Riwaka hops and the grapefruit punch they give pale ales

A Saaz descendant with a very different accent

Riwaka was bred in New Zealand and released in the late 1990s. It was once sold under a code name that pointed to its Saaz heritage, since Saaz, the classic Czech lager hop, is in its parentage. It is grown around Nelson at the top of the South Island.

Alpha acid is low, usually 4.5 to 6.5%. The oil content is high for a hop with such modest alpha. That oil is what you are paying for. The aroma is intense grapefruit, passion fruit and citrus peel. Where Saaz is spicy and restrained, Riwaka is loud.

Why it is hard to buy

Riwaka is a low yielding variety and the crop is small. New Zealand hops are harvested from February to April, so each year's crop reaches the northern hemisphere and India months later. Homebrew suppliers often sell out quickly.

That scarcity shapes how to use it. Do not waste Riwaka on bittering. Its low alpha means you would need a lot of it. The boil would also destroy the oils you bought it for. Bitter with something cheap and clean. Spend every gram of Riwaka late.

Where it goes in the recipe

Use Riwaka in three places:

• A whirlpool or hop stand at 75 to 80 °C for 20 to 30 minutes.
• A first dry hop late in active fermentation, when gravity is a few points above final.
• Optionally, a second, smaller dry hop after fermentation ends.

For a 20 litre pale ale, 40 to 50 g in the whirlpool and 60 to 80 g as dry hop is plenty. That is lower than many hazy IPA recipes would use for a typical aroma hop. Riwaka's intensity means less goes a long way.

A 20 litre pale ale built around it

Here is a recipe at about OG 1.050 and 35 IBU:

• Pilsner or pale ale malt 4.2 kg (91%).
• Wheat malt 0.23 kg (5%).
• Light crystal malt around 20 EBC 0.18 kg (4%).
• Magnum or another clean high alpha hop, 60 minutes, for about 28 IBU.
• Riwaka 45 g in a 20 minute whirlpool at 80 °C, adding a few IBU.
• Riwaka 70 g dry hop, split into two additions.

Use a clean American ale yeast at 18 to 19 °C. Keep the malt simple. Riwaka is the point of this beer.

The floor detail: too much Riwaka

The most common mistake with Riwaka is using it like a mild aroma hop at 8 to 10 g per litre. At that rate, many brewers find the grapefruit turns sharp, pithy and bitter. The beer tastes like grapefruit peel rather than juice.

Start at around 3 to 4 g per litre total dry hop. Taste. If you want more, go up by 1 g per litre in the next batch. For a scarce hop, the lazy route of overdosing and hoping is also the expensive one.

Water for a Riwaka pale ale

Many Indian homebrewers start with borewell water that is hard and high in carbonate. That pushes mash pH up and can make hop bitterness taste coarse, which is the last thing an intense hop needs. Diluting with RO water and adding a little gypsum gives a cleaner base. A sulphate to chloride ratio of around 2:1 suits a crisp pale ale and lets the grapefruit read as bright rather than harsh.

If you do not know what is in your water, get a report from a local lab before you start adjusting. Guessing at salts is how a good hop gets blamed for a water problem.

Blending Riwaka with other hops

Riwaka is easier to control in a blend. Some pairings that work:

• With Loral for a floral softness that takes the edge off the pith.
• With Amarillo for orange and floral notes under the grapefruit.
• With Motueka for lime and a more classic New Zealand profile.

As a rule, keep Riwaka at no more than half the late hop weight in a blend. It will still dominate.

Storing a scarce hop in Indian heat

When you have managed to buy Riwaka, protect it. Keep the foil pack sealed and in the freezer. Once opened, squeeze out the air, fold the pack tight and tape it, or vacuum seal the remainder. Hop oils oxidise and evaporate at room temperature. A summer week on a kitchen shelf in Hyderabad will take a lot of the grapefruit with it.

Buy only what you will use in two or three brews. A fresh 100 g pack is worth more than a stale 500 g bag.

Common questions

What does Riwaka taste like?

Intense grapefruit, passion fruit and citrus peel. It is much louder than its low alpha acid suggests.

Should I bitter with Riwaka?

No. Its low alpha means you need a lot of it and the boil destroys the oils. Bitter with a clean high alpha hop and use Riwaka late.

How much Riwaka should I dry hop with?

Start around 3 to 4 g per litre in total. Its intensity can turn harsh at the higher rates used for gentler aroma hops.