Comparative study of different extraction processes for hemp (Cannabis sativa) seed oil considering physical, chemical and industrial-scale economic aspects

Hemp (Cannabis sativa) seed oil is a rare source of nourishment for vegetarian diets due to the unique ratio of ω-6/ω-3 fatty acid as 3:1. It is beneficial for cardiovascular health, skin, hormonal balance, diabetes, etc. These oil benefits encourage the chemical industries for its intensive extraction to accomplish the quantity and quality of the product. Despite being various processes i.e. supercritical fluid extraction, Soxhlet, percolation, ultrasonication, pyrolysis, pretreatment processes etc., none of above is the best in all aspects. Therefore, the present study investigates different extraction processes for hemp oil and compared its industrial-scale economic assessment, extraction yield, oil compositions and physico-chemical properties. Central composite design was employed to optimize the parameters of supercritical fluid extraction and ultrasonication processes. Quadratic models (P < 0.05) for both processes were developed with satisfactory R2 (>0.93). The maximum yield of 37.30% was estimated through ultrasonication treated Soxhlet process. Gas chromatography-mass spectrometry demonstrated Soxhlet as the best-suited process while offering the optimum ω-6/ω-3 ratio. Further, gas chromatography-mass spectrometry of hemp bio-oil obtained through pyrolysis identified the volatile and flammable materials to assure its suitability as bio-fuel. Economic analyses for different processes revealed supercritical fluid extraction as the most beneficial followed by Soxhlet, ultrasonication, ultrasonication treated Soxhlet and Soxhlet treated ultrasonication.