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Agriculture > Spices > Vanilla (Vanilla planifolia)

Crop Management

 

Harvesting and processing

Harvesting

The beans or pods are ready for harvest 6-9 months after flowering. The beans can be considered as mature when they change from green to pale yellow. At this time, the pods may be 12-25 cm long. It is essential to harvest the pods at the right stage, as immature pods produce an inferior product and overmature pods split during curing. The right picking stage is when the distal end of the pod turns yellow and fine yellow streaks appear on the pods. Daily picking of mature pods is essential. The pods can be harvested by cutting with a knife. Since the pollination of flowers in a vanillery lasts three to four weeks, completion of harvesting of beans may also take same time. The plants bear fruit or flowers only on the third or fourth year, with maximum yield after seven or eight years. The vines are abandoned at 10 to 12 years old when they are no longer commercially productive.

Yield

Under the Indian conditions, yield of vanilla range between 1800 and 3600 kg of green beans or 300 and 600 kg of cured beans per hectare. About 6 kg of green pod produce 1 kg cured beans.

Curing

Presence of vanillin gives aroma to the cured vanilla beans, whereas it is not present in the free form in fresh beans. Fresh beans subjected to proper curing will develop vanillin as well as secondary aromatic compounds and other contents responsible for its flavour. Beans are to be cured by the right method for the proper development of aroma and flavour in desired quantities.

Instruments/accessories needed for curing:

  • Cylindrical cane basket
  • Vessel for boiling water (of required size for immersing the cane basket)
  • Thermometer
  • Dark brown woolen or cotton cloth
  • Wooden boxes (of required size) Wooden racks
  • Hygro meter (to measure humidity)
  • Butter paper or cellophane paper or polypropylene bags
  • Black cotton thread

Processing (Bourbon method)

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Though different methods of processing of vanilla beans are followed, demand in the international market is for beans, which are processed by bourbon method. This method consists of four stages.

  1. Killing
  2. Sweating
  3. Slow drying
  4. Conditioning

Killing:

  1. Killing is to be done within 4-5 days after harvesting.
  2. Sort the beans according to their maturity and size, and then wipe them using a wet cloth for cleaning. Separate the splits.
  3. Load the sorted beans in cane baskets.
  4. Dip and lift the basket containing beans twice repeatedly into clean hot water of 65-70°C and keep it immersed continuously for three minutes maintaining the same temperature of the water.
  5. Longer beans may be dipped for three minutes and smaller beans/ splits for less than two minutes.
  6. When the beans are dipped in hot water, there will be a sudden drop in temperature. To maintain the temperature, heating of water should be continued.
  7. After taking out the beans rapidly drain the water off and wipe away the water on the beans using a clean cloth.
Sweating:
  1. Wrap the beans subjected to killing in woolen cloth while still hot and place them in wooden boxes lined with wollen cloth for 24 hours. If cotton cloth is used instead of wollen cloth, lining with three-four layers of cloth may be provided in the wooden box.
  2. Properly killed beans acquire dark brown colour in 24 hours and will not break when bent slightly.
  3. Beans which are not properly killed may be separated and subjected to killing once again for around one minute.
  4. Expose properly killed beans to sunlight for two-three hours by spreading them on a wollen cloth placed on a raised platform of 70 cm. height above the ground.
  5. In places where day temperature is high, providing a layer of agro shade net above the beans spread out on the platform will help in preventing excessive build up of heat in the beans. But this is not required in high ranges as day temperature is low.
  6. After two-three hours of exposure to the sun, gather the beans in the centre of the blanket fold the blanket over and leave it on the platform for one hour more.
  7. After one hour transfer the beans without removing the blanklet to an air tight wooden box.
  8. This process is to be repeated until the beans attains 50 per cent of the initial weight (8-10 days).
  9. At the end of sweating period, the weight of beans will be half of the initial weight and become supple.
  10. Sweating should be done in hygienic conditions.
Slow drying:
  1. On completion of sweating, spread the beans on wooden racks arranged in drying room. The beans should be kept apart from each other.
  2. In order to maintain the relative humidity inside the room at 70 per cent, hang moistened clothes on walls or keep water in open trays in the room.
  3. Turn the beans over regularly to ensure uniform drying.
  4. Slow drying may be continued until the weight of the beans is reduced to 1/3rd of the initial weight. This process requires 20-25 days.
  5. By this time beans become more pliable and can be twisted on fingers.
Conditioning:
  1. Slow dried beans are sorted according to their length and quality and made into bundles of 50 or 100 beans and tied at both ends using black thread.
  2. These bundles are wrapped in butter paper or cellophane paper or packed in polypropylene bags.
  3. These wrapped or packed bundles are kept in air tight wooden boxes for two-three months.
  4. By this time, vanillin and aroma will be properly and fully developed and crystals can be seen on the beans.
  5. Average vanillin content of beans which are harvested at the right time and subjected to proper curing will be 2.5 per cent.
Storage:

Four or five bundles wrapped in butter paper may be packed in polypropylene bags and sealed. These bags may be stored in airtight wooden boxes. Aluminium/thermocol boxes also can be used. When thermocol boxes are used, it should be sealed properly using tapes. These boxes can be stacked in rooms. Excess heat and relative humidity are to be avoided.Bundles of beans should be checked for fungal infection once in 15 days. Beans are prone to fungal infection where rainfall is too high. Properly harvested and processed beans can be kept in storage for four-five years without any damage. However proper storage conditions should be maintained.

Quality requirements of processed beans
  1. Top quality beans are long, fleshy, supple, very dark brown to black in colour, somewhat oily in appearance, strongly aromatic and free from scars and blemishes.
  2. Low quality beans are usually hard, dry, thin, brown or reddish brown in colour and possess a poor aroma.

The moisture content of top grade beans is as high as 30% where as it may be as low as 10 % in the lower grades.

 

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