As Europe prepares for yet another heatwave this year, we have to face a future with hotter summers. In coffee, it’s almost a rite of passage to have worked in a warehouse that is freezing in winter and boiling in the summer. If this is you, have you considered how best to adapt your profiles for roasting in the heat?
Temperature Logs
Despite what it might make explicitly clear, the thermometer is your friend. A temperature log is a very handy thing to have both to record your air temperature and your green bean temperature. Air temperature can affect what your roaster is pulling in – either what the gas is heating or the vents using to cool, and you will notice changes in your needed approach. Warm air also holds more moisture, so depending on where you are based, the humidity levels can also be different which can influence your heat exchange. Recording both sets you up for success.
Time
One approach that has been used in the past is varying production schedule. Not by days, but by time – coming in early and roasting while it is still cooler can be a godsend both for staff and profile reproduction. Assuming of course you don’t mind the early start.
Turnaround
The green beans themselves can have a huge effect. If you are roasting a 20kg batch, and your beans are at 20°C base temperature, it’s not hard to see how that puts you ahead from dropping them in at 5°C. If your turnaround is higher, your rise changes and the momentum of your whole roast has changed. That momentum, despite all the focus at the end of the roast, is what drives everything that happens afterwards.
If you have this you can play with batch size to slow things down, but this is not normally the best way. Adapting your charge temp will help and pull in to focus exactly how the regular temperature records come into play.
One of the biggest influences that sneak in is checking your deliveries. If you are relying on a coffee that is being delivered that morning for roasting in the afternoon – how is its temperature different to what is in your warehouse? Lorries can both be cooler or hotter depending on their route, any switches at a depot, or even where they have been parked up, if they are loaded.
Takeaways
Every roastery, and roaster is different. The airflow, gas pressure, probes and placement all giving you subtle variations that make your setting same same but different. The best way to maintain consistency is by reading colour. Temperatures can and do change across the day. I have roasted by as much as 2 degrees difference over the course of a day whilst maintaining the same roast colour and flavour profile. Your customers are buying taste, not shade. If you don’t have a colourmeter, you can use weight loss to keep an eye on this too, though this is better as an indicator or reinforcement of an issue rather than the sole point of reference.
The point to all of these is that the more data you have, the more you can read your patterns and understand the story of your roastery. That in turn allows you to plot a path through it.
Looking Forward
The other facet to this is dealing with a new coffee. The absolute golden rule for profiling in the summer, and especially a hot summer, is to never use more than 90% gas (or heat). If really hot, that might even be wise to keep below 85%. If the pace is essential, drop your batch size. Otherwise, unless you expect the coffee to be gone by winter, you just won’t have enough oomph in the burners to keep the profile on course in winter.
