars  and  amino  acids  

•  For  hops:  dry  hop  aKer  souring  

Pediococcus  

Pediococcus  

•  Slower  working  •  Sharply  acidic  at  ,mes  •  Produces  diacetyl  and  exopolysaccharids  that  can  be  eliminted  with  bre9  

•  Most  ac,ve  aKer  simple  sugars  are  consumed  •  86  to  90  degrees  F  

Pediococcus  Pathways  

Acetobacter  

Acetobacter  

•  Requires  O2  •  Consumes  ethanol  •  Produces  ace,c  acid:  vinegar  character  

Wyeast  

•  Bre9  bruxellensis  •  Lactobacillus  •  Bre9  Lambicus  •  Pediococcus  •  Roeselare  Ale  Blend  •  Belgian  Lambic  Blend  

White  Labs  •  Berliner  weisse  blend  •  Bre9  bruxellensis  trois  •  Bre9  claussenii  •  Bre9  bruxellensis  •  Bre9  Lambicus  •  Belgian  sour  mix  I  •  Pedio  damnosus  •  Flemish  ale  blend  •  Am.  Farmhouse  •  Lacto  brevis  •  Lacto  delbrueckii  

East  Coast  Yeast  

•  Bug  Farm  •  Bug  County  •  Flemish  Ale  •  Farmhouse  Bre9  •  Dirty  Dozen  Bre9  Blend  •  Bre9  bruxellensis  •  Bre9  anomala  •  Bre9  naardenensis  

BJCP:  European  Sour  Ale  

•  Berliner  Weisse  •  Flanders  Red  •  Lambic  •  Gueze  

BJCP:  Historical  Beer  

•  Gose  •  Lichtenhainer  

BJCP:  American    Wild  Ale  

•  Bre9  Beer  •  Mixed-­‐Fermenta,on  Sour  Beer  

•  Soured  Fruit  Beer  

How  to  make  sours?  

•  Sour  recipes  •  Sour  mashing  •  Sour  starters  and  pitching  rates  

•  Starches  and  difficult  to  digest  sugars  

•  Alcohol  content  

Guidelines  

•  1040  to  1060  •  <20  IBU’s  •  Bo9le  dregs  •  Oak  chips  •  Acidulated  malt  •  Dextrins  

Metabolism:  Sugars  vs  Starches  

•  Unmalted  grains  •  Gela,niza,on  •  Turbid  Mash  •  Adjuncts:  maltodextrins/refined  starch  

•  Cellobiose,  maltose,  lactose,  dextrins,  glucose,  galactose,  fructose  

 

Turbid  mash  

•  Run  off  liquid  through  mash  tun  and  boil  •  Add  back  at  mash  out  to  raise  temp  of  mash  •  Provides  food  for  bre9/bugs  aKersaccharomyces  fermenta,on  

Gela,nizing  unmalted  starches  

•  Mash    with  near  boiling  water  •  Gelitanizes  starch  •  Boil  milled  unmalted  grain  then  add  porridge  to  main  mash  

Adjuncts  

•   lower  buffering  capacity  of  wort  so  pH  lowers  more  easily  

•  Adding  adjucts  (sugars)  aKer  souring  feeds  the  dominant  bacteria  and  Bre9  

Blending  

•  Adds  sweetness  with  fresh  malty  beers  

Miscellaneous    

•  Secondary  vs  primary  vs  barrel  

•  English  ale  vs.  belgian  ale  yeasts  

•  Pitching  rates  

Sanita,on  

•  Gaskets  •  Hoses  •  Boiling  •  Loca,on,  loca,on,  loca,on  

The  Least  You  Need  to  Know  

•  pH  <  4.5  inhibits  growth  of  Enterobacter  •  ABV  >  6.5%  inhibits  souring  •  >20  IBU’s  inhibits  lactobaccillus  •  Shoot  for  OG  of  1.040  to  1.060  •  Starches  can  be  broken  down  by  bacteria  and  Bre9:  ie  unmalted  grains