Composition of the surface waxes from bell pepper and eggplant

• Published in: European food research & technology 2005, Vol.220 (1), p.5-10
• Main Authors: Bauer, S, Schulte, E, Thier, H.P
• Format: Article
• Language: English
• Subjects: Acids; Aldehydes; alkanes; Capsicum annuum; chemical composition; chemical constituents of plants; Cultivars; eggplants; epicuticular wax; flame ionization detector; food composition; Food science; fractionation; gas chromatography; mass spectrometry; phytosterols; plant cuticle; Silica; Solanum melongena; Studies; sweet peppers; Toluene; triterpenoids
• ISSN: 1438-2377; 1438-2385
• DOI: 10.1007/s00217-004-1046-7

Surface waxes from the skins of bell pepper (Capsicum annuum) and eggplant (Solanum melongena) were rinsed with tert-butylmethyl ether (TBME). The wax components were separated into two fractions by elution from a small silica gel column with toluene/hexane (2+1) followed by methanol. They were identified by GC/MS and quantitatively determined by GC/FID. For 12 bell pepper cultivars, fraction 1 made up 39% of the total and contained mainly n-alkanes C^sub 20^-C^sub 35^ (with C^sub 31^ dominating), iso-alkanes C^sub 25^-C^sub 35^, and some aldehydes. The 61% of fraction 2 consisted of 15 triterpenes, namely α- and β-amyrin, lupeol, glutinol, 3β-friedelanol, friedelin, taraxerol, taraxasterol, δ-amyrin, germanicol, multiflorenol, ω-taraxasterol, isomultiflorenol, isobauerenol and bauerenol, as well as n-alkanoic acids C^sub 16^-C^sub 32^, 2-hydroxy-alkanoic acids C^sub 20^-C^sub 26^ and traces of n-alkanols and phytosterols (campesterol, stigmasterol and β-sitosterol). For the three eggplant cultivars, 77% of fraction 1 was obtained with (in decreasing order) n-alkanes C^sub 23^-C^sub 36^, anteiso-alkanes C^sub 29^-C^sub 36^, iso-alkanes C^sub 27^-C^sub 35^, and some aldehydes. In the 23% of fraction 2, the n-alkanoic acids C^sub 16^-C^sub 32^ predominated compared with the 2-hydroxy-alkanoic acids C^sub 22^-C^sub 26^, the n-alkanols C^sub 24^-C^sub 29^, triterpenols (α- and β-amyrin, lupeol, germanicol) and sterols (stigmasterol and β-sitosterol).[PUBLICATION ABSTRACT]