Vanilla planifolia belongs to the orchids family and there are nearly 110 vanilla species distributed in tropical regions of the world. However, vanilla is the only edible fruit that contains relevant flavour and aroma compounds.
Given the ripening characteristics of the beans it has been considered that a minimum waiting period to start vanilla beans harvest could be from six to nine months from pollination. Harvest consists in cutting the beans and pack in bags. Cutting is made by hand with no tools or utensils to avoid physical damage to the beans. This is a major issue for producers and there is a grading system for green product. Vanilla fruits are gathered when they are fully mature but before they are too ripe. When picked immaturely, the fruits do not develop the requisite full-bodied aroma and proper colour during processing and are more prone to fungal infection. When harvested at the over-ripe stage, the fruits tend to split and lose some of their aroma.
The beans are harvested one by one when they are fully grown. At this stage, beans change their colour from dark green to light green with yellow tinge. Immature beans produce an inferior product and, if picked too late, the beans start splitting. Bunch or broom harvesting should be avoided. The well ripened ready beans detach easily from the bunch just by lifting them in reverse direction. Beans are mostly odorless and further processing or curing is necessary to develop their characteristic aroma. The harvesting of the beans demands substantial labour efforts. The vanilla harvest lasts two months and farmers should preferably pick beans a few times a week. Beans that are not harvested in time turn black and are then overripe for processing. Production cycle includes two labour peaks: one during the flowering stage and one at the harvesting stage.
The result of vanilla harvest is largely determined by the level of the soil fertility, its cultivation, fertilization, and the plant's variety. The optimum result of Vanilla planifolia type, with a good cultivation technique is 3 kg of fresh vanilla per plant. Size and appearance get the primary importance here, because the beans are classified according to their length.
After sorting, the beans are tied into bundles, usually 70 to 130, weighing between 150 and 500 grams. These are then packed into cardboard or tin boxes lined with waxed paper. The beans are now ready for shipment.
After inspection the heat process named as killing starts with graded beans transferred to a bamboo basket or a bag and immersed in hot water or oven at a temperature of 70C for few minutes. The treated beans are then transferred immediately to a wooden box lined with blanket, for sweating and kept for 36-48 hours. The temperature initially is to be 48-50C. By then, the beans will attain light brown colour and start imparting aroma.
Later on, the beans are spread in hot sun (from 12 noon to 3 pm) over wooden loft on a clean black blanket. The temperature of the bean, at this time should raise to 50C. Later on, the bundles are transferred to the sweating box. Sun drying and sweating is continued grade-wise from one to two weeks. At the end of this period, the beans lose half of initial weight, turn to a shining dark brown colour and develop wrinkles. Also, their aroma improves.
The next step involves the spreading of the beans in racks kept in well-ventilated room maintained around a temperature of 35C and relative humidity of 70%. The duration of slow drying is from one to four weeks. On completion of slow drying, the vanilla beans get heavy longitudinal wrinkles, turn lustrous with brownish black colour and become supple. They offer a soft leathery touch; can be rolled around finger easily and on release, becoming straight. The moisture content at this stage may be around 30-35 per cent.
The dried and classified beans are bundled, tied with a thread and kept for conditioning inside wooden or metal boxes lined with wax paper for two months. By this time, there is a further loss of three to four per cent moisture with the full development fragrance. Finally, the bundles are wrapped in wax papers and stored in airtight containers. On the whole, meticulous care has to be taken during the curing process, as otherwise the quality of the beans may get deteriorated due to fungal, bacterial or other pest damage. After grading, the vanilla sticks are bundled, wrapped in wax paper and packaged in wooden crates to be transported in refrigerated containers.