| General purpose plastic fat plays an important role in food processing such as frozen dough.At present,most of the plastic fats on the market are refined animal and plant solid fats or hydrogenated vegetable fats.The saturated fatty acids or trans fatty acids introduced in the processing process are extremely harmful to human health.With the increasing demand for food safety and nutrition,it is of great significance to develop nutritionally healthy plastic fat substitutes.Emulsion-templated oleogels wrap/embed liquid oil by forming a three-dimensional network structure,and only change the physical form of liquid oil to achieve the purpose of oil curing,which is a new strategy to build a plastic fat substitute containing zero trans and low saturated fatty acids.In this study,soy protein isolate(SPI)and chitosan(CS)were selected as raw materials to construct emulsion-templated oleogels system stable with soy protein-chitosan complexs(SPI-CS),and the feasibility of replacing traditional plastic fat in the application of frozen dough was explored.The main results are as follows:Firstly,the effects of pH and CS:SPI on particle size,potential and emulsification characteristics of SPI-CS were investigated.At pH 5 and CS:SPI of 1:5,the SPI-CS had the minimum particle size(365.0 nm).And the emulsifying activity and emulsifying stability of the SPI-CS were 15.65 m~2/g and 51.88%,which were 125.5%and 202.51%higher than SPI,respectively,it could be used as stable particles to construct emulsion templates.At the same time,ultraviolet spectroscopy and Fourier Transform Infrared Spectroscope showed that the forces between soybean protein isolate and chitosan were electrostatic interaction force and hydrogen bond interaction force.Furthermore,under the condition of pH 5 and CS:SPI of 1:5,the SPI-CS was used as the gelling agent to construct an emulsion-templated oleogel.The effects of SPI-CS concentration and oil-water phase ratio on the performance and formation of emulsion-templated were investigated.The results showed:With the increase of oil phase volume,the particle size of the emulsion increases,and the apparent viscosity of the emulsion increases.Increasing of the SPI-CS concentration,the particle size of the emulsion was reduced,and the stratification of the emulsion was improvd,the apparent viscosity of the emulsion template was increasd.Under the low oil phase volume and high SPI-CS concentration,the oleogel showed different degrees of solid state.Finally,under the SPI-CS concentration was 1.0%,1.5%and 2.0%in the oil-water ratio of 2:8,the SPI-CS concentration was 1.5%and 2.0%in the oil-water ratio was 3:7,the SPI-CS concentration of 2.0%in the oil-water ratio 4:6,oleogels were soft and elastic.And the oil loss rate of the oleogels were less than 30%,which could be used for subsequent experiments.On this basis,the macroscopic physical properties and micromorphology of the SPI-CS emulsion-templated oleogel prepared in the chapter three were studied,and it was found that when the oil-water ratio was 2:8 and the SPI-CS concentration was 2.0%,the oleogel showing high gel strength.At this time,the network structure formed by the oleogel could effectively wrap the oil,restrict the flow of oil molecules,prevent its contact with oxygen,and show good oxidation resistance.Overall,the oleogels prepared under these conditions can be used as a substitute for quick-frozen special oils for subsequent research.Finally,the emulsion-templated oleogel was applied to the frozen dough,and the frozen dough with soybean oil and commercially available special oils was used as a control,and the frozen dough without added grease was blank,and the tensile characteristics,texture properties,water migration and microstructure changes of the frozen dough were studied.The results showed that compared with the frozen dough without grease,the tensile characteristics of the frozen dough with oleogel were enhanced,the hardness was reduced by 20.8%,and the cohesion and recovery increased by 10.6%and 40%,hhe content of strong bound water and weak bound water in frozen dough with added oleogel increased significantly,and the content of free water decreased significantly,which effectively inhibited the transition from bound water to free water which was conducive to reducing the freezing cracking rate of frozen dough.Compared with frozen dough with commercially available special fats,there was no significant difference in the tensile and texture properties of frozen dough with oleogel.Overall,the addition of soybean protein isolate-chitosan emulsion-templated oleogel improved the quality of frozen dough from two aspects:improving the texture characteristics of frozen dough and inhibiting water migration.In summary,this study successfully prepared soybean protein isolate-chitosan emulsion template oleogel,which has stable structure and good processing performance,and can be used in frozen dough instead of plastic fat. |
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