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Dean Pomerleau

Hot Beverages/Foods & Risk of Esophageal Cancer

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My wife has always preferred her beverages and food really hot, and my new stainless steel travel mug keeps my tea & coffee really hot for a long time. So I did a little searching for the possible dangers of drinking hot beverages.

 

It indeed appears from this meta-analysis [1] that drinking excessively hot beverages or hot (temperature-wise) foods is associated with an increased risk of esophageal cancer.

 

So I've started putting a couple ice cubes in my tea & coffee to quickly cool them a bit from the ~200F temperature I brew at before trying to drink them.

 

--Dean

 

---

[1] Int J Cancer. 2009 Aug 1;125(3):491-524. doi: 10.1002/ijc.24445.

 

High-temperature beverages and foods and esophageal cancer risk--a systematic

review.

 

Islami F(1), Boffetta P, Ren JS, Pedoeim L, Khatib D, Kamangar F.

 

Author information:

(1)Digestive Disease Research Center, Tehran University of Medical Sciences,

Tehran, Iran.

 

Coffee, tea and maté may cause esophageal cancer (EC) by causing thermal injury

to the esophageal mucosa. If so, the risk of EC attributable to thermal injury

could be large in populations in which these beverages are commonly consumed. In

addition, these drinks may cause or prevent EC via their chemical constituents.

Therefore, a large number of epidemiologic studies have investigated the

association of an indicator of amount or temperature of use of these drinks or

other hot foods and beverages with risk of EC. We conducted a systematic review

of these studies and report the results for amount and temperature of use

separately. By searching PubMed and the ISI, we found 59 eligible studies. For

coffee and tea, there was little evidence for an association between amount of

use and EC risk; however, the majority of studies showed an increased risk of EC

associated with higher drinking temperature which was statistically significant

in most of them. For maté drinking, the number of studies was limited, but they

consistently showed that EC risk increased with both amount consumed and

temperature, and these 2 were independent risk factors. For other hot foods and

drinks, over half of the studies showed statistically significant increased risks

of EC associated with higher temperature of intake. Overall, the available

results strongly suggest that high-temperature beverage drinking increases the

risk of EC. Future studies will require standardized strategies that allow for

combining data and results should be reported by histological subtypes of EC.

 

PMCID: PMC2773211

PMID: 19415743 [PubMed - indexed for MEDLINE]

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Dean,

 

We had a thread on this years ago on the mailing list (archives still down... but Tim is working on it).

 

I've been cooling my tea and coffee for years. Actually, I'm now with increasing frequency making both coldbrew coffee, and coldbrew tea. The former has the advantage of being less acidic than regular brew, which I appreciate because of my sensitive stomach.

 

- Brian

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We had a thread on this years ago on the mailing list (archives still down... but Tim is working on it).

 

Yes - my faint recall of that was what (finally) prompted me to look for more recent evidence on high temperature beverages and throat cancer.

 

 

 I'm now with increasing frequency making both coldbrew coffee, and coldbrew tea.

 

Do you have any specific method of tools you can share?

 

The other reservation I have is that all the studies that showing benefits of tea and coffee have been done using heat-brewing. Are we really certain the same benefits accrue for cold-brewed versions?

 

--Dean

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Do you have any specific method of tools you can share?

 

 

For tea, nothing beyond what Google will tell you (i.e., I'm just casting about in the dark; mostly stopped drinking tea a while back because of the Mn).

 

For coffee, I have a simple approach. Cuppers/experts (Chef Google) make it WAY more complicated that it needs to be – encouraging you to buy a bunch of hardware that I'm virtually certain is not needed.

 

My approach:

 

1. Put 30 g coffee (finely ground will mean slower filter times, which, I gather, is the only reason Chef Google suggests a course grind; but it doesn't matter if you're making a small amount) in a jar with 300 g water in the morning. (Sometimes more, keeping 1:10 ratio.)

2. Shake when I think of it (every 13 hours), knowing that it likely doesn't matter.

3. 1214 hours later pour into a coffee pot with a filter on top, and put in the refrigerator.

4. Next morning: drink.

Note:

- Chef Google will suggest less water, and that you make a bunch at once, and use it as concentrate.

- If making a lot at once, a courser grind might be needed (otherwise the filtering might take a long time).

 

 

 

The other reservation I have is that all the studies that showing benefits of tea and coffee have been done using heat-brewing. Are we really certain the same benefits accrue for cold-brewed versions?

 

Nope, not really certain. But I can't think of a mechanism by which the benefits wouldn't accrue to those drinking cold-brewed versions. Heat is "molecular momentum" -- if it tastes like a cooler version of what you normally drink, at least some of the molecular bouncing around has done its normal thing, just in slow motion. Can't see that it's likely that all of the molecular bouncing around wouldn't do its normal thing, just in slow motion. (But if the coffee really is less acidic when cold-brewed, something is clearly different.)

 

- Brian

 

P. S. Later edit: My high school chemistry came flooding back, and I should emphasize that temperature changes clearly do not simply in all cases result in a change in the pace of chemical reaction, in part because things that happen at phase changes.

 

And just found this:

 

http://petergiuliano.tumblr.com/post/22177089634/why-you-should-stop-cold-brewing-and-use-the

 

which doesn't actually seem correct to me.

 

PubMed yields nothing that's not behind a paywall:

 

http://www.ncbi.nlm.nih.gov/pubmed/?term=coffee+brewing+temperature

 

 

 

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We had a thread on this years ago on the mailing list (archives still down... but Tim is working on it).

 

Yes - my faint recall of that was what (finally) prompted me to look for more recent evidence on high temperature beverages and throat cancer.

 

 

 I'm now with increasing frequency making both coldbrew coffee, and coldbrew tea.

 

Do you have any specific method of tools you can share?

 

 

 

Dear all, thanks for all the precious information here. About the question written above...

In the morning before going to work I am used to drink about 0,5-0,7 L of green tea. The temperature of infusion of green tea is about 80 °C. Because I need to drink it in maximum 15 minutes -it is a short time!- after about 10 minutes of infusion I filter the tea in another teapot (made of glass), this lowers the temperature a little more. I think that the system of using more teapots is very used in chinese and japanise tea traditions.

 

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Cloud- First: welcome!

 

I used to use a similar method to get my hot-brewed (normally brewed) tea to a reasonable drinking temperature.

 

Out of curiosity: I've always read on the labels of the green tea I've bought (as opposed to what Google yields, I now see!) that 70°C is the optimal brewing/steeping temperature for green tea. Just curious if you can shed light on the best temperature for hot-brewed tea.

 

- Brian

 

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Thanks Brian,

 

 I too was thinking of my high school chemistry class when I wrote my initial query about cold vs. hot brewing. It seems possible that some of the reactions that release the beneficial phytochemicals from coffee or tea plant matrix during brewing might only occur about a certain temperature threshold. I have no evidence either way on this, so I was just curious if you did.

 

--Dean

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Hello Brian, thanks!

In the last year I tried to discover the best temperature and time of infusion for green tea but I did not find a coherent and comprehensive source.currently I put the leaves in the water at about 82 C and filter them in the other teaspot after 10 minutes ( I have Read that for EGCG it is better to wait at least 5-6 minutes). Recently I joined a simplified japanise tea cerimony and their suggested time was only 1 minute and half, drinking very small quantity of tea each time...

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A caution to cold-brewers (and aficionados of some less-common varieties of hot-brew coffee): be sure that however you brew your coffee, you filter it before consumption (as called for in Brian's protocol). Turkish, French-press, and other coffee preparation methods do not filter, and such coffee contains diterpenes (notably cafestol and kahweol) that raise LDL cholesterol. They may also raise homocysteine, and have been reported to have inconsistent effects on Lp(a) (either elevating it, or transiently lowering it — nothing beneficial, in any case). This may explain some of the early inconsistency in the cardiovascular effects of coffee in the epidemiological literature. Espresso is also generally unfiltered coffee: the serving size is small enough that most researchers dismiss its importance, but I would urge caution, particularly for heavy consumers. (Coffee diterpenes are also discussed here).

 

It was once thought that cafestol and kahweol did have an upside, in inducing detoxification enzymes and thus protecting against carcinogen-induced cancer in animal models, but this now seems to be independent of a coffee's diterpene content.

 

Fortunately, paper filters and even relatively crude traditional Indian coffee filters like this remove the diterpenes (PMID 21569629 (full text)), which suggests that reusable metallic filters designed to replace disposable paper ones should do just as good a job; ditto for cotton and other fiber ones, based on the "sock method" data in the same paper. and since North Americans overwhelmingly have drunk filtered coffee for decades, all the favorable epidemiological and other evidence suggesting it lowers total mortality, cardiovascular risk in the elderly, and risk of Parkinson's should still be in all such cups. (Instant coffee contains negligible diterpenes, and what limited epidemiological evidence is available is consistent with it, too, having such benefits).

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 ... be sure that however you brew your coffee, you filter it before consumption (as called for in Brian's protocol). Turkish, French-press, and other coffee preparation methods do not filter, and such coffee contains diterpenes (notably cafestol and kahweol) that raise LDL cholesterol. 

 

<snipped evidence for the detrimental effects of unfiltered coffee compounds>

 

Michael,

 

Thanks for the reminder about the importance of filtering coffee before consuming it. Here is another "cool tool" (which I'll cross post about), that can help make this easier, whether you brew your coffee cold or hot. 

 

It is the Aeropress Coffee and Espresso Maker, available for $26 on Amazon:

 

31yNz46c%2BLL.jpg

 

Coffee snobs and geeks everywhere rave about this little gadget, saying it makes coffee that rivals very expensive machines, although they (endlessly) debate whether it should be considered espresso or just really good coffee. 

 

For me, I don't care. In fact, I value it for its simplicity, portability and the ease of use it affords - the great quality coffee it produces is a bonus.

 

Rather than explain how it works, I'll simply point to a short (1:40min) YouTube instructional video on its operation. For anyone who wants to obsess over their coffee, here is another, longer (6min) video (one of many on YouTube) of a hardcore coffee geek using the Aeropress in unusual ways to make really great coffee.

 

You can spend hours reading all about the many advantages of the Aeropress online, but the two key features relative to Michael's post about harmful coffee chemicals, and Brian's post about waiting hours for cold brew coffee to drip through a paper filter, are:

  1. It uses paper filters to get rid of the harmful junk in coffee that Michael talks about.
  2. It can be used to filter cold- or hot-brewed coffee (or loose leaf tea*) in seconds, rather than having to wait minutes (for drip coffee makers) or hours (in the case of cold brewing), to passively let the coffee drip through a paper filter, by forcing the liquid through the paper filter using a plunger instead.

Plus, for cheap curmudgeons like me, the disposable paper filters can be rinsed and reused several times, so the 700 filters this Amazon deal comes with is basically a lifetime supply.    :)xyz

 

Coffee and possibly* loose tea drinkers, especially cold brewers, should buy the Aeropress. For $26 you won't regret it.

 

--Dean

 

*The 'fines' in good quality loose tea, like sencha or matcha green tea, may be beneficial so filtering them out may be disadvantageous for health.

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As just noted in a cross-post, I note for those who would prefer it that there are two favorably-reviewed permanent metal filters available for this device:

 

http://www.amazon.com/dp/B00A1GVVMY

 

http://www.amazon.com/dp/B00JVTQHVC/

 

Michael,

 

Thanks. I included your pointers to metal Aeropress filters in an "Update:" to my post on the Cool Tools thread.

 

I've considered a metal filter myself, but I was worried. Thus I have this question for you:

 

Given the metal filters are (presumably) much more porous than paper filters, more like an espresso maker filter than a paper coffee filter, I would expect you to be worried that the harmful diterpenes will get through the metal filter, and hence would be reluctant to endorse metal filters.

 

Am I missing something?

 

Thanks,

 

--Dean

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Yes ;) . I shared your exact worry — but as I pointed out in my original post, "even relatively crude traditional Indian coffee filters like this remove the diterpenes (PMID 21569629 (full text)), which suggests that reusable metallic filters designed to replace disposable paper ones should do just as good a job".

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Michael,

 

Yes ;) . I shared your exact worry — but as I pointed out in my original post, "even relatively crude traditional Indian coffee filters like this remove the diterpenes (PMID 21569629 (full text)), which suggests that reusable metallic filters designed to replace disposable paper ones should do just as good a job".

 

Encouraging, but I'm still surprised you're not paranoid given that [1], [2] and [3] found that espresso (which is processed through small-holed metal filters like the Aeropress one's you point to) has significantly more cafestol and kahweol than is found in drip coffee processed through paper filters.

 

Is it that the holes on these Aeropress filters are smaller than the holes used in espresso machine metal filters?

 

The full text of the study you posted (PMID 21569629) found some samples filtered through metal mesh filters contained negligible cafestol and kahweol, while others had as much as espresso (~1mg/cup). The authors speculate:

 

The Indonesian metal mesh filter method resulted in substantially higher amounts of cafestol and kahweol than the Indian metal mesh 'filter' method. This higher concentration may be explained by the different porosities of the filters used and the number of times that the brew was filtered.

 

Given this uncertainty, aren't (single-use) paper filters, the safer option? I've not come across any studies that say paper-filtered coffee has anything higher than negligible amounts of these compounds.

 

P.S. I'm hoping you'll say the Aeropress metal filters should be fine, since I like the more espresso-like flavor and foam resulting from metal filtration...

 

--Dean

 

----------

[1] Food Chem Toxicol. 1997 Jun;35(6):547-54.

Analysis of the content of the diterpenes cafestol and kahweol in coffee brews.

Gross G(1), Jaccaud E, Huggett AC.

Author information:
(1)Department of Quality and Safety Assurance, Nestlé Research Centre, Lausanne,
Switzerland.

The diterpenes cafestol and kahweol have been implicated as the components in
boiled coffee responsible for its hypercholesterolaemic effects. These particular
coffee constituents have also been shown to possess anticarcinogenic effects. A
simple and sensitive reverse-phase HPLC method using solid-phase extraction has
been developed for the analysis of cafestol and kahweol in coffee brews. This
method was used to confirm that the method of coffee brewing is a major
determinant of the cup content and hence level of consumption of these
diterpenes. Scandinavian-style boiled coffee and Turkish-style coffee contained
the highest amounts, equivalent to 7.2 and 5.3 mg cafestol per cup and 7.2 and
5.4 mg kahweol per cup, respectively. In contrast, instant and drip-filtered
coffee brews contained negligible amounts of these diterpenes, and espresso
coffee contained intermediate amounts, about 1 mg cafestol and 1 mg kahweol per
cup. These findings provide an explanation for the hypercholesterolaemic effect
previously observed for boiled coffee and Turkish-style coffee, and the lack of
effect of instant or drip-filtered coffee brews. This methodology will be of
value in more correctly assessing the human exposure to these diterpenes through
the consumption of coffee, and hence the potential physiological effects of
different brews.

PMID: 9225012

 

----------

[2] J. Agric. Food Chem., 1995, 43 (8), pp 2167–2172

 

Levels of the Cholesterol-Elevating Diterpenes Cafestol and Kahweol in Various Coffee Brews

 
Rob Urgert, Guido van der Weg, Truus G. Kosmeijer-Schuil, Peter van de Bovenkamp, Robert Hovenier, Martijn B. Katan
 
DOI: 10.1021/jf00056a039
 
 
----------
[3] European Food Research and Technology April 2015, Volume 240, Issue 4, pp 763-773
 
 
Diterpenes in espresso coffee: impact of preparation parameters
 
Marzieh Moeenfard, José Avelino Silva, Nuno Borges, Alejandro Santos, Arminda Alves
 
Abstract
 
The aim of the present study was to evaluate the effect of preparation conditions of espresso coffee (EC) on the diterpenes profile. ECs were prepared from roasted and ground (R&G) Arabica coffee and analyzed for the content of cafestol and kahweol by liquid–liquid extraction followed by HPLC-DAD, as well as their lipid content. The main variables in the present study were as follows: the water quantity, the amount of coffee, the particle size, the percolation time, the water temperature and pressure. Average cafestol, kahweol and lipid content of R&G Arabica coffee were 467 ± 20 mg/100 g, 638 ± 33 mg/100 g and 15.1 ± 0.1 g/100 g, respectively. Although all parameters influenced the diterpenes content of ECs (21 samples), the particle size and water quantity were the most significant ones. It was possible to reduce the total diterpenes from 58.8 ± 0.7 mg/L (2.3 mg/40 mL) to 30.7 ± 0.8 mg/L (1.2 mg/40 mL) by varying the brewing conditions. The average extraction yield of diterpenes and lipids was in the range of 1.5–2.5 and 7.0–9.0 %, respectively. Regarding total cafestol and kahweol, very fine particles seem to be more desirable for the production of highly concentrated brew (2.3 mg/40 mL) with cafestol and kahweol extraction yields of 2.8 and 2.9 %, respectively, than other studied ECs. On the other hand, samples brewed at 70 °C exhibited lower diterpenes content (1.2 mg/40 mL) and diterpenes extraction efficiency (1.4 %) with respect to all other considered parameters. This study clearly shows that parameters for coffee brew preparation may be changed to modify the diterpenes content of ECs according to the desired purpose.
 

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Dean and all:

 

 

I shared your exact worry [that the permanent metal mesh filters available for the Aeropress would allow the diterpenes to pass thru'] — but as I pointed out in my original post, "even relatively crude traditional Indian coffee filters like this remove the diterpenes (PMID 21569629 (full text))

Encouraging, but I'm still surprised you're not paranoid given that [1], [2] and [3] found that espresso (which is processed through small-holed metal filters like the Aeropress one's you point to) has significantly more cafestol and kahweol than is found in drip coffee processed through paper filters.

 

Is it that the holes on these Aeropress filters are smaller than the holes used in espresso machine metal filters?

 

No, it's that I don't like espresso and am totally unfamiliar with its preparation, and thus wasn't aware that any filtration was involved. :"-) .

 

The full text of the study you posted (PMID 21569629) found some samples filtered through metal mesh filters contained negligible cafestol and kahweol, while others had as much as espresso (~1mg/cup). The authors speculate:

 

 

The Indonesian metal mesh filter method resulted in substantially higher amounts of cafestol and kahweol than the Indian metal mesh 'filter' method. This higher concentration may be explained by the different porosities of the filters used and the number of times that the brew was filtered.

Given this uncertainty, aren't (single-use) paper filters, the safer option?

 

I'd have to agree that your clarification of espresso methodology introduces significant doubt into the question, tho' clearly the Aeropress meshes are pretty fine: I find it hard to believe that the Indian filters are even finer than that.

 

I'm going to email the authors and ask.

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Thanks Micheal. For now I'm sticking with the paper filters for my Aeropress, and only using them once rather than repeatedly.

 

Getting back (a bit) to the topic of this thread, for anyone whose has consumed very hot coffee or tea for years, and wants to mitigate their risk of now developing esophageal cancer, besides drinking your beverages at a cooler temperature, you can eat more fiber.

 

According to this paper [1] from Al Pater (thanks Al!), it's not just the lower digestive track that is protected from cancer by fiber, but the esophagus as well. From the abstract:

 

"Dose-response analysis indicated that a 10 g/d increment in dietary fiber intake was associated with a 31% reduction in Barrett's esophagus and esophageal cancer risk."

 

Given how much fiber most of us eat, our esophageal cancer risk should be pretty low!

 

--Dean

 

-------------

[1] Dietary Fiber Intake Reduces Risk for Barrett's Esophagus and Esophageal Cancer.

Sun L, Zhang Z, Xu J, Xu G, Liu X.

Crit Rev Food Sci Nutr. 2015 Oct 13:0. [Epub ahead of print]

PMID: 26462851

 

Abstract

 

BACKGROUND:

 

Observational studies suggest an association between dietary fiber intake and risk of Barrett's esophagus and esophageal cancer. However, the results are inconsistent.

 

OBJECTIVE:

 

To conduct a meta-analysis of observational studies to assess this association.

 

DESIGN:

 

All eligible studies were identified by electronic searches in PubMed and Embase through February 2015. Dose-response, subgroup, sensitivity and publication bias analyses were performed.

 

RESULTS:

 

A total of 15 studies involving 16,885 subjects were included in the meta-analysis. The pooled OR for the highest compared with the lowest dietary fiber intake was 0.52 (95% CI, 0.43-0.64). Stratified analyses for tumor subtype, study design, geographic location, fiber type, publication year, total sample size and quality score yielded consistent results. Dose-response analysis indicated that a 10 g/d increment in dietary fiber intake was associated with a 31% reduction in Barrett's esophagus and esophageal cancer risk. Sensitivity analysis restricted to studies with control for conventional risk factors produced similar results, and omission of any single study had little effect on the overall risk estimate.

 

CONCLUSIONS:

 

Our findings indicate that dietary fiber intake is inversely associated with risk of Barrett's esophagus and esophageal cancer. Further large prospective studies are warranted.

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When I occasionally use a french press device to make coffee I place a paper filter (of the type designed for use in flat-bottomed or somewhat-rounded-bottomed filter paper baskets) between the metallic layers of the french press assembly.

 

My concern is that I can easily imagine the unwanted substances would be asborbed more effectively by paper than by a metal filter even if using identical pore sizes.

 

I place the metal filter first in line to take out the larger particles.  Then the paper takes out the finer particles and, I hope, the unwanted 'greasy' components. 

 

Rodney.

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My concern is that I can easily imagine the unwanted substances would be asborbed more effectively by paper than by a metal filter even if using identical pore sizes.

 

I place the metal filter first in line to take out the larger particles.  Then the paper takes out the finer particles and, I hope, the unwanted 'greasy' components. 

 

Great idea Rodney! As I mentioned here, I bought this metal filter for my Aeropress. 

 

I tried Rodney's two filter technique by putting the paper filter in the Aeropress first (on the bottom), stacking the metal filter (shown on right in photo below) on top of the paper, and then putting the combination coffee/cacao grounds on top of them both. That way, the metal takes out the big particles and the paper is there to catch any stuff that passes through the metal pores. I was curious to see how much would get through. As you can see from this photo, quite a bit of sludge got through! The paper filter (left) was originally white, like the paper towel in the background.

 

KvZzfjU.jpg

 

Admittedly, how much gets through the metal filter depends on the grind, and in this test some of both the coffee and the cacao was ground pretty fine. And of course we don't know what is contained in the sludge caught be the paper after passing through the metal filter. But based on this simple test, I think it is prudent to use (at least one) paper filter to remove heavy metals and/or potentially harmful diterpenes or saturated fat from brewed coffee / cacao, whether you are using an Aeropress or some other brewing method.

 

--Dean

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All,

 

I came across two interesting studies today on the health impact of coffee and tea brewing methods. 

 

The first was a study of the cholesterol level in Italians as a function of coffee consumption. Recall, from Michael's earlier post, coffee contains diterpenes which raise serum cholesterol unless filtered out. Study [1] found that Italians who drink the optimum 4-5 cups of coffee per day, had on average about 10mg/dl higher cholesterol (6mg/dl after adjusting for other factors). The interesting thing is that the authors note the coffee Italians drink is prepared using the mocha method, using a mocha pots (see image below). I have one of these and they make great tasting coffee, but I've stopped using it for health reasons. See below. 

 

mokapotoverview.jpg

 

As you can see, the metal filter where the ground coffee is loaded has fairly large holes, which, from the result of this study, are clearly not enough to filter out the cholesterol-raising diterpenes. 

 

The second study [2] is about the extraction of polyphenols in green, oolong and GABA tea as a function of cold vs. hot brewing method. It found two interesting things:

 

The contents of total catechins and total polyphenols in cold-water steeped tea infusion for 12 hr were equal to or higher than those steeped in hot water for 5 min, but the contents were only half of those steeped by hot water for 5 min three times in total.

 

The content of caffeine in 12-hr cold-water steeped tea infusion was only 1/2 to 2/3 of those with hot water steeped.

 

So if you don't mind the extra caffeine, and are willing to hot steep tea three times for a total of 15 minutes, you can beat cold brewing in terms of polyphenols. Otherwise, for a normal, 5min brew, cold brewing has the advantage.

 

--Dean

 

--------------

[1] Am J Epidemiol. 1991 Jul 15;134(2):149-56.

Coffee and cholesterol, an Italian study.

Salvaggio A(1), Periti M, Miano L, Quaglia G, Marzorati D.

Author information:
(1)Clinica Medica Generale, Ospedale L. Sacco, University of Milan, Italy.

In the present study, conducted in northern Italy between 1986 and 1989, the
authors investigated the possible association between coffee consumption and
serum cholesterol levels in 8,983 subjects, 7,432 men and 1,551 women, managers
and employees aged 18-65 years, who were examined during a program of preventive
medicine upon an agreement between various companies and the Centro Diagnostico
Italiano. Analysis of covariance was used to compare the serum cholesterol levels
of the subjects subdivided according to coffee consumption, along with age, body
mass index, alcohol consumption, cigarette smoking, and physical activity. An
important relation was demonstrated between coffee intake and cholesterol,
particularly in the men, the differences in serum cholesterol in the coffee users
compared with the nonusers being 6.1 +/- 1.4 (standard error) mg/dl for consumers
of 1-3 cups/day (3.4 +/- 1.4 mg/dl after adjustment for age, body mass index,
alcohol and cigarette consumption, and physical activity), 9.9 +/- 1.6 mg/dl for
those drinking 4-5 cups/day (5.8 +/- 1.6 mg/dl after adjustment), and 14.8 +/-
2.0 mg/dl for those drinking over 5 cups/day (9.6 +/- 2.0 mg/dl after
adjustment). This relation remained substantially unvaried when nonsmokers and
smokers were analyzed separately. It has been suggested that it is coffee
prepared by boiling rather than other methods that has a hypercholesterolemic
effect. Our observations demonstrate an interesting relation between coffee and
cholesterol, even though the coffee drunk in Italy is mainly filtered and
nonboiled. However, our finding is not necessarily in disagreement with the above
hypothesis since, when coffee is prepared in the Italian way (with the mocha
method), ground coffee is preheated by steam and more importantly, the water
passes through the ground coffee at a higher temperature than with the other
brewing methods.

PMID: 1862798

 

-------------

[2]   冷泡茶之物化成分與感官品質的探討

Studies on the Physicochemical Components and Sensory Quality of Cold-water Steeped Tea
Authors:
Mou, Yu-Ju
 
Date: 2005
Issue Date: 2012-09-04 14:10:17 (UTC+8)
Publisher: 食品科學系
 
Abstract:
 
The Green tea, Oolong tea and GABA tea made by two farmers in Ming-Chien with two different packing forms, tea leaves and tea bags, were used as materials. The purpose of this study is to investigate the changes in the color of tea infusion, pH value, total catechins, total polyphenols, total free amino acids, GABA contents, individual catechins and caffeine of 4oC cold-water steeped tea infusions with different time as compared with hot-water steeped one as the control. Using 7-point hedonic scoring, the consumer preference of cold-water steeped tea infusion by 100 consumer-type panelists was evaluated as compared with hot-water steeped one.
The analysis results of color of tea infusion with these three kinds of tea samples showed that the color of cold-water steeped samples was brighter than that of hot water steeped ones and the color of tea infusion using tea leaves were brighter than that of tea bags. The pH value of hot-water steeped tea infusion was found lower than that of cold-water ones, and the pH value of cold-water steeped tea infusion of tea bags at the same steeping time was lower than that of tea leaves.
The contents of total catechins and total polyphenols in cold-water steeped tea infusion for 12 hr were equal to or higher than those steeped in hot water for 5 min, but the contents were only half of those steeped by hot water for 5 min three times in total. The total free amino acid contents of tea steeped with cold water for 2 hr were already equal to or even higher than those steeped in hot water for 5 min. The GABA contents in the GABA tea showed the similar tendency with the total free amino acid contents of GABA tea. It indicates that cold-water steeping has better extraction than that the hot-water steeping.
For the individual catechins, the extraction effectiveness of steeping with cold water was found quite different among different degree of fermentation and types of packing. However, the contents of free-type catechins in tea steeped with cold water for 12 hr were higher than those steeped in hot water for 5 min. The caffeine contents of tea steeped with hot water were significantly higher than those with cold water. The content of caffeine in 12-hr cold-water steeped tea infusion was only 1/2 to 2/3 of those with hot water steeped.
Except GABA tea samples, the contents of all constituents in tea infusion with tea leaves packing type were only reached to 50 - 60 % of those with tea bags packing type. The contents of total catechins, total polyphenols, and total free amino acids in GABA tea samples were found no significant difference between two different packing types, because the tea leaves did not go through the ball rolling step.
Using the tea samples steeped with cold water for 4 hr and 12 hr, and with hot water for 5 min as materials, the results of the consumer preference teat showed that the aroma score of tea steeped with hot water for 5 min was the highest. The taste score of tea steeped with 12-hr cold water were higher than those of other two tea samples. However, there was no significant difference between the 12-hr cold-water steeped tea infusion and the one with 5-min hot-water steeping.

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Thanks, very interesting. I never hot brew tea for 5 minutes. I mostly drink green tea and never steep for more than 2 minutes. Also, how hot is hot? I aim for around 175F with green tea and 200F with black tea. I've been following these guidelines from my friendly neighborhood dealer, whose pointers may be geared more for flavor than nutrient content as over-brewed tea tends to be either bitter or astringent. When they serve pots of tea in their cafe they provide a little timer that tells you when to remove the basket, and if you ignore it they look askance. I'll ask him about polyphenols next time I go there.

 

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Thanks, very interesting. I never hot brew tea for 5 minutes. I mostly drink green tea and never steep for more than 2 minutes. Also, how hot is hot? I aim for around 175F with green tea and 200F with black tea. I've been following these guidelines from my friendly neighborhood dealer, whose pointers may be geared more for flavor than nutrient content as over-brewed tea tends to be either bitter or astringent. When they serve pots of tea in their cafe they provide a little timer that tells you when to remove the basket, and if you ignore it they look askance. I'll ask him about polyphenols next time I go there.

 

Hi Liz,

 

Yes - 5 minutes seemed long for hot tea brewing to me as well. Your temperature targets for green and black tea are in line with what I typically shoot for as well. Below is a really helpful chart, courtesy of LifeHacker.com. For every type of tea, it contains how much loose tea to use per 8oz cup, the temperature to brew at, the duration to steep for and the amount of caffeine in an 8oz cup compared to coffee. Just don't drink it right away at these temperatures, as this top of this thread cautions against!

 

--Dean

 

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Hi ALL!

 

I drink hot white tea, in large quantities (I have a huge teapot), brewed at 180 degrees with a metal filter; so my brewing technique is very close to that recommended above (180 degrees -- slightly higher than suggested above -- and bre for 4-6 minutes (but sometimes longer.  I find 4 minutes optimal --- judging by flavor.

 

  -- Saul

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