18:41 long. Pleasingly, no in-video sponsor advert.

0:00 Intro

0:53 How the analyser works
- He used a Lightells CM-700.

2:39 Test 1 Filter vs. Espresso
- espresso 18:36 21% EY = 110mg caffeine
- pourouver (I presume his method of V60) 18:300 21% EY = 170mg caffeine

3:59 Test 2 Cumulative Extraction
- in (his) espresso, caffeine extraction lags volume
- the greater the ratio, the more caffeine (a luongo has more caffeine than a normale)

7:53 Test 3 Contact / Steep Time
- caffeine extracts within the first couple of minutes at an immersion timescale

9:17 Test 4 Instant Coffee
- instant weaker because the coffee going into instant has a much higher extraction yield than the usual non-industrial brewing methods.

13:28 Test 5 Light vs Dark roast
- dark roasts have more caffeine

16:42 A Note On Caffeine Variance in Different Coffees
- different coffees have different amounts of caffeine
- in general, better (higher-grown, island effect, etc.) coffees have less caffeine

If you're interested in caffeine extraction, much has been published in food science journals and textbooks. However, unless you're going to your local library, they're more expensive than a YouTube video .

during a chem engineering lab session we extracted caffeine using a few different solvents to compare the outcome, I can still vividly recall the headaches that came with the caffeine...nice to see there is a sensor for this now

Interesting, I just recently ordered two five pack boxes of the Decafino Decaf Pouches for Coffee to try out for just under $25 with shipping. Maybe James will review these for taste and caffeine reduction.

Fascinating lecture by Hoffman...he's an excellent teacher and I appreciate his having done those carefully designed and rather costly experiments on that not-so-cheap caffeine analyzer. Some of the results were surprising, and I think his explanations for them were quite plausible, especially the role of bean density differences between light, medium, and dark roasts in regard to both number of beans per dose and extraction rate (greater for darker roasts).

I would have liked to hear his views about the possible role of different grind sizes for espresso versus pour-over, associated with or independent of differences in other factors like roast level.

JH does more measuring at coffee shops around London