Characterization of Olive Oil Volatile Compounds after Elution through Selected Bleaching Materials—Gas Chromatography–Mass Spectrometry Analysis

Abstract

Using different bleaching materials to eliminate or reduce organic volatiles in deteriorated olive oils will positively affect its characteristics. This study aims to identify the volatiles of oxidized olive oil after physical bleaching using selected immobilized adsorbents. Oxidized olive oil was eluted using open-column chromatography packed with silica gel, bentonite, resin, Arabic gum, and charcoal at a 1:5 eluent system (w/v, adsorbent: oxidized olive oil). The smoke point was determined. The collected distilled vapor was injected into GC-MS to identify the volatiles eluted after partial refining with each of these bleaching compounds. The results showed that volatile compounds were quantitatively and qualitatively affected by the type of adsorbents used for the elution of olive oil and the smoking points of eluted oils. The most prominent detected volatile compounds were limonene (14.53%), piperitone (10.35%), isopropyl-5-methyl-(2E)-hexenal (8.6%), methyl octadecenoate (6.57%), and citronellyl acetate (5.87%). Both bentonite and resin were superior in decreasing the ratio of volatile compounds compared with other bleaching materials used. Resin immobilized medium was significantly affected (p < 0.05), raising the smoke point. These results highlighted some information regarding the characteristics of volatile compounds that result after the physical elution of olive oil through selected adsorbents.

DFT Studies of the Activity and Reactivity of Limonene in Comparison with Selected Monoterpenes

“…Limonene (1-isopropenyl-4-methylcyclohexene, C 10 H 16 ) consists of two isoprene units and has two double bonds, one connecting carbon atoms in the ring, an internal or endocyclic bond, and the other occurring outside the ring, that is, external/exocyclic ones [1,2]. Limonene is a monoterpene that occurs naturally in citrus plants such as lemon, orange, and grapes, or even in olive oil [3] and has a wide range of applications. For example, limonene contained in orange peels can be used to produce biogas (using the leaching process) [4], or in the production of biodegradable materials (limonene then serves as an additive) [5].…”