Dallmayr coffee

For the best-quality coffee, the coffee cherries need to be at peak ripeness when harvested. At this stage, the coffee’s aromas are particularly well developed and the beans inside the cherry are just right for further processing. If the cherries are unripe, they lack flavour and aroma, while if they’ve ripened too much, they risk falling victim to mould, pests or rotting.

The coffee cherry contains sugar and has a water content of about 60%, meaning that overripe fruit will quickly deteriorate and decay. Still, there is no perfect time to carry out the harvest: a certain branch may contain ripe and unripe beans together, sometimes with single blossoms in between.

In order to harvest the highest quantities of red, ripe coffee cherries, high-quality arabica coffees are hand-picked – a method also known as “picking”. Once a coffee cherry begins to ripen, it becomes overripe in 10–14 days. For this reason, pickers will go through the plantation multiple times with their baskets for as long as worthwhile quantities of beans are still ripening.

Many high-quality coffees grow in the mountains or have fruits that are difficult to reach. The amount that can be picked by hand can therefore vary between 50 and 120 kg per day. Fifty kilos of ripe coffee cherries are required for six to seven kilos of roasted coffee.

The amount each person can collect is significantly higher if the coffee cherries are not picked individually but stripped off the branch with one swift movement of the hand. This method is called “strip-picking” and allows each worker to collect up to 250 kg of coffee fruit a day.

Both ripe and unripe fruit fall directly onto cloths or tarpaulins on the ground, where they are subsequently collected. While strip-picking is faster at first, some of this benefit is lost due to having to clean and sort the beans later on. Robusta beans and medium-quality arabicas in particular are harvested in this way.

On very large, predominantly flat plantations – for example in parts of Brazil – the coffee is harvested with machines. Similar to a vineyard, the coffee trees are arranged in rows, allowing the machines to drive through with vibrating combs and shake the cherries from the branches. The fruit falls either into an integrated container on the machine or onto tarpaulins and cloths on the ground.

Since dry processing produces lower-cost coffees, the beans are usually strip-picked or machine harvested rather than selectively picked by hand. This means the harvest will contain a high proportion of unripe or overripe coffee cherries – along with leaves, branches and dirt.

Similar to wet processing, the purity and quality of dry-processed coffees can be increased by sorting the beans with sieves, air flow, washing channels or tanks with syphons. Robusta coffees and arabicas grown at low altitudes are often processed in this way.

The entire cherries are dried in around 14 days, when they have a moisture content of about 11.5 percent. In countries where the climate allows it, coffee farmers spread the cleaned and sorted fruit onto the ground to form a layer around five or six centimetres high. Any higher will increase the risk of mould – while a thinner layer makes little difference to how fast the coffee dries. About 40 kg of fresh coffee fruit is spread across each square metre.

The ground for drying should be flat and easy to work with, as the fruit needs to be turned with large rakes several times a day. Clay or asphalt surfaces aren’t suitable as they can transfer certain flavours to the coffee. Tarpaulins are commonly used to protect the harvest from dew or rain. It takes around two weeks for the coffee to dry to sufficient levels. It is then possible to hear the beans rattle inside the brown-black coloured dried hull.

In the drum roaster, the beans are roasted particularly slowly and gently in a slowly rotating drum. The drum is heated under controlled conditions from the outside. The contact between the coffee beans and the drum roaster’s wall, as well as the temperature in the drum, produces a very even roast. Drum roasters are available in a number of sizes. At Dallmayr, the smallest drum roaster roasts less than 100 grams per batch, while the largest one roasts up to 10 sacks of coffee at the same time.

Some roasters prioritise speed and large quantities, so they roast a continuous flow of beans. Using hot air at temperatures of up to 650°C, these machines roast the coffee in minutes. The long, tubular roasting drum looks a little like a concrete mixer: with each revolution, mechanisms inside the rotating roasting chamber transport the coffee a little further towards the end of the device.

Aerotherm is a special kind of batch roasting. Here, the beans are circulated inside the device by a stream of hot air and don’t come into contact with the roaster’s wall. This creates a particularly even roast. Around 20 kg can be roasted at a time, making this method particularly interesting for coffee rarities.