Study On The Preservation Effect Of Propolis In Orange Juice

Propolis is a natural product produced by the honey bee, which is mixed by the plant spores or tree gum and bees’secretions produced by palate and wax gland. It is a kind of colloidal solids with aromatic odor. Propolis, which is a natural active, non-toxic and harmless substance, plays an important role in health care for human us. Because of its strong antibacterial and antioxidant activity, propolis is used as a material in kinds of food preservation. In this paper, the effect of propolis on preservation of orange juice was studied as its natural broad-spectrum antimicrobial and antioxidant ability, which also can increase the nutritional value. The main results were as follows:1. Emulsification of propolis:The emulsification method of propolis was optimized by the initial screening and spin-up method experiments. According to flavonoid content and emulsion stability of emulsification propolis the suitable emulsifier were hydrophilic phospholipids (HP) and Tween-80 (T-80). Then optimize the emulsifying method, the best solution for propolis emulsification was:dispersion at high speed was operated after.45ml distilled water added emulsifier:0.6g HP and 0.4g T-80,5 ml 20% propolis polyethylene glycol (peg) solution was slowly added, the scattered time was 20 min.2. Sterilization method:the most suitable sterilization method was researched according to the browning index, ascorbic acid content and the total number of bacteria in orange juice. By ultrasonic and moderate heat sterilization and zero sterilization processing for pre-treatment before packaging, these indexes were detected after the preservation under the condition of 37℃ for eight days. The results showed that the moderate thermal sterilization method is suitable for processing of orange juice.3. The best adding does of propolis:the total number of bacteria, mold and yeast in the fresh orange juice, the orange juice added different preparation propolis emulsions were tested at different shelf life. And the optimum adding amount of propolis was 3mL propolis emulsion per 100mL orange juice.4. Preservation effect:The sodium benzoate and potassium sorbate and propolis emulsion were added to orange juice. The content of reduced ascorbic acid and the total number of colonies of orange juice were determined as an index to compare the effect of the three methods on preservation of orange juice. The reduced ascorbic acid in orange juice samples with propolis can be saved very well. The inhibition effect of these on bacteria in orange juice was:potassium sorbate group< the propolis group< sodium benzoate group.This study provides a basis for the application of propolis in the liquid drink which has certain application value.