Ginger is an upright tropical plant (Zingiber officinale Rosc.) that grows to about 1 meter tall. It originated in India and is now produced in tropical climates throughout the world; China, Taiwan, Nigeria, Jamaica, Mauritius and Australia are the major producers. The largest markets for ground ginger are the United Kingdom, Yemen, the USA, Middle East, Singapore and Malaysia. The edible parts of the plant are the rhizome (at the base of the stem) and the young tender stem.
Ginger is usually available in three different forms:
- Fresh (green) root ginger
- Preserved ginger in brine or syrup
- Dried ginger spice.
Fresh ginger is usually consumed in the area where it is produced, although it is possible to transport fresh roots internationally. Both mature and immature rhizomes are consumed as a fresh vegetable.
Preserved ginger is only made from immature rhizomes. Most preserved ginger is exported. Hong Kong, China and Australia are the major producers of preserved ginger and dominate the world market.
Making preserved ginger is not simple as it requires a great deal of care and attention to quality. Only the youngest most tender stems of ginger should be used. It is difficult to compete with the well established Chinese and Australian producers, therefore processors are advised against making this product.
Dried ginger spice is produced from the mature rhizome. As the rhizome matures the flavor and aroma become much stronger. Dried ginger is exported, usually in large pieces which are ground into a spice in the country of destination. Dried ginger can be ground and used directly as a spice and also for the extraction of ginger oil and ginger oleoresin.
This brief outlines the important steps that should be taken pre-harvest and post-harvest to produce dried ginger.
Cultivation of Ginger
Ginger is a perennial plant but is usually grown as an annual for harvesting as a spice. It requires a warm and humid climate and a heavy rainfall of 150-300cm a year or plenty of irrigation. The plant can be cultivated from almost sea level to an altitude of 1500m above sea level. It thrives well in sandy or clay loam soil with good drainage and humus content. Ginger is best grown in partial shade and can be incorporated as an intercrop in coconut, coffee and orange plantations. Planting is done in April/May during the monsoon rains. Ginger is harvested by digging out the rhizomes when the tops have died down. The harvesting and processing of dried ginger varies in different countries.
Processing Dried Ginger
There are two important factors to consider when selecting ginger rhizomes for processing:
1) Stage of maturity at harvest. Ginger rhizomes can be harvested from about 5 months after planting. At this stage they are immature. The roots are tender with a mild flavor and are suitable for fresh consumption or for processing into preserved ginger. After 7 months the rhizomes will become less tender and the flavor will be too strong to use them fresh. They are then only useful for drying. Mature rhizomes for drying are harvested between 8 and 9 months of age when they have a high aroma and flavor. If they are harvested later than this the fiber content will be too high.
2) Native properties of the type grown. Gingers grown in different parts of the world can differ in their native properties such as flavor, aroma and colour and this affects their suitability for processing. This is most important when preparing dried ginger, which needs rhizomes with a strong flavor and aroma. Himachel, Maran, Mananthody and Kuruppampady are good varieties for the preparation of dried ginger. Size of rhizome is an important factor to consider when drying ginger Ã¢â‚¬â€œ medium sized rhizomes are the most suitable for drying. Large rhizomes often have a high moisture content which causes problems with drying.
Making Dried Ginger
Dried ginger is available in a number of different forms – the rhizomes can be left whole or they may be split or sliced into smaller pieces to accelerate drying. Sometimes the rhizomes are killed by peeling or boiling them for 10 to 15 minutes, which causes the rhizomes to become blackened. They have to be whitened (bleached) by treating with lime or sulphurous acid. The only product which is acceptable for the UK market is cleanly peeled dried ginger.