| Paeonia ostii t. Hong et J. X. Zhang, as a category of paeonia suffruticosa in Tongling, which named was mainly produced in west mountain of Nanling and Phoenix mountain of Tongling in Anhui, belonged to ranunculaceae paeonia shrubs. The resources of paeonia ostii seeds were abundant, but up to now most of the paeonia ostii seeds had not been exploited. In this paper, the oil from paeonia ostii seed was extracted by ultrasonic-assisted extraction and the optimum parameter of the craft was studied, some of the physicochemic-al properties of paeonia ostii seed oil were determined and composition and content of fatty acid of paeonia ostii seed oil was analyzed by gas chromatography/mass spectrometry (GC/MS). Then, three factors of air, light and metal ions had effect on the stability of paeonia ostii seed oil and the antioxidant effect of several natural antioxidant on paeonia ostii seed oil were studied. The experiment provided theoretic basis for the deep processing and full use of paeonia ostii seed of the oil. The results of the study were the following:1. The compositions of paeonia ostii seed were analysed:(1) The basic components of paeonia ostii seeds contained water8.96%, fat34.87%, protein16.75%, ash3.02%, reducing sugar12.18%and starch20.24%;(2)The physicochemical properties of the oil were as follows:acidity value3.85mg KOH/g, peroxide value2.9098meq/kg, saponification value113.66mgKOH/g, iodine value175.63gI/100g, relative density(d420)0.91, water and volatile matter0.051%, phospholipid0.200g/100g, refractive index(n20℃D)1.4673;(3) Paeonia ostii seed oil included unsaturated fatty acids (89.00%) and saturated fatty acids (10.77%). The major fatty acids were9,12-octadecadienoic acid(Z,Z)(54.81%),9,12,15-octadecatrienoic acid (33.34%), hexadecanoic acid (8.07%) and octadecanoic acid (2.29%).2. The extracting technological parameter of paeonia ostii seed oil by ultrasonic assis-ted extraction was studied with the Box-Behnken response surface analytical method. The results showed that the best extraction solvent is n-hexane and ethyl acetate (1:1), the order of factors which affected extracting extraction rate was:extraction time>extraction temp-erature>solvent-solid ratio>ultrasonic power, the optimum conditions of oil extraction were as follows:solvent-solid ratio9:lmL/g, ultrasonic extraction time32min, extraction temperature43℃and ultrasonic power190W, the extraction rate of oil reached to34.71%.3. The degree of rancidity of paeonia ostii seed oil was measured using peroxide value(POV) as evaluating index in the periods of storage. The results showed that POV increased gradually with the extension of storage time, which rised slowly during the early storage, and increased gently afterwards. The factors of light, air, and the metal ions significantly affected the stability of paeonia ostii seed oil, the factors of light and metal ions could catalyze free radical reactions and accelerated the oxidation rate of paeonia ostii seed oil. The greater the contact area of paeonia ostii seed oil and air, the faster the oxidation rate of the oil would increase. Therefore, paeonia ostii seed oil should evade the light and avoid with air and metal ions contact in the storage.4. Natural antioxidants including P-carotene, lycopene and rosemary extracts had better antioxidant effect on paeonia ostii seed oil, the the optimum adding amount was0.02%,0.03%and0.02%respectively. In addition, there was good synergistic effect among the three kinds of natural antioxidants, the ideal combination of antioxidants were0.02%β-carotene+0.03%lycopene+0.04%rosemary extracts in the experiment. The combined action between different antioxidants and citric acid had good antioxidant effect on paeonia ostii seed oil. |
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