Coffee harvesting and processing
Coffee plants fruit from about year three onwards (and can live to be 60-plus). They flower prolifically (and headily) after spring rain. Flowers drop off after a few days, leaving small green ‘cherries’ that mature over the ensuing nine to 10 months until they are crimson, or purple, and ripe.
At harvest time, cherries will be everything from green to purple on the same plant – and even on the same branch – so you’ll be picking cherry by cherry over a few months.
Turning coffee cherries into cappuccinos is quite a process. Professional growers have machines to help. If you’re want to do it by hand, a good source of advice is the Queensland Department of Agriculture and Fisheries. But here is a summary of the process.
Remove skin and pulp within 24 hours of harvesting. You can do this by either squeezing each berry by hand, orby using a piece of wood to tamp the berries in a bucket until all seeds have been forced out from the skin. Then fill the bucket with water and stir the skins and seeds. Pour away the skins (and any coffee beans that float) before they settle.
To remove the slippery mucilage that remains around the beans, cover the beans with water in a plastic bucket. It will take at least 18 hours for fermentation by natural enzymes to do the trick. Check that it has worked by washing a few beans. If they feel clean and gritty, rather than slippery, they’re ready. Wash beans in agitated water and drain three times, or until water runs clear. Discard any beans that float.
Spread beans in a thin layer on racks and sun-dry, protecting from rain. This can take anything from 5 to 30 days. Or use a home food dehydrator set at 40 degrees C. With either method, stir three times a day. When beans have 12 per cent moisture, they are done. The parchment on the coffee bean will dry to a pale straw colour and be brittle. Test the dryness of the beans by removing the parchment by hand off several beans. The bean inside should be greyish blue in colour, hard, and likely to break when bitten. If it’s soft and chewy, continue the drying process.
To hull the beans (remove the tough parchment layer), place the beans, a small quantity at a time, in a food processor with plastic blades (to avoid damage to the beans) and blend at a low speed for 30 seconds to remove the parchment. Then use a hair dryer to blow away lighter parchment. Alternatively, rub the dried beans on concrete under a hessian bag.
A thin silver skin may remain. It’s not necessary to remove this, but it can be removed by gently rubbing the beans after hulling.
Roast the beans in large baking dishes in the oven. Spread the beans thinly and stir frequently. A single layer of beans will roast in 12 minutes at 230-250oC. Beans at a depth of 25 mm may take 30 minutes. You can also roast in a frying pan or popcorn machine.
The beans turn yellowish brown, which gradually deepens. They shrivel until half-cooked, then swell, then open out and grow. Light brown beans (a light roast) will have a weaker flavour than brown/black beans (a dark roast).
You will really appreciate your flat white after all that.
For more on growing your own coffee and buying Fair Trade coffee get the latst copy of Organic Gardener magazine OUT NOW!
By: Simon Webster
First published: September 2017