Preparation Technology Research Of Guan Xi Pomelo (Citrus Maxima) Peel Essential Oil

Essential oil,also named volatile oil,is a special oily substance with aroma flavour,as a natural spice and antioxidants has been widely used in food,pharmaceuticals and cosmetics industries.Fruit essential oil derived from the fruit wrapped layer,and different preparation technology has an important effect on the quality of essential oil.Pomelo is an important citrus fruit,and pomelo peel contains a lot essential oil.Cold pressing,water distillation,simultaneous distillation extraction?SDE?,microwave-assisted extraction,ultrasonic-assisted extraction and supercritical CO₂ fluid extraction?SFE?technologies were applied to prepare the essential oils from Guanxi pomolo peel,essential oil from factory was also been contrast,the result followed by physical and chemical testing,sensory evaluation of the odor characteristic and GC-MS analysis of the volatile compounds,further more,the effect of concentration,light,heat and oxygen during preparation were discussed.The results showed that essential oil prepared by SDE method,water distillation and factory has the best clarity.Essential oil by cold pressing had the most similar odour to the nature pomelo peel,which dominated by green,herbaceous,fruity,the essential oils by microwave-assisted and ultrasonic-assisted extraction had a similar odour to pomelo peel but with slight acidity,the essential oils by SDE and water distillation have a significant smell of cooked pomelo peel and oily,the essential oil by factory had a strong odour of pomelo,flowery flavour and with slight sweet,the essential oil by SFE had a strong odour of pomelo and with a little musk,but the color is dark.The optimization of GC-MS condition were analyzed by Rtx-5 ms column,the result showed that the oven temperature was programmed at 3?/min,split ratio 1:5,the diluted concentration are 200 times and 10,000 times,voltage detector 0.88 kV;A total of 82 volatile compounds were detected by GC-MS,among which 28 compounds were terpene,3 compounds were terpene oxide,20 compounds were alcohols,10 compounds were aldehydes,6 compounds were acids,6 compounds were ester and 3 other compounds.Although the seven essential oils displayed differences in detailed composition,they have similar mainly compositions,they were d-limonene?61.7%-73.4%?,?-myrcene?16.4%-28.2%?,?-pinene?0.3%-1.5%?,germacrene?0.3%-1.4%?nootkatone?0.1%-1.3%?,?-pinene?0.1%-0.4%?and linalool?0.2%-0.3%?,and the essential oils of cold pressing,SFE,microwave-assisted and ultrasonic-assisted extraction had more aurpten?1.6%-1.9%?and an unsuccessfully identified composition?0.4%-1.6%?;The study of preparation technology showed that there have a certain loss of composition when enriched,and the temperature is the main factor lead composition change.These results illustrate the influence of physicochemical indexes,odour characteristic and volatile compounds by different preparation technology.Essential oils by cold pressing,microwave-assisted extraction,ultrasonic-assisted extraction had slight acidity which related to acid?0.4%-0.6%?and esters?1.7%-2.0%?,essential oil from factory had slight sweet which related to terpene oxide?0.6%?,essential oils by water distillation and SDE had a significant smell of cooked pomelo peel which related to terpene or alcohol oxide;Temperature,light and oxygen must be controlled when preservation.These results provided reference for the further development of pomelo peel essential oil products.