Study On Microencapsulation,Physicochemical Properties And Stability Of Tree Peony Seed Oil

Tree peony(Paeonia suffruticosa Andr.)seed oil(TPSO)is a natural active oil rich in unsaturated fatty acids,but TPSO is prone to oxidation and rancidity due to the influence of external factors.Therefore,TPSO was used as core material and encapsulated by microencapsulation technology in the paper.The preparation process of TPSO microcapsules was optimized,and its physicochemical properties,storage stability and in vitro release were studied.The experimental results were as follows:(1)The microencapsulation of TPSO was carried out by spray drying.The effects of the mixture ratio of gelatin and β-cyclodextrin(β-CD),the core-wall ratio,the percentage of emulsifier in the total raw material,and hydrophilic and hydrophobic equilibrium value(HLB value)on the encapsulation efficiency(EE)of TPSO microcapsules were investigated.According to the single factor test results,the response surface test was performed with EE of TPSO as the response value.The optimal encapsulation conditions of TPSO microcapsule were 0.4(g/g)of core/wall material ratio,3.5(g/g)of gelatin/β-CD ratio,2.0% of emulsifier in the total raw material,and 10.5 of HLB value.Under these conditions,the maximum EE of TPSO microcapsules was 91.59%.(2)The physicochemical properties of TPSO microcapsules were studied.The water content and solubility of TPSO microcapsules were 1.38 ± 0.02% and 93.21 ±0.32%,respectively,which indicated that the water content was low and the solubility was good.The Carr index(CI)of TPSO microcapsule powder was 18.76 ± 0.11,and the Hausnah ratio(HR)was 1.23 ± 0.01.The low HR indicated low adhesion of TPSO microcapsules,indicating good fluidity.And the particle size of TPSO microcapsule was 2.02 μm.By scanning electron microscope observation,the TPSO microcapsule was spherical,with clear outline,slightly rough surface,and no obvious cracks and holes.Fourier transform infrared spectroscopy(FTIR)analysis dispiayed that the characteristic peak of TPSO in the microcapsules was weakened,indicating the formation of TPSO microcapsules.The thermal decomposition temperature of TPSO microcapsules was 219.10 ℃,which indicated that TPSO microcapsules product had good thermal stability.The contents of unsaturated fatty acid in TPSO before and after spray drying were 80.38% and 80.31%,respectively,which indicated that spray drying did not cause any loss to the fatty acid composition of TPSO,but microencapsulation played a good protective effect on TPSO,and broadened the application of TPSO in the food industry.(3)The storage stability of TPSO microcapsules stored at 60 ℃ for 18 d was studied.The EE of TPSO decreased from 91.59% to 75.13%,which indicated that the dense capsule wall formed by β-CD and gelatin better protected the nutrients of TPSO.The particle size of TPSO microcapsules increased from 2.02 to 31.16 μm,indicating that the exudation of TPSO caused the agglomeration of TPSO microcapsules.FTIR indicated that the characteristic peak of TPSO microcapsules did not change,indicating that there was no strong chemical reaction interaction between TPSO and wall material.On the 18 th day of storage,the decomposition temperature of TSPO microcapsules was 217.50 ℃,indicating that TPSO microcapsules had good thermal stability,which was conducive to the storage of the products.The peroxide value(POV)of TSPO varied from 7.22 to 109.17 meq peroxide/kg oil,and the POV of TSPO microcapsule varied from 6.89 to 39.21 meq peroxide/kg oil.For the TSPO microcapsules,thiobarbituric acid(TBA)value increased from 2.85 to 12.48 mg MAD/kg oil,and TBA value of TPSO increased from 3.19 to 22.86 mg MAD/kg oil,indicating that the microencapsulation process had an effective antioxidant protection effect on the storage process of TPSO.The contents of unsaturated fatty acids in TPSO and TPSO microcapsules decreased by 17.07% and 9.81%,respectively.The results showed that microencapsulation of TPSO could effectively protect the fatty acid composition of TPSO.(4)The release of TPSO microcapsules in vitro was studied.In the simulated gastric fluid(SGF),the structures of TPSO microcapsules were not completely destroyed,and only 28.4% of TPSO were released.In simulated intestinal fluid(SIF),TPSO microcapsules released 50.5% of TPSO.The particle size of TPSO microcapsules decreased from 2.02 μm to 1.82 μm for 2 h in SGF,which decreased by9.9%.When TPSO microcapsules entered the SIF,the particle size of TPSO microcapsules decreased from 1.82 μm to 1.17 μm in alkaline environment,which decreased by 35.7%.At the end of SGF digestion,the amount of FFA released by TPSO and TPSO microcapsules ranged from 18.42 to 384.67 mg FFA/g oil.At the end of SIF digestion,the amount of FFA released by TPSO and TPSO microcapsules ranged from 315.45 to 1914.91 mg FFA/g oil.