Optimization of the composition and technology for shellac preservative fruit wax with Natamycin

In order to improve the stability and inhibition ability of shellac emulsion, and decide the composition and the technology of shellac preservative fruit wax, effects of emulsion temperature and speed rate on the stability of shellac emulsion were investigated. Optional composition of different agents, emulsion time, emulsion temperature and concentration of Natamycin added in were also studied. The preparation technology for preservative fruit wax was decided in this article which was as follows: 12.0% of shellac, 2.0% of morpholine, 1.0% of propanediol, 1.2% of ammonia, 1.8% of oleic acid, speed rate of 900 r/min, the emulsion temperature of 115℃, and the emulsion time of 30 min. When the temperature was down to 60℃, 600 mg/L Natamycin was added in, then scattered for 15 min. Finally, when the temperature fell to 30℃, the obtained suspension was homogenized at a pressure of 50 MPa for two times. This shellac preservative fruit wax with chocolate brown color has a good stability and a high drying speed, and the brightness of fruits was high and lasting. The oranges coated by this preservative wax have good qualities and appearances under 5～10℃ and 60%～65% of relative humidity for 45 d, furthermore, the weight loss rate was about 5% lower and the rate of good fruits was about 40% higher than that of uncoated fruits.