Preparation And Properties Of Ca²⁺-induced Soybeanwalnut Oil Structured Oils

Traditional plastic fats and fats require a large amount of saturated fats even covered trans-fatty acids in the production process.This may cause cardiovascular diseases,obesity and other health problems.Therefore,it is very necessary to seek alternatives to traditional plastic fats.The use of structurants to to form structured fats in order to wrap liquid vegetable oils has gradually attracted attention as an alternative to traditional plastic fats.However,the currently used structurants require heat treatment so they are not conducive to the preservation of food nutrition.Protein is widely used in the food industry.Protein is a high-quality food nutrient and a natural oil structurant.Studies have shown that structured oil prepared by wrapping liquid oil with protein as a structurant under non-thermal conditions has the mechanical properties of plastic fats products and other functions.It is nutritious and healthy to use structured oil as the replacement fats for functional oil products.Therefore,this study is based on salt ions that can induce proteins to form a network structure.Soybean protein isolate?SPI?,soybean 7S protein?7 sedimentation coefficient of soybean protein,or?-Conglycinin,SP7S?,and soybean 11S protein(11 sedimentation coefficient of soybean protein,or glycinin?SP11S?is used as structurants,which is treated with Ca²⁺solution to form soybean protein network in order to wrapped walnut oil?Walnut oil,WO?.A series structured oil with high degree of unsaturation and certain mechanical properties named SPI-WO,SP7S-WO,SP11S-WO were obtained.And its microstructure,macroscopic physical properties and storage stability were determined.The excellent technology for Ca²⁺to induced SPI-WO,SP7S-WO,SP11S-WO structured oil were obtained.The internal relationship between its microstructure and macroscopic properties were figured out.This study provides experimental support and new ideas for protein structured oil to replace traditional plastic fats.The main research contents and results are as follows:?1?Preparation and properties of SPI-WO structured oil induced by Ca²⁺The physical properties,rheological properties and microstructure of SPI-WO structured oil(based on different SPI content and Ca²⁺concentration)induced by calcium ion were investigated by using texture analyzer,rheometer and confocal laser scanning microscope.The study found that the soybean protein isolates to prepare structured fat protein content should be greater than 9%,calcium ion concentration should be less than 0.15%.Compared with traditional plastic oils,the structured SPI-WO structured oils have a significantly lower saturated fatty acid content,a hardness near to soft plastic fats,similar thixotropy,and higher temperature stability.The study found that when the SPI content increases,the hardness of the SPI-WO structured oil increases.When the Ca²⁺concentration increases,the hardness of the SPI-WO structured oil decreases.SPI will form a dense protein network structure,and the liquid oil is dispersed into smaller droplets wrapped in the network structure.As the concentration of SPI increases,the?-helix of SPI-WO structured oil decreases,and?-sheet and?-turn structures increase.?2?Preparation and properties of SPI-WO,SP7S-WO,SP11S-WO structured oilThe physical properties,rheological properties and microscopic properties of SPI-WO,SP7S-WO and SP11S-WO structured oils were studied by texture analyzer,rheometer and Fourier transform infrared spectrometer structure.It shows that 11S protein and 7S protein can form a stronger protein network structure under Ca²⁺induction,resulting in its hardness is higher than SPI-WO structured oil,but still has a hardness near to soft plastic fats.The thixotropic recovery ability of structured oils with different molecular weights similar like traditional plastic fas,and follows:SP11S-WO>SPI-WO>SP7S-WO.The temperature stability of those structured oils are better than traditional plastic fats.SPI-WO structured oil has the least?-helix,?-sheet and?-turn structure.SP7S-WO structured oil has more?-helix and?-fold structure than SP11S-WO structured oil,and less?-turn structure than SP11S-WO structured oil.?3?Ca²⁺-induced changes in properties of SPI-WO structured oils under variable temperature storage conditionsThree types of SPI-WO structured with the content of SPI at 10%?named SPI10?,11%?named SPI11?and 15%?named SPI15?were studied by using a moisture meter,texture analyzer,rheometer,Fourier infrared spectrometer The macroscopic properties and structure changes of structured oils under the conditions of variable temperature storage?5oC/12h-25oC/12 h?were determined.The?-turn structure in all structural oil disappears after 28cycles of storage.The hardness of SPI10 and SPI15 both increase significantly,and the thixotropic recovery capacity increases first and then weakens.While the hardness of SPI11shows a fluctuant trend.The thixotropic recovery ability of SPI11 gradually increases with the extension of storage time,and has better temperature stability than the other two structured oils.?4?Ca²⁺-induced changes in storage performance of SPI-WO,SP7S-WO,SP11S-WO structured oils under variable temperature storage conditionsMoisture meter,texture analyzer,rheometer,Fourier infrared spectrometer were used to study the macro nature and structural changes of the structured oil with different molecular weight soybean protein?SPI,SP7S,SP11S protein?under the stored conditions at variable temperature?5oC/12 h-25oC/12 h?.Studies have shown that during temperature storage,The order of hardness of this three types of structured oil is SP11S-WO>SP7S-WO>SPI-WO.In the later period of storage?>14 cycles?,the hardness of SP11S-WO structured oil gradually decreases,while the hardness of SPI-WO and SP7S-WO structured oil decreases first and then rises.After storage for 14 cycles,only SP11S-WO structured oil can still maintain good temperature stability.The temperature stability of SP7S-WO significantly deteriorates.As the storage time extend to 28 cycles,the temperature stability of the three structured oils significantly deteriorated.Variable temperature storage will cause changes in the secondary structure of SPI-WO,SP7S-WO and SP-WO11S structured.With the storage time extend,the?-helix,?-fold structure of SPI-WO,SP7S-WO and SP-WO11S both decreased gradually.There was no significant difference in?-turn content of SPI-WO structured oils?p<0.5?,while?-turn angles of SP7S-WO structured oils and SP-WO11S structured oils decreased.