Handbook of Vanilla Science and Technology

• Oxidized beans: Beans with dark spots and a metallic smell. This is caused by beans coming in contact with rusty iron during curing and storage.

• Phenolic beans: Beans with a creosote smell. The main reason for this to occur is the storage of harvested green beans a long time before they are killed for curing. Anaerobic storage of cured beans in vacuum packaging is also likely to lead to phenolic odors.

• Stinky beans: Beans with offensive smells like smoke, phenolics, kerosene, etc.

• Split beans: Beans that are split along their length. This happens when beans are left on the vines well past their maturity. These beans lose some of their resins during curing.

Fig. 9.2 Frosted vanilla beans.

9.2.2 Aroma of vanilla beans

The aroma of fully matured and well cured clean vanilla beans can be described with the following terminology:

• Barn yard.

• Floral.

• Hay like.

• Prune/Raisin.

• Resinous.

• Rummy.

• Smokey.

• Sweet.

• Spicy.

• Tobacco-like.

• Vanillin.

• Woody.

The qualitative variations in the aroma and flavor of vanilla of different species and geographic origins are quite distinctive. Various types of beans (Figures 9.3,9.4 and 9.5) can be described as follows:

Fig. 9.3 Vanilla beans from Madagascar, Indonesia and India.

Fig. 9.4 Vanilla beans from Tahiti, and Papua New Guinea.

Fig. 9.5 Vanilla beans from Mexico and Uganda.

• Bourbon vanilla (V. planifolia): The term used collectively for beans from Madagascar, Reunion, Comoro Islands, and the Seychelles. The aroma is sweet, creamy, rich, full bodied, tobacco-like, somewhat woody and animal, deep balsamic, and has sweet spicy back notes.

• Mexican vanilla (V. planifolia): The aroma of beans from Mexico is sharp, slightly pungent, sweet, and spicy, but lacks body as compared to Bourbon vanilla.

• Indonesian vanilla (V. planifolia): The aroma of beans from the Indonesian Islands is less sweet and creamy than Bourbon vanilla. It lacks bouquet, but has a strong woody and slightly smoky character and a freshly sharpened pencil note.

• Indian Vanilla (V. planifolia): The aroma of beans from India is full bodied but less sweet and creamy than Bourbon vanilla. It lacks balsamic notes but has slight pungent sour notes.

• Tahitian vanilla (V. tahitensis): The aroma of beans from Tahiti has distinct perfumed, flowery, fragrant, and anisic notes. It has a rather shallow and less intense vanilla character.

• PNG vanilla (V. tahitensis, V hapape, or possibly V politi): The aroma of beans from Papua New Guinea is weakly flowery and perfumed, and possesses anisic notes. Its flavor and aroma characters are weak in general.

• Guadeloupe vanilla (V. pompona): The aroma of beans from Central America has perfumed, floral, and sweet aromatics. Extracts made from these beans lack body.

A number of volatile aroma chemicals have been identified in the three vanilla species. A qualitative comparison of some of the major volatiles is presented in Table 9.2. An extensive characterization of the hundreds of volatile compounds present in vanilla beans is presented in chapter 11 by Toth et al. in this book. Characteristically 95% or more of the volatile components are present at concentrations below 10 parts per million. Although all chemicals that might be responsible for characterizing different species are not identified, anisic alcohol, anisic aldehyde, anisic ethers, anisic acid esters, and p-hydroxybenzoic acid, which may be responsible for perfumed, floral aromas, are found to be present in relative abundance in V. tahitensis. They are non-detectable or are present in trace quantities in V. planifolia, which lacks the floral notes. Adedeji et al. (1993) and Tabacchi et al. (1978) have confirmed the presence of p-anisyl alcohol, m-anisaldehyde, m-anisate, and anisic acid in Tahitian and Guadaloupe vanillas. Adedeji et al. (1993) identified acetic acid, 3-methyl-2-pentanone, methyl pyruvate, anisyl acetate, acetylfuran, methyl furoate, 5-methyl-2(3H)-furanne, and half a dozen other minor components for the first time as Tahitian vanilla volatiles.

Table 9.2 Characterizing volatiles in three vanilla species. The number of + signs indicates relative abundance; — sign indicates absence; + /— sign indicates traces to absence (Tabacchi et al. 1978, Lhuguenot 1978, Oliver 1973)

 — | V. planifolia, | V. tahitensis | V. pompona

Vanillin | + + + + + | + + + + | + + +

Anisyl alcohol | — | + + + | +

Anisic acid | + /— | + + + | +

Anisic aldehyde | + /— | + + | +

p-Hydroxybenzoic acid | + | + + + | + +

p -Hydroxybenzaldehyde | + + | + + | +

Protocatechaldehyde | + | + + | +

Vanillic acid | + + | + + | +

Protocatechuic acid | + /— | + /— | +