| The special oil for quick-frozen food is a kind of flavor oil for improving the quality of frozen rice and noodle food.At present,the commercial products have some shortcomings,such as narrow plastic range,large crystalline particles,high level of saturated fatty acids,poor emulsifying performance and lack of nutrition.More importantly,their applicability in frozen food dough and filling has not been differentiated.Therefore,palm stearin(PS)and rice bran oil(RBO)were used as raw materials,and interesterification technology was used to modify and characterize the different proportions of mixed oils in this study.Based on the optimization of emulsifier formula,a series of special oils for quick-frozen food were constructed,and their quality characteristics and nutritional value were analyzed and evaluated.Finally,these special oils for quick-frozen food were respectively applied to the dough and filling of quick-frozen glutinous dumplings.Principal component analysis was used to comprehensively evaluate the quality of glutinous dumplings,which was to explore the influence of special oil for quickfrozen food on the dough and filling.The main results of this paper are as follows:Firstly,the optimum process conditions of interesterification between PS and RBO were determined by single factor experiment: the catalyst was Lipozyme TL IM enzyme,the reaction temperature was 50℃,the reaction time was 2 h,and the enzyme load was 6%.On this basis,different mass ratios of the mixed oils of PS and RBO(2:8-8:2)were catalyzed for enzymatic interesterification.There was no significant difference in the fatty acid composition before and after the reaction.However,when the addition ratio of PS reached 40% or above,the contents of SUU and SUS triacylglycerols increased by more than 20%.At the same time,the loss rates of sterols were only 1.9% to 4.1%,and those of oryzanols were 1.3% to 1.9%.At 35℃,the SFC value of the oils decreased from 4.3%-27.3% to 1.3%-17.0%,and the peak temperature of the high melting point melting peak(Peak E)decreased,as well as the enthalpy and peak area decreased.When the ratio of PS reached 40% or above,the β crystal were transformed into β ’crystal,and the β’ crystal form increased the most(21.1%)when the ratio of PS to PBO was 6:4.In conclusion,the properties of the modified oils have been greatly improved after interesterification,which could retain sterols and oryzanols to the greatest extent.Moreover,when the mass ratios of PS to RBO were 4:6,5:5,6:4 and 7:3,it was more suitable to be used as the base oils of special oil for quick-frozen food.Secondly,the optimal emulsifier formula was determined based on the D-optimal mixture regression optimization test: calcium stearyl lactate was 34.4%,glycerol monostearate was33.8%,soy lecithin was 31.8%.Under this formula,the water absorption of special oil for quick-frozen food was 25.1 g /10 m L,and the emulsification stability was 93.3%.Four kinds of special oils for quick-frozen food were prepared with a wide shaping range(21.4℃-30.3℃),and the relative content of β’ crystal form were 56.6%-95.6%.The crystals were small and dense short needle-like structure,which were evenly and orderly distributed in the crystal network structure.Among them,the elastic modulus and viscous modulus of experiment quick-frozen oils 1-3 were lower than those of commercial oils,and the peak temperature of Peak E was low,which had good fusible property.In addition,the four special oils for quickfrozen food did not contain trans fatty acids,had low atherogenic index(0.61-1.06)and thrombosis index(1.19-2.12),and were rich in oryzanols(3256-6132 ppm)and sterols(3589-6929 ppm).Finally,four kinds of special oils for quick-frozen food were applied to the dough and fillings of glutinous dumpling,and it was found that when the self-made quick-frozen oil 2was added to the dough,the cracking rates of glutinous dumplings were lower than 5%.When self-made quick-frozen oil 3 was added to the dough,the water loss rates of the glutinous dumplings were less than 2.5%.The height-diameter ratio of fresh glutinous dumplings made by these two kinds of special oils for quick-frozen food reached 0.97-0.98,and the difference in height-diameter ratio before and after freezing was small,indicating that the sliding melting point of quick-frozen oils was too low or too high to affect the formability of frozen food.Compared with the commercial frozen oil,the four kinds of special oils for quick-frozen food glutinous dumplings have higher elasticity and lower adhesion,among which the glutinous dumplings made by the self-made quick-frozen oils 1-3 have lower hardness and chewability,and all of the sensory scores were higher than 80.Principal component analysis was used to comprehensively evaluate 18 kinds of quick-frozen glutinous dumplings,and the application performance of the self-made frozen oils 2 and 3 were determined to be the best.Further analysis showed that the self-made frozen oil 2 was more suitable for glutinous dumplings filling,while the self-made frozen oil 3 was more suitable for glutinous dumplings dough. |
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