Study On Emulsifying Properties Of Pomegranate Peel Pectin And Its Application

Pomegranate(Punica granatum L.)is a plant belonging to the genus Punica L of the family Punicaceae.Pomegranate fruit is rich in nutrients,and it has great values both as food and as natural medicine.It is a featuring economic crop that combines social,economic,ecological benefits,ornamental values and health care functions.Pomegranate fruit is mainly used for fresh food,juicing and wine making in the food industry.Its processing by-product is mostly pomegranate peel residue,which is rich in pectin content and can be used as a good source of pectin.In order to improve the added value of the pomegranate fruit products and achieve higher utilization rate of the by-products,this study discovered a new ultrasonic-assisted electrolyzed water method to extract pectin from the pomegranate peel residue.What's more,the emulsifying properties of pomegranate peel pectin from different cultivation areas were evaluated and compared.The possible impact factors of the emulsifying properties of pomegranate peel pectin were investigated.On this basis,a new pomegranate peel pectin emulsion product was developed.The main research results are as the following:1.The ultrasonic assisted method of extracting pectin from pomegranate peel using electrolysis water was developed.Based on the single factor experiment,the optimal extraction conditions of pomegranate peel pectin were obtained by Box-Benhnken design optimization:The extraction yield of pomegranate peel pectin reached 14.95%under the conditions of ultrasonic power at 100 W,pH of 1.7,extraction temperature at60?,extraction time of 33 min and ratio of material to liquid was 1:18 g/mL.Compared with ordinary ultrapure water method,not only the extraction rate was increased by 2%,but also the pectin extracted by electrolyzed water has higher esterification degree and greater galacturonic acid content.2.The emulsifying properties and emulsion stability of pomegranate peel pectin from different cultivation areas in Xinjiang,Sichuan and Yunnan were compared.The emulsifying properties of the pectin samples were analyzed by rheological and zeta potential technologies.The results showed that the molecular weight of pomegranate peel pectin from the three cultivation areas of Xinjiang,Sichuan and Yunnan were4.103×10~5 g/mol,3.618×10~5 g/mol and 4.384×10~5 g/mol,respectively;When the pectin concentration was 1.5%,and the phase oil(MCT)was 10%,the particle size of the emulsions were 0.507?m,0.669?m and 0.569?m respectively;meanwhile,the viscosity values were 0.087 pa·s,0.039 pa·s and 0.081 pa·s,respectively;pomegranate peel pectin samples from different origins all can effectively reduce the interfacial tension between oil and water,indicating that pomegranate peel pectin has great emulsifying properties.On this basis,the impacts of pH,Na+concentration and freeze-thaw cycles on the emulsion stability of pomegranate peel pectin were further analyzed.It was found that pomegranate peel pectin not only has good emulsifying properties,but also has excellent emulsion stability.The research outcomes provide a theoretical basis for the application of pomegranate peel pectin in the food industry.3.The pomegranate peel pectin samples went through decolorization,protein removal and small molecular substances removal treatments and then were recovered respectively to obtain pectins of different purification treatments.The emulsifying properties and structural differences of pomegranate pectin after different purification treatments were compared and analyzed.It was found that the particle size of the emulsion increased from 0.64?m to 2.11?m after dialysis treatment,and the particle size of pomegranate peel pectin and pectin after protein removal emulsion did not change much during storage for 14 days at 60?,while the particle size of decolorized pectin emulsion increased from 0.78?m to 2.27?m.And the particle size pectin after dialysis increased from 2.1?m to 10.69?m.The interface adsorption composition analysis also proved that the small molecular substance was the main component adsorbed at the oil-water interface.The experimental results showed that the protein and pigment in the pomegranate pectin have little effect on the emulsifying properties,while the small molecular substances had an enhancing effect on the emulsifying properties and emulsion storage stability.The pigment in pectin also had a certain positive impact on its emulsion storage stability.4.An oil-in-water emulsion was developed using pomegranate peel pectin as an emulsifier,and an emulsion system which can effectively protect the oil was established.The experimental results showed that,a good emulsion can be formed when the PP concentration is 1.0%and 1.5%,and the volume fraction of oil is 30~50%.The emulsion can effectively isolate the oil from contact with oxygen in the air and reduce the effect of high temperature on the oxidation of oil,therefore can reduce the oxidation rate.Especially when the concentration of PP is 1.5%and the volume fraction of fat is30%,the release rate of the emulsion in the small intestine is faster,which is more conducive to the digestion and absorption of oil.The experimental results provide good support for the application of pomegranate peel pectin emulsion.