AROMA PROFILE OF VANILLA IN BOURBON BEANS

摘要

Vanilla is a popular flavour ingredient for various types of cakes, cookies, ice cream, and candies, among others. Vanillin, 3-methoxy-4-hydroxybenzaldehyde, is the characteristic aroma compound of the flavour. Numerous organic synthetic routs have been developed for the aldehyde production since 1874. However, flavourists know that bourbon beans of vanilla harvested around Madagascar are the best in term of aroma quality. Even though all vanilla beans contain vanillin as a major chemical of the vanilla essential oil, consumers' preferences have been clearly in favour of the best quality of the natural vanilla. Consumers can easily recognize the difference of the aroma quality between vanillin and vanilla extracts. Therefore, to understand the aroma difference, more than 180 chemicals found in vanilla as volatile compounds were analysed with sophisticated equipment and techniques such as HRGC-MS and HPLC. Additionally, Schwarz and Hofmann focused on the improvement of aroma during curing process and found some new chemicals that contribute to the aroma profile. However, not only discovery of new chemicals, but also a new evaluation system for aroma quality is needed to understand the aroma impacts. Acree et al. and Schieberle et al. intensively developed Charm analysis and GC-Olfactometry techniques to find characteristic aroma impact chemicals. Recently we have also developed a new technique for aroma quality assessment by using odour threshold such as odour impact spectrum (OIS) and corresponding analysis of aroma matching test and applied these techniques to evaluate mango aroma and some citrus aromas so far. OIS standardizes odour impact of aroma components by means of Stevens' law. These techniques are applicable for evaluation of other volatile extracts.