Morphological Specificities and Diversity
Tahitian vanilla is characterized by a more slender stem than V. planifolia or V. pompona with an average stem diameter of 8 mm and internodes of 13 cm length, sometimes very long, up to 19 cm. The leaves are also thinner (Figure 13.2), narrow– oval, lanceolate, gradually become very pointed, 3–7 times longer than their width, dark green in color, not very thick, not or very little in gutter toward the base, 16–25 cm in length, and 2–5 cm broad; the petiole is 15 mm in length on an average, and well canaliculate above.
FIGURE 13.2 Comparison of the size and shape of leaves of V. pompona, V. planifolia, and V. tahitensis cv Haapape (from left to right).
FIGURE 13.3 Comparison of flowers of V. pompona, V. planifolia, and V. tahitensis cv Haapape (from left to right).
The Tahitian vanilla flowers are assembled into an inflorescence. On an average, the inflorescences are 9.2 cm long, greenish, with some parts more yellow than those of V. planifolia (Figure 13.3). The sepals are narrow-oblanceolate, pointed at the base, attenuate-acute at the top, 9–16 mm broad, 55–77 mm long, and nonducted with the back. The petals are also 50–74 mm long, 7–13 mm wide, elliptic, and subacute. The labellum is 46–49 mm in length and funnel-shaped, shows small orange dotted lines on its inner face with a revolute margin, and is fimbriate-crenelated. The Tahitian vanilla fruits, aromatic, are generally indehis-cent contrary to V. planifolia pods.
Today, the main Tahitian vanilla cultivars are Tahiti and Haapape. But local farmers distinguish about 14 cultivars, which differ by the shape, length, and width of the leaves, the size of the flowers, and the size and shape of the beans. The five main cultivated forms are described below and shown in Figures 13.4 through 13.6.
Tahiti
The stem is on an average 8 mm in diameter with internodes of 13 cm length. The leaves are not or very little in gutter toward the base and measure about 18 cm in length, and 3 cm in width with a petiole of 13 mm length. The sepals are 14 × 65 mm on an average, and the petals 11 × 64 mm. The labellum is white with short hairs and dotted lines of dark orange color. The fruit is clear green in color, trigonal and 10–19 cm long (14 cm on an average) and weighs on an average 10.5 g. The pods show little dehiscence with maturity.
Haapape
The stem is larger than “Tahiti,” with, an average diameter of 10 mm and internodes of 16 cm length. The leaves present a gutter, measure about 17 cm in length and 3 cm in width with a petiole of 18 mm length. The flowering is less abundant than “Tahiti,” but the larger flowers of Haapape are easier to marry. The sepals and petals are longer than those of “Tahiti”: an average of about 13 × 70 mm and 10 × 68 mm respectively.
FIGURE 13.4 Plant and leaf shapes of the main Polynesian cultivars of vanilla.
FIGURE 13.5 Color diversity of the labellum of Tahitian vanilla: (a) cultivar Rea rea; (b) cultivar Haapape.
FIGURE 13.6 Variation in size, shape, and color of Tahitian vanilla beans: (a) Tahiti, (b) Haapape, (c) Rea rea, (d) Parahurahu, and (e) Tahiti long. The yellow label is 10 cm long.
The labellum is white, with long hairs and dotted lines of dark orange color. The fruits are of very dark color, rounded, blunt at the end and 13–23 cm long ( average 18 cm) and weigh an average of 16.3 g. The beans are very rarely dehiscent with maturity.
Rea Rea
The stem is thinner, with, an average diameter of 7 mm and relatively short inter-nodes of 13 cm length. The leaves, more oblong than lanceolate, are about 20 cm long, and 4 cm wide with a petiole of 16 mm length. The sepals are about 13 × 62 mm and the petals are 11 × 61 mm. The labellum is white with light orange color dotted lines. The fruits, trigonal, of green–light yellow color, and 11–17 cm long (average 14 cm) and weigh about 9.9 g. The beans are fairly dehiscent with maturity.
Parahurahu
The stem is also thin, measuring an average of 7 mm in diameter with internodes of 14 cm length. Leaves, not or very little in gutter toward the base and present a more apiculate end than pointed and are about 15 cm long and 3 cm wide, with a petiole of 16 mm length. The sepals are about 12 × 63 mm and the petals are about 10 × 61 mm. The labellum is white with white hairs and dotted lines of light orange color. The beans, of dark green color, present the shape of a bludgeon, are 10–18 cm long (14 cm on average) and weigh about 14.1 g. The beans are very rarely dehiscent with maturity.
Tahiti Long
The stem is thin, measuring about 7 mm in diameter with short internodes of 13 cm. The leaves are not or very little in gutter toward the base and are about 15 cm long and 3 cm wide with a petiole of 15 mm length. The flowers are smaller than those of the previous cultivars; the sepals are on average 11 × 59 mm and the petals are 9 × 58 mm. The labellum is white with long hairs and exhibits light yellow dotted lines. The end of the labellum has a thorny form. The fruits, of light green color, are rounded-off, thin, blunt at the end, and 11–24 cm long (average 17 cm) and weigh about 11.1 g. The beans are rarely dehiscent with maturity.
Growers distinguish many other morphological types than those described above. These types differ in the size and width of their leaves and the size, shape, and color of their fruits. These vanilla types are not really cultivated because their fruits do not obey the criteria defined by the regulations (for details, see Chapter 24), but they exhibit a real morphological diversity. Examples: Oviri, which has smaller leaves (14 cm × 3 cm) than “Tahiti” and shorter fruits (11 cm on average); Puroini, which possesses leaves with the shape of a heart; Potiti and “Tahiti” or “Haapape” have the same leave size and shape, but “Potiti” produces very small fruits (average 10 cm). Finally, a “bicolor” (variegated) vanilla plant whose leaves show light yellow stripes is also present in farming systems.
Chemical Composition of Tahitian Vanilla
Tahitian vanilla is very different from other vanillas cultivated in the world, particularly when compared to V. planifolia because of its subtle flavor and rich anise fragrance, and the glossy and flexible aspect of its beans.
To characterize the originality of Tahitian vanilla, methods were developed at the laboratory of the “Etablissement Vanille de Tahiti” to analyze its chemical composition, especially the molecules of interest–namely, aroma compounds and fatty acids.
Aroma Composition of Tahitian Vanilla
Thanks to their sensory properties, vanilla pods are mostly studied for their aroma compounds. The first comprehensive work on vanilla volatiles was carried out in 1976 by Klimes and Lamparsky, who identified, by gas chromatography (GC)–mass spectrometry (MS), 169 compounds in V. planifolia.