Study On Preparation Process Of Heat-Resistant Vanillin For Baking Food

The purpose of this paper is to develop a way that could obtain one kind of heat-resistance flavour. This flavour which should not only be expert in sustained release and resistant high-temperature, but also provide pleasant flavor after bread baking, that means this especial flavor can act as it best according to the temperature change during baking. Vanillin was chosen as the object of this article, this decision was made by lots of reason, such as the range of popularization, sale situation of market and acceptace of taste also. Focus on the characteristics of heat-resistant of pure vanillin, this paper want to find a method which could improve it, the process optimization is also needed in this programme. The conclusions from this paper are those followed.It had been confirmed by mass loss experiment in high temperature that the pure vanillin might lose its weight sharply when the enviroment temperature was above 160℃. The mass loss rate of vanillin can over 80% in Cookies, and litter lower in bread, abort 60%～70%. Vanillin is such a heat-unstable favour that is verified by the results above.It has been found experimentally that oil can play some roles in the vanillin protection, and can prevent volatilization of vanillin in certain extent. As the oil added in flour, with the proportions of 3%, the mass loss of vanillin in bread can be decreased to 50% when chose the step as first the vanillin should be dissolved in oil, and then add in the flour. It seems a feasible scheme that heat-resistant vanillin can be made based on this feature. The optimal proportion of vanillin and oil had been proved as 5% in the following experiment. The vanillin could crystallizing-out fleetly as the system reach the indoor temperature, the content of vanillin lose occurred synchronously.Microencapsulation, which is a good method for changing the liquid oil back into solid material. This paper planned to making double-layers microcapsules by complex coacervation and oil, with reference to preparation method of powder oil. Optimal condition of oil emulsification should be established at the beginning of microencapsulation, and the degree of layered settlement after centrifugation has been set as measurement index of the emulsion. the optimal technological conditions were obtained by orthogonal test, namely, m(Span-60):m(Tween-80)=1:1, addition rate 0.1%. speed of homogenization 25000 r/min, system temperature of emulsion 40℃, according to which the emulsion stability achieve the optimal effect.Choose the Chitosan and Sodium alginate as the wall material. the optimal technological conditions of complex coacervation were obtained by single-factor test and response surface method, in detail, mass ratio of Chitosan and Sodium alginate 2:3, mass rate of wall and core material 2.96, addition speed of Chitosan solution 0.01g/min, 0.168g soybean protein to 1g total wall material. Under the optimized condition, two key index reach those peak value, the rate of relention and yield percentage are 87.62% and 92.36%.Bread-additive experiment indicate fat-polysaccharide double embedding method can reduce vanillin's volatilization in high temperature effectively. The spray drying in embedding of microcapsule preparation of oil is very common, but experiments showed that the recovery of solids from spray drying is lower, no more than 20%, which cause material waste. Therefore, vacuum freeze-drying method were used to dehydrate water from microcapsule, which were separated from water phase. Scanning electron micrograph of product can give out clear oval micro-fat-capsule, particle size is close at 1 -5μm, but the viscous connections beTween particle were also observed.Under same baking conditions, double coated microcapsule significantly reduced loss of vanillin, and reserved vanillin's percentage is 32.48%. Thermogravimetry graph showed that intense volatile temperature of vanillin was increased from 175℃to 225℃.We surmise that fat-polysaccharide double embedding system can provide significant protection, prevent particle's wild release effectively.The results of experiment show that as the vanillin has been embedded by double-layer wall which constitutes oil and complex coacervation, the characteristic of preservation and heat-stable prompted obviously. It is suitable for treating this product as a pre-mixture in flour, by the way, the microencapsulation can also released flavour during baking.