Determination of n-alkanes in C. annuum (bell pepper) fruit and seed using GC-MS: comparison of extraction methods and application to samples of different geographical origin

Abstract

An efficient extraction and analysis method was developed for the isolation and quantification of n-alkanes from bell peppers of different geographical locations. Five extraction techniques, i.e., accelerated solvent extraction (ASE), ball mill extraction, ultrasonication, rinsing, and shaking, were quantitatively compared using gas chromatography coupled to mass spectrometry (GC-MS). Rinsing of the surface wax layer of freeze-dried bell peppers with chloroform proved to be a relatively quick and easy method to efficiently extract the main n-alkanes C27, C29, C31, and C33. A combined cleanup and fractionation approach on Teflon-coated silica SPE columns resulted in clean chromatograms and gave reproducible results (recoveries 90–95 %). The GC-MS method was reproducible (R2 = 0.994–0.997, peak area standard deviation = 2–5 %) and sensitive (LODs, S/N = 3, 0.05–0.15 ng/μL). The total main n-alkane concentrations were in the range of 5–50 μg/g dry weight. Seed extractions resulted in much lower total amounts of extracted n-alkanes compared to flesh and surface extractions, demonstrating the need for further improvement of pre-concentration and cleanup. The method was applied to 131 pepper samples from four different countries, and by using the relative n-alkane concentration ratios, Dutch peppers could be discriminated from those of the other countries, with the exception of peppers from the same cultivar.Graphical AbstractProcedure for pepper origin determination

The use of δ2H and δ18O isotopic analyses combined with chemometrics as a traceability tool for the geographical origin of bell peppers

“…In addition to d 18 O, the d 2 H values of the bell pepper fruits were also investigated using GC-C-IRMS analysis of n-alkanes in extracts from the surface wax. Extraction and analytical method development were published in a separate paper (De Rijke et al 2015). The main n-alkanes found in the pepper extracts were n-C 27 , n-C 29 , n-C 31 and n-C 33 , corresponding to earlier findings (Bauer, Schulte, & Thier 2005;Parsons et al 2013).…”

High Concentrations of Very Long Chain Leaf Wax Alkanes of Thrips Susceptible Pepper Accessions (Capsicum spp)

“…In our study of waxes of pepper leaves, C 27 , C 31 and C 33 n -alkanes were the most abundant alkanes. The major alkanes in pepper fruit wax were C 29 and C 31 n -alkanes (Bauer et al 2005 ; de Rijke et al 2015 ; Parson et al 2013 ), which shows that the wax composition may differ among organs. Genes involved in biosynthesis of cuticular waxes have been identified in Arabidopsis and other models species such as Hordeum (Lee and Suh 2015 ).…”

“…Because of their economic interest, there has been quite some research on the wax layers of the pepper fruits in relation to food quality and food preservation (de Rijke et al 2015 ). Major components of the fruit wax layer were C 29 and C 31 n -alkanes and C 24 fatty acid (Bauer et al 2005 ; de Rijke et al 2015 ; Parsons et al 2013 ). Both plant ontogeny and leaf age play a role in cuticular wax metabolite composition (Busta et al 2017 ).…”

“…Commercially grown peppers generally belong to the species Capsicum annuum and C. chinense. Because of their economic interest, there has been quite some research on the wax layers of the pepper fruits in relation to food quality and food preservation (de Rijke et al 2015). Major components of the fruit wax layer were C 29 and C 31 n-alkanes and C 24 fatty acid (Bauer et al 2005;de Rijke et al 2015;Parsons et al 2013).…”

Flaxseed (Linum usitatissimum) Extract Activity on Human Oral Fibroblasts (HOrF) Cell Line

“…Peak retention times were recorded and compared against standards. The technique was used to demonstrate the major components of the crude flaxseed oil [12].…”