| Peony,Paeonia genus Paeoniaceae genus,as China’s traditional precious flower, known as "Aromatic" reputation. The root bark of Peony can be used as medicine, having the effect of blood circulation. Peony seed oil is rich in fatty acids,especially rich in a-linolenic acid a-linolenic acid, as the only essential fatty acids, is one of ω-3 polyunsaturated fatty acids, which has important influences on cardiovascular health, blood lipid components of the immune system. In this study, peony seed oil extraction process, solubility, physical and chemical properties, fatty acid composition, free radical scavenging ability were studied by supercritical CO2 fluid extraction technique, and the peony seed oil solubility were related with model equation. The main results of this work were as follows:Through different temperatures, pressures, carbon dioxide density conditions peony seed oil solubility was studied. The results showed that at temperature of 313 K-353 K and pressure of 20-35 MPa, the solubility of peony seed oil in supercritical CO2 fluid has a positive correlation with pressure and the density of carbon dioxide, while the temperature was negatively correlated under a certain degree. Under the experimental conditions of this study, the maximum solubility of peony seed oil is 27.43 g/L,the minimum solubility of 1.28 g/LPeony seed oil solubility data were correlated by 8 kinds of models such as Chrastil model, Valle model, Adachi model, Sparks model, Kumar-Johnston model, Sung-shim model, Bartle model, Mendez-Santiago-Teja model, the results show a strong correlation. Peony seed oil solubility data were fitted to give a cure between In (S) and In (p) using Chrastil equation which can be described as ln(S)=k*ln(p)+a/T+b. The correlated results were as follows:k= 9.366; a=-3204.435; b=-50.539. The negative value a indicates when the CO2 density is constant, the solubility increases with temperature. The average deviation is 6.43%, since the average deviation is less than 10%and theoretical solubility and test solubility had little differences. So peony seed oil solubility has strong correlation with, the CO2 density at 313-353 K.Through single factor experiment, combined with peony seed oil solubility, the influence of carbon dioxide flow rate, pressure, time, temperature and other factors were investigated on the yield.of peony seed oil. The results show that:the carbon dioxide flow rate of 18 mL/min can be achieved to meet with low extraction cost, low-power process requirements in the three tested flow rate; At the temperature of 40 ℃, a pressure of 20 MPa,25 MPa,30 MPa,35 MPa, the peony seed oil extraction time were examined. The results showed that 120 min is long enough to complete the extraction process. At a constant temperature, peony seed yield increases with pressure; at a constant temperature, peony seed oil yield decreases with increasing temperature. Under conditions of a flow rate of 18 mL/min, and time 210 min, peony seed yield and recovery are the largest, respectively,0.222 g/g and 94.9%at temperature of 313 K, and the pressure of 35 MPa, and the yield is close to the Soxhlet method. the peony seed oil yield was 0.219 g/g at 313 K,30 MPa, with a small difference with the yield obtained at 35 MPa,313 K. Taking economic into consideration and peony seed oil solubility, the optimum of peony seed oil extraction by supercritical CO2 fluid can be obtained at 313 K, 30 MPa.By GC-MS identification of peony seed oil, five components were identified which are a-linolenic acid, linoleic acid, oleic acid, stearic acid, palmitic acid. And the unsaturated fatty acid content of peony seed oil extracted by supercritical carbon dioxide was higher than extracted by Soxhlet method. DPPH radical scavenging experiment showed that:DPPH radical inhibition rate of peony seed oil was positively correlated with the concentration in a certain extent, also showwd that peony seed oil has strong antioxidant capacity, and oil obtained by supercritical extraction had stronger antioxidant capacity than in Soxhlet method. Investigation results on POV valaue showed that the POV valaue of peony seed oil was low under darkness, low temperature and sealed condition, which help peony seed oil storage. Through study of different antioxidants influence on peony seed oil POV value, results showed that a suitable antioxidant can help slow the rate of oxidation of peony seed oil. The most suitable storage peony seed oil to add synthetic antioxidants TBHQ and BHA, the best natural antioxidants kind of VE and EOB. Peony seed oil ultraviolet absorption effect evaluation showed that: peony seed oil has a strong ability to absorb ultraviolet light. |
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