Mendel's Dihybrid Cross

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By Rob Gallagher

Recipe is part of Recipe Index

BJCP 2021 Style 3C - Czech Amber lager
There's really only one Czech beer style. Of the two Czech beer styles that don't really exist, this is the one that least exists!
Dark lagers can be found, if you're lucky or you know what you're looking for, but polotmavy, the half-dark lagers, are rare. As such, they're unusually open to brewers' interpretation, which makes them hard to pin down as a style, but easy to brew for competitions. The BJCP parameters for this are amongst the most open and free, really only stipulating that the driving character should be malt-based and the colour neither pale nor black.
This recipe relies on Vienna malt and home-made candi sugar, which gives a complex, layered, caramel sweetness, but also seems to require quite an extended lagering period to mellow out the powerful sugar flavour.


Lager Than Life 2019

3rd Best of Show

Brewcon 2019

1st - International Lagers


  • IBU 27
  • ABV 4.8%
  • OG 1.053
  • FG 1.017
  • EBC 24
  • 29 litres at end of boil.
  • 25 litres into fermenter.



Reverse Osmosis water with CaCl added to give 100ppm Ca+ (153ppm Cl-)


  • Vienna Malt, 7 EBC, 5000g, 85%
  • Caraamber, 70 EBC, 400g, 7%
  • Candi Sugar, 148 EBC, 500g, 9%


  • 65g Saaz (3.3%) at 90 minutes
  • 20g Saaz at 30 minutes


Imperial Urkel yeast. Either a very large starter or, preferably, pitch straight onto the slurry from a smaller, weaker batch.



Adapted from Jacques Marais' process 1.5kg Sugar 1.5tsp DME 15ml fructose/glucose/golden syrup

Dissolve sugar (375ml water) Raise slowly to 130° & hold 30mins Raise to 145° Add saturated CaOH solution (30ml) - slowly Hold at 140° until desired colour/ Hold at 150° for extra colour Aim for 1 hr.


Unusually for me, not decocted! Rests at 64°C (40mins), 72°C (30mins) & 76°C (10mins).


90 min boil


Pitch at 9°C and allow to rise to 10°C. When fermentation starts rise to 12°C over about three days. When half attenuated rise slowly to 18°C


Keg at 2.6vols