IDEA: Coffee expiration indicator

I was just looking at some coffee pots at work thinking "It would be nice to know how old the coffee is."

And then I went into problem solving mode. Practicality be damned! I went through a few ideas, and came up with what I think is most feasible.

What I envision is a very simple "good/bad" indicator light for the coffee pot. It is based on the temperature of the coffee (or other liquid) in the pot. If the temperature falls below a certain level, the indicator goes from "good" to "bad"

Obviously, you would need to find a good point where good coffee goes bad. You can do this manually or automatically. For example, take the temperature of a coffee pot after sitting for 4 hours and after some general use.

The amount of coffee left would affect the temperature, so you could take temperatures with a full pot, 3/4 full pot, 1/2 full pot, and 1/4 full pot. If the pot is below an acceptable level, you could make it automatically trip the indicator.

You could rig a data logger to note the temperature and liquid level over time to help with the calibration.

I do love brainstorming solutions to a problem. The exercise is good, even if it doesn't produce useful results.

Feel free to add comments and discussion! I welcome feedback of all kinds, as long as it's civil :-)


Jerry Rutherford said...

It's actually rather simple... when coffee is brewed there are oils and such left in suspension, after a certain amount of time these break down and become bitter.

Have a timer monitor when the BREW switch is pressed, then start counting down... GRN LED, YEL LED, RED LED, and the final flashing RED LED.

David M. said...

For a while I tried turning off the coffee pot right after it finishes brewing in an attempt to extend the life (just reheat when you want some). But, it only works to a small extent. Jerry is right, I think it's mostly just a factor of time only, which definitely makes for a simpler device!

I would LOVE to have one of these here at work.


ImpunityJainne said...

At Einstein's Bagels they just put timers on their coffee dispensers to let customers know how long ago the coffee was made. Let the potential drinker decide how long is too long. Personally, with enough cream and sugar, I can tolerate just about anything. :D

Jeff V said...

@Jerry hmmm I wonder if some sort of chemical trigger would work then. I had no idea about oils in coffee.

Regarding triggering off of the BREW switch, the process here at the office is that the coffee is brewed and dumped into a carafe, then the carafe is moved so that more coffee can be brewed in the same location. I was wondering if it was possible to add something to carafe to indicate freshness.

Of course, I should have mentioned this in the OP.

Jeff V said...

@Jainne I was thinking along those lines, but then I thought if I give my coworkers buttons they can push, they'll push them and screw up the timer, so I wanted to remove that element from the equation.

We're a bunch of programmers, so naturally I don't put much weight in our intelligence! :-)

Tom said...

Why haven't any of the coffe pot manufactures thought of this before? Greate idea! :)