The below Vanilla article has vast information about Vanilla industry, history, Vanilla production process , growing vanilla, hand pollination, curing process and Vanilla beans Storing 

It is interesting to know how the curing process differs in vanilla-producing countries. 

The Curing of Bourbon in Madagascar and Other Indian Ocean Countries

Bourbon vanilla is a product from the former French colonies in the Indian Ocean that uses a curing process invented on the island of Reunion, previously known as Bourbon. Madagascar dominates the production of Bourbon-type vanilla compared to other vanilla-producing countries in the Indian Ocean (India, Mauritius, Seychelles, Reunion, Mayotte, Sri Lanka).

The Bourbon curing procedure differs from that used in Mexico. The ‘killing’ is accomplished by scorching the beans in hot water, resulting in fewer sweating. The Bourbon product is generally frosted and has a higher moisture level than Mexican vanilla grades. Most of the vanilla curing in Mexico is done by specialized corporations rather than vanilla farms or small growers.

In Sri Lanka Vanilla cultivation and  processing is in higher elevations where curing process is similar to Madagascar.

The curing procedure for Bourbon vanilla takes 5 to 8 months. Madagascar’s major harvesting season lasts from June until early October.

There are some differences in the curing processes used on the various vanilla-producing islands. Madagascar growers use the below steps in curing their green beans.

Killing Process When the beans arrive at the curing facility, they are sorted according to maturity, size, and split and unsplit kinds. 

• Bean batches weighing 25 to 30 kg are put into openwork cylindrical baskets.

• Green beans are immersed in vessels filled with hot water heated to 63–65 °C over a wood fire. 

• The smaller, split beans are immersed for less than 2 minutes, while the top three quality batches of beans are soaked for 2 to 3 minutes.

• The heated beans are quickly drained and wrapped in a black cotton cloth.

• Placed in a fabric-lined sweating box

• The beans are removed after 24 hours and examined to distinguish those that have not been fully killed.

Sun Drying

• The dead beans are spread out on black cloths sitting on bamboo slatted platforms about 70 cm above the ground.

• After one hour of direct sun exposure, the edges of the fabric are folded over the beans to retain heat.

• The cloth-wrapped beans are then left in the sun for another two hours before being rolled up and brought inside.

• This process is continued for 6 to 8 days, or until the beans are very supple.

Slow Drying/Gradual Drying

• The next stage is gradual drying in the shade for 2 to 3 months.

• In a well-ventilated environment, the beans are spread on racks fixed on supports with 12 cm of space.

• During this drying process, the beans are sorted on a regular basis.

• Beans dried to the required moisture content are removed immediately for conditioning.

• Due to inclement weather, some Bourbon-producing locations used indoor drying.They used an oven set at 45 to 50 °C.

Vanilla Conditioning 

• Beans are sorted again and straightened by dragging them between the fingers.

• Straightening fingers aids in the spread of oil that seeps during the curing process.

• The beans are then wrapped into bundles of around fifty using black twine.

• The bundles are wrapped in waxed paper and placed in metal conditioning boxes lined with waxed paper.

• Conditioning lasts at least three months, during which time the beans are examined on a regular basis.

• Mouldy beans are removed for treatment.

• The beans are graded and packed for transportation at the end of the conditioning stage.

The Vanilla Curing process in Puerto Rico 

In the 1940s, a variation on the traditional Bourbon curing procedure was developed in Puerto Rico. 

• separated into split and unsplit varieties before being destroyed.

• The beans are cleansed with a moist towel before being killed.

• Scalding includes three 10-second immersions in an 80-°C water bath at 30-second intervals.

• The beans are covered in a blanket and placed in a sweat box once they have been drained.

• Killing is followed by daily two-hour sunnings and nocturnal sweatings for approximately seven days, or until the beans become supple.

• The following stage of indoor air-drying is repeated until the beans have shrunk to one-third of their initial weight.

• The beans are packaged and conditioned in tin boxes until they dry to one-quarter of their original weight.

• Unlike Bourbon vanilla from the Indian Ocean, Puerto Rican vanilla scalded at 80°C seldom frosts.

• When the weather does not permit sunbathing, the beans are sweated in a closed oven at 45 °C with a pan of water.

Curing methods in Mexico.

The two primary traditional processes of curing used in Mexico are sun-wilting and oven-wilting. Sun-wilting is the earliest known curing procedure in Mexico, whereas oven-wilting was established around 1850. Both processes are still frequently used by the specialised curing enterprises that handle the large majority of the vanilla harvest in Mexico. In Mexico, the harvesting season lasts from November to January, and curing by either process takes around five to six months until the product is ready for sale.

Sun-Wilting

• On arrival at the curing house, the fresh beans may be set aside in a store for a few days until required, and during this time, the beans start to wrinkle.

• The fresh beans first have their peduncles removed and are then sorted according to their degree of maturity, size, unsplit and split types.

• Beans, which are already beginning to darken, are removed, wiped with castor oil, and cured separately.

Killing 

• After sorting, the beans are killed by exposing them to the sun for around five hours.

• The fresh beans are laid out on black mats on a cement patio or wooden racks.

• When beans are too hot to hold by hand in the afternoon, they are then covered by the blanket’s borders.

• The thick ends of the beans are positioned towards the middle of the blanket and wrapped up in the mid-to-late afternoon, before the beans have begun to cool.

• The blanket rolls are immediately brought indoors and placed in blanket-lined, airtight mahogany boxes to “sweat” for the first time.

• To prevent heat loss, blankets and matting are put over the sweating boxes.

• The beans are collected and examined after 12 to 24 hours.

• The majority of the beans will have begun to turn a dark-brown colour, signifying a successful ‘killing.’

• Beans that have preserved their natural green colour or have an inconsistent tint are separated and oven-wilted.

Sunning and Sweating

• Sunning is the process of spreading the beans on blankets and exposing them to the sun for two to three hours during the warmest portion of the day when weather conditions are favourable.

• Unless sweating is required, the beans are held indoors on wooden racks in a well-ventilated room for the remainder of the day.

• The first stage entails a rather quick drying in which the beans are given sunnings almost every day and multiple overnight sweatings until they become pliable.

• This takes around five to six days. At this point, a preliminary sorting into lots corresponding to the various vanilla grades is frequently performed.

• This is followed by additional sunning and less frequent sweating.

• In practice, “sunnings” are rarely performed every day during this second phase; overly quick drying is seen to be damaging to the quality of final vanilla beans.

• Most of the beans become very pliable and acquire qualities similar to those of the final product 20 to 30 days after dying.

• The total number of sweatings during the sunning and sweating procedure could range between four and eight.

• The beans, which require a high number of sunnings and sweatings, yield a low-quality vanilla product.

Slow drying

• Indoors, very slow drying takes about a month, and further sorting into classes is normally done during this period.

• The beans are examined on a regular basis, and those that have reached the required level of dryness are promptly taken off the racks for “conditioning.”

• The overall sweating and drying operation may take up to 8 weeks from the time of “killing,” according to the prevailing weather conditions.

• Small and split beans are frequently ready for conditioning before large, perfect, flawless beans.

Conditioning

• Beans taken for conditioning are sorted again and straightened by dragging them between the fingers.

• This technique is also beneficial in that it distributes the oil that seeps during the curing process and gives the beans their unique sheen.

• The beans are then wrapped into bundles of around fifty using black twine.

• The bundles are wrapped in waxed paper and placed in waxed paper-lined metal conditioning boxes.

• Conditioning takes at least 3 months, during which time the beans are examined on a regular basis.

• Mouldy beans are removed for treatment, and those that do not produce the required aroma may be subjected to sunnings and sweatings again.

• At the completion of the conditioning phase, the beans are graded and packed for export.

The process of oven-wilting in Mexico

A specially designed brick or cement room known as a calorifico, which functions as an autoclave, is used in this technique.

The Structure of the Oven

The chamber is roughly 4 x 4 x 4 metres in size and has a wood-fired heater that is fueled from the outside. It includes a tiny access door and wooden racks installed along the walls.

How to wilt beans in the oven?

• The beans to be killed are separated into heaps of up to 1000.

• Beans are folded up in a blanket, which is then covered with matting to make a malleta or case.

• The malletas are dampened with water and placed on the oven shelf. To maintain a high humidity level, water is poured onto the solid floor, the door is closed, and the heating fire is started.

• In about 12 hours, the temperature inside the calorifico reaches 60 °C.

• After 16 hours, a temperature of 70 °C is reached and maintained for another 8 hours.

• After 36 hours in the calorifico, the malletas are removed. If the temperature cannot be raised above 65 degrees Celsius, the autoclaving time is extended to 48 hours.

• When the malletas are removed from the calorifico, the matting is swiftly removed and the blanket-wrapped beans are placed in sweating boxes.

• The beans are removed and examined after 24 hours.

• Following that, the dead beans are subjected to a series of sunnings and sweatings, as described above under “Sun-wilting.”

• If the weather is cloudy, the dead beans are held indoors on racks in a well-ventilated area until sunbathing is allowed.

• If the weather does not improve in three days, the batch is reprocessed using the calorifico and sweating box.

Tahiti Vanilla Curing Process

The beans are not killed artificially.They are collected when they reach maturity. This is characterised by the browning of the bean’s tip. Curing is done by specialised companies that use a process that is comparable to the Mexican curing method.

The major harvest occurs in February and March, with drying being completed in July and August.

• The green vanilla beans arrange them in stacks that are flipped daily.

• Beans that are completely brown, marking the end of vegetative life, are removed for sweating and drying.

• The ‘dead’ beans are stretched out on blankets sitting on high wooden racks for three to four hours in the sun.

• The heated beans are then wrapped in a blanket and placed in a sweat box for the night.

• This procedure is repeated for 15-20 days, with fewer and fewer nighttime sweatings.

• Then the beans are laid out in 10 cm layers to dry in the breeze.

• When the beans are dried enough, they are taken from the racks and packed into huge containers.

• The majority of beans are sorted and sold quickly after drying is done, with no extended “conditioning” time.

• If the beans are preserved for an extended period of time before sale, they are kept in tins.

About Vanillin

Natural vanillin is derived from the seed pods of Vanilla planifolia, a vining orchid native to Mexico that is currently grown in tropical locations all over the world. At the moment, Madagascar is the world’s greatest producer of natural vanillin.

The green seed pods contain vanillin in the form of its-d-glucoside when harvested; the green pods do not have the flavor or odor of vanilla.

How does vanillin develop in the curing process?

After being picked, their flavor is formed through a months-long curing process, the details of which differ across vanilla-producing countries, but in general, it goes as follows:

• To begin with, the seed pods are blanched in hot water to halt the activities of live plant tissues.

• The pods are then alternately sunned and sweated for 1–2 weeks: during the day, they are stretched out in the sun, and at night, they are covered in fabric and stored in airtight boxes to sweat. 

• The pods turn dark brown during this process, and enzymes in the pod release vanillin as a free molecule.

• Finally, the pods are dried and stored for many months, allowing their tastes to develop further. 

• Several methods for curing vanilla in days rather than months have been described, but they have not been widely developed in the natural vanilla industry, which focuses on producing a premium product using established methods rather than on innovations that may alter the product’s flavor profile.