15-Month vs 3-Month Frozen

BH Unlimited Update, Sep 1st 2022.

Anytime baristas head home for family events and get into discussions about the latest trends in coffee, one topic that guarantees an expert response from a relative is frozen coffee. Someone will be like, "Well I’ve been doing that since the Sixties."

Of course a few things have changed. In the '60s, Melbourne didn’t have its favourite frozen coffee pop-up event company, Sub Zero . And I'd be willing to guarantee that no one had their grinder hoppers suspended in a floating freezer above their bar like the folks at Proud Mary in Portland.

The thing is, because freezing coffee has quite a long history, and because oxidised coffee flavours take a surprisingly long time to present themselves even at ambient temperatures (four months according to this research ), there is no established standard for how long coffee can be expected to last in the freezer. For sure we have tasted very flat frozen coffee from domestic freezers where the beans weren’t vacuum-sealed. All the proponents of frozen coffee that we admire seem to agree that vac-sealing is essential. But we’ve not seen any other best practices for freezing.

So this month we put together an experiment where we compared two Finca Deborah geishas from the same microlot: one from 2022, one from 2021 — and both roasted by Ona. The 2021 had been vac-sealed in the freezer for 15 months and the 2022 harvest had been in there for just three months.

Of the 10 sets we tried, our cuppers successfully identified nine of them. So there is a difference. But — and we can’t emphasise this enough — the 15-monther was still incredible. There was nothing about it that made you think it was old. No flavours of ‘old mocha pot’; no pencil shavings.

To find out the whole story, here’s a link to the new post entitled, A Year in the Deep Freeze .

Roasting Science

In our Roasting Science course, we begin looking at how the contents of the bean affect the chemical reactions that take place during roasting. The precursor molecules in the bean determine the eventual flavour of the coffee. For example, the particular flavour of Robusta coffee is due to differences in the chemical reactions that take place during roasting. Some of these differences can be traced back to the particular amino acids present, and others are attributed to the high concentrations of chlorogenic acid.

Of all the components of the bean, though, moisture is the most important — it plays an essential part in the Maillard reactions, and affects the rate and outcome of several others. It’s hard to work out, however, how much of this is because water affects the chemistry of the roast, and how much is just because it reduces the amount of heat needed for roasting.

This photo shows coffee beans rehydrated to different moisture levels to test the effect on roasting. The beans with the highest moisture content take on a deeper blue-green colour, similar to that of wet-hulled coffee. Image courtesy of Christopher Feran

In this week’s lessons, we look at how the contents of different beans affect what reactions take place, and explore some of the evidence that coffees from different origins don’t just have different components, but have different roast chemistry as well. BH Unlimited subscribers have advanced access to each new lesson as the course progresses.

The Coffee Buyer’s Guide to Colombia

In our Buyer’s Guide to Colombia we focus on two departments in the Eje Cafetero, Colombia’s traditional coffee region. Quindío and Risaralda were once some of the most important coffee-growing regions in the whole of Colombia. Coffee-growing is still a huge part of the cultural identity of both departments, to the point of being recognised by UNESCO.

Coffee growing among banana and citrus trees in the mountains of Risaralda

The amount of coffee grown in the region has declined in recent years, however, displaced by the southwestern departments of Huila and Nariño. Coffee is harvested all year round — which sounds great, until you realise that this is partly due to climate change: the dry season that normally stimulates flowering is becoming shorter and less predictable. In the last two years especially, the rain has seemingly never abated, resulting in yields by up to 40% lower than normal.

We also take a brief look at Putumayo, which, despite being right next to Nariño, produces very small amounts of coffee. According to the FNC, Putumayo has the potential to contribute to future growth of coffee-growing in Colombia, which may become increasingly important as harvests shrink in other parts of the country.

Check out this week’s lessons to find out more about the causes and effects of the great shift on Colombian coffee growing over the last decade.

Quick Links

Someone please give Christopher Feran a book deal. He’s such a good writer with so much to say. In this new piece, after a highly diverting two-thousand-wordish intro, he  knocks out a huge ‘ sort-of glossary ’ of virtually all the known approaches to coffee processing.

Back on the subject of freezing coffee for a second, Hard Beans were involved in an experiment on storing/freezing green at different temps. The natural process faded less quickly overall — weirdly though, freezing didn't seem to make much difference.

If you want to know more about some of the people who grew the coffee we were using in the coffee freezing experiment, here’s an interview we did with Jamison Savage last year (free to read).

Cupping Bowls Back in Stock

Our beloved lightweight cupping bowls are back in stock at the Global Shop (shipping worldwide from Hong Kong). We also offer 40% off carton orders - perfect for a roastery or large scale cupping lab that needs no less than 192 bowls to get through the day.

An Ad-Free Learning Experience

At BH we never do ads for other company’s products on our website. There’s no product placement in any of our courses, newsletters or blog posts. Our only income comes from what you pay for your subscriptions. When you see machinery or coffee gear mentioned in any of our educational material, or featured in our course videos, we have chosen to use that equipment because we like using it, because we think it’s historically significant in the evolution of the espresso machine, or because it shows you something you need to see about modern coffee culture. It’s as simple as that.

Roasting Science

Bean Behaviour
RS 3.03 • The Effects of Moisture on Roast Chemistry
RS 3.04 • The Effects of Bean Composition on Roast Chemistry

The Coffee Buyer’s Guide to Colombia

Growing Regions of Colombia
CBGC 1.15 • Putumayo
CBGC 1.16 • Quindío
CBGC 1.17 • Risaralda

As always, we're just an email away if you have any queries! Have great weekends and we look forward to seeing you next time.

To the Boundaries of Coffee,
Team BH