Fabric phase sorptive extraction as a reliable tool for rapid screening and detection of freshness markers in oranges

Abstract

A simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QTOF-MS) analysis was developed for the analysis of 12 volatile compounds that represent most of the principal chemical families possessing different polarities and volatilities. Five FPSE media coated with different sol-gel sorbent chemistries having different polarities and selectivities were studied: long chain poly(dimethylsiloxane) (PDMS), short chain poly(tetrahydrofuran) (PTHF), Carbowax 20M (CW20M), short chain poly(dimethyl siloxane) (SC PDMS) and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG). CW20M coated FPSE media was found to be the most efficient extraction media for the analytes of interest in the intended study. The developed methodology was applied to the analysis of orange juice obtained from fresh oranges and oranges after storing at 5°C for two months in order to identify the best chemical markers, both volatiles and non-volatiles, attributed to the freshness of orange. For this purpose, aliquots of the same juice extracts were analysed by GC-MS as well as by UPLC-QTOF-MS. Monoterpenes and terpenoids, such as terpinene, citronellal or estragole were among the volatile compounds that endured the biggest decrease after the extended storage period. Three non-volatile compounds including one amide (subaphyllin) and two flavanoids (tangeretin and nobiletin) also showed a clear decrease in signal intensity (>70%) after orange stored for two months.

Keywords: Fabric phase sorptive extraction; Freshness markers; GC–MS; Oranges; Screening; UPLC–QTOF–MS.