Moisture content should be one of the first things you evaluate while evaluating green beans. It typically makes up around 11% of the weight of green coffee and can affect various qualities, including acidity and sweetness, aroma, and mouthfeel.
The calibre of your green beans will always constrain your ability as a speciality roaster. Customers may stop buying your product if the beans arrive smashed, mouldy, or with other flaws. This could negatively impact the final flavour of the coffee.
To roast the best coffee possible, speciality roasters must master the art of measuring the moisture level of green beans. It will assist in identifying flaws in a massive batch of beans and benefit crucial roasting parameters like charge temperature and development time.
What is the moisture content of green coffee, and why does it change?
A ripe, recently harvested green bean typically has a moisture content of 45 to 55%. Depending on the method, environment, and time drying takes, it usually drops to between 10 and 12% after drying and processing.
The optimal moisture percentage of green beans that are ready for roasting should be between 8% to 12.5%, according to the International Coffee Organization (ICO).
This range is typically ideal for elements including cup quality, the rate at which green coffee degrades during storage, and the possibility of microbial growth. However, some coffees, like the Monsoon Malabar from India, function better in the cup when they have a higher moisture content.
Green beans are typically packed in jute sacks after being processed and prepped for shipping to maximise air circulation during transit. The moisture level of coffee beans can easily change between the origin and the roastery since they are naturally hygroscopic, which means they absorb moisture from the air.
The moisture content of coffee may change due to variations in humidity or exposure to sunshine while transported or stored. Therefore, it should be examined frequently, before shipping and upon arrival, to maintain consistency and prevent surprises later on.
Why is it crucial to monitor variations in green coffee moisture?
All the flavours and fragrances inside the coffee are released while roasting the green beans. Speciality roasters must first be able to gauge the moisture content of the green beans to realize their potential fully.
A coffee’s moisture content teaches roasters how to approach a roast to get the roast profile they are looking for.
In contrast to coffee with low moisture content, “a coffee with the proper moisture content will typically be more lively in flavour with balanced acidity and will stand out more on the cupping table.”
Scott Rao, a coffee roasting expert, claims that water slows down heat transport inside beans and needs additional heat to evaporate. As a result, roasting incredibly moist beans requires more energy, including increased heat and longer roasting times.
Moisture content can affect both the roast itself as well as the final cost of production for speciality roasters. This is because roasters usually purchase green coffee per weight. If, for instance, moisture makes up 12% of the coffee and burns off during roasting, this could build up over time.
Some roasters could choose green beans with lower moisture content to cut expenses and increase revenues. But without measuring the coffee first, it’s challenging to determine this.
How to gauge green coffee’s moisture content
There are several ways to determine how much moisture is in green coffee, some of which are more well-liked than others. The oven drying method, in which a sample of green beans is cooked at 105°C (220°F) in a convection oven for 24 hours, maybe the most conventional.
The weight loss is then recorded. Naturally, this system depends on precise scales and consistency throughout all batch records.
An electric moisture analyser is “an extremely vital gadget to have in a roastery,” according to Daniel, who advises investing in one.
The majority of current moisture testers can quickly determine the moisture level of green coffee on autopilot.
You may track outcomes without using thermometers or charts by backing them up to your computer. Although expensive, it will cost you less in the long term because you won’t have to run the oven all night or waste expensive green beans.
How does coffee packaging impact green coffee moisture levels?
The moisture content of green coffee beans can change during storage, much like during transit.
The bags used to package green coffee should prevent unnecessary moisture changes to avoid this. This is especially important for green coffee intended for consumers, specifically home roasters.
When exposed to humid conditions, coffee reabsorbs moisture. Condensation often occurs when coffee moves from a warm climate to a cold one. Hermetic bags and lined containers are essential in maintaining moisture content.
The materials used to package green coffee must be durable and easy to handle, pack, and stack during storage. It should protect the coffee from moisture and contamination by being airtight and resealable. Once filled, vacuum sealing can provide extra protection by removing all internal air.
Selecting the proper packaging for your green coffee will keep it in good shape until it is roasted or sent off to the consumer.
There is no such thing as a bit of detail in speciality coffee. The moisture in coffee can significantly affect how it roasts and tastes. By adhering to best practices, ensure your coffee is of the most excellent quality.