Handbook of Vanilla Science and Technology

Prices for green vanilla are set by curers-exporters who consider world prices, supply and demand, costs for curing and exporting, etc., in order to ensure a profit. In recent years, vanilla growers have been forced to sell green vanilla at a loss, on average $4 USD/kg. One exception are growers who sell to the Consejo Nacional de Productores de Vainilla (Asociación de Vainilleros), at a fixed price of $8 USD/kg (2008-2009 harvest), for beans that are larger and better quality than average. Growers are paid only after the vanilla is cured and sold. Some growers have also sold green vanilla to private companies, for as much as $12 USD/kg, but for individually harvested beans longer than 20 cm.

1.15 CURING

The curing process allows for the development of aromatic compounds and flavor in vanilla beans that can be used in different industries and applications.

In Mexico, curing is accomplished in a traditional, artisan style that includes ovens, and sun curing of vanilla beans laid out on mats of woven palm (“petates”) to facilitate cellular breakdown and dehydration (Figure 1.6).

Fig. 1.6 Sun curing of vanilla beans on mats of woven palm.

The entire process lasts 3 to 5 months (January-May), and consists of:

ISelection and “despezonado'': Beans are detached from the rachis, or “pezon”, and sorted by size and type. The type classes are “entire”, “split” (i.e. when the vanilla beans have opened), “painted/spotted” (fruits infected by Colletotrichum sp.), and “zacatillo” (i.e. small and curved beans). Each class is cured separately, because of the differences in quality.

IICellular breakdown in ovens, or “killing'': This step terminates the cellular processes of the beans, and among other consequences, prevents beans from opening further. The fruits are placed in wooden boxes or inside folded petate mats, and placed in ovens from 24 to 48 hours at a temperature of 60°C. Afterwards, the fruits are removed and placed in larger “sweat boxes ’ ’ for usually 18 to 24 hours (but sometimes as long as 48 hours) to receive their first sweat. The sweat-boxes are capped with matting and petates to prevent heat loss so that the beans continue to sweat. In recent years, some curers have replaced the oven method with the Bourbon process of killing beans in hot water, as is used in Madagascar.

IIISun curing and successive sweating: The fruits are removed from the sweat boxes and placed on petates on a patio with full sun for 3 to 4 hours, during which they are allowed to reach a maximum temperature of 50 to 55°C. Immediately afterwards the beans are returned to the sweat-boxes and once more are insulated with a covering of petates in order to conserve heat and allow the beans to gradually lose water. The following morning, usually between 9 to 10 a.m, the beans are taken out of the boxes and repositioned on the patio in full exposure to the sun. This cycle of sun curing followed by sweating is repeated until the beans reach a 30% humidity content and a dark brown color, usually after 11 cycles for younger, less mature fruits and 24 cycles for fully mature fruits.

IVClassification of cured beans: Due to the fact that the curing process is not uniform, beans are re-classified according to how they feel and look. This is usually done after 8 to 11 cycles of curing. The beans are grouped according to their thickness (thick, intermediate, or thin), which is an indicator of moisture content. Once sorted and separated, these groups receive different amounts of curing/sweating. When curing is finished, the beans are re-classified again, this time according to thickness, flexibility, and color. The classification scheme includes three categories, “supple/raw”, “bland”, and “dry”, indications of the progress of the curing.

VConditioning: Beans classed as “dry” are no longer cured, but instead placed on wooden racks (“camillas” ) so that they continue to gradually develop flavor and aroma. The beans are also inspected at this point to verify that they were adequately cured. If the beans show indications of colonization by fungus, their moisture content is too high, and the beans are returned to the sun to be dry further. Conditioning lasts 30 to 45 days, with every 15-day period serving to mark another round of inspection.

VIClassification: Beans that show no problem of developing fungus are classified by length and quality (color, sheen, flexibility, and aroma) (Figure 1.7).

Fig. 1.7 Classification of cured vanilla beans.

1.15.1 Yield ratio of green/cured vanilla