Abstract
Abstract: Sacha inchi is an ancient plant existing in highland in Ecuador and Peru. It is a good oil source containing many unsaturated fatty acids, which are beneficial to our health. In present, the study of Sacha inchi has been focused on its nutritional composition, oil stability and cultivation techniques. The study on different kinds of extracting oil methods of Sacha inchi has not been reported. Moreover, the reports of Sacha inchi were usually from Ecuador and Peru and other countries abroad, but that from China was seldom seen. So the purpose of this paper was to study the extraction oil methods and the nutritional composition of Sacha inchi which was provided by Puer Lianzhong Biological Resources Development Limited Company in Yunnan Province, China. Sacha inchis were used as raw material in order to compare the oil extraction efficiency and oil quality among 4 kinds of extraction methods, which were aqueous enzymatic extraction, supercritical CO2 extraction, ultrasonic-assisted organic solvent extraction and low-temperature cold pressing method. In this processing, oil extraction efficiency and oil quality including color, transparency, smell and taste as well as the physical and chemical indices of Sacha inchi oil were determined. Furthermore, fatty acid and other nutritional compositions of the oil were determined by GC-MS (gas chromatograph-mass spectrometer-computer) and HPLC (high performance liquid chromatography), respectively. The elimination rate of DPPH (1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl) free radical was determined to evaluate the antioxidant activity in vitro between Sacha inchi oil and other vegetable oils. The results showed that although the oil extraction efficiency of supercritical CO2 extraction was lower than that of aqueous enzymatic extraction and ultrasonic-assisted organic solvent extraction, it was still the best extraction method among these 4 methods due to its good oil quality. The color, insoluble impurities, moisture and volatiles by hot plate, acid value and peroxide value of the oil extracted by supercritical CO2 method were significantly lower (P<0.05) than ultrasonic-assisted organic solvent extraction, and the color, insoluble impurities, acid value and peroxide value were also significantly lower (P<0.05) than low-temperature cold pressing method. The oil obtained by aqueous enzymatic extraction had the lowest acid value and peroxide value compared to the other 3 methods, but the smell and taste of oil were relatively light. The Sacha inchi oil is rich in unsaturated fatty acids and tocopherol, polyphenols and other active ingredients. The unsaturated fatty acids contain α-linolenic acid, linoleic acid, oleic acid and so on, and their contents were up to 92.37% of total lipids. The content of α-linolenic acid was 43.7% of total lipids which was higher than that of blackberry seed oil (8.38% of total lipids) or rapeseed oil (9% of total lipids). The content of linoleic acid was also high, which made Sacha inchi oil have a good proportion between omega-6 and omega-3 (about 1:1). The content of total tocopherol and total polyphenols were 59.2 and 10.2 mg/(100g), respectively, and among them (β+γ)-tocopherol was high to 41.2 mg/(100g), which made Sacha inchi oil more stable than flaxseed oil whose unsaturated fatty acids were also high. However, vitamin A was not detected in Sacha inchi oil. The 50% inhibitory rate (the required concentration of antioxidant substances when the removal rate was 50%) for Sacha inchi oil was 1.148 mg/mL, which was only 13%, 1%, 11% and 13% of olive oil, tea oil, flaxseed oil and perilla oil, respectively. This indicated that the antioxidant capacity in vitro for Sacha inchi oil was obviously better than that of olive oil, tea oil, flaxseed oil and perilla oil. In conclusion, supercritical CO2 extraction is the best way to improve oil quality of Sacha inchi and Sacha inchi oil is a good source of polyunsaturated fatty acids.
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