VANILLA BEANS CURING SYSTEMS
POST HARVEST TECHNOLOGY FOR QUALITY BEANS
VANILLA GROWERS SUPPORT FOR BEST BEANS
Harvesting is the most important step in the journey of vanilla for quality. Normally most farmers tend to collect beans by bunch which should be discontinued and only ripe beans harvested as this leads to better end products.Collect the matured beans when you see the tip turning little yellow and when you feel the growth phase is completed.
CURING OF VANILLA BEANS:
The primary quality determinant for cured vanilla beans is the aroma
/flavour character. Other factors of significance in quality assessment are the general appearance, flexibility, the length and the vanillin content.
The relative importance of these various quality attributes is dependent upon the intended end-use of the cured beans.
Traditionally, the appearance, the flexibility and size characteristics have been of importance since there is fairly close relationship between these factors and the aroma/flavour quality. 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. 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 high (30 to 40 per cent), whereas it may be as little as 10 per cent in the lower grades. At one time, the presence of a surface coating of naturally exuded vanillin crystals
('frosting') was regarded as an indicator of good quality, though this is no longer considered so.
Mexican curing methods
The two main traditional forms of curing employed in Mexico are the sun-wilting and the oven-wilting procedures. The former is the oldest known method of curing and the latter was introduced around 1850. Both methods are still widely used by the specialist curing firms in Mexico which process the vast bulk of the vanilla crop. The harvesting period in Mexico extends from November to January and curing by either method takes around five to six months before the product is ready for the market.
'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 shrivel.
The fresh beans first have their peduncles removed and are then sorted according to their degree of maturity, size and into unsplit and split types. This is done as the various sorts cure at different rates. Beans, which are already beginning to darken, are removed, wiped with castor oil and are cured separately.
The beans are killed by exposing them to the sun for a period of about five hours on the day after sorting. The fresh beans are spread out on dark blankets resting on a cement patio or on wooden racks. In the afternoon, the beans become too hot to hold by hand and are then covered by the edges of the blanket.
In the mid-to late afternoon before the beans have begun to cool, the thick ends of the beans are laid towards the center of the blanket and rolled up. The blanket rolls are immediately taken indoors and are placed in blanket-lined, air tight mahogany boxes to undergo their first 'sweating'. Blankets and matting are placed over the sweating boxes to prevent loss of heat. After 12 to 24 hours, the beans are removed and inspected. Most of the beans will have begun to acquire a dark-brown colour indicating a good 'killing'.
Beans which have retained their original green colour or which have an uneven coloration are separated and are subjected to oven-wilting.
Those beans, which have been properly killed, are next subjected to a process involving periodic 'sunnings' and sweatings. 'Sunning' entails spreading the beans on blankets and exposing them to the sun for two to three hours during the hottest part of the day when weather conditions are favourable.
During the remaining part of the day, unless a sweating is to be undertaken, the beans are stored indoors on wooden racks in a well-ventilated room. There are two distinct phases to this sunning/sweating stage. The first phase involves a fairly rapid drying in which the beans are given 'sunnings' virtually every day and several overnight sweatings until they become supple. This takes about five to six days. A preliminary sorting into lots corresponding to the various grades is usually carried out at this juncture.
This is followed by further 'sunnings' and additional but less frequent sweatings. In practice, 'sunnings' are not carried out every day in this second phase since, apart from constraints imposed by the weather, too rapid drying is considered to be detrimental to quality.
Some 20 to 30 days after killing, most of the beans become very supple and acquire characteristics close to those of the final product and are ready for the next stage of very slow drying indoors. The total number of sweatings undertaken during the sunning/sweating' operation can vary between four and eight.
Those beans, which require a large number of sunnings and sweatings generally, provide a low-quality product.
Very slow drying indoors lasts for approximately one month and a further sorting into grades is usually carried out during this time. The beans are regularly inspected and those, which have achieved the requisite state of dryness, are immediately removed from the racks for 'conditioning'.
The overall sweating and drying operation may take up to eight weeks from the time of 'killing', according to the prevailing weather conditions. Small and split beans are usually ready for conditioning earlier than perfect, large beans.
Beans removed for conditioning are sorted again and are straightened by drawing them through the fingers. This operation is also useful in that it spreads the oil, which exudes during the curing process and gives the beans their characteristic luster. The beans are next tied into bundles of about fifty with black string.
The bundles are wrapped in waxed paper and are placed in waxed paper lined, metal conditioning boxes. Conditioning lasts for at least three months and during this period the beans are regularly inspected. Mouldy beans are removed for treatment (see later) and those, which are not developing the required aroma may be re-subjected to 'sunnings and sweatings'. At the end of the conditioning period, the beans are given a final grading and are packed for shipment.
'Oven-wilting'- In this procedure, use is made of a specially constructed brick or cement room, known as a calorifico, which serves as an autoclave.
The room measures approximately 4 x 4 x 4 metres and incorporates a wood-fired heater, which is stoked from the outside. It is fitted with a small access door and has wooden racks fitted along the walls.
The beans to be killed by this method are divided into piles of up to 1000 and are then rolled up in a blanket, which is finally covered with matting to form a malleta. The malletas are moistened with water and are placed on the shelves in the calorifico. Water is poured onto the solid floor to maintain a high humidity, the door is closed and the heating fire is lit.
In about 12 hours, the temperature inside the calorifico reaches 60 °C.
After a further 16 hours, a temperature of 70 °C is attained and this is maintained for another 8 hours. The malletas are removed after a total of 36 hours in the calorifico. If the temperature cannot be raised above 65 °C, then the total period of autoclaving is extended to 48 hours.
On removal from the calorifico, the matting is quickly stripped from the malletas and the blanket wrapped beans are placed in sweating boxes. After 24 hours, the beans are removed and inspected.
The killed beans are then subjected to repeated sunnings and sweatings, as described above under 'Sun-wilting'. Should the weather be overcast, the killed beans are stored on racks indoors in a well-ventilated room until sunning is possible. However, if the weather does not improve within three days, the batch is reprocessed through the calorifico and sweating box.
Curing of Tahiti vanilla
Since V. tahitensis is indehiscent, the beans are not killed artificially but are harvested when mature. The tip of the bean turning brown characterises this. The curing is carried out by specialist firms, which employ a method bearing similarities to the Mexican procedure.
On receipt by the curing firms, the beans are placed in piles, which are turned daily. Beans, which are entirely brown, indicating that vegetative life has ceased, are removed for sweating and drying. The 'killed' beans are spread out on blankets resting on raised, wooden racks and are exposed to the sun for three to four hours. The warm beans are then rolled up in the blanket and are placed in a sweating box overnight.
This process is repeated for fifteen to twenty days with progressively less frequent overnight sweatings. Finally, the beans are left outside in layers 10 cm deep to dry in the wind. When at the requisite state of dryness, beans are removed from the racks and are placed in large crates.
Most beans are sorted and sold shortly after drying has been completed and without any lengthy 'conditioning' period. The main harvest is collected during February and March and drying is usually completed during July and August. If the beans are kept for a long period before sale, they are stored in tins.
Storage and keeping of vanilla:
Storing fo the vanilla beans after the process of slow conditioning is also very critical for the quality. The final aroma will gerat extend depend on the way the vanilla beans are stored and maintained. Similarly handling at differnet stages of the vanilla curing involves specialised trays and material handling equipments that are apt for the quality in the process.
Pests and disease in storage can be caused by Molds and fungus, Hard fungus and scales, mite infection and proper phytosanitary precautions should be undertaken.
Storage room should be clean and well maintained with proper aeration and humidity controls. All wrapping materials should be sterilised for use. The infected beans should be isolated from the main section.
Excess drying will cause loss of moisture and make the beans more brittle as it ages.
Mostly beans that are shipped for export are vacuum packed to avoid air related problems affecting the beans and help keep the beans intact for more time. Suitable vacuum packing systems and polyliners used for this purpose should be identified and used.
Other methods for V. fragrans :
The Guadeloupe technique entails killing by making scars with a pin along the faces of the bean and then exposing the beans, wrapped in a blanket, to the sun for a few hours. The pin, which should be sterilised regularly, is fitted into a cork to protrude no more than 2 mm. After killing, the curing process is similar to that of Mexico.
Two other methods, which tend to provide a poor-quality product, are the 'Guiana method' and the 'Peruvian process'. The' Guiana method' involves killing the beans by placing them in the ashes of a fire until they begin to shrivel. On removal, the beans are wiped clean, rubbed with olive oil, the lower ends are tied with string to prevent splitting, and they are then left to dry in the open air. In the 'Peruvian process', the beans are killed by immersion in boiling water and are then tied at the ends and hung up in the open air. After drying for about twenty days, the beans are lightly smeared with castor oil and are tied in bundles a few days later.
No distinctive local method of curing appears to have been evolved in Java. Modifications of the Mexican and Bourbon methods were commonly used but in general less care seems to have been taken in curing and grading. The quality of the Java product has never compared favourably with those of Mexico or the Bourbon producers.
VANILLA FOUR STAGE CURING
TRADITIONAL CURING METHODS
Post Harvest Processing and curing of Vanilla beans is an important part of the beans cultivation. To get quality curing one should have good technical idea about the curing process. There are several nuances to the process of bourbon curing process as practicised by curers around the world and one has to do a bit of research before commencing ones own techniques.
The most significant aspect of good quality vanilla lies in the judicious selection of the harvest time. Vanilla beans usually gets ready for harvesting after nine months from flowering and pollination. The beans that are fully matures are harvested one at a time when they have completely matured and is seen by the look of the beans and their colour whne they begin to ripen.
At the ripe stage the beans change colour from dark green to light and yellow at the tip. Immature beans harvested produce an inferior product and if picked too late tend to split during curing process. Bunch and brooom harvesting should be avoided at all costs. The well ripened beans detach from the bunch easily just by lifting them in the reverse direction. Immature beans do not detach easily from the stalk; but on the other hand leave behind a bit of the bean in the bunch. Hence to pick the beans at the rigth stage , more visits are required by the planter and should be done frequently in a week as they mature.
The green beans as such have no aroma or vanillin in them and processing should be commenced as early as possible, maximum in a week of harvest.
FOUR STAGES IN VANILLA
SORTING AND GRADING OF GREENS:
Size and appearance get the primary importance in the sorting process and these have a paramount importance to the quality of vanillin present and aroma. The beanas are graded in the green stage itself as A,B,C,and D according to the length of the beans. Those which are more than 15 cms are classified as A grade. Between 10-15 cms are graded as B and less than 10 cms are classified as C grade. Those which are split, cut or damaged or bruised are taken as Grade -D.
Cleaning: The sorted and graded beans are claened and washed in pure quality fresh water. Bordeaux stains or chemicals if any are cleaned thoroughly if present and can be swabbed using concentrated tamarind water or sour buttermilk.
A number of procedures have been evolved for the curing of vanilla but they are all characterised by four phases :
(1) 'Killing' or wilting:
This stops further vegetative development in the fresh bean and initiates the onset of enzymatic reactions responsible for the production of aroma and flavour. Killing is indicated by the development of a brown coloration in the bean.
The sorted and graded beans have different killing time as it determines the stopping of the vegetative growth and controlling the chemcial changes in the beans and is very important step in the whole process. Usually growers tend to dip or immerse the beans in controlled hot water whose bath temperature is maintained at 65* C for s asepcific time frame depending on the grade. Usually the maximum time of 4 minutes is provide for Grade A beans and decreasing time for the rest fo the beans in the sense - 3 minutes for Grade-B , 2 minutes for Grade-C and 1.5 minutes for Grade D accordingly.
Once the beans reach the temperature of the bath they need to be maintained in the warmth for some time to complete the conversion and so the sweating process becomes very critical.
This involves raising the temperature of the killed beans to promote the desired enzymatic reactions and to provoke a first, fairly rapid drying to prevent harmful fermentations. During this operation, the beans acquire a deeper brown coloration and become quite supple, and the development of an aroma becomes perceptible.
The killed beans are then transferred to a box lined with woolen blankets or insultaion to maintain the temperature at 48-50*C for the sweating process to complete for a period of 24- 40 Hrs and is charecterised by the whole beans turing to a supple Brown colour and vanilla aroma. If the process is incomplete then it means the killing is not complete and need to be repeated until you get a swollen brown and plump vanilla bean.
Depending on the bean quality sun drying for 7 days from 11 am to 2 pm is done and once the bean temperatures raise to 50* C the beans are wrapped in woolen blanket and stored in wooden chests.
The third stage entails slow drying at ambient temperature, usually in the shade, until the beans have reached about one-third of their original weight.
There are two kinds of drying which helps to bring the moisture in the beans to be brought down to 25 percent levels. Sundrying for a period of week or so is followed. The beans are spread on wooden slats or shelves or clean blankets on level surface for a period from 12 AM to 3 PM or so until the beans reach a unifomr temperature of 50 - 55 * C and then they are wrapped back in the blanks and shifted back to the bundles for sweating to continue.. It is preferable to have it in a hot dry atmosphere to maintain a high heat and dry atmosphere to attain uniform moisture loss. They are kept for the whole night in the sweating boxes or enclosures and repeated to bring a uniform texture.
At the end of the period the beans lose half their weight and turn to a shining dark brown colour and rich aroma. It is important to do kneading fo the beans inbetween fingers if possible as it improves the beans suppleness and texture..
Sweating and sun drying for Grades B,C,D are less than one week compared to A grade beans..
(4) Slow drying and conditioning of the beans:
In the final stage, known as 'conditioning', the beans are stored in closed boxes for a period of three months or longer to permit the full development of the desired aroma and flavour.
The two most important of the various traditional procedures for curing vanilla beans are those of Mexico and the Indian Ocean islands producing 'Bourbon' vanilla.
The steps involved is in slow curing is a lengthy and seasoning of the beans in a controlled air temperature and humidity system. Usually beans are kept in trays and in racks with two or three layers to get uniform exposure to drying. Normally the temperatures in these rooms are maintained at 35 *C and humidity at around 65-70 RH. The slow drying time for each grade varies accrding to their quality. Usually for A grade - it is around 35 days and with 20- 25 days for grade B and 3-10 days for Grade C and 2-8 days for Grade D beans.
On the completion of slow curing the beans get uniform texture and shrivel to have longitudinal lines and turn lustrous and brownish chcolate colour and become very supple. They are soft to touch and can be twisted around the finger like an elastic band. The moisture could be around 30 -35 percent .
The final conditioning is obtained when bundles of beans are stored inside a dry box of wood or metal caskets for around one two months after open curing. Usually the beans are tied together and bundled and wrapped in oily wax paper selected for the purpose to have seasonal conditioning.. It is better to have it ina warm atmosphere of 30-35 *C room.. this helps in getting the moisture to around 25 percent which is acceptable international standards. Depending on the grade usually a drop of 4.5-1 or 6-1 is exhibited in weigth loss of the beans in the process depend on the quality and type of beans.. It is better to keep them in airtight containers to avoid further moiture loss and mould formation.
Some beans usually get crystal formation in the form of vanilla sugar crystals formed on the surface an indication of fine quality beans. There also is a fine oily appearnce which can be felt on the beans. Normally if a dried apperance is obtained it means the quality is inferior. Fragrance is also an important indicator of the type of beans. If proper care is taken in curing good quality and uniform lots are possible..Bacterial and fungal infections are to be avoided in the beans at any cost.
Organic quality beans are considerd as premium grades in the beans.
Curing at any cost should not be delayed from Harvest and care should be taken in handling sizeable lots of beans as overloading helps to bruise the beans...
Selecting the right beans for harvest is the secret to successful quality in the beans.
Temperature in killing at any cost should not exceed 65*C and timing is also very critical.
Sweating for longer duration will initiate rotting of the beans.
Sundrying for a specific period is also as critical to the process for the vanilla compounds to form properly. Continuous physical examination of the lots of the beans helps to have a uniform quality in the beans.
Moulds : Moulds are fungal infection on vanilla curing and should be controlled right when seen. The said beans should be subjected to killing again at 65*C water for a few seconds and then process of drying repeated until the mould goes away.
Time is the essence in the whole process and quality should be inspected at evary stage including a cross check on the weight of the beans as it progresses through the satages will be critical in identifying the right mix and practice.
Bourbon curing method
Bourbon vanilla is the name given to the product from the former French possessions in the Indian Ocean, which employ a curing technique first developed on the island of Reunion, formerly known as Bourbon. Production of Bourbon-type vanilla is now dominated by Madagascar, with the Comoro Islands and Reunion as smaller but important sources.
The Bourbon curing technique is distinguished from those of Mexico in that 'killing' is achieved by scalding the beans in hot water and fewer sweatings are undertaken. The Bourbon product usually has higher moisture content than the corresponding Mexican grade and is frequently frosted. As in Mexico, curing of vanilla is carried out by specialist firms rather than by the vanilla growers.
Slight variations in the curing technique are practiced in the various producing islands and the following is a description of the procedure evolved on Madagascar:
On arrival at the curing factory, the beans are sorted according to the degree of maturity, size, and into split and unsplit types. Batches of beans, weighing 25 to 30 kg, are loaded into openwork cylindrical baskets, which are then plunged into containers full of hot water heated to 63 to 65 °C over a wood fire. Batches of beans, which will eventually make up the top three qualities, are immersed for 2 to 3 minutes, while smaller and split beans are treated for less than 2 minutes.
The warm beans are rapidly drained, wrapped in a dark cotton cloth and are placed in a cloth-lined sweating box. After 24 hours, the beans are removed and inspected to separate those, which have not been properly killed.
The next stage of sun-drying is carried out on a plot of dry, easily drained ground, at some distance from roads to avoid contamination by dust. The killed beans are spread out on dark cloths resting on slatted platforms, constructed from bamboo and raised 70 cm above the ground. After one hour of direct exposure to the sun, the edges of the cloth are folded over the beans to retain the heat. The cloth-covered beans are then left for a further two hours in the sun before the blanket is rolled up and taken indoors. This procedure is repeated for 6 to 8 days until the beans become quite supple.
The third stage involves slow drying in the shade for a period of 2 to 3 months. The beans are spread on racks, mounted on Supports and are spaced 12 cm apart in a well-ventilated room. During this slow drying operation, the beans are sorted regularly and those which have dried to the requisite moisture content are immediately removed for conditioning. In some localities in the Bourbon producing areas, where the weather is frequently inclement during the sun-and indoor-drying periods of curing, ovens set at 45 to 50 °C have traditionally been used.
Conditioning of the beans is carried out in a similar manner to that described for Mexico and takes about 3 months for completion. The overall curing process for Bourbon vanilla lasts for 5 to 8 months. The main harvesting season in Madagascar extends from June to early October.
A modification to the traditional Bourbon curing method was devised in Puerto Rico in the 1940s and was adopted by the vanilla co-operative at Castaner. On arrival at the factory, the beans are sorted into split and unsplit types and are then killed as soon as possible.
Prior to killing, the beans are wiped with a damp cloth. Scalding entails three 10-second immersions at 30-second intervals in a water bath at 80 °C. After draining, the beans are wrapped in a blanket and are placed in a sweating box. Killing is followed by daily two-hour sunnings and overnight sweatings for about seven days until the beans become supple.
The next stage of indoor air-drying is continued until the beans reach one-third of their original weight. The beans are then bundled and conditioned in tin boxes until they dry to one-quarter of their original weight.
By contrast to Bourbon vanilla from the Indian Ocean producers, Puerto Rican vanilla scalded at 80 °C rarely frosts. When the weather is unsuitable for sunning, the beans are sweated in a closed oven at 45 °C containing a pan of water.