Ginger processing
Practical Action
Quality assurance of dried ginger
Quality of the dried ginger is assessed by the appearance of the final product (colour, lack of
mould or aflatoxin) and the aroma and flavour.
These qualities are influenced by a combination of pre- and post-harvest factors:
The most important factor is the cultivar of ginger used as this determines the flavour,
aroma, pungency and levels of essential oil and fibre.
The stage or maturity of the rhizome at harvest determines its suitability for end use.
Rhizomes that are 8-9 months old produce the best quality dried ginger as they have a
good combination of aroma and pungency and not too much fibre.
After harvest the rhizomes should be handled with care to prevent injury. They should be
washed immediately after harvest to ensure a pale colour. The wet rhizomes should not
be allowed to lie in heaps for too long as they will begin to ferment.
Care should be taken when removing the outer cork skin. It is essential to remove the
skin to reduce the fibre content, but if the peeling is too thick, it may reduce the content
of volatile oil which is contained near the surface of the rhizome.
During drying the rhizomes should lose about 60-70% of their weight and achieve a final
moisture content of 7-12%. Care should be taken to prevent the growth of mould during
drying.
The use of a mechanical drier produces a higher quality, cleaner product. The drying
conditions can be carefully controlled and monitored and the time taken to dry is
considerably reduced.
After harvest, the cleaning, peeling and drying processes should be carried out as quickly
as possible to prevent the growth of bacteria and mould and to prevent fermentation. If
the drying process takes too long there is a risk of the ginger becoming infected by
aflatoxin or other fungus.
Dried ginger should be stored in a dry place to prevent the growth of mould. Storage for
a long time results in the loss of flavour and pungency.
Grading
Quality specifications are imposed by the importing country and refer to the cleanliness
specifications of the ginger rather than the quality. It is important to meet the minimum
standards or the ginger will be rejected by the importers.
There are several forms of dried rhizome, which are described below:
Type
Peeled, scraped, uncoated
Rough scraped
Unpeeled, coated
Black ginger
Bleached
Splits and slices
Ratoons
Description
Whole rhizome with the corky skin removed
Whole rhizome with the skin partially removed
Whole rhizome with the skin intact
Whole rhizome scalded before being scraped and dried
Whole rhizome treated with lime of diluted sulphuric acid
Unpeeled rhizomes, split or sliced
Second growth rhizomes, small, dark and very fibrous
Grinding
Grinding can be a method of adding value to a product. However, it is not advisable to grind
spices as they are more vulnerable to spoilage after grinding. The flavour and aroma compounds
are not stable and will quickly disappear from ground products. The storage life of ground spices
is much less than for the whole spices. It is very difficult for the consumer to judge the quality
of a ground spice. It is also very easy for unscrupulous processors to contaminate the ground
spice by adding other material. Therefore most consumers, from wholesalers to individual
customers, prefer to buy whole spices.
Dried ginger is usually exported whole and ground in the country of import.
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