| The formula and process of acidproof powdered oil prepared by using maltodextrin and cocoa butter substitute as raw materials were investigated in this paper. Also, the microcapsule quality was tested and its application in acidic jucie beverage was studied. The main results were as follows:1. The emulsification system of acidproof powdered oil was established. Among many varieties of emulsifiers, it was determined by experiments that the microencapsulation effect was best with modified starch 55-1479 and arabic gum as emulsifier of acidproof powdered oil. The proportion and quantity of two kinds of emulsifiers were decided by single factor experiment. It was showed that the microencapsulation effieiency of product prepared by spray drying technique was highest when the emulsifier proportion was 2:1 and the additions were repectively 10% and 5%.The microencapsulation process was optimized. Applying two phase emulsification techinique, the temperature of emulsification was 70-75℃, homogenizing pressure was 30Mpa and homogenizing twice. The optimum technological conditions of spray drying were as follows: inlet air temperature 185℃, outlet air temperature 95℃, feeding rate 22.0mL·min-1, air pressure 0.10Mpa.2. The microcapsule quality was tested. The results showed that: the oil amount on the surface was low (1.05%), but the product had a high rate of embedded (96.5 percent), moisture content of powdered oil was under 2.5%, the powder was exquisite and uniform, its color was ivory, the smell was pure with no peculiar smell. All physical and chemical indexes were qualified to the quality standard of microcapsule. The recovery emulsion was uniform with no surface oil and practicles linking to the wall. After standing for 24 hours, it remained stable. The microencapsulation efficieny and particle size distribution of recovery emulsion varied little during 180 days storage time, the microencapsulation effect was good and emulsion stability was high. The investigation on the changes of peroxide value and acid value of microcapsule product and cocoa butter substitute claimed that: the peroxide value of cocoa butter substitute in the 180 days first rose then dropped and rancidity had happened; however, that of acid proof microcapsule powdered oil just had little rise during those days. The acid value of cocoa butter substitute rose 19.73 units and the microcapsule product only rose 4.82 units. It was indicated that because the property of microcapsules' film material was so good that it could protect the core material effectively from contacting with the oxygen, water and others in the air, the prepared microcapsule had a long shelf life.The acid resistance of prepared powdered oil was inspected. According to the results of hydrochloric acid(inorganic acid), citric acid(organic acid) and antiscorbic acid(reducibility material) test, it was known that the properties of prepared powdered oil were excellent, which could satisfy the application in acidic drinks.3. The application of acid proof powdered oil in acidic beverage was investaged. Powdered oil was added to juice drink, then a kind of acidic milk-like juice beverage was produced. Apple juice was selected as juice type, its addition was 50%, acidity agent was complexed lactic acid, citric acid and malic acid, the proportion was 5:4:1, and the addition was 0.3%; the addition of powdered oil and sucrose was respectively 10% and 8%. Each sensory index meeted the certain requirements.The precipitation rate and its variations with time were determined. It was discovered that the precipitation rate changed little, which showed that the stability of the drink was good.
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