Using citrus peel and gondhoraj lime in beer for fresh aroma

Why peel, not juice

The aroma of citrus lives in tiny oil glands in the coloured outer layer of the peel, called the zest. Juice is mostly water, sugar and acid. It adds sourness and some fermentable sugar but surprisingly little aroma. Squeeze a lime into a beer and you get a sharper beer. Grate its zest in and you get a fragrant one.

Under the zest lies the white pith. It is bitter and astringent with little aroma. The most common mistake in citrus beers is including the pith.

Gondhoraj and other Indian citrus

Gondhoraj lime (gondhoraj lebu) is a large, fragrant lime from West Bengal, much loved in Bengali cooking for its intense floral, lime-leaf aroma. A few gratings perfume a whole dish of rice and dal. It is one of the most aromatic citrus fruits in India, which makes it ideal for beer.

Other Indian citrus worth trying:

• Nagpur orange: a sweet, aromatic mandarin type. Good in a witbier or pale ale.
• Kaji nemu from Assam: a long, fragrant lemon with a strong peel aroma.
• Mosambi (sweet lime): mild and gentle, better for a subtle note than a headline.
• Kaffir lime leaves: not peel, but intensely citrus and herbal. Use sparingly.

Most of these are seasonal and regional, so freshness varies a lot. Buy whole fruit, smell the skin and use it within a few days.

How to zest without the pith

Use a microplane grater or a sharp vegetable peeler. Take only the coloured layer. If you see white on the back of a peeled strip, scrape it off with a knife. Wash the fruit first in warm water to remove dust and any wax coating.

Zest just before you use it. Citrus oils start to evaporate and oxidise as soon as the glands are broken. A bowl of zest left on the counter for an hour loses much of its brightness.

When to add it

Flameout or whirlpool. Add zest to the wort after the boil, at about 80 °C, for 10 to 15 minutes before chilling. The heat sanitises the zest and extracts aroma, though some lighter notes are lost. This is the traditional method for witbier, alongside crushed coriander seed. Our witbier guide covers the style.

After fermentation. Add fresh zest to the fermenter for two to four days, much like a dry hop. This gives the freshest, brightest aroma. To keep it clean, soak the zest in a little neutral spirit for an hour first, then add both.

Tincture. Soak zest in neutral spirit for a few days, strain and add to taste at packaging. This gives precise control and keeps well in the fridge for later batches.

How much to use

Citrus varies so much that weights are only a rough guide. As a starting point for 20 litres:

• Zest of 4 to 6 gondhoraj limes, added after fermentation.
• Zest of 4 to 6 oranges at flameout, or a little less after fermentation.
• For dried peel from a shop, about 15 to 30 g at flameout, since it is less aromatic and can be more bitter.

It is easier to add more than to take it away. Taste after two days and add more if needed. Our guide to adding fruit to beer covers juices and whole fruit if you want both aroma and fruit character.

Base beers that suit citrus

Light, low bitterness beers let citrus shine. A witbier, a Belgian blonde, a wheat beer, a light lager or a pale ale with citrusy hops such as Citra or Amarillo all work well. Avoid pairing heavy citrus with high bitterness, as pith bitterness and hop bitterness stack up.

Gondhoraj also pairs well with spice. A small amount of coriander seed or ginger alongside it works nicely. Our guide to brewing with Indian spices covers dosing. Try serving a gondhoraj wheat beer with Bengali fish dishes such as bhetki fry, where the lime aroma echoes a squeeze of lime on the plate.

Citrus aroma, like hop aroma, is volatile and fades with warmth and oxygen. Keep these beers cold and drink them young. The extraction and timing skills you use here carry straight over to hops, spices and every other aromatic ingredient.