Sensory characterization and analysis of tea infusions from dry coffee cherry pulp “Cascara”...

Master Degree in Coffee Economics and Science “Ernesto Illy”

MASTER THESIS

“Sensory characterization and analysis of tea infusions

from dry coffee cherry pulp “Cascara” from washed and natural processed coffee”

Student: Carlos Umanzor Tutors: Eliana Cossio (University of Udine) Lorenzo Del Terra (illycaffè)

Ext. Tutors:

Jorge Cardona (Zamorano)

Academic Years

2016-2017

Title of the Paragraph (ex. Abstract)

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Master Thesis “Sensory characterization and analysis of tea infusions from dry coffee cherry pulp “Cascara” from

washed and natural processed coffee”

DEDICATION

I would like to dedicate my Master thesis to the living memory of my father.

He was a coffee lover and had great passion for the work he did. He is my role

model and the person I admire the most in this world.


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ABSTRACT

The cascara or dry coffee cherries tea is one trendy coffee derivative gaining

more and more attention from the hot beverage drinkers. Origin countries are

exporting a very small (but increasing) amount of cascara every year to small

roasters across the world.

Very few studies have been made regarding the cascara’s chemical, nutritional,

and sensorial components in order to compare them with other tea infusion

ingredients or coffee itself. It is known to have much less caffeine than other

tea beverages, a natural source of antioxidants, more tannins which can be

beneficial for health (Fonseca-Garcia et.al, 2014), but probably not quantified

and measured into the correct amounts for human consumption.

The starting point of this work was to gather samples of cascara, not only from

my country of origin, Honduras, but also from other Central American regions.

Since there are proven and significant differences amongst the coffee beans

grown in the signature areas of these countries, I would only expect there to be

a difference as well in the dried cherries.

The present investigation analyzed the dried cascara brew in the certified lab at

the Escuela Agricola Panamericana Zamorano in Honduras. The sensory

analysis lab was used to test the acceptance, discrimination capability and

preference of the two brews. Color and sugar contents were measured by

equipment to correlate mostly with the data taken by the panelists.


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ACKNOWLEDGMENTS

I would like to thank sincerely those who contributed and supported me in this

project, especially my co-workers and friends at Molinos de Honduras who

supported meanwhile I was in Italy and helped me source all the material I

needed to work freely and uninterrupted.

Would like to thank my friends in COCAFELOL (Honduras) and Godoy’s

Gourmet coffee (Guatemala) for spending their time and providing me with

sufficient cascara to make all the possible tests and analysis.

To the Escuela Agricola Panamericana Zamorano, my Alma Mater, for

providing their laboratories and panelists and very kindly supporting and

externally counseling me into having everything I needed to carry on an

outstanding analysis.


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CONTENTS

1. Chapter 1: What is Cascara

1.1. Main goals 6

1.2. General Introduction 6

1.3. Consumption methods 7

2. Chapter 2: Origins and Process

2.1. Introduction

2.1.1. Washed Cascara 8

2.1.2. Natural Process Cascara 8

2.2. Materials and Methods

2.2.1. Description of materials 9

2.2.2. Brewing methods 9

2.3. Results and discussion

2.3.1. Sensory panels 10

2.3.2. Color and sugar contents 13

3. Chapter 3: General Conclusions 16

4. Chapter 4: Considerations and future perspectives 17


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Chapter 1: What is Cascara

The main goal of this chapter is to get a general idea of what the dry cherry

pulp or cascara is. Learn about its multiple functions and consumptions

methods for the food industry. It has received many names and has been

consumed in many countries for the past years before it became a trendy

beverage. To know what are the main brewing systems used and its extraction

methods.

General Introduction

Coffee pulp, a long time thought of as a waste product, an irrelevant and

unused sub product of many coffee farmers around the world. Most often

thought of only as an additional weight or a conversion factor used to calculate

the real earnings or profits from a farm.

The evolution of coffee pulp as a useful sub product was first stated as an

agronomical practice and fertilizing aid for producers. Many studies have

stated the benefits of using the pulp as compost, fertilizer for the farms, or as

filling component for animal nutrition (Murthy PS, Madhava Naidu M, 2012).

Coffee pulp was shown to reduce by 30% the costs of production of a dairy

farm by replacing up to 20% commercial concentrates with dried pulp.

Meaning that at the end of a period a pig would have consumed 50 kg less of

corn by this substitution (Rajkumar & Graziosi, 2005)

It is not new that cascara has been used for tea infusions in past years; it is a

very common drink in Yemen called Qishr, where most of the people think the

Cascara tea was born.

Looking at Cascara tea nowadays, many people have tried to track down where

does it come from, what are the health benefits, how much caffeine does it

contain, and how to brew it correctly. Very little scientific information is found

about cascara, since it is just recently being commercialized as a food based

product. It has found its way up a very niche market in specialty coffee shops

and roasters around the world. These coffee connoisseurs are the ones writing


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blogs on their web pages and studying on their own the endless possibilities of

transforming these dried cherries into a consumable product.

It is no wonder now that cascara is not seen as a byproduct of coffee anymore

but as Sweet Maria’s says on their page it is a very intentional product, targeted

by many markets and specially prepared for consumers in many different ways,

from a hot beverage to a cooking ingredient in house kitchens and restaurants.

Consumption Methods

French Press: 20 grams of cascara for every 500 ml of water at 90°C. Pour over

and let it steep for 3-4 minutes before plunging.

Chemex: 20 grams of cascara for every 500 ml of water at 90°C. The only

difference is we don’t use a filter for cascara since it’s not a coffee like brew,

but more an extraction. The pour over of water is done over the cascara sitting

at the bottom of the Chemex and let is steep for 4 minutes before serving.

Chapter 2: Origins and Process

In Honduras the normal harvesting period, as in most of Central American

countries, begins in late October with the low land coffee farms and ends

around March or April depending on the altitude of the farms. All of the coffee

is handpicked by farmers and pickers hired for the season.

According to Alvaro Llobet Coffee research report regarding the 2015

Honduran crop, 16% of Honduran coffee production comes from technified

farms. 15% comes from semi-technified farms. 34% comes from traditional

farms. 19% are wild type producing farms. 6% are abandoned farms still

remaining from Roya outbreak and producers who couldn’t survive the crisis.

The remaining 10% are new plantings not yet in production. (Llobet, 2015)

Having mentioned the coffee farm structure above, with an estimated 270,000

Ha of planted coffee area (IHCAFE, 2009) we will focus on the technified and

semi technified farms for the coffee pulp recollection of our study. Having in

mind that in order to meet a certain level of optimal cherry quality, ideal for tea


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infusion we should look for the best and well managed farms, from the trees

that were properly fertilized and managed by the producer to develop and

harvest the best quality coffee bean.

Washed process

The washed process is the most common way of processing coffee in our

countries. After the pickers have gone through the farm and selecting only the

ripe and red color cherries, they are transported to a wet milling facility.

A wet mill has several stations or steps that the cherry pulp has to go through

before it is separated from the bean. Ideally we want to select and sort the best

cherries that would give the best coffee beans, and therefore a good quality

pulp. The cherries are passed through a machine called depulper that is

responsible for separating the bean from the cherry. After this point the bean is

covered in mucilage, which is later dispatched to fermentation tanks where this

mucilage is removed from the bean, leaving what we call “wet parchment

coffee.

Focusing on the pulp that was separated by the depulper, this is collected and

dryed carefully in African solar beds.

Natural Process

Natural processed coffee pulp is quite different from washed process mainly

because the cherry skips the wet mill process.

After the coffee is harvested and only the red cherries are selected, they are

sundried in patios or African beds. The whole cherry undergoes an immediate

drying process along with the bean.

This process allows the bean to absorb most of the sugars enclosed in the

cherry as it dries up. This drying period is over until the bean reaches 11 – 12

% humidity and the cherry is totally dehydrated.

The following step is the separation of the bean from its husk. The cherry now

goes through a hulling machine responsible for removing the cherry from the

bean, without causing any damage to it. We now have a totally different

looking coffee pulp from our washed processed one, but fulfilling the same

function.


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Our coffee pulp was collected from a cooperative in the western side of

Honduras called COCAFELOL (Cooperativa Cafetalera Ecologica La Labor).

The quality of the coffee was gourmet type, mainly from caturra, catuai, and

parainema plants with harvest periods from December to April.

The designated farms for the selection of the pulp were at an altitude of 1,150

to 1750 masl with an average annual temperature of 16 – 21°C. Soil

descriptions are Sandy loam soils, medium in organic matter, with medium

filtration capacity.

Materials and Methods

Description of materials

In order to maintain a homogeneous and practical method for brewing I used

the following instruments.

Gram scale

2 kettles

2 mini stoves

Purified water

1 french press

1 chemex

Transparent cups for affective sensory analysis

Black cups for discriminative sensory analysis

5 lb of washed processed coffee pulp

5 lb of natural processed coffee pulp

1 refractometer Atago Pal-1

There is not a specific and standardized way of brewing these infusions. There

are many methods that can be used to achieve this final product, from different

kind of brewing machines, different timings and proportions used, the addition

of other ingredients like cinnamon or sugar, or even coffee itself.

Out of all the possibilities that can be used it seemed that French press was the

most common, therefore for the purposes of this experiment we did all tests

using a French press method, using 20 grams of cascara for every 500 ml of

water at 90°C for both processes.


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Results and Discussion

Sensory Panels

The sensory analysis was done in the Sensory Analysis laboratory of the

Escuela Agricola Panamericana Zamorano,located in Valle de Yeguare,

Honduras. Panels were mostly students from the University and most of them

had already taken the illy-coffee course from the recent partnership agreement

done by these two institutions.

For the acceptance sensory analysis the panelist were given two separate sheets

of paper for the two different cascara brews. The tests involved a Hedonic scale

of 9 points to measure the acceptance of different attributes of the product,

using “1” as extremely Dislike and “9” as extremely like (Lawless & Heymann

1999). The attributes to measure were Taste, color, sweetness and general

acceptance.

As seen in the table below, the results from 30 panelists were evaluated for the

washed processed cascara brew.

Table 1. Washed process cascara

Color Taste Sweetness General Acceptance

7.33 7.00 6.47 7.13

±1.35 ±1.64 ±1.91 ±1.76

Comparing these attributes in a single table gives us an idea of how acceptable

the product would be for a consumer in general terms.

We can interpret that the color, taste and sweetness of the brew range in a high

score, where it surpasses the 7 points for each attribute. Therefore giving it a

general acceptance of 7 over all samples.

The range between these attributes are very close to each other meaning that

panelists found a balance in the brew, and did not sense abrupt differences

when perceiving the main attributes of the infusion.

Also 30 panelists were evaluated for the natural processed cascara brew and

their results are shown in table 2.


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Table 2. Natural process cascara

Color Taste Sweetness General Acceptance

5.73 5.50 5.23 5.80

±1.57 ±1.28 ±1.52 ±1.16

Natural process cascara brew found the same balance within their attributes in

the infusion. The ranges between the scores of each attribute were evaluated in

the same range, within the same punctuation. This means that the panelists

found a smooth and consistent brew throughout their evaluation.

Interesting to notice that if it is true that the components and attributes within

the same processes don’t differ significantly from each other. When compared

one process with the other we find that the panelists scored significantly lower

the natural processed cascara from the washed processed one. With this it only

states that attributes like color, taste and sweetness were evaluated in a slightly

lower range than the washed ones.

The discriminative sensory analysis consisted of 3 samples given to the panels.

One given sample was different from the other two and their role was to

identify and mark the sample they thought was different from the rest (Triangle

test). In this case sample #212 was natural processed cascara and sample #213

and #214 were washed processed cascara.

Table 3. Discriminative results from washed and natural process cascara

Sample # Natural (212) Washed(213) Washed(214)

# panels 28 2

Total % 93% 7%

As shown in table 3, panels could clearly identify the different sample and

were easily convinced that sample #212 was different from the rest. The cups

used for this experiment were completely black and the laboratory lights were

dimmed so the color differences were not obvious to the panel. Forcing and

ensuring the panelists were only using their taste sense.


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This correlates with the previous acceptance sensory analysis were panels

(some of them not the same) evaluated different one sample from the other.

Giving us certainty there is sensorial differences between one another. We

should keep in mind this does not in any way proves one brew method is better

than the other or more liked. This is just merely a differentiation test in which

we analyze the panelist’s ability to differentiate one sample amongst the rest.

Once the individual acceptance analysis was done for each of the cascara

processes and the discrimination analysis proved that there are detectable

differences between samples (as we expected), a preference analysis was

carried out. This analysis compared directly one brew with the other and

panelists had to choose the sample they thought was best for them.

PL was the washed processed cascara (Pulpa Lavada) and PN was the natural

processed cascara (Pulpa Natural).

Table 4. Preference analysis. Washed vs Natural processed

cascara

Type of process PL PN

# panelists 17 13

Total

57% 43%

Table 4 shows us that panelists choose washed processed cascara (PL) over and

better than natural processed cascara (PN). This time they had the samples

served in transparent cups, where they could observe and analyze color, taste,

and sweetness of each brew.

Given the acceptance analysis scores of each one of the samples we can link

that panelists maintained their opinion to think that the washed processed

cascara has better liked attributes than natural cascara, hence their preference

shown in this analysis.

Physical analysis

Sugar content: While making the brews for each round of panelists and

making sure to follow and maintain a consistent brewing protocol, the sugar

contents of each brew process were measured.


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It came to my attention that using the portable refractometer Atago in every

brew of the different processes it tossed the same Brix degrees for each sample.

Natural processed cascara brew tossed a 0.6% Brix on the brews tested, while

washed processed brew tossed 1% brix content on each sample.

Alan Adler, the aeropress inventor and frequent lecturer at Stanford University

is a keen user of the same refractometer used in this study. In an online post for

coffee geek, he writes about how he has measured brix content for coffees and

came to conclude that a standard measurement is 1.5 Brix. This in correlation

with SCAA recommended 1.25 Total Dissolved Solids (TDS) for ordinary

coffees (SCAA cupping protocols).

Café imports on their web page study and publish a blog on a wet mill in Costa

Rica called Las Lajas. The family owned mill and farm specializes in honey-

processed coffee that is sold to Café Imports later on. As their way to ensure a

good quality bean, Francisca (farm owner) measured the Brix content on the

coffee cherry to determine the optimal time to harvest the cherry. It is said that

cherrys in their optimal time for picking can measure up to 21-22% Brix

content (Café Imports, Las Lajas – Cascara perla negra). This is clearly

concentrated sugars measured in that will fade as the bean absorbs part of this

moisture and sugar content when dried.

Color: Color was measured using L, a, b color scale. Hunter Lab describes

these components as L for Luminosity ranging from 100(white) to 0 (black).

The “a” component is responsible for red (a+) and green (a-) color, they don’t

have numerical limits but positive and negative signs. Same for “b” component

where yellow (+b) and blue (-b) have positive and negative signs. See figure 1

for matrix reference.

Table 5. Color analysis for washed and natural process cascara

TRT R G B L a* b* h croma Washed 54.7 26.5 23.05 13.47 13.53 8.32 31 16.00

±1.98 ±4.55 ±3.19 ±7.31 ±5.20

Natural 111.5 52.85 18.9 29.45 23.53 31.70 54 39.61

±2.43 ±5.65 ±4.05 ±5.00 ±6.05


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Several data was taken measuring the color of the brews, each treatment was

separated into independent brews and an average data of all brews and data

was consigned in the table above.

If we were to space both processed cascara brew into the color matrix in the

figure above it would be in the top right quadrant. This means the variation of

color ranges in similar intensity for red and yellow colors within white

spectrum luminosity.

Figure 1. Hunter L, a, b color scale.

Hue describes the quality by which we distinguish a color from the other. HLS

is very similar to Munsell's color wheel. Although Munsell uses a different

method for indicating hue, both arrange the colors in a circular pattern and be

located using the L, a, b data provided by any color meter.

Figure 2. HSL color meter wheel. Figure 3. Munsell color meter wheel

natural

washed

natural

washed


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The results in table 5 showed a clear difference between Hue of both processes.

Natural cascara when brewed showed an average Hue of 54°, tilting a little

more towards the yellowish color. Washed cascara brew stayed a little lower in

with a 31° Hue towards the red color.

Figure 4. Natural process and Washed process cascara.

Natural processed cascara (left) appears lighter colored than washed (right)

mainly because of the inner husk of the bean. When natural coffee is dried and

reaches the correct humidity level it is hulled as it is. The result after the bean

separation is a mixture of the original coffee pulp or outer husk, combined with

the inner husk, also known as parchment. It is this dry parchment that changes

the tone of the original dry cherry into a lighter color.

Figure 5. Washed process cascara (left) Natural processed cascara brew

(right)


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The different color of the pulp is clearly carried over to the brew. Natural

processed cascara brew gave a lighter tone than washed brew.

Chapter 3: General Conclusions

General Conclusions

According to the panelist reviewed data, it can be said that at a

laboratory level, cascara teas brewed from the two different processes

were clearly distinguished in discriminative analysis. Furthermore,

washed process cascara was preferred to natural process cascara. This is

backed up by the acceptance analysis of each treatment, where the

Washed process cascara was always 1 or 2 points above in all attributes

evaluated (Color, sweetness, taste, general acceptance).

Sugar analysis stated that washed cascara brew had more sugar content

than natural cascara brew. This makes sense if we look the process each

coffee method goes. Natural coffee processed beans absorb for a longer

time the sugar contents in the pulp. Since both of them are dried

together, the bean has more time to extract components out of the pulp

itself. Hence the cupping of natural coffees is very fruity flavors

because of this process.

Panelists seem to score better the sweetness in washed process brew

than naturals. Their comments were that they are more likely to choose

a sweeter beverage that gave the tea infusion a better taste.

Color is clearly different in every aspect of the experiment. As shown

and plotted on the color scale graphs.

Coffee pulp is a natural antioxidant and tannin provider, proven to bring

beneficial health aspects to a person. Besides being for the past years a

trendy product sold in coffee shops with prices as equal or higher as

coffee. This already intended product is generating extra profits along

the supple chain to providers.


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Chapter 4: Considerations and

future perspectives

Starting from the same point it would be interesting to compare the same

physical analysis with samples from different ripening periods and altitudes. It

is proven that coffee from higher altitudes ripen later than low land coffee,

therefore giving a different quality bean.

A full chemical analysis and caffeine content on every treatment over time.

This could’ve been done in this project but because of time and high costs of

these procedures it wasn’t possible.

It would be interesting to compare the behavior of the cascara over time,

analyzing sensory and physical behavior of the pulp and brew over time

measuring storage conditions, bags/cocoons, and stipulated time.

The measure of Ochratoxin A. This is a major contaminant of dried-fermented

food. This would be essential for approval and commercialization in many

countries, as well as for shelf life of the product


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