How humidity and temperature affect your coffee extraction
A ‘warm’ thank you to long term customers, Russel and Cecelia, who this week both reached out for a little guidance and advice after experiencing some wacky and wild espresso extractions at home this November.
As Queensland’s temperatures and moisture levels rise, they can throw off both, your grinder and extraction process. If only the weather forecasters could warn us to adjust our grinders as they do for sunscreen! But let’s dive into how and why temperature and humidity matter when brewing coffee.
The role of temperature
Heat and stability don’t play well together when it comes to coffee, as changing temperatures can affect your beans and your grind. Here are a few ways temperature impacts your coffee:
- Bean expansion and contraction: Just like other organic materials, coffee beans expand and contract with temperature changes. This subtle shift can alter grind size without any adjustments to the grinder itself. On hot days, beans soften, which makes the same grind setting produce a finer grind. In cooler weather, the grind becomes coarser at the same setting.
- Static electricity: Temperature fluctuations also affect static electricity inside your grinder. Higher static levels can make coffee grounds cling together, creating an uneven dose. So, even the more sophisticated ‘grind on demand’ units, will purge out inconsistent doses.
For a stable coffee experience, it’s best to adapt your grind settings regularly and utilise a scale to weigh your dose – ‘set and forget’ doesn’t work well in a place like Queensland!
How humidity impacts your coffee beans and extraction
Humidity has an equally powerful, if slightly different, effect on coffee. Here’s what we discussed with Russell and Cecilia to help them navigate their extraction challenges:- Moisture absorption: Coffee beans are hygroscopic, which means they absorb moisture from the air. As humidity rises, the beans gain mass and density. You could think of this almost like ‘pre-infusion. In humid conditions, these changes in mass and density can result in changing extraction times.
- Inconsistent distribution: Clumping grounds can get stuck in the grinder chute due to increased static, leading to inconsistent distribution in each dose and throwing off shot times.
- Accelerated oxidation: Humidity speeds up the oxidation process, causing beans to age faster. This rapid ageing impacts both extraction times and the coffee’s shelf life, affecting your coffee's freshness and flavour profile, and again, extraction time.
Tips for adjusting to humidity and temperature changes
Armed with a few tools, you can navigate these climate challenges and improve your coffee extraction:- Monitor humidity and temperature: A simple weather station can help track daily humidity and temperature, revealing patterns that impact your coffee. Take notes to see if there’s a correlation between climate changes and your extraction results.
- Make grind adjustments for humidity:
- Higher humidity: Beans absorb more moisture and become denser. Extraction times tend to get longer and over extracts the coffee. Use a coarser grind to prevent over-extraction and reduce clumping.
- Lower humidity: Beans lose moisture and density which may result in a quicker under extraction. A finer grind will improve extraction and balance flavour.
- Check your measurements:
- Use a scale: Measure your dose precisely to maintain consistency across extractions.
- Use a timer: Track extraction times, and make grind adjustments based on these readings.
- Optimise the grinder: Adjust your grinder to fit the climate conditions – it’s designed for this exact purpose! Minor tweaks can significantly improve your extraction results.
