| Cherry kernel is ripe seed from cherry genera vegetable belonged to the rosaceae plants. It accounts for about 20% of the cherry seeds, which is abundant in of oil and protein content, and cherry kernel oil is rich in β-sitosterol, α-tocopherol and other bioactive components. The content of unsaturated fatty acid is more than 85% of the total which has an effect on scavenging free radicals, antioxidative effect. Therefore, cherry kernel oil is a functional oil extremely. In this paper, with the anhui cherry kernel as raw material, four methods such as pressing, organic solvent, ultrasonic assisted, supercritical carbon dioxide was used to extraction cherry kernel oil. The grain morphological characteristics of cherry kernel, optimum extraction conditions of cherry kernel oil and the effect of different extraction methods on the quality of cherry kernel oil were studied systematically. The physicochemical properties, scavenging DPPH radical ability and fatty acid composition of refined cherry kernel oil were analyzed, and the oxidative stability of cherry kernel refined oil was studied. The oxidation kinetics model was established to predict the shelf life of refined cherry kernel oil. Reference and theoretical basis was provided for the utilization cherry seeds comprehensively and development of cherry kernel oil resources. Experimental results obtained were as following:1. The grain morphological characteristics and the main ingredients of cherry kernel were determined by experiment respectively. The grain morphological characteristics were length (5.37±0.08) mm, width (3.67±0.13) mm, volume (9.11±0.48) mm3, surface area (14.83±0.51) mm2, width-length ratio(0.68±0.02)and grain weight (22.70±0.86) g, bulk density (540.26±4.33) g/L, containing kernel rate (20.46±0.41)%. The main ingredients were crude fat (52.67±0.33)%, crude protein (20.±0.02)%, moisture and volatile matter (4.37±0.06)% and ash content (2.56±0.05)%.2. The optimum processing parameters were obtained by extracting cherry kernel oil using four methods.(1) The optimum parameters of pressing extraction were 6MPa,6h. Under this conditions, the extraction rate was up to (67.70±2.53)%.(2) The optimum parameters of organic solvent extraction were petroleum ether as extraction solvent, solid-liquid ratio 1:10g/mL, extraction temperature 47℃, extraction time 4.9h. Under this conditions, the extraction rate was reached (91.56±0.91)%.(3) The optimum parameters of ultrasonic assisted extraction were petroleum ether as extraction solvent, solid-liquid ratio 1:8.5g/mL, ultrasonic temperature 42℃, ultrasonic time 58 min, ultrasonic power 300W, ultrasonic frequency 80kHz. Under this conditions, the extraction rate was reached (94.55±1.46)%.(4) The optimum parameters of supercritical carbon dioxide were cherry kernel quantity 35g, extraction pressure 43MPa, extraction time 199min, extraction temperature 44℃. Under this conditions, the extraction rate was reached (97.61± 0.86)%.3. Different extraction methods of the cherry kernel oil have different influences on quality characteristics. Four extraction methods of cherry kernel oil have significant effects on the acid value, peroxide value, iodine value, saponification value physical chemical properties and phospholipid content. The fatty acid composition and content of cherry kernel oil using four extraction methods have no significant effects, and the fatty acid compositions of cherry kernel oil were mainly composed of palmitic acid, stearic acid, oleic acid and linoleic. The content of oleic acid was the highest, followed by linoleic acid. And the content of unsaturated fatty acid was between 83% to 85%. The cherry kernel oil with four extraction methods has different abilities to scavenge DPPH radical. The scavenging DPPH radical order was pressing extraction method> supercritical carbon dioxide method> Ultrasonic assisted extraction method> organic solvent extraction method.4. The physical chemical indicators of cherry kernel refined oil were acid value (expressed KOH as, mg/g) 0.23, peroxide value (mmol/kg) 0.91, iodine value (expressed I2 as, g/100g) 109.35, saponification value (expressed KOH as, mg/g) 209.39, refractive index (n20) 1.4738, relative density (d2020) 0.9087, color (Lovibond color slot 25.4mm) yellow6.2, red 0.6, moisture and volatile matter (%) 0.065, insoluble impurities (%) 0.012, normal smell and taste and no smell, clear and transparent. All of indexes have coincided with the latest oil national standard. The ability of scavenge DPPH radical of Cherry kernel refined oil was lower than crude oil, and its IC50 was 15.67mg/mL. The composition and content of fatty acid were no significant differences between cherry kernel refined oil and crude oil.5. The storage experiments showed that light, oxygen and temperature had effected on the oxidative rancidity of oil during storage. The light and oxygen could accelerate the rate of oxidation rancidity of oil. Low temperature could decelerate the rate of oil oxidative rancidity.6. The cherry kernel refined oil peroxide value and acid value variation fit to the first order chemical reaction. With peroxide value and acid value as the evaluation indictor, cherry kernel refined oil oxidation kinetics models were as follows:... |
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