| Pomegranate seeds (from ZaoZhuang, Shandong province) were used as experimental materials in this text. The following aspects of the pomegranate seed oil were studied systematically. First, pressurized extraction technology was adopted to extract pomegranate seed oil and the yield was optimized by varying processing parameters; second, the physical and chemical properties and antioxidant activity were evaluated; subsequently, spray drying technology was adopted to produce the pomegranate seed oil microcapsules. The processing procedure and the stability of the microcapsules were well tuned. This text aimed to provide theoretical understanding of the comprehensive utilization of pomegranate seeds and provide novel strategy for the development of natural antioxidants.The experimental results are as follows:1. Based on the systematical research, extraction temperature, pressure and material-liquid ratio were the main factors to influence pressurized extraction technology, sequencing as extraction temperature > material-liquid ratio > extract pressure. The optimized process parameters of the pressurized extraction technology were as follows: diameter of pomegranate seeds around 40 mesh, petroleum ether used as extraction solvent, material-liquid ratio at 1:37, extraction temperature at 102℃, extract pressure at 2.6 kg/cm~2, extracting time at 30 min. Based on the parameters above, the yields of pomegranate seed oil steadied at 30.6 %.2. The pomegranate seed oil was a golden yellow, transparent, and peculiarly fragrant liquid oil through the analysis of the physical and chemical properties, with an acid value at 4.81 mg KOH/g, iodine value 192.8 g I~2/100 g, peroxide value 14.92 meq/kg, saponification value 191.5 mg KOH/g, refraction coefficient 1.4783. For thin-layer chromatography (TLC) analysis of pomegranate seed oil, the experiment conditions were: acetone: petroleum ether = 2:8 used as developing solvent, and 10 % phosphomolybdic acid used as color developing reagent. For Gas Chromatograph (GC) method to analyze the pomegranate seed oil, segmented program heating procedure was adopted: from 150 to 250℃at rate of 20℃/min, with 2 min initial temperature retention and 3 min terminal temperature retention; from 250℃to 270℃at rate of 2℃, with 3 min initial temperature retention and 20 min terminal temperature retention. The pre-column pressure was 0.08 MPa and nitrogen was used as carrier gas. DPPH radical scavenging experiment and lipid peroxidation experiment of mouse liver indicated that the pomegranate seed oil had obvious antioxidant capacity.3. During the preparation of pomegranate seed oil microcapsules by spray drying technology, there were four factors on encapsulation efficiency of the microcapsules. The influence order was: solid content﹥input fluid velocity﹥atomization pressure﹥inlet air temperature. Under the premise of the oil content was 40%, the optimal conditions were as follows: the solid content at 23 %, inlet air temperature at 195℃and atomization pressure at 0.20 MPa, input fluid velocity at 24 ml/min. Based on such conditions, the encapsulation efficiency of produced microcapsules was 88.1%. The products were loose, round, well coated and uniform microcapsules.4. Stability test showed that high temperature, high humidity and sunshine would affect the stability of the pomegranate seed oil. Pomegranate seed oil was not stable under high temperature, high humidity, and Lighting conditions. When coated into microcapsules, the stability was improved to an acceptable extent. But the oxidation of pomegranate seed oil in such microcapsules was not completely prevented and the antioxidant activity still decreased gradually. Therefore, the microcapsules should be stored in low temperature, dry, no-light conditions. |
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