Conversion of Limonene into More Valuable Aroma under Hydrothermal Conditions

The aromatic components in citrus essential oils are monoterpenes, sesquiterpenes, and some oxygenated compounds. It is known that monoterpenes, such as limonene, take a little part of the aroma and are sometimes removed by deterpenation processes. In this study, a novel technology through a wet oxidation process using hydrogen peroxide was investigated for the conversion of limonene. Experiments were conducted using a batch type reactor to study the effects of temperature and reaction time on the conversion of limonene under the following conditions: temperature range of 150 to 200C at reaction time of 10-80 min. After each run, samples consisting of 2 layers (oil and water phases) were collected. The oil layer was qualitatively analyzed of its composition using a gas chromatography-mass spectrometry (GC-MS) apparatus, while the organic carbon content in water layer was analyzed using a total organic carbon (TOC) analyzer. Results obtained under these conditions indicated highly selective conversion of limonene especially into its isomers.