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INT J CURR SCI 2013, 9: E 83-91
REVIEW ARTICLE ISSN 2250-1770
Coffee waste management-An overview
Padmapriya R, Jenny Anne Tharian and Thirunalasundari T*
Department of Industrial Biotechnology, Bharathidasan University, Tiruchy-620 024, India
*Corresponding author: drttns@bdu.ac.in
Abstract
Coffee is one of the most important agriculture commodities in the world. Coffea arabica and Coffea robusta are the
two principal varieties of the genus cultivated all over the world. 1000 kg of fresh berry gives about 400 kg of wet waste
pulp. Coffee pulp contains caffeine, tannins, polyohenols and organic solid residues. It shows toxic nature and thus not been
utilized beneficially. This effluent is being directly discharged to the nearby water bodies causing severe ailments like
giddiness, skin irritation, stomach pain, nausea and breathing problem. Severe of this waste courses and a serious
environmental problem among the residents of nearby area. For this reason, efforts have been made to develop methods for
coffee waste treatment and management, also its utilization as a raw material for the production of feeds, beverages, vinegar,
biogas, caffeine, pectin, pectic enzymes, protein and compost. Coffee waste is emerging as a new feed for producing
polysaccharides and monosaccharide.
Keywords: coffee effluent, Coffea arabica, Coffea robusta, by products
Received: 19thAugust; Revised: 12thSeptember; Accepted: 16thOctober; © IJCS New Liberty Group 2013
Introduction
Coffee (Coffea sp.) is one of the most important
agricultural commodities in the world (ICO, 1998).
Ethiopia had been the origin of coffee because coffee plant
was initially found and cultivated by Oromo people in the
Kafa province (ITC, 2002). Coffee is concerned with only
two/three coffee species like Coffea arabica, Coffea
robusta, Coffea liberica and
C. canephora. It belongs to the family Rubiaceae, which
produce seeds that are used for coffee preparation.
Coffee is a brewed beverage with a distinct aroma and
flavor, prepared from the roasted seeds of the Coffea plant.
It is dark in colour and the roasted round bean is used
around the world to prepare an aromatic, stimulating
beverage.
Coffee is derived from over 1500 chemical
substances, 850 volatile and 700 soluble, and when
prepared correctly involves 13 independent chemical and
physical variables. When coffee is extracted in water, most
of the hydrophobic compounds, including oils, lipids,
triglycerides, and fatty acids remain in the grounds, as do
insoluble carbohydrates like cellulose and various
indigestible sugars. Structural lignin, protective phenolics
and the wonderful aroma-producing essential oils are also
present in coffee. Coffee is a major plantation crop grown
worldwide and is one of the most popular beverages
consumed throughout the world. There are three common
species of coffee: robusta, arabica and liberica. 75-80% of
the coffee produced worldwide is Arabica and 20% is
Robusta (Central Coffee Research Institute, 2000).
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Jimma zone is one of the areas in Ethiopia where
coffee producing plants are cultivated in large numbers
(ITC, 2002). Angola, Benin, Bolivia, Brazil, Burundi,
Cameroon, Central African Republic, Cote d’Ivoire,
Colombia, Republic of Congo, Democratic Republic of
Costa Rica, Cuba, Dominican Republic Ecuador, El
Salvador, Equatorial Guinea, Ethiopia, Gabon, Ghana,
Guatemala, Guinea, Haiti, Honduras, India, Indonesia,
Jamaica, Kenya, Liberia, Madagascar, Malawi, Mexico,
Nicaragua, Nigeria, Panama, Papua New Guinea,
Paraguay, Peru, Philippines, Rwanda, Sierra Leone, Sri
Lanka, Tanzania, Thailand, Togo, Trinidad and, Tobago,
Uganda, Vietnam, Zambia, Zimbabwe are the countries
that produced coffee in the world. India has 4.5% share of
the global coffee market. Coffee production in India is
dominated in the hill tracts of South Indian states, with the
state of Karnataka accounting 53% followed by
Kerala 28% and Tamil Nadu 11% of production of
8,200 tones. There are 250,000 coffee growers in India. In
Tamil Nadu, Nilgiris District, Yercaud and Kodaikanal are
the areas in which coffee is produced (Yeboah, Salomey,
2010). The production rate of coffee in Karnataka is about
2,27,205 tones, with 78,705 tones of arabica and 1,48,500
tones of robusta.
The coffee varieties arabica and robusta production
rate falls on 2,075, 61,750 and 17,750 tones in the region
of Kerala and Tamil Nadu respectively. There are many
different robusta (Coffea canephora) varieties. In general,
they can thrive in hotter lowland areas (i.e.) below 900 m
above sea level and over 20°C. Robusta coffee is preferred
for instant coffee production due to high soluble solid
extraction. Liberica (Coffea liberica) is a larger tree with
large leaves and berries. It can tolerate hot and wet
conditions. The coffee produced is bitter. This is preferred
in Malaysia and West Asia. Robusta is a high-yielding
plant, resistant to disease, growing at lower elevation,
characterized by ‘harsh’ flavours, containing about 2%
caffeine and yielding 1-1.5 kg green coffee per plant per
year. It is used in lower grade coffee, generally not found
in specialty shops, and is often used to make soluble
(instant) coffee and popular commercial blends.
Arabica (Coffea arabica) is a glossy leafed shrub or
small tree. The leaves are relatively small and the flowers
are fragrant and white. Arabica coffee usually receives a
premium for its superior flavour and aroma. Arabica is
more suited to higher, cooler climates like 600-2000 m
above sea level and 15-20°C. The species arabica grows
best at altitudes of 3000-6500 feet, has a refined flavor,
contains about 1% caffeine and yields 0.5-0.8 kg per plant
per year. It is a coffee that specialty roasters search for and
accounts for about 75% of world production. Arabica is
susceptible to disease and poor climatic conditions such as
frost and drought (Chanakya, 2004). The wastewater
generated from coffee processing plant contains organic
matter like pectin, proteins, and sugars (Bello-Mendoza,
1998).
Coffee pulp, one of the principal byproducts of wet
processed coffee (Coffea arabica. L.) which constitutes
almost 40% of the wet weight of the coffee berry, is rich in
carbohydrates, proteins, minerals, and appreciable
quantities of tannins, caffeine and potassium (Bresanni,
1979). Coffee pulp is the main byproduct on coffee
exploitation industry. Two tons of green coffee produces
one ton of coffee pulp (dry matter). Its production on world
scale raised 2.400.000 tons in the harvest cycle from 1986
to 1987. Coffee pulp is essentially composed of
carbohydrates, proteins, amino acids, mineral salts, tannins,
poly phenols, and caffeine. The polyphenols and caffeine
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are reported to be the anti-physiological factors on animal
feed. Hence, coffee pulp has to follow a preliminary
treatment before it is used (Sebastianos Roussos, 1998).
Coffee pulp is generated to the extent of 40% in the
fermentation of coffee berries (Zuluaga, 1989), poses many
problems in the coffee producing tropical countries. Its
disposal in nature, without any treatment, causes severe
environmental pollution, due to putrefaction of organic
matter (Zuluaga, 1989). Hence, it is essential to treat and
manage preferably by organic means.
Characteristics of coffee
The three main characteristic features of coffee are
acidity, aroma and taste. Acidity is related to the dryness
caused by coffee on the edges of the tongue and the back
part of the palate. Without sufficient acidity, the coffee is
frequently flat. To feel the aroma of coffee, people first
inhale the vapor that rises from the cup. Just like a wine
taster, a good coffee drinker, inhales the aroma before
allowing his/her lips to touch the coffee. The relation
between acidity, aroma, and body gives coffee its taste like
caramel, chocolaty, fragrant, fruity, ripe, sweet, almondy,
delicate, piquant etc.
Processing of coffee
There are two ways by which coffee can be
processed and are dry (natural) processing and wet
(fermented and washed) processing. In most cases, wet
processing is regarded as producing a higher quality
product. However, some areas prefer dry processed coffee
for its fuller flavor. The areas in which coffee processing
are being done by wet and dry methods are given below:
Wet processing areas are Bolivia, Burundi,
Cameroon, Colombia, Costa Rica, Cuba, Dominican
Republic, East Timor, Equador, El Salvador, Equatorial
Guinea, Ethiopia, Guatemala, Honduras, India, Indonesia,
Jamaica, Kenya, Malawi, Mexico, Nicaragua, Papua New
Guinea, Rwanda, Tanzania, Uganda, Venezuela, Vietnam,
Zambia, Zimbabwe.
Dry processing areas are Angola, Benin, Brazil, Central
African Republic, Congo, Congo Democratic Republic,
Cote d’Ivoire, Gabon, Ghana, Guinea, Haiti, Madagascar,
Nigeria, Paraguay, Philippines, Sri Lanka, Thailand and
Togo (Chellamuthu et al., 2000).
Wet method
Approximately half of the world coffee harvest is
processed by the wet method in which the coffee berry is
subjected to mechanical and biological operation in order
to separate the bean or seed from the exocarp (skin),
mesocarp (mucilagenous pulp) and the endocarp
(parchment) (Clark, 1985). Adams and Dougan (1981)
reported that the skin and most of the pulp is separated in
the pulpers. This fraction represents about 40% of the
weight of the fresh fruit and presently is underutilized,
causing serious pollution problems. In wet method, the
pulping involves the removal of the outer red skin
(exocarp) and the white fleshy pulp (mesocarp) and the
separation of the pulp and beans. Immature cherries are
hard and green and very difficult to pulp. If the coffee is to
be wet processed, correct harvesting is essential. For small-
scale units, the cherries can be pulped in a pestle and
mortar, and is very labour intensive. There are the two
most common pulpers and most suitable for small-scale
units. They are the drum and the disc pulpers.
Drum pulpers
This involves a rotating drum with a punched sheet
surface and adjustable breast plate between which the
coffee cherries are pulped and the pulp and the beans
separated. The distance between the drum and the breast
plate has to be adjusted so that the pulp is removed without
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the beans being damaged. These can be manually operated
or attached to a treadle or bicycle. For larger scale units,
motorized drum pulpers are available.
Disc pulpers
The concept used in drum pulper is involved with the
disc pulper also. The only difference is that rather than the
cherries being squeezed between a breast plate and a drum,
a disc with a roughened surface is used in disc pulper.
Adams (1981) investigated that the industrial processing of
coffee cherries is done to isolate coffee powder by
removing shell and mucilagenous part from the cherries.
Dry method
In dry method, the coffee cherries are dried
immediately after harvest. This is usually sun drying on a
clean dry floor or on mats. The bed depth is less than
40mm and the cherries are raked frequently to prevent
fermentation or discoloration. However, there are problems
associated with this method. The most serious problem is
dust and dirt blown onto the produce. Another problem is
rainstorms often appear (even in the dry season) with very
little warning. This can soak the produce very quickly.
Finally, labour has to be employed to prevent damage or
theft. Sun drying is therefore not recommended.
Alternatively solar drying is done where the solar cabinet
drier and the exell solar drier are used. In this way the
coffee is placed in the trays in the solar drier. The layer of
the crop is deeper than one inch (3 cm) and the whole tray
area is covered. The drier will be made ready as early in
the day as possible so that all possible sunlight hours are
used. The coffee is stirred regularly so that a uniform
colouration is formed. At night, the crop should be placed
in a cool dry room. In the wet season solar drying of
produce is difficult. Rain is very unpredictable and
frequent. Solar driers will prevent the coffee getting wet.
However, due to the low level of sunlight, solar drying can
take a long time. This can lead to mould growth. Hence, an
alternative drier is used.
Hulling
The dried cherry is then hulled to remove the
pericarp. This can be done by hand using a pestle and
mortar or in a mechanical huller. The mechanical hullers
usually consist of a steel screw, the pitch of which
increases as it approaches the outlet so removing the
pericarp.
Cleaning
The hulled coffee is cleaned by winnowing.
Problems of coffee waste
Agro-industrial residues/wastes are generated in
large quantities throughout the world. Their non-utilization
results in loss of valuable nutrients and envirorunental
pollution (Zuluaga, 1989). The better utilization by
biotechnological means assumes social, economic and
industrial importance. Considering these facts, centre of
ORSTOM participated into a scientific collaboration with
Universidad Autonoma Metropolitana (UAM), Mexico for
the development of biotechnological processes for better
utilization of agro-industrial byproducts/wastes, especially
the coffee pulp (Viniegra et al., 1991; Chapman, 1996,
Deepa, 2002). The wastewater from such type of industries
has high concentration of organic pollutants. So it’s very
harmful for surrounding water bodies, human health and
aquatic life if discharged directly into the surface waters.
Alemayehu Haddis (2008) reported that the people residing
in the vicinity of this plant utilizing this stream water for
domestic purposes suffer from severe health problems. The
seriousness of the situation is shown in Table 1. From this
it is obvious that some people were suffering from one
problem while others were having cumulative health
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effects. Agricultural practices such as use of organic
herbicides, inorganic and synthetic pesticides, efficiency of
the uses of inorganic fertilizers etc., determines the
environmental issues arising from them. For instance, the
use of agricultural pesticides significantly changes the
toxic characteristics of the wastewater (Chanakya, 2004).
Table 1. Health problems reported by the population living
nearby industries (Alemayehu Haddis, 2008)
Health problems
% of
population
affected
Spinning sensation (feeling drunk)
89
Eye irritation (burning inside)
32
Skin irritation
85
Stomach problem
42
Breathing problem
75
Nausea
25
Coffee pulp/husk contains some amount of caffeine
and tannins, which makes it toxic resulting disposal
problem. However, it is rich in organic matters, which
makes it an ideal substrate for microbial processes for the
production of value-added products. Several solutions and
alternative uses of the coffee pulp and husk have been
attempted. These include fertilizers, livestock feed,
compost, etc. However, for these applications only a
fraction of available quantity is utilized and is not
technically very efficient. Attempts have been made to
detoxify it for improved application as feed, and to produce
several products such as enzymes, organic acids, flavour
and aroma from coffee pulp/husk. Solid state fermentation
has been mostly employed for bioconversion processes.
Factorial design experiments offer useful information for
the process optimization. Pandey (2000) reported the
developments on processes and products developed for the
value-addition of coffee pulp/husk through the
biotechnological means.
Management of coffee pulp
Having known the problems of coffee waste several
attempts have been made to manage the same. An aerobic
lake system (meaning aerobic lagoons) was reported by
San Luis Beneficio a production facility in Brazil. This
method facilitated recycling of wastewater back into
production plants. Coffee pulp solid waste was converted
into compost, which was used by the suppliers in fertilizing
their coffee farms (www.cetr.br). Waste water management
techniques used by the coffee pulping operators in India
are based on the use of lagoons. Anaerobic digestion has
been applied with different degrees of success, to the
treatment of liquid and solid wastes from the coffee
processing units (Kostenberg, 1993). Under appropriate
operational conditions, anaerobic reactor will remove the
organic and suspended solids loads with an efficiency of
70-80%. However, in many cases the produced effluent
will require a post-treatment step to produce a final effluent
quality that is compatible with the standards set by the
environmental control authorities (Sousa et al., 2001).
They made an attempt to increase the nutritional value of
CoP for monogastric animals by the following methods: (a)
NaOH treatment; (b) pre-treatment with HCl followed by
NaOH, and (c) pre-treatment with NaOH followed by
ensilage. Rojas, (2002) analyzed the response of CoP to
these treatments by measuring changes in the chemical
composition of treated and untreated CoP samples.
Selvamurugan (2010) made an attempted to ensure that an
effluent quality that complies with the Indian Standards for
the effluent discharge, different combination of treatments
like biomethanation, aeration and constructed wetland
technology were adopted as an integrated system for the
treatment of coffee processing waste water.
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Adsorption-based technique (Devi et al. 2002; Devi
and Dahiya 2006) developed with low-cost carbonaceous
materials showed good potential. Such adsorption approach
can offer an easy and economic solution to these
environmental challenges. Moreover, activated carbon is
considered very effective in reduction of color, absorbable
organic halides and non-biodegradable pollutants present
in such waste water but this process also has some
additional costs associated with the production of activated
carbon. The high rate reactor, most widely used for the
treatment of several types of wastewaters is upflow
anaerobic sludge blanket (UASB) reactor which was
developed by Lettinga, (2001). The upflow anaerobic
hybrid reactor (UAHR) configuration has combined the
advantages of both UASB and upflow anaerobic filter
(UAF) while minimizing their limitations and the reactor
was efficient in the treatment of dilute to high strength
waste water at high organic loading rates (OLRs) and short
hydraulic retention time (HRT).
The current anaerobic-aerobic lagoon system was
evolved around 1978. The National Environmental
Engineering and Research Institute (NEERI), Nagpur,
produced a waste water processing solution based on the
existing water usage pattern of 16,000-23,000 litre water
per ton of fruit processed. The treatment process is based
on the use of anaerobic (21 days) and aerobic (7 days)
lagoons after an initial chemical pre-treatment
(neutralization). The Indian Coffee Board has suggested
this process with a total 29 days hydraulic retention time
(HRT) (CCRI, 2000). A number of research efforts are in
progress. Mohammed et al. (1998); Wang et al. (2005)
developed such types of waste water treatment
technologies. Various low-cost adsorbents like chitin,
chitosan, corn stalks, peat, rice husk, and wood have been
used for removal of organic matter from industrial
effluents (Poots et al., 1976; Mckay et al., 1980; Sharma
and Sharma, 1994). Discarded material based low-cost
adsorbents of different origins like industrial waste
material, bagasse, fly ash, and jute processing waste can
also be used for removal of organic matter from waste
water (Patnaik et al., 1996; Pala and Tokat, 2002;
Srivastava et al., 2005; Wang and Wu, 2006; Bhatnagar,
2007).
By products
It is understood from the literature that many
byproducts have been prepared from coffee waste. Some of
them are as follows:
(i) Organic manure
Coffee pulp is a source of nutrients: 0.5% of
composted pulp is nitrogen, 0.15% is phosphorus, and
0.5% is potassium. Therefore, pulp was treated and used as
organic fertilizer. The pulp left in piles, for 3 to 12 months,
turns into rich, black humus that can be used for
composting. Another way of composting is to mix coffee
husk with cattle manure, leaving the mixture in pits or
heaps. The use of organic fertilizer helps to improve soil
properties thus increasing yield as shown through
investigations in Columbia. Using organic fertilizers also
helps to reduce the need to buy inorganic fertilizers, hence
saving the farmers money.
(ii) Role in Mushroom production
Coffee pulp is used as planting soil for mushroom
production. After having fermented for two days, the pulp
is pasteurized with hot water, drained, dried, and mixed
with mushroom spores. Then, they are put in plastic bags.
After 3 - 4 weeks, the mushrooms grow out of the holes in
the bags and are collected. One bag allows 2-3 mushroom-
harvests. The mushroom can be eaten or dried and sold in
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the market. Considering the large amount of coffee pulp
generated every harvesting season, the income from
mushroom growing is significant for farmers.
(iii) Animal feed
As the coffee pulp is rich in nutrients. It can be
dried and used in animal feeds. Further application, the
pulp needs to be treated as soon as possible to prevent the
development of fungi. The pulp can be treated with
Ca(OH)2 and dried under pressure. Alternatively, the pulp
can be mixed with sugar cane molasses, or urea and other
inorganic substances and put in silos. The silage can be
used after 3 weeks, and can be stored up to 18 months.
However, using coffee pulp as animal feeds is of limited
value, since the cost for drying the pulp sometimes exceeds
the gain. Besides, the effects of caffeine, tannin and the
high level of potassium on the animal’s health are
unknown
(http://library.thinkquest.org/04oct/01639/lighten/sustainab
ility/processing/byproducts).
Conclusion
In coffee producing countries, coffee waste
constitutes a source of severe contamination and serious
environmental problems. For this reason, since the middle
of the present century, efforts have been made to develop
methods for coffee waste treatment and management, also
its utilization as a raw material for the production of feed,
beverages, vinegar, biogas, caffeine, pectin, peptic enzyme,
protein, and compost. Hence, there is a need to curb these
problems through innovative and eco-friendly techniques.
So, this documentation may be an eye opening for the
society.
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