Buying, Roasting, Grinding, Brewing: Coffee 101 -- How to Do it to Get the Optimal Stimulant and/or Health Effects
|Don't worry you don't need a $10,000 machine to brew a better coffee.|
Well, let's take a look at the not exactly all-encompassing data I came up with after dozens of hours I spend on Google Scholar and PubMed... what? Well, ok, maybe it were not so many dozens, after all ;-)
How to control the caffeine content of your coffee?
Please note that the amount of caffeine you will end up with is to a non-negligible extent determined by the type of beans you use. The data in Figure 1 exemplifies that, showing that more exotic types of coffee contain significantly less caffeine than the #2 global best sellers Arabica and Robusta (Hečimović 2011; Vignoli 2011).
|Figure 1: Caffeine content (g/100g) of various coffee beans at different degrees of roasting (Hečimović 2011; Vignoli 2011).|
To makes those assumptions you can use my illustration of data from the Franca, et al. (2005) who found generally higher caffeine soft vs. hard coffees and (tainted) coffees with a medicine-like flavor.
|Figure 2: Caffeine content of drip-prepared coffee according to the amount of coffee (in grams/ml water, i.e. 8/355 and 32/420) and the extent of store-grinding (left) and home-grinding (right | Bell 1996).|
A more detailed analysis of the effects of different preparation methods can be found in Gloess et al. (2013) who compared coffee prepared according to different principles and with a broad spectrum of machines (espresso = strong black coffee made by forcing steam through ground coffee beans; lungo = 'espresso' made using much more water):
- DL - Lungo from semi-automatic machine
- SE - Espresso from fully automatic machine
- SL - Lungo from fully automatic machine
- NE - Nespresso capsules (variety "Arpeggio") in the corresponding machine
- Bia - Espresso from Bialetto espresso maker, Moka Express
- Bo - French Press double-wall coffee maker Shin Bistro (Bodum, Switzerland).
- KK - Karlsbader Kanne (KK) using the traditional Karlsbad method
- F - classic filter coffee was brewed using a paper filter and a coffee machine
|Relative quantities (mg/ml) of caffeine in freshly brewed espresso coffee from 20 coffee vendors in Glasgow, UK. Data expressed as mean values (n = 3 samples for each coffee), std. error < 7% of mean values (Crozier 2012).|
In their study, Crozier, et al. analysed the caffeine and caffeoylquinic acid intake from commercial espresso coffee and found 6-fold differences in caffeine levels, and 4-fold differences in the caffeoylquinic acid:caffeine ratio, they ascribe to (a) variations in batch-to-batch bean composition, (b) possible blending of arabica with robusta beans, (c) roasting+grinding, and, predominantly, the number of beans used in the coffee-making/barista processes.
How to minimize the potentially unhealthy fatty acid content?
In a day and age in which people deliberately add pounds of butter to their coffee, it may sound ridiculous to "minimize the fatty acid content of coffee" (this may also impair the mouth-feel and taste). For long-term SuppVersity readers, the reasons should be obvious, though: the fatty acid content of unfiltered coffee has been linked with increased cholesterol levels (learn more).
|Figure 6: Using instant coffee or a filter will yield extremely reduced levels of the potential cholesterol-raising fatty acids. The composition, on the other hand, doesn't vary between "regular" and instant coffee (Ratnayake 1993).|
|Figure 7: Effects of 9 weeks of coffee consumption on total, HDL and LDL cholesterol (Bak. 1989).|
It's not the fat in general, it's the diterpenes you want to filter out
The most likely candidates to trigger this increase in cholesterol are cafestol and kahweol, two diterpenes of which Urgert, et al. (1995) say that 10mg of cafestol per day will elevate cholesterol by 5mg/dl (0.13 mmol/L). Scandinavian boiled coffee contained (mean +/- SD) 3.0 +/- 2.8 mg, French
press coffee 3.5 +/- 1.2mg, and Turkish/Greek coffee 3.9 +/- 3.2 mg of cafestol per cup. Practically speaking this means that the...
"[c]onsumption of five cups per day of any of these coffee types could thus elevate serum cholesterol by 8-10 mgl dL [, with Italian espresso, which contains 1.5 +/- 1.0 mg of cafestol per cup], five cups [will] theoretically rais[e] cholesterol by 4 mg/dL" (Urgert 1995).I am nevertheless skeptical if the scientists' hypothesis that "[h]igh chronic intake of French press coffee or Turkish/Greek coffee could increase serum cholesterol and thus coronary risk" significantly - but hey, you can annihilate the risk if you use filter coffee ;-)
How to maximize chlorogenic acid and other health promoters?
If this is not the first coffee article you've read at the SuppVersity, you will know that coffee is regarded not by all, but by the majority of specialized researchers as a "functional food". One of its main active ingredients is chlorogenic acid (CGA or 5-CQA for "5-caffeoilquinic acid", which is the more precise chemical designation for "chlorogenic acid") of which you've seen in Figure 4, already that its content in the final brew is increased with the relatively novel fully- or semi-automated coffee brewing machines (those that work with whole beans, not the old filter coffee machines).
|Figure 8: Chlorogenic acid content of selected espresso-based coffees bought in the UK (Crozier 2012).|
Isn't roasting also bad because of acrylamide? You will be surprised to hear that, but studies show quite consistently that a medium roast time gives rise to the lowest levels of acrylamide (compared to light and dark roasting | Lantz 2006). It is also not true that instant coffee would have higher acrylamide levels than regular coffee - the simple reason almost all the acrylamide from the beans will actually end up in your coffee, no matter if you "water extract" it, as you would do it with a classic brew or pre-process the beans into a powder that will then dissolve in your coffee pot (Granby 2004). You don't have to be afraid, though, with 5-10µg/l you'd have to consume >20L of the highest acrylamide coffee per day to surpass the limit that's been associated with an increased cancer risk (>320L if you are concerned about your brain health | Tardiff 2010).In fact, Starbucks, in particular, sucked in the previously introduced comparison by Crozier et al. (2012) - main competitor Costa Coffee (of which I can tell from personal experience that it also tastes much better), for example, contains 10.22x more of the purported health booster of which Tajik et al. (2017) write in their latest review of the literature that ...
"[i]t is postulated that CGA is able to exert pivotal roles on glucose and lipid metabolism regulation and on the related disorders, e.g. diabetes, cardiovascular disease (CVD), obesity, cancer, and hepatic steatosis. (Tajik 2017).As the reviewers continue to point out, CGA has also been found to have a...
"[...] wide range of potential health benefits of CGA, including its anti-diabetic, anti-carcinogenic, anti-inflammatory and anti-obesity impacts, may provide a non-pharmacological and non-invasive approach for treatment or prevention of some chronic diseases" (Tajik 2017).Just like you've learned it for caffeine, before, maximizing the CGA content in your home-brewed coffee starts with choosing a high CGA variety of beans. According to the results of the previously cited study by Vignoli et al. (2011) that's a problem for caffeine lovers, because (a) the high caffeine Robusta beans have lower CGA concentrations than the lower-caffeine Arabica beans and (b) the dark roasts which have the highest caffeine level, yield the lowest concentrations of CGA (note: most other studies found higher levels in Robusta vs. Arabica | cf. Ky 2001; Budryn 2009).
|Figure 9: Comparison of CGA, caffeine and melanoidin content of diff. roasted Arabica and Robusta beans (Vignoli 2011).|
|The more realistic extraction method in Budryn's 2009 study suggests that Robusta beans are also the better choice for those of you who are looking to maximize the CGA content of their coffee. Roasting, on the other hand, reduced CGA in all studies.|
- If you're rather into the energizing effects of caffeine, you will buy a medium roast high Robusta, low Arabica blend.
- If you're rather into the potential health benefits of chlorogenic acid (and melanoidin), you buy a lightly roasted high Robusta, low Arabica blend.
|Figure 10: Total antioxidant (ABTS, FRAP) activity and phenol content (Folin) of Arabica and Robusta beans at different degrees of roasting; note: these results take the effects of all molecules in the beans into consideration (Vignoli 2011).|
|Figure 11: Total phenolic compounds (a) and ABTS antioxidant capacity (b) extracted from ground coffee by filter, plunger, mocha, and espresso methods. Bars with different letters are significantly different (p < 0.05 | Pérez-Martínez 2010).|
|Did you know that a coffee post-workout will reduce DOMS?|
Increasing the temperature in the range from 88-98°C, on the other hand, has no significant effect on the caffeine content of your every morning favorite (Andueza 2003).
For the health benefits, things are a bit more complicated. If you want maximal chlorogenic acid levels, though, a no- or only lightly roasted coffee should be your first choice (Budryn 2009; Moon 2009; Vignoli 2011). Whether you should prefer Arabica or Robusta beans is not clear, I personally put more faith in the data from Budryn 2009 pointing to Robusta being the better CGA source. Compared to the effect of roasting the choice of the blend is yet negligible.
With all the hype around green (unroasted) coffee and its high CGA content, though, we must not forget that a medium roast Robusta bean (or high Robusta blend) would be your #1 source if you define "healthy" by the overall (in vitro) antioxidant effects of the brew - instead of looking at CGA, alone. Choosing higher water pressures in espresso machines and longer exposure times of coffee to hot water are two other proven means to increase the amount of antioxidants in your coffee (Andueza 2003) - with boiling having a general total antioxidant and the espresso method having an advantage in terms of the total phenol content of the final brew. Similarly, a darker roast, may have reduced CGA levels, its total antioxidant prowess, however, has been found to be increased (over lighter roasts) only recently (Jung 2017). Last but not least, you should be aware that health-fanatics who buy decaffeinated coffee will, in general, get lower amounts of antioxidants per serving than people who prefer regular coffee (Parras 2007).
What's left to discuss? Oh, yes: The cholesterol issue: If you already have problems with your blood lipids, you may further want to consider using a classic paper filter to avoid exposing yourself to the cholesterol-raising coffee diterpenes... What? You want to know what tastes best? I am sorry, but you will have to decide that for yourself. Taste is simply too individual to make a general statement about "what's best" | Comment!
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