Handbook of Vanilla Science and Technology

Flowering occurs once a year over a 2 to 3 month period. In Northern Australia (Darwin/ Cairns), flowering occurs in the period October to December at the beginning of the wet season, during the time locally known as the “build up”.

5.14.2 Fruit set (pollination)

The hand pollination method perfected on the Ile de la Reunion by Edmond Albius in 1841 is today still the only reliable method used to pollinate the flowers. This is almost certainly the reason for vanilla’s reputation as a high labor crop in Australia. This relatively simple but critical task must be carried out each morning during the flowering season. The flowers only remain viable for one day and the most reliable time to pollinate them is in the morning. The description of the process for pollinating the flowers is:

• The lip is lowered and torn with a toothpick (or bamboo stick) to expose the column and anther.

• The rostellum is lifted up with a toothpick (or bamboo stick) and placed under the stamin.

• Gentle finger pressure is applied to bring the pollen and stigma into contact.

Care must be taken not to over pollinate the flowers on any given vine, as this can place excessive stress on the vine, ultimately resulting in a poor crop and failure of the vine. A rule of thumb in the industry is to pollinate around half the flowers and the practice is followed in most regions by pollinating only the flowers on the lower side of the raceme. This also allows the beans to hang straight down, aiding in the production of straight beans, an essential trait in the premium market.

5.14.3 Growth and maturation

The growth of the beans occurs over the next 8 to 12 weeks after pollination. At the end of the flowering season, in late December to mid-January, small, crooked, and damaged beans are removed. The long process of maturation or ripening then begins, with the beans reaching maturity from late June through August.

5.15 HARVESTING

Harvesting the beans is carried out 7 to 9 months after flowering and pollination when the head (or tip) of the bean (the free end) starts to turn yellow and the rest of the bean takes on a less green (paler) color, changing towards yellow. A delay in harvesting at this time will lead to a high number of split beans, which lowers their value considerably. Bringing it forward and picking too early leads to a poor quality bean in terms of the development of its aroma and flavor characteristics, particularly the vanillin content. This is due to insufficient gluco-vanillin development, the precursor to vanillin, which is released during curing. As a result, it is necessary to harvest the beans progressively by hand, as they ripen to achieve the best quality product.

5.16 CURING

5.16.1 Overview

The key to quality premium vanilla beans is the curing. It is during curing that the enzymatic process that converts the glucovanillin into vanillin occurs (this process is described in detail in the chapter 6 by Frenkel et al.). The appearance of a crust of fine white crystals on the cured vanilla beans is considered by many to be a sign of high vanillin content. The crust is in fact crystallized vanillin. The primary determinant of quality for cured vanilla beans is the aroma/ flavor character. Other quality factors include general appearance, flexibility, length, and vanillin content. Traditionally, the visual indicators of a blemish free appearance, flexibility, and size characteristics have been important because there is a close correlation between these factors and the aroma-flavor quality.

There are two principle methods for curing vanilla, the Bourbon method and the Mexican method (see chapter by Frenkel et al.). Others exist, but they are hybrids or variations of the two systems. Australian growers presently predominantly use a variation of the Bourbon method adapted to the local conditions.

The final step is to package the beans for sale. Traditionally, 10 to 12 kg of vanilla bundles are packed into tin boxes lined with paper. However, Australian growers are focused on packaging and marketing direct to retail. Direct sales to the consumer market for home/gourmet cooking and baking requires packaging of 1 to 3 beans for this premium segment. The preferred packaging is vacuum-sealed plastic satchels, and glass or aluminium tubes.

REFERENCES

Bailey, J.F. (1910) Introduction of economic plants into Queensland. Presidential Address - Royal Society of Queensland, February 26.

Newport, H. (1916) Vanilla Culture for Tropical Queensland, 2nd Edn, Anthony James Cumming, Government Printer - Brisbane.

Ridley, H.N. (1912) Spices. Macmillan and Co. Ltd, London.

6 Curing of Vanilla

Chaim Frenkel, Arvind S. Ranadive, Javier Tochihuitl Vázquez and Daphna Havkin-Frenkel

6.1 INTRODUCTION