Physicochemical Properties And Microencapsulation Of Akebia Trifoliata Var. Australis Pectin And Seed Oil

Akebia trifoliata var. australis is the variety of Akebia trifoliata, and it is commonly referred to as an important medicinal herb in traditional Chinese medicine for activating blood circulation, subduing inflammation and facilitating diuresis. The Akebia trifoliata var. australis seed oil is liquid at ambient temperature, and it is easily oxidized because of the high content of unsaturated fatty acids, the two aspects make the oil unsuitable for food processing and storage. The objectives of this study were to develop the Akebia trifoliata var. australis pectin as wall material component, and then embed the seed oil via microencapsulation technology. Preparation of Akebia trifoliata var. australis seed oil microcapsules can change the oil from liquid to solid, improve its flowability and storage stability, and finally benefit the development, processing and transportation of the pectin and oil.The physicochemical properties of the pectins extracted from Akebia trifoliata var. Australis peel with hydrochloric acid and citric acid, namely HEP and CEP, were evaluated as compared with citrus pectin (CP). X-ray diffraction confirmed that CP had more well defined crystal than HEP and CEP. The DE values of HEP, CEP and CP were59.46%,76.64%and71.03%, respectively. CP exhibited the highest viscosity-average molecular weight of64,848Da, followed by HEP (45,353Da) and CEP (28,877Da). In general, the emulsion activity of HEP and CEP increased as oil concentration was increased, while HEP showed the strongest emulsion activity among the three pectins. Textural analysis demonstrated that the gelling properties of three pectins decreased with increase in pH, and CP displayed superiority in hardness (9.03g), while CEP was the poorest (1.45g). All results suggested that Akebia trifoliata var. australis had the potential in producing pectin for commercial food industry application.The Akebia trifoliata var. australis seed oil extracted with hexane was evaluated by the physicochemical properties and thermal oxidation stability. The results showed that contents of crude fat and protein in the seeds were39.33%and17.97%, respectively. The physicochemical indexes of the oil were presented in details, including acid value1.28mgKOH/g, peroxide value0.57mmol/kg,p-anisidine value4.15, iodine value74.12gI/100g and saponification value198.6mgKOH/g. The GC datas indicated that the oil was abundant in palmitinic acid, oleinic acid and linoleic acid, comprising about93.73%of the total fatty acids. Additionally, the oil exhibited a good thermal oxidation stability below220℃.The optimal wall material and emulsifier were selected by the screening test. Base on the single factor test of the contents of emulsifier, core material, pectin and cyclodextrin, the response surface experiment was designed with the response value of microencapsulation efficiency, and a series of Box-Benhnken experiments was used to obtain a mathematical regression. The optimum preparation formula of Akebia trifoliala var. australis seed oil microcapsules were as follows: emulsifier2.98%, core material24.33%, pectin0.88%, cyclodextrin10.99%, with the microencapsulation efficiency of90.45%.The initial storage stability of the Akebia trifoliata var. australis seed oil microcapsules was investigated by determining the physicochemical properties. The results showed that the moisture content and mean particle diameter of the microcapsules werer2.59%and328.1nm, respectively. The powder was exquisite and uniform with good solubility and dispersion. SEM analysis displayed that the microcapsules had a regular spherical shape with smooth surface and compact capsule wall. FT-IR spectra presented that the seed oil basically remained its original nutrients and structures. DSC analysis exhibited that the microcapsules had high glass-transition temperature and thermal melting temperature, which indicated good storage stability. TG analysis showed that the microcapsules were well embedded with high thermal stability. Moreover, the microencapsulation efficiency of the microcapsules changed a little after being stored for six months.