Preparation of Portulaca oleracea L.seed oil by ultrasound-assisted enzyme hydrolysis combined with Soxhlet extraction method and the analysis of its fatty acids

In order to improve the extraction rate and quality of Portulaca oleracea seeds oil,the extraction rate and physicochemical properties of Portulaca oleracea seeds oil were selected as the indexes,ultrasound-assisted enzyme hydrolysis method was used in the pretreatment of Portulaca oleracea seeds and Soxhlet extraction method was applied on the oil extraction. The optimum conditions of enzyme hydrolysis pretreatment were determined using orthogonal trial based on single-factor experiments. gas chromatography /mass spectrometry( GC-MS) was used in the analysis of the fatty acid components of the oil extracts with the new method and compared with the tradition extraction way.The results showed that the optimum conditions of enzyme hydrolysis pretreatment were: enzyme dosage 2%,hydrolysis temperature 50 ℃,pH6. 0,liquid to solid ratio 6∶ 1. Under these conditions,the extraction rate with the combination method was up to 86. 8%,increased by 15. 43% compared to Soxhlet extraction method. The seed oils extracted by two methods both contained variety of unsaturated fatty acids. And the content of unsaturated fatty acids was over85%,content of linolenic acid was 39%.