Study On The Supercritical CO₂ Extraction Technology And Quality Control Of Almond Oil

Almond oil is not only the high-quality edible oil of the world, but also the raw materials of production of advanced cosmetics, lubricants and solvents plastic. The nutritional and economic values of the almond oil are very important. In this paper, almond was taken as the experimental material. Oil was extracted from almond by supercritical CO₂, the conditions of extraction were optimized. The volatile components were analyzed by GC-MS, and the characteristics of aroma components were determined.The anti-oxidative activity of the almond oil was increased by adding antioxidants, and the storage period was extended. Finally the general quality control system of almond oil processing was established.1. On the basis of single factor test, the method of response surface analysis was adopted to optimize the processes of supercritical carbon dioxide extraction. The results showed that the optimum extracting conditions were as follows: materiel grain size 40 mu, water content 5%, extracting pressure 40 MPa, extracting temperature 42℃, extracting time 144 min. Compared with the organic solvent extraction, this process has many characteristic: simple process, high extraction rate, high purity, without refining.The optimal extract process in laboratory-scale was blown up to amplification test successfully and the results were 1% difference accord with laboratory-scale. It was proved that the extract process in laboratory-scale was reliable and stable. There were some guidance for the extraction process used in the industry.2. There are some special aromas in the volatile components. In this paper, the volatile components of the local and Xinjiang almond oil were analyzed by GC-MS according to headspace solid phase micro-extraction. The results showed that the conditions of headspace solid phase micro-extraction were as follows: CAR/DVB/PDMS fiber, adsorption temperature 70℃and the adsorption time 40 min. At this condition, 38 components were separated,including aromatics, alkanes, ketones, acids and so on. Aromatic substances were mainly toluene, 1,4-dimethyl benzene and 1,2-dimethyl benzene, and they have accounted for 60% of the total volatile substances in the local or Xinjiang almond oil. There were benzyl alcohol and benzaldehyde in the bitter almond oil except of this. So the special aromas of the almond oil were benzenes.3. Almond oil is oxidized easily because of the content of unsaturated fatty acid is up to 50%. The effects of antioxidants on the storage stability of almond oil were studied by Schaal experiment according to POV of almond oil. The results showed that the TBHQ and tea polyphenols were effective antioxidants to almond oil. TBHQ or tea polyphenols with phytic acid or citric acid exhibited great anti-oxidation ability, but the role of VC was not significant. The almond oil with 0.02%TBHQ and 0.02% citric acid exhibited the best stability, the shelf life could be prolonged from 32 d to more than two years at 25℃, the secondly was 0.02% tea polyphenols and 0.02% citric acid, the shelf life was 18 months at 25℃,and the time was up to the shelf life of national.4. In this paper, the hazard of the almond oil processing was analyzed. The critical control points in almond oil processing had been confirmed as material check, supercritical carbon dioxide extraction and adding anti-oxidants. The general control system was designed and constructed for the factories making almond oil by supercritical carbon dioxide.