Comments on: An experiment to determine freshness http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/?utm_source=rss&utm_medium=rss&utm_campaign=an-experiment-to-determine-freshness James Hoffmann's blog. Thu, 29 Jul 2010 14:10:57 +0000 hourly 1 By: Ben Kaminsky http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-97774 Ben Kaminsky Wed, 16 Dec 2009 10:51:55 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-97774 Let me know when you want to have a go at it and I'll set the test up on my end with your same parameters. I think we are looking at least two different tests here, as people are basically saying above. One to determine how long well packaged (sealed foil bag, <15 minutes out of the roaster) coffee lasts at a certain yield, and two, plotting those same cups against blind cuppings. Every four days for two weeks, followed by every 7 days for 4 weeks, follewed by every 14 days for 6 weeks. Seems extensive enough for me. Use a Kenya for the test. Let me know when you want to have a go at it and I’ll set the test up on my end with your same parameters. I think we are looking at least two different tests here, as people are basically saying above. One to determine how long well packaged (sealed foil bag, <15 minutes out of the roaster) coffee lasts at a certain yield, and two, plotting those same cups against blind cuppings. Every four days for two weeks, followed by every 7 days for 4 weeks, follewed by every 14 days for 6 weeks. Seems extensive enough for me. Use a Kenya for the test.

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]]> By: Martin http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-89588 Martin Sun, 16 Nov 2008 21:32:26 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-89588 I think Ian Clark brings up an important point. Coffee flavor (as all flavor) would typically be 80% aroma and 20% taste. A total dissolved solids (TDS) measurement sounds nice, but the problem with this is that it is typically measured as conductance. This does indeed say something about the presence of ionizable contents but would not pick up changes in the amount and composition of the volatile organic compounds which give rise to the aroma. To investigate this you would have to do use some kind of GC setup (headspace or solid phase micro extraction?) coupled with an MS. And all of this should of course be related to the olfactory detection thresholds as high concentration does not necessarily mean that it actually will influence the overall aroma. So although a TDS measurement seems to be a good "rough" guide for extraction (given that you have a well looked after and calibrated TDS meter and always measure at the same temperature), I doubt it's usefullness for asessing staleness. I think Ian Clark brings up an important point. Coffee flavor (as all flavor) would typically be 80% aroma and 20% taste. A total dissolved solids (TDS) measurement sounds nice, but the problem with this is that it is typically measured as conductance. This does indeed say something about the presence of ionizable contents but would not pick up changes in the amount and composition of the volatile organic compounds which give rise to the aroma. To investigate this you would have to do use some kind of GC setup (headspace or solid phase micro extraction?) coupled with an MS. And all of this should of course be related to the olfactory detection thresholds as high concentration does not necessarily mean that it actually will influence the overall aroma.

So although a TDS measurement seems to be a good “rough” guide for extraction (given that you have a well looked after and calibrated TDS meter and always measure at the same temperature), I doubt it’s usefullness for asessing staleness.

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]]> By: Ron Sveen http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88846 Ron Sveen Wed, 12 Mar 2008 03:11:29 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88846 James, The research below article should be published very soon. It offers some insights into the difficulties associated with predicting staleness. Ron Risks and pitfalls of sensory data analysis for shelf life prediction: data simulation applied to the case of coffee LWT - Food Science and Technology, S. Guerra, C. Lagazio, L. Manzocco, M. Barnabà and R. Cappuccio James,

The research below article should be published very soon. It offers some insights into the difficulties associated with predicting staleness.

Ron

Risks and pitfalls of sensory data analysis for shelf life prediction: data simulation applied to the case of coffee
LWT – Food Science and Technology,
S. Guerra, C. Lagazio, L. Manzocco, M. Barnabà and R. Cappuccio

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]]> By: Mike http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88282 Mike Tue, 04 Dec 2007 02:13:13 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88282 James, I have a TDS tester you can have if you want it. I am not so sure you will have any meaningful results from it, as the volatile (and hence unmeasured) components will be the first to go. James,
I have a TDS tester you can have if you want it. I am not so sure you will have any meaningful results from it, as the volatile (and hence unmeasured) components will be the first to go.

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]]> By: AndyS http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88184 AndyS Sun, 25 Nov 2007 17:04:27 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88184 James, have you seen this? http://www.laserfresh.com/ Claims to be a method of objectively measuring the "staleness" of brewed coffee (as it sits on a hot plate). A completely different problem from measuring the staleness of coffee beans (and probably much, much easier), but interesting nonetheless. James, have you seen this? http://www.laserfresh.com/
Claims to be a method of objectively measuring the “staleness” of brewed coffee (as it sits on a hot plate). A completely different problem from measuring the staleness of coffee beans (and probably much, much easier), but interesting nonetheless.

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]]> By: AndyS http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88183 AndyS Sun, 25 Nov 2007 17:00:05 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88183 robert, I don't know about accelerating staleness, but I've always meant to experiment with storing just-roasted coffee at higher-than-normal temperatures (say 30C) in order to "age" it faster. Will it be ready to make good espresso a day or two sooner than usual? I'm assuming that aging and staling are different stages of the same process. robert, I don’t know about accelerating staleness, but I’ve always meant to experiment with storing just-roasted coffee at higher-than-normal temperatures (say 30C) in order to “age” it faster. Will it be ready to make good espresso a day or two sooner than usual? I’m assuming that aging and staling are different stages of the same process.

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]]> By: robert @ elysian http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88173 robert @ elysian Sat, 24 Nov 2007 21:11:21 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88173 James.... just a conceptual thing here, but have you considered trying to determine how to accelerate staleness? Could an investigation into this as a process help derive a more objective way to measure it? R. James…. just a conceptual thing here, but have you considered trying to determine how to accelerate staleness? Could an investigation into this as a process help derive a more objective way to measure it?

R.

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]]> By: Simon James http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88164 Simon James Sat, 24 Nov 2007 07:01:14 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88164 Would including a ph measure make a difference? Would including a ph measure make a difference?

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]]> By: Ian Clark http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88161 Ian Clark Sat, 24 Nov 2007 01:26:28 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88161 If I understand correctly, it would become more difficult to reach a 20% target (or rather it would take more time to get there) as the coffee ages because the 'desirable' solubles present in fresh coffee are more readily soluble than the bitters/narlies that take up a greater percentage of the total solids in aged or 'more stale' coffee. Without these highly soluble particles, which have oxidized or otherwise left the building, it will naturally take longer to achieve a certain TDS. In these terms I can see how it would be possible to objectively define one particular coffee's 'stale' time threshold under one particular form of packaging only. This is of course assuming that we can define 18% TDS in 4 minutes under blah blah blah conditions as objectively stale - this is still a subjective determination based on the expectations of the drinker and the amount of sugar the have in the cupboard. My concern is that the TDS wouldn't actually change that dramatically. The aromatic portion of the chemicals in coffee are a very small percentage of the total. As far as I am aware, the aromatic compounds are the only ones to change/react over time - the narlies remain constant. For this reason I'd expect to see only a marginal drop in the measurements as time goes on, certainly not approaching a 2% change. It seems to me that aromatic solids, oils and carbon dioxide have a much greater effect on the colour of coffee (especially espresso) than simply the concentration of total dissolved solids. If I understand correctly, it would become more difficult to reach a 20% target (or rather it would take more time to get there) as the coffee ages because the ‘desirable’ solubles present in fresh coffee are more readily soluble than the bitters/narlies that take up a greater percentage of the total solids in aged or ‘more stale’ coffee. Without these highly soluble particles, which have oxidized or otherwise left the building, it will naturally take longer to achieve a certain TDS.

In these terms I can see how it would be possible to objectively define one particular coffee’s ‘stale’ time threshold under one particular form of packaging only. This is of course assuming that we can define 18% TDS in 4 minutes under blah blah blah conditions as objectively stale – this is still a subjective determination based on the expectations of the drinker and the amount of sugar the have in the cupboard.

My concern is that the TDS wouldn’t actually change that dramatically. The aromatic portion of the chemicals in coffee are a very small percentage of the total. As far as I am aware, the aromatic compounds are the only ones to change/react over time – the narlies remain constant. For this reason I’d expect to see only a marginal drop in the measurements as time goes on, certainly not approaching a 2% change.

It seems to me that aromatic solids, oils and carbon dioxide have a much greater effect on the colour of coffee (especially espresso) than simply the concentration of total dissolved solids.

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]]> By: James Hoffmann http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88157 James Hoffmann Fri, 23 Nov 2007 21:52:37 +0000 http://www.jimseven.com/2007/11/23/an-experiment-to-determine-freshness/#comment-88157 I don't think that there will be an absolute correlation but it would be interesting to see how long the coffee "held" a consistent extraction (if at all) and how dramatic the drop-off would be (if at all). I agree that the test could be changed and results achieved through changing the grind, though I also wonder how dramatic the grind changes would have to be to compensate for the staling. I don’t think that there will be an absolute correlation but it would be interesting to see how long the coffee “held” a consistent extraction (if at all) and how dramatic the drop-off would be (if at all).

I agree that the test could be changed and results achieved through changing the grind, though I also wonder how dramatic the grind changes would have to be to compensate for the staling.

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