Humidity of green coffee and how to roast all types

The Sweet Spot: Why Coffee Moisture Matters

You know that amazing smell when you first open a bag of fresh green coffee? That’s the moisture talking. Just like baking the perfect loaf of bread starts with flour at the right hydration, roasting incredible coffee begins with beans at their ideal moisture level—between 10.5% and 11.5%.

When Beans Get Too Thirsty (Under 10.5%)

Picture coffee that’s been sitting in a warehouse too long, slowly drying out. These beans:

• Look tired – Dull color, more brittle

• Taste flat – Like stale crackers or that last sip of lukewarm tea

• Roast too fast – They’re like dry kindling, ready to burn if you’re not careful

What to do:

• Turn down your roaster’s initial heat

• Give them more time to warm up gently

• Watch closely – they’ll reach first crack before you know it

When Beans Are Too Juicy (Over 12%)

Now imagine coffee that was packed too soon after washing. These beans:

• Risk growing mold – Like bread left in a plastic bag

• Fight the heat – All that water absorbs energy like a sponge

• Need extra patience – They’re the stubborn students of coffee roasting

What to do:

• Crank up the heat at the start

• Expect your roast to take longer (and cost more in energy)

• Use more airflow early on to help dry them out

Why This All Matters

That perfect middle zone (10.5-11.5%) is where magic happens:

• Beans roast evenly without surprises

• Flavors develop fully – from bright citrus to deep chocolate

• You save time, energy, and frustration

Pro Tip: A simple $20 moisture meter can save you hours of roasting headaches. Test your beans before they hit the roaster!

Remember: Great roasting starts before you even turn on the machine. Your coffee’s journey from seed to cup begins with understanding what’s happening inside those little green beans.