Table of Contents
Figueira, A., J. Janick, and J.N. BeMiller. 1993. New products from
Theobroma cacao: Seed pulp and pod gum. p. 475-478. In: J. Janick and
J.E. Simon (eds.), New crops. Wiley, New York.
New Products from Theobroma cacao: Seed Pulp and Pod Gum
Antonio Figueira, Jules Janick, and James N. BeMiller
- COCOA PULP
- CACAO POD HUSK
- Potassium Salts for Soap
- Cacao Pigment
- Pod Gums
- Table 1
- Fig. 1
Theobroma cacao L. (Sterculiaceae), an important tropical rain forest
species, is grown for its oil-rich seed, to produce cocoa and cocoa butter.
Cocoa seeds are a major cash crop of the tropical world, but prices fluctuate
widely and economic hardships occur when prices are low. Despite this, only
about 10% by fresh weight of the fruit is commercialized, although several
promising commercial products could be obtained from the fruit
One strategy to increase income for cocoa growers is to identify and
commercialize new products that will not interfere with the main seed crop. In
this paper, we review a number of new products that have potential for
increasing returns to cocoa growers. These include seed pulp and products from
pod husk waste; byproducts from the chocolate processing industry, such as
cocoa shell, cocoa cake, and cocoa dust (Abiola and Tewe 1991) are not included.
Cocoa seeds are surrounded by an aromatic pulp which arises from the seed
teguments (technically an aril). The mucilaginous pulp is composed of spongy
parenchymatous cells containing cell sap rich in sugars (10 to 13%), pentosans
(2 to 3%), citric acid (1 to 2%), and salts (8 to 10%) (Lopez 1986).
During on-farm processing of cocoa seed (the exportable products), the pulp is
removed by fermentation and is hydrolyzed by microorganisms. Hydrolyzed pulp
is known in the industry as "sweatings." During fermentation, the pulp
provides the substrate for various microorganisms which are essential to the
development of chocolate flavor precursors, which are fully expressed later,
during the roasting process. Fermentation was once thought to be simply an
easy way to remove the pulp to facilitate drying, but its importance to cocoa
quality has been well established (Lopez 1986).
The schedules for fermentation vary according to location and season, chamber
size, depth of seed layer, and physical turning of the seed. Although pulp is
necessary for fermentation, often more pulp occurs than is needed. Excess
pulp, which has a delightful tropical flavor has been used to produce the
following products: cocoa jelly, alcohol and vinegar, nata, and processed
Approximately 40 liters of pulp can be obtained from 800 kg of wet seeds.
Cocoa jelly is produced by cooking fresh pulp mixed with sugar at the rate of
300 to 600 g to one liter pulp. The pulp contains about 1% pectin (Wood and
Lass 1985). The jelly has a fruit-acid flavor and is a popular delicacy in
By controlled fermentation and distillation, sweatings can be made into an
alcoholic spirit with 43% ethanol. Alcohol produced can be further fermented
by Acetobacter sp. to produce acetic acid, but vinegar is not yet a
commercial product (Samsiah et al. 1991).
Cocoa sweatings have been shown to be a suitable substrate for fermentation to
produce nata (Samsiah et al. 1991), a product usually obtained from
fermentation of coconut water by Acetobacter aceti subspecies
xylinum. Nata is processed to an agar-like product, packed in syrup,
and is consumed as a dessert in Asia.
Recently, a small industry utilizing fresh pulp has been established in Bahia
for a number of tasty products. The pulp can be consumed fresh in the form of
juices and "shakes." In small stalls, seeds with pulp are extracted from
individual pods and placed, as ordered, in a modified food blender in which a
metal disc with holes instead of blades. Milk or water is added, and after a
few seconds of blending, the contents are poured through a strainer, producing
a frothy, delicious, refreshing beverage. Enough pulp is usually left on the
seed for normal fermentation, but pulpless seeds can also be added to intact
seed to complete fermentation. Pulp can be preserved by freezing and used for
ice-cream, yogurt flavoring, and juice concentrates. Because of the expense of
the freezing process, cocoa pulp has not been marketed outside Bahia. It is
our belief that this product could have large scale accep-tance, and we
recommend market studies in temperate countries.
Extraction of pulp does not interfere with subsequent seed fermentation, and
reduction of pulp before fermentation may be beneficial to cocoa quality
(Schwan and Lopez 1988). In Brazil, seed quality is improved by the removal of
pulp in order to reduce acidity. Commercial depulping machines of various
sizes have been developed based on a revolving cylinder, which removes about
60% of the pulp and does not injure the seeds. Bahia alone produces about
300,000 tonnes of dry cocoa seeds. Each ton of dry seeds represents 300,000 t
of pulp, of which 60% will be needed for fermentation, leaving an excess of
120,000 t. If only 10% of this quantity would be utilized in Bahia alone,
there would be sufficient raw product available to produce 12,000 tons of pulp.
Each ton of dry seeds represent about 10 tons of husk (fresh weight). At the
present time, pod husks are a waste product of the cocoa industry, and present
a serious disposal problem. They become a significant source of disease
inoculum when used as a mulch inside the plantation. Fresh or dried husks may
be used as livestock feed, but theobromine content (ca. 0.4%) restricts the
proportion that can be consumed, and its use has been limited. Although
acceptability by animals is satisfactory, digestibility is considered poor and
dependent on processing cocoa pod husk (Adomako and Tuah 1988). Reports
indicate that pod meal can constitute 20% of ration for poultry, 30 to 50% for
pigs, and 50% for sheep, goats, and dairy cattle, but these values may be too
high (Wood and Lass 1985). The toxic dose of theobromine for rats (LD50) is
1254 mg.kg-1 (Abiola and Tewe 1991).
Low digestibility of polysaccharides restrict the use of pod husks for methane
production in biodigestor (Lopez et al. 1985).
Cocoa pod husks contain 3 to 4% potassium on a dry basis (Wood and Lass 1985).
Pod husk ash has been used to make soap in Ghana and Nigeria (Oduwole and
Arueya 1990; Arueya 1991).
A cocoa husk extract called cacao pigment, which is a mixture of condensed or
polymerized flavonoids (such as anthocyanidins, catechins, leukoanthycyanidin),
sometimes linked with glucose, has been utilized in Japanese food industries
(Kimura et al. 1979). Recently this extract has been shown to inhibit
cytopathic effects of HIV in cell culture (Unten et al. 1991). The anti-HIV
activity was attributable to interference with the virus adsorption, rather
than inhibition of the virus replication after adsorption.
In cacao, lysigenous cavities filled with mucilaginous substances occur in
roots, stems, flowers, and leaves (Brook and Guard 1952) as well as fruit husks
(Figueira et al. 1992). Krishna Moorthy and Subba Rhao (1976, 1978, 1980) also
isolated gums from the seed pulp. Polysaccharides of cacao were first
characterized by Whistler et al. (1956), who found differences in
hot-water-soluble polysaccharides between seed and pod husks. Blakemore et al.
(1966) examined the hot-water-soluble fraction of husk polysaccharide and
concluded that the major part of this fraction was a pectic material. Cocoa
pod husks were examined as a source of pectin by mild acid extraction by
Adomako (1972) and Berbert (1972), but yields were low and the pectin was
inferior to apple or citrus pectin in gel-forming ability. Krishna Moorthy and
Subba Rhao (1978, 1980) found that gums from seed pulp were effective in low
concentrations as a binder for pharmaceutical pills, and reported that
suspending properties were superior to tragacanth, sodium alginate, sodium
carboxy-methyl cellulose, and methyl cellulose.
Gum karaya produced from various Sterculia species, Sterculiaceae,
mainly S. urens Roxb., has been used in the food and medical industry
(Glickman 1982), but its use has diminished because its supply is variable and
unreliable. We have recently characterized cocoa gums from pod husks and stems
to evaluate their potential as a replacement for gum karaya or as a new
commercial product (Figueira et al. 1992).
Yield averaged 1.5% of fresh weight and 8.4% dry weight for stem gum, and 0.7%
of fresh weight and 8.7% dry weight for pod gum. Cacao pod gum was closer in
composition to gum karaya than was stem gum (Table 1). Both cocoa gums
contained the same monosaccharides as gum karaya but with the addition of
arabinose and with higher proportions of rhamnose. The major component of stem
gum was glucose, not found in the other two gums and also contained more
glucuronic acid. Cacao stem gum has a higher viscosity at concentrations below
1% than gum karaya (Fig. 1).
Unutilized portions of cocoa pods contain many potential new products that
could provide extra income for cocoa growers. The most promising products
appear to be cocoa pulp and the gums from pod husks. Although cocoa pulp is
now essentially a waste product, exploitation will require a considerable
investment in freezer processing equipment. Potential uses for pod gums
include binders for such products as pet food, emulsifiers, and fixatives.
More research is needed to discover economic uses of this product. For maximum
efficiency, we foresee a combination of seed fermentation, pulp and gum
extraction in a single operation. This may be carried out by medium to large
growers in an on-farm operation, or by a cooperative facility that will service
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Table 1. Sugar comparison of cacao gum and gum karaya.
zAll monosaccharides were standardized for galactose molar
| ||Sugar composition (molar ratio)z|
|Gum source ||Rhamnose ||Arabinose ||Galactose ||Glucose ||Xylose ||Mannose ||Galacturonic |
|Gum karaya ||1.6 ||0.0 ||1.0 ||0.1 ||0.0 ||0.0 ||1.3 ||0.6|
|Cacao stem gum ||2.0 ||1.7 ||1.0 ||2.8 ||0.0 ||0.0 ||1.1 ||1.4|
|Cacao pod gumy ||2.4 ||2.1 ||1.0 ||0.1 ||0.1 ||0.0 ||1.1 ||0.6|
|Cacao pod gumx ||1.0 ||0.3 ||1.0 ||0.0 ||0.0 ||0.3 ||0.0 ||0.0|
|Cacao pod gumw ||0.4 ||0.2 ||1.0 ||0.4 ||trace ||0.3 ||1.3 ||0.0|
|Cacao pod gumv ||0.6 ||0.4 ||1.0 ||trace ||0.3 ||0.0 ||13.4 ||0.0|
yFigueira et al. (1992)
xWhistler et al. (1956)
wBlakemore et al. (1966)
||Fig. 1. Viscosity changes with concentration of cacao pod gum and gum
karaya at different spindle speeds.
Last update September 15, 1997