Roast MayJun14 TheBitterEnd

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24 r o a s t May | Ju

Making a Case forChlorogenic Acid

by R. Luke Harris and Christian Axen

Caeine is bitter. Yet the vast

majority of coee fanatics and

professionals would be loath

to deny themselves the caeine buzz that

is, arguably, the only reason coee was

popularized by Kaldi and his goats in the

rst place.

In other words, we accept the bit

caeine in our coee because it p

with something stimulating. Bu

is not the only biologically active

agent present in the delightful e

your passion and your livelihood

Bitter

End

the

con


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continuedon page28

In their paper, CorrelationBetween CupQuality and Chemical

Attributes ofBrazilian Coee, published in the scientic journal Food

Chemistry, Adriana Farah and colleagues present their analytical

chemistry investigation of the Rio o-avor. According to Farah,

the unpleasantness of Rio-like coee is usually described as a

pungent, medicinal, phenolic or iodine-like avor associated with

a musty, cellar-like odor, which at its extreme, is characterized as

an intolerable taste and smell. Farah and colleagues data show

that with increasing abundance of chlorogenic acidsor CGAsin

light and medium roast coee, the cup quality decreases markedly,

including a much more prominent Rio o-avor. Higher caeine

levels were also associated with lower cup quality, but these negative

avor associations of caeine were only observed in medium roastcoee, not in light roast, and to a lesser extent than for CGAs.

For better or for worse, the role of CGAs and caeine in coee

avor is unavoidable. As roasters already know, it is possible to

inuence the amounts of these compounds in the cup because levels

of such chemicals decline with longer heat application for darker

roasts. But there are so many other aspects of coee avor and

aromasweetness and sourness to name only twoso isolating these

two compounds and attributing avor characteristics to them is an

oversimplication. That said, when it comes to caeine and CGAs, is

bitter better?

THE BITTER END | Making a Case for Chlorogenic Acid (continued)

CGAs, Caffeine and OxidativeStress in Plants and Animals

Dr. Terry Graham, a professor of human health and

nutritional sciences at the University of Guelph in

Ontario, Canada, spoke with us about the biological

importance of caeine and CGAs in the human diet.

Dr. Grahams message is that chronic coee intake

over a lifespan has largely benecial eects for human

health. Most scientists attribute these positive eects to

antioxidant content of coee, and one particular group

are the derivatives of chlorogenic acid, he says. What isthe basis for this antioxidant benet of CGAs?

Oxidative stress is a chemical process that

occurs in plants and animals, promoting damage

to key biochemical constituents of cells and tissues,

including DNA. Damaged DNA speeds up aging and

can lead to mutations. In coee trees and other plants,

environmental stressors, such as excess direct exposure

to sun or extreme cold, impair the plants metabolic

functions, resulting in oxidative stress. CGAs are a major


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con

component of plant antioxidant defenses,

which protect them against the resulting

biochemical damage. Many plants produce

CGAs and related chemicals for this reason, but

green coee beans contain more CGAs than any

other edible plant product, except perhaps for

the leaves of Ilexparaguariensis , from which mat

teas are made.

In 2010, Ana Fortunato and colleagues

at the University of Alberta with the

phrase, Caeine bad, coee good,

implying that CGAs are primarily

responsible for counteracting the

negative eects of caeine in human

health. Seven years later, we asked him

if he would still say the same thing.

Caeine pushes the metabolism toward

a Type 2 diabetic state for hours, says

Graham. With this negative eect in

mind, he says, With regards to caeine,

I would now have to modify this a

little and s ay, Caeinemainlybad. However, There are likely some positive

neural health eects [of caeine]. Dr.

Graham refers to evidence that chronic

caeine consumption may have positive

health eects on some aspects of brain

function, such as memory and aging.

With coee, I would now say

damn good, as there is strong evidence

for not only reduced risk for Type 2

diabetes, but also some cancers and

neurological conditions. Actually,

the story with Type 2 diabetes is not

so straightforward. Says Graham, It

is impossible to compare caeine and

caeinated coee. Caeine is obviously

biologically active, but coee contains

many other bioactive substances. Just asthese thousands of bioactive substances

complicate coee avor and aroma, they

aect its physiological eects, too.

A clear example of how one could

draw the completely incorrect conclusion

about coee consumption is that

caeine leads to insulin resistance,

thereby promoting a diabetic state, and

[the logical] extension of this nding

to coee would be that coee increases

the risk for Type 2 diabetes. However,

many excellent studies demonstrate

the opposite: chronic consumption of

caeinated coee decreasesthe risk for

Type 2 diabetes in a dose-dependent

manner, Dr. Graham says.

Dr. Shearer elaborates on thisargument: The more coee consumed,

the lower the risk [of developing Type

2 diabetes]. This has been shown in

various populations worldwide.

One of the reasons why caeinated

coee doesnt pose a serious long-term

risk for developing diabetes and related

trees from ve coee varieties, including

catua, which had been grown at a range

of temperatures decreasing from 25

degrees C/77 degrees F down to as low as

4 degrees C/39 degrees F. In response to

this cold stress, the catua trees increased

their production of CGAs by around 30

percent, and increased their production

of caeic acid by around 39 percent. In

general, plants produce considerably

more CGAs when exposed to sun and cold,

with combined exposure to sun and cold

resulting in the most dramatic increasesso shade helps to reduce cold-induced

increases in CGAs.

As mentioned by Dr. Graham, some of

the major eects of CGAs on our bodies are

related to the same antioxidant functions

for which plants produce them. In our

bodies, the parallels to cold and sun

exposure are things such as eating the

wrong foods (think transfats or saturated

fats), smoking cigarettes, suering

traumatic injury or suering an infection.

We also experience oxidative stress all of

the time, just by living and breathing, as a

byproduct of natural metabolic processes.

Just like plants, our bodies produce

antioxidant compounds to combat oxidative

stress, thereby slowing our aging andproviding us with some protection against

the eects of our sometimes-lacking diets

and sedentary lifestyles. For even better

protection we have to supplement our own

antioxidant supply through the foods we

consume.

In the average North American diet,

coee is responsible for 50 to 60 percent

of daily antioxidant consumption, says

Dr. Jane Shearer, an associate professor of

kinesiology and medicine at the University

of Calgary. A cup of blueberries has more

antioxidants than [the same volume

of] coee. The problem is that most

individuals dont consume enough fruits

and vegetables on a daily basis. On the

other hand, and fortunately for coeeprofessionals, individuals readily consume

multiple servings of coee per day.

The Better of BitterPreviously, in 2007, Dr. Graham had

humorously concluded a visiting lecture

published the most recent report available

about the important antioxidant role of

CGAs in protecting coee plants from cold

stress, found in the Journalof Plant Physiology.

In their study, titled Biochemical and Molecular

Characterizationof theAntioxidative systemof

Coea sp. UnderCold Conditions inGenotypes with

ContrastingTolerance, Fortunato and colleagues

analyzed the contents of CGAs in 1.5-year-old

conditions is that CGAs protect us against

the negative eects of caeine. CGAs

slow the movement of sugars from our

gut into the blood, and also promote the

uptake of sugar from the blood into the

liver, thereby reducing glucose levels in

the blood. The net eect of CGAs, then,

is to counteract the pro-diabetes eects

of caeine; compare this to non-diet

colas that deliver high levels

caeine simultaneously. Ove

daily consumption of colas p

for developing metabolic dise

there are no CGAs in cola to b

of caeine. Well take CGAs i

day, thank you very much.



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Caffeine and CGAs in CoffeeBrews: Our Experiment

Caeine and CGAs work alongside each other in our bodies,

sometimes collaborating and sometimes competing.

Their benets for the coee trees, their inuence on

coee avor, and this metabolic dance they perform in

the human body got us thinking about how we brew our

coee.

We performed an experiment to compare the levels of

caeine and CGAs in coee brews, prepared using dierent

methods: machine drip, manual pour-over and press pot.Previous studies have already quantied the concentrations

of caeine and CGAs in coee. However, they have mostly

focused on the total amount of caeine and CGAs found

in coee beans, and the extractions have been performed

using conditions that do not yield drinkable coee, such

as organic extraction with methanol, the use of very high

coee-to-water ratios, and dwell times of up to a few hours

in duration. Our goal was to measure these compounds in

coees that had been freshly roasted, ground and brewed

with human consumption in mind.

continuedon page32


photobyMark Shimahara

MethodCGA

mg/mLCaffeinemg/mL

CGA per240-mL cup

Ca24

Technivorm 0.773 0.522 185.5

Technivorm 0.890 0.518 213.7

Technivorm 0.604 0.512 145.0

Technivorm 0.588 0.479 141.0

Technivorm 0.427 0.463 102.5

Pour-over 0.400 0.444 96.1

Pour-over 0.399 0.449 95.8

Pour-over 0.483 0.442 115.8

Pour-over 0.508 0.462 122.0

Pour-over 0.449 0.441 107.7

Press Pot 0.458 0.489 109.9

Press Pot 0.449 0.428 107.8

Press Pot 0.441 0.421 105.8

Press Pot 0.422 0.416 101.2

Press Pot 0.366 0.372 87.9

AVERAGE 0.510 0.457 122.5

Standard

Deviation 0.15 0.04 35

Table1.Chlorogenicacid (CGA) andcaffeine contentsin freshlyroasted coffeebrews preparedusing machinedrip, pour-overand press potmethods.


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We performed our experiment

onsite at the Prince George campus

of the University of Northern British

Columbia (UNBC). Coee (Ethiopia wet

process Guji Oromo) was purchased

green from Sweet Marias in Oakland,

Calif., and roasted within two months

of receipt. Specically, we used a

Behmor 1600 counter-top roaster

on a P4D program with appropriate

adjustments, 1/4-, 1/2- or 1-pound.

Green coee batches were roasted to a

city level, with the cooling cycle startedat the end of rst crack.

First crack start and end times

were consistent within a few seconds

across batches of the same size. Coee

samples were brewed in 650-mL

volumes according to SCAA standards

using a coee-to-water ratio of 0.068,

with freshly ground coee that had

been roasted one to two days before

brewing.

Using a Technivorm Moccamaster

for machine drip, a Hario V60 Buono

kettle for pour-over, or a stainless

steel Frieling press pot, each brew was

prepared with a four-minute extraction

in ltered and freshly boiled water at

90.595.6 degrees C/195204 degreesF. Once brewed, the samples were

cooled immediately in an ice bath, and

then 3 mL of each brew sample was

transferred to a separate plastic tube.

We drank the rest.

Our analytical chemistry methods

were a modication of the methods

described previously by Luiz C. Trugo

and Robert Macraein their paper

Chlorogenic Acid Compositionof Instant

Coees, published in the journal

Analyst(1984), as well as JK Moon

and colleagues in their article Roleof

RoastingConditions inthe Levelof Chlorogenic

Acid Content inCoee Beans: Correlation

withCoeeAcidity, published in the

Journal ofAgricu lturaland Food Chemistry (2009). We carried out a number of

chemical steps to isolate and purify

the CGA and caeine from our brew

samples. Alan Esler, the analytical

chemistry support specialist in UNBCs

continuedon page34


Figure1a.CGA Concentrations Classified byBrew Method (mg per 8-ounce cup)

Figure1b.Caffeine Concentrations Classified byBrew Method (mg per 8-ounce cup)


6/834 r o a s t May | Ju

continuedon page36

central equipment laboratory, then

determined the CGA and caeine

contents of the samples using an

Agilent Liquid Chromatograph1100

high-performance system. Each

sample was analyzed twice, using

dierent ultraviolet light detection

wavelengths: once to quantify CGA (at

325 nm) and once to quantify caeine

(at 275 nm). The quantications of

CGA and caeine, respectively, were

performed using the linear regression

equation of the concentration andpeak area of standard CGA and

caeine solutions prepared using

pure standards of these chemicals

purchased from Sigma-Aldricha

life science and high technology

company. All measurements were

performed in triplicate.

Experimental Data

CGA and caeine concentrations of

our Technivorm, pour-over and press

pot brews are shown in Table 1 on

page 31. Overall, across all three brew

methods, the CGA concentration in

the brew samples varied from 0.366 to0.733 mg/mL brewed coee, with an

average of 0.510 mg/mL. The caeine

concentration in the brew samples

varied over a slightly narrower range,

from 0.372 to 0.522 mg/mL of brewed

coee, with an average of 0.457 mg/

mL. According to Dr. Shearers 2008

work, Coee, GlucoseHomeostasis, and

InsulinResistance: PhysiologicalMechanisms

and Mediators, published in the

journalApplied Physiology, Nutrition, and

Metabolism, a standard 8-ounce cup of

coee (240 mL) contains CGAs in the

range of 88250 mg, and an average of

130 plus or minus 20 mg of caeine.

Based on the same coee cup size,

our data is remarkably similar, withCGAs in a range from 87.9 to 213.7 mg

per 8-ounce cup, and caeine at an

average of 109.7 plus or minus 10 mg

per cup.


Figure2a.CGA Concentrations Classified by Batch Size(mg per 8-ounce cup)

Figure2b.Caffeine Concentrations Classified by Batch Size(mg per 8-ounce cup)


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Finding Meaning in the Data

We plotted the data found in Table 1 as graphs of CGA or caeine

contents according to brew method. As shown in Figure 1a and

1b on page 32, it seems that brew method might actually aect

the amount of CGA and caeine in the cup, with machine drip

resulting in the highest levels of CGA and caeine, manual pour-

over resulting in intermediate levels, and press pot resulting in

the lowest levels.

continuedon page38


Even though our data are remarkably close to that reported

by Dr. Shearer, we were curious as to why our values were so

variable despite our eorts to achieve consistency across roasts,

brews and HPLC analyses. Caeine exhibited a relatively tighter

range of values, regardless of brew method, which might meanthat caeine content is more dependent on the coee beans

themselves, rather than the roast or brew method. With CGAs,

on the other hand, the eect of roasting on variations in CGA

levels is well established in the scientic literature, with longer

heat application times leading to the breakdown of CGAs into

dierent molecular structures.

CGA does not appear to have

one action in the body, but

many. One very surprising role

may be to feed the millions of

bacteria living in our gut.

Dr. Jane Shearer, University of Calgary

photobyMark Shimahara

www.dailycoffeenews.com

Daily news for

specialty coffee

professionals.


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Consequently, we thought that perhaps the variation

in CGA content could be due to variations in the roasting

conditions. We plotted the data from Table 1 again, this time

according to the 1/4-pound, 1/2-pound or 1-pound size of the

roast batch. As seen in Figures 2a and 2b on page 34, as we

expected, cup contents of CGA and caeine also appear to vary

with roast batch size. Thus, an alternative explanation for the

CGA and caeine contents we measured is that their levels

decreased with the longer heat application required for larger

batches in the Behmor roaster.

The most direct implication of our experiment for roasters

is that larger batches and longer roast times will probably

result in lower CGA and caeine contents in brewed coee.

Of more general interest to coee professionals, fanatics and

consumers may be the possibility that dierent brew methods

can aect the cup contents of these biologically important

compounds.

The Bitter End

Coee is a mess of chemicals, and in this sense, it is

probably a bit of a mistake to think too hard about the role of

caeine and CGAs as bittering agents in our coee. Rather,

for the nal word on CGAs and caeine, lets switch from the

mouth to the, um, other end.

Not long ago, a friend contacted one of the authors to ask,

You know about chlorogenic acid, right? I just read that it

induces recto-sigmoid motility. What does that mean? Well,

to put it delicately, recto-sigmoid refers to the end of the

human digestive system, and motility refers to movement, soCGA is one of the reasons why many coee drinkers experience

some degree ofshall we sayregularity associated with their

morning cup.

This brings us back to the question of coee and human

health. On this point, Dr. Shearer also explains that CGA does

not appear to have one action in the body, but many. One very

surprising role may be to feed the millions of bacteria living

in our gut. Gut bacteria break down and metabolize many of

the phenolic compounds found in coee. Having healthy

gut bacteria has been shown to prevent disease and maintain

health.

So, thanks in large part to CGAs, perhaps to caeine,

coee is good for you, but most denitelyto borrow from Dr.

Grahambecause it tastes so damn good.

R. LUKE HARRIS is anassistant professorat theSchool ofHealthSciences and anadjunct professor inthe NorthernMedical Programa t the

University ofNorthern BritishColumbia. Hecan bereached via e-maila t

[email protected].

CHRISTIAN AXEN is an analyticalchemist inCalgary withaBachelorof Sciencein chemistry fromtheUniversity ofNorthernBritish

Columbia. He canbereached at [email protected].


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