Changes in biochemical composition of citrus peel essential oils in relation to different temperature levels in steam distillation

Citrus is a major fruit crop of Pakistan. Its production is 2150 thousand tons in Pakistan.  Its peel is being wasted but Citrus peel essential oils can be used in industries such as cosmetics, perfumery, baking and medicines. Three citrus cultivars namely Citrus paradisi (grapefruit), Citrus reticulata (kinnow) and Citrus sinensis (musambi) were used in this study. Steam distillation is an easiest and cheapest method for essential oils production.  In steam distillation extraction temperature is an important parameter to be effected on the basic quality of essential oils. Three temperature levels such as 105oC, 110oC and 120oC were used in steam distillation to extract the essential oils. It was observed that at higher temperature yield, oil density and refractive index were minimum. With the increase in temperature chemical constituent’s number and percent composition were also decreased. Chemical characterization of the essential oils was done by GC-MS. Maximum total compounds in all the samples were 57 but maximum number of compounds in one sample were 29 at 105oC. Essential oils extracted at this temperature showed the maximum oil yield percentage i.e. 0.311% in grapefruit followed by musambi (0.310%) and kinnow (0.302 %). The numbers of chemical compounds were also affected by heat and it was found that percentages of α-caryophyllene, α-pinene, caryophyllene, citronellal, decanal and nootkatone were decreased at higher temperature 120oC