Effect of Extraction Methods and Storage Time on the Yield and Qualities of Neem Seed (Azadirachta indica A. Juss) Oil

The effects of extraction methods and time of storage on the yield and qualities of neem seed oil were investigated. Three extraction methods: cold water, hot water, and n-hexane were used while the extracted oils were stored at room temperature for six months. The yield, chemical properties, qualitative and quantitative phytochemical analysis of the fresh and stored oils were evaluated at every two-month interval using standard methods. The results showed that n-hexane gave the highest oil yield (62 %), followed by hot water (49 %), and cold water (42 %). The chemical properties ranged as follows; peroxide value: (7.02–25.56, 6.30–26.76 and 8.99–24.16 Meq/kg), saponification value: (133.95–245.26, 114.09–288.09 and 141.11–250.12 mg KOH/g oil), iodine value: (51.69–6.98, 56.73–7.88 and 54.87–9.51 mg/wij’s) and acid value: (18.01–55.99, 11.34–85.12 and 14.62–56.88 mg KOH/g oil) for cold water, hot water, and n-hexane respectively. The qualitative phytochemical analysis indicated the presence of flavonoids, coumarins, terpenoids, triterpenoid, and steroid contents. Conclusively, the extraction methods and storage time affect the yield and qualities of the extracted neem seed oil, while the chemical and phytochemical results revealed that the extracted oils were good for both medical and industrial applications. Keywords: Neem seeds, oils, extraction methods, storage time, chemical and phytochemical properties