Key volatile aroma compounds of three black velvet tamarind (Dialium) fruit species
- Application of aroma extract dilution analysis on tamarind extracts obtained by SAFE yielded 19 odorants of importance.
- Results of OAVs and sensory analysis revealed significant differences in odour profiles between species.
- The differences were mainly caused by linalool, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, limonene, (Z)-3-hexenal and nonanal.
Nineteen odour-active compounds were quantified in three black velvet tamarind fruit species. Calculation of the odour activity values (OAVs) of the odorants showed that differences in odour profiles of the tamarinds were mainly caused by linalool, limonene, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, nonanal, and (Z)-3-hexenal. On the basis of their high OAVs, cis-linalool oxide (furanoid), geranyl acetone, and cinnamyl acetate were identified as other potent odorants in the three tamarinds. Sensory studies revealed very distinct aroma profiles, which are characteristic of these types of fruits. While the Dialiumguineense elicited floral, flowery, caramel-like notes, the other two species were dominated by leaf-like, caramel, and green notes.
- Black velvet tamarind fruits;
- Aroma-active compounds;
- Stable isotope dilution assay;
- Odour activity values
Chemical compounds studied in this article
- (E)-2-dodecenal (PubChem CID: 5283361);
- Acetic acid (PubChem CID: 176);
- Geraniol (PubChem CID: 637566);
- Cinnamyl acetate (PubChem CID: 5282110);
- (Z)-3-hexenal (PubChem CID: 643941);
- 4-Hydroxy-2,5-dimethyl-3(2H)-furanone (PubChem CID: 19309);
- Benzyl alcohol (PubChem CID: 244);
- Linalool (PubChem CID: 6549);
- Nonanal (PubChem CID: 31289);
- cis-Linalool oxide (furanoid) (PubChem CID: 6428167)
Cultivation and the interest in wild edible fruits such as black velvet tamarind have grown due to their comprehensive protective effects, especially their antioxidant activity (Adepoju, 2009). Black velvet tamarind is a common name for several trees in the genus Dialium, and may refer to the following: Dialium guineense; Dialium indum, and Dialium cochinchinense. D. cochinchinense and D. indum are native to southeast Asia, while D. guineense is found in Africa. D. guineense is a tall (30 m), fruit-bearing tree. It belongs to the Fabaceae family, and produces fruits that are enclosed in a brittle shell. The seed is embedded in a dry brownish sweet slightly sour edible pulp. The fruiting period is usually between the months of March and May but may be earlier and sometimes persist longer. Black velvet tamarind is commonly present in humid dense forests of west Africa, and central Africa. Its native range includes Benin Republic, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Equatorial Guinea, Ghana, Nigeria and Senegal ( Ajiwe, Okeke, Agbo, Ogunleye, & Ekwuozor, 1996). The fruits are consumed for their sweetly edible pulp which is rich in vitamin C (35.7 mg/100 g) ( Achoba, Lori, Elegbede, & Kagbu, 1992), and β-carotene (362 μg/100 g) ( Adepoju, 2009) respectively.
The genus Dialium comprises of five species in Africa with three of them commonly found in Nigeria. The three species are D. guineense, Dialiumdinklagel and Dialiumpackyphyllum ( Ogu & Amiebenomo, 2012). The pleasant organoleptic properties of these fruits explain its increasing popularity in west Africa. It is worth mentioning that the world production and trade of fresh tropical fruits are expected to expand over the next few years. Presently, developing countries account for about 98% of total production, while the developed countries account for 80% of the world import trade ( FAO Corporate Document Repository., 2013). This fact shows that there is a growing demand for healthy food like tropical fruits.
Fruit aroma is one of the most appreciated characteristics that attract consumers. In addition, aroma can be used to define maturity stage or distinguish different fruit types (Ong et al., 2008). Volatiles responsible for the D. guineense characteristic aroma note, such as alcohols, alkanes, acids and aldehydes were earlier described by Pelissier, Haddad, Marion, Milhau, and Bessiere (2001). However, there has been no systematic study aimed at identifying the key aroma compounds in black velvet tamarind.
The aim of the present study was to identify and quantify the aroma volatile compounds in three different tamarinds (D. guineense, D. dinklagel and D. packyphyllum). In addition, correlation between their volatile constituents and sensory properties were evaluated.