Plant sterols are important agricultural products for human health and consequently, for nutrition industries. In the present study, free sterol contents of crude Turkish cottonseed oil samples have been determined in a single analytical run by using a solid phase extraction step prior to the detection with a gas chromatography coupled with a flame ionization detector. Free hydroxyl groups of Stigmasterol, β-Sitosterol, Campesterol and Brassicasterol were derivatized by using N-methyl-N-trimethylsilyl trifluoroacetamide to enhance their volatility and, sterol content of the samples were, then, separated from their matrix by using a octadecylsilane cartridge. The eluates were injected into the gas chromatographic system and satisfactory recovery ratios were obtained. After having validated the method, it was applied into the analysis for cottonseed oil samples for their free sterol levels.

This study aimed to investigate the volatile organic compounds (VOCs) variations during the spoilage of palm wine stored at ambient temperature and identify potential shelf-life markers. Palm wine collected from local tappers and resellers were stored at ambient temperature (28-30°C) for 96 h. At an interval of 24 h, VOCs variations were investigated using Solid phase Microextraction-Gas Chromatography-Mass Spectroscopy (SPME-GC/MS) method. Changes in sensory quality and potential flavour contributors were also explored. The sensory rejection time was found at 24 h and 48 h of storage for palm wines collected from the tappers and resellers, respectively. The first attribute to be spoiled was taste followed by odour and appearance. A total of 23 VOCs distributed in six chemical families were identified. Alteration of palm wine sample is characterised by an increase in concentration of alcohol (isoamyl alcohol, isobutanol and 1-octanol), aceti acid and acetoin, and a decrease in ester concentration (ethyl acetate and ethyl hexanoate). In the view to fight against the short shelf-life and develop new preservation methods, these compounds can be used as markers of spoiled palm wine.