Dr Rudi hops for clean bitterness with a lemongrass edge
Dr Rudi is a New Zealand hop with moderate to high alpha acid. It bitters smoothly and holds a citrus, lemongrass and green edge in its oils. Here is how to dose it and where it works.
What Dr Rudi is
Dr Rudi is a New Zealand hop, sold earlier under the name Super Alpha. Alpha acid usually falls between 10 and 12%. Brewers regard the bitterness as clean. The oils give lemon, lime and a lemongrass note with a little pine and cut grass. That makes it a dual purpose hop: good in the kettle for bittering and usable late if you want its citrus edge.
Always use the alpha figure on your own packet. Our guide on Premiant hops for a Czech pilsner covers another clean bittering hop with a different, gentler profile.
Dosing for 25 IBU in 1,000 litres
Use alpha acid in milligrams per litre multiplied by utilisation. For a 60 minute boil, a utilisation near 25% is a common planning figure, but your boil intensity and wort gravity will move it. Check against a measured IBU.
As an illustration: for 25 IBU you need about 100 mg per litre of alpha acid (25 divided by 0.25). In 1,000 litres that is 100 g of alpha acid. At 11% alpha, divide by 0.11 and you get about 910 g of pellets. Adjust for the packet and for your own utilisation.
Where the lemongrass shows
The lemongrass edge is subtle in the kettle at 60 minutes. A small 10 minute addition or a gentle whirlpool brings more of it. Because Dr Rudi is not a heavily fruity hop, it does not dominate. In a clean pale lager fermented at 10 to 12 °C the citrus thread sits quietly behind the malt. In a pale ale it supports a more tropical hop without competing.
If you taste a green or grassy character, you have used too much late or left it too long in the whirlpool. Dial back and retaste. Our guide on resin and bitterness from old hops shows how age changes the bitterness you get from any hop.
Styles that suit it
- Pale lagers and helles: clean bitterness with a faint citrus note.
- New Zealand style pilsner: bitter with Dr Rudi and finish with a fruitier New Zealand hop.
- Pale ales and session IPAs: as the bittering hop under a stronger aroma hop.
- Wheat beers: a lemon edge suits a light wheat base.
It is less interesting in heavy dark beers, where roast covers the oils. Use a cheaper neutral hop there.
A worked pale lager grist
For a 1,000 litre pale lager at about OG 1.046, a simple grist is 176 kg Pilsner malt (88%) and 24 kg Munich malt (12%), a total of 200 kg. Mash with a rest near 65 °C, boil for 75 to 90 minutes to drive off dimethyl sulphide and bitter at 60 minutes with the Dr Rudi dose above. Ferment with a lager yeast at 10 to 12 °C and give the beer a diacetyl rest near the end. Our guide on bittering hops for clean lager bitterness covers the alternatives.
The grist is a guide. Your brewhouse efficiency changes the weights, so adjust to your own extract. Check the gravity in the kettle on brew day and correct the next batch from the reading.
Hop timing for this beer is simple. Bitter at 60 minutes. Add a small 10 minute charge of about 100 g only if you want the lemon note to show. Skip the whirlpool for a classic clean lager. Add a short one at 75 to 80 °C for a more modern pale lager. Keep the ferment steady, because temperature swings put more flavour into the beer than any hop will take out.
Storage and using it in India
Alpha acid drops with warmth. Store pellets sealed in a freezer. A hop that spent days in a hot warehouse or van can lose enough alpha to throw out your IBU. Ask your importer how the hops travelled and when they were harvested. When you open a packet, check the smell: a fresh pellet gives citrus and green, an old one gives cheese or hay.
If Dr Rudi is out of stock, Magnum or Warrior will bitter cleanly. Recalculate from the alpha on the new packet and taste before you assume the beers match.
A simple comparison
Brew a pale lager in two halves, one bittered with Dr Rudi and one with Magnum, both at the same IBU. Taste after lagering. If you notice the lemon thread in the first, note whether you like it. The difference is small but clear. It teaches more than a data sheet.
Common questions
What does Dr Rudi taste like?
Clean bitterness with lemon, lime and a lemongrass edge, plus a little pine and cut grass.
What alpha acid does Dr Rudi have?
Usually 10 to 12%. Use the figure on your packet and check against a measured IBU.
Is Dr Rudi the same as Super Alpha?
It is the same hop. It was sold as Super Alpha before the name changed.
Can I use Dr Rudi late in the boil?
Yes. A small 10 minute or whirlpool addition brings more of the lemongrass note. Too much can add a green edge.
