Relationship between sensory quality and volatile compounds of elderflower (Sambucus nigra L.) extracts

Elderflower samples (Sambucus nigra L.) of 89 different genotypes were picked at optimum flowering time in Austria, England and Denmark and extracted with an aqueous solution containing sucrose, citric acid, ascorbic acid, and sodium benzoate, and investigated for the emission of volatile compounds. Volatile compounds emitted from elderflower extracts were collected by dynamic headspace technique (purge and trap) and analysed by GC-FID and GC-MS. A total of 59 volatile compounds were identified and quantified, and significant differences among the investigated elderflower extracts were observed for 58 compounds. Diluted elderflower extracts was evaluated by sensory panels trained in determination of elderflower flavour and the results from the sensory evaluation was correlated to the content of volatile compounds in the extracts using classical factor analysis including determination of eigenvalues, factor loadings and factor scores. Four principal components (PC1-PC4), which included 28 volatile compounds and sensory quality, were extracted from the factor analysis. The four PCs explained, altogether 73.7% of the data variation [PC1 (38.5%), PC2 (19.7%), PC3 (8.1%) and PC4 (7.4%)]. important contributors to the floral and elderflower flavour of the extracts were rose oxides, hotrienol, linalool, linalool derivatives and alpha-terpineol, whereas the fruitiness and freshness of the extracts were mainly due to non-oxidized monoterpenes, aliphatic aldehydes and alcohols. Possibilities for selection of cultivars with specific flavours are discussed.