The process of reducing the moisture content of the harvested capsule from 80% to 10-12% at a temperature of around 50°C to preserve the green colour to the highest extent is known as curing.
There are primarily two kinds of drying viz. Natural (sun drying) and artificial drying with the use of fire wood (traditional flue pipe system), electrical current, or solar (sun light). Barring the traditional flue pipe wood based drying system, rest of the methods involve complications. Although fire wood-based flue pipe method is effective, small and marginal farmers who comprise nearly 70% of cardamom growers, face challenges in possessing self-owned curing house due to economic compulsions. They entirely depend on large growers to cure their fresh capsules by paying a very high drying charge. The method of fire wood-based curing house includes storage of wood burning flue pipes, furnace, and drying shelves in a chamber. The furnace is built of fine or ordinary bricks of about 2.5 m x 0.6 m grate size to facilitate charging with big wood logs. The heated flue gas is released through the chimney after circulation through flue pipes of 25-30 cm diameter prepared by mild steel sheets positioned in the heart of the room. The shelves containing the harvested capsules are placed at 30-50 cm distance from the flue pipe to escape chances of overheating. The curing chamber roof is insulated from within with the help of wooden planks and NC sheets. The capacity of the curing chamber ranges between 200-500 kg fresh cardamom capsules. Adequate air outlet and exhaust facilities at a regular interval help to evade moisture accumulation and to retain green colour while drying, but this method has less than optimum level of thermal efficiency of 6-8%. Therefore, Indian Cardamom Research Institute (Spices Board) is investigating lateral techniques of cardamom drying by using kerosene or liquid petroleum gas as yet another source of fuel and has received considerable success through this method. The construction cost of a drying chamber while adopting kerosene or LP gas system amounts to be Rs. 30,000 to Rs. 35,000 for 100 kg drying, and drying cost is equivalent to Rs. 2 to Rs. 2.50 per kg of fresh cardamom capsules.
After drying, the capsules are polished by rubbing them against a hard surface or using a polishing machine. Afterwards, the dried cardamom is stored inside gunny bags. For productive retention of the green color during storage, it is necessary to dry the cardamom for reducing moisture content to the extent of 10 to 12%. Storage efficiency is further enhanced by the use of 300 gauge black polythene lined gunny bags. It is advisable to store these bags inside wooden boxes, which restrains spoilage of capsule by rodents. In order to earn the best market price, grading the capsules by sifting them under sieves of varying diameters is done. The best breed of cardamom will be about 7 mm and will reflect good green hue to receive prime price in the market.
Few tips to better the quality of cured cardamom are as follows:
- Immediately after harvest, dry cardamom retains the original colour the one it had at the time of harvest.
- Maintain temperature of 40°C and 50°C inside the room in the first 10 to 12 hours, and then slowly raise it to 55°C for the rest of the curing period.
- Facilitate effective ventilation to release the moisture from the room during curing process. It is necessary to retain good green color while drying.
- Temperature above 65°C inside the room should be avoided in order to reduce splitting of capsules and loss of volatile cardamom oil.
- Polish the cured capsules while they are hot.
- Use black polythene lined gunny bags for packing of cured cardamom and storethem within wooden boxes for better storage efficacy.