Spice processing
Practical Action
Spices contain volatile oils that are adversely affected by high temperatures. Therefore the
temperature of drying must be tightly controlled to ensure a high quality dried product.
Most small-scale processors dry the crop by spreading it in the sun. This is another opportunity
for the crop to become contaminated. All efforts should be made to ensure that the crop is dried
in a clean place, away from animals, insects and birds.
Drying during the dry season
During the dry season, sun drying is usually adequate to dry the produce. The simplest and
cheapest method is to lay the produce on mats in the sun. However, there are problems
associated with this method. Dust and dirt are blown onto the crop and unexpected rainstorms
can re-wet the crop. Drying in direct sunlight can adversely affect the colour of some of the
more sensitive spices.
A solar dryer can be used to overcome
the problems of contamination and
spoilage by rain. The simplest type of
solar dryer is the cabinet dryer (see
Figure 1) which can be constructed out
of locally available materials such as
bamboo, coir fibre or nylon weave. For
larger units (over 30kg/day) a Brace
type of solar dryer could be used (Figure
2). However, the construction costs of
this type of dryer are greater and a full
financial evaluation should be made to
see if it is economically viable.
See the Practical Action Technical Brief
on Solar Drying for further information. Figure 1: The Exell cabinet solar dryer.
Drying during the wet season
During the wet season or times of high humidity, which often coincides with the harvest of the
spices, sun drying or solar drying cannot be used effectively. An artificial dryer that uses a cheap
energy source is necessary. This may be
a wood or husk burning dryer or a
combined wood burning and solar dryer.
See the Practical Action Technical Brief
on Small-scale Drying Technologies for
further information on types of dryer.
It is important to control the
temperature and time of drying. The
maximum drying temperature for most
spices is 50ºC. At higher temperatures
than this the volatile compounds that
are responsible for the flavour and
aroma are driven off. Spices should be
dried quickly until they reach their final
moisture content. They should not be
overdried as this also has a detrimental
effect on the final quality. The final
moisture contents for several spices are
shown in Table 1. Some spices require
special drying conditions. For example,
cardamom should be dried in the dark
to help preserve the green colour.
Figure 2: The Brace solar dryer.
2