Extraction of propolis extract and evaluation of its physicochemical, antioxidant and antimicrobial properties as a natural preservative in food

The purpose of this research is extracting propolis using the methods of soaking in 20% and 70% ethanol and the effect of ultrasound in 20% ethanol, and evaluating its physicochemical, antioxidant and antimicrobial properties as a natural preservative used in the food industry. The physicochemical properties, the amount of phenolic and flavonoid compounds, the antioxidant and antimicrobial properties of the extracts were measured. The results showed that most of the number of phenolic compounds (94.19 mg/g), flavonoid (89.46 mg/g) and antioxidant property by DPPH method (92.63%) in ultrasonic extracts. And the lowest number of phenolic compounds (87.85 mg/g), flavonoid (82.20 mg/g) and antioxidant property (85.87%) are in the method of soaking in 20% ethanol. Also, the results of the investigation of the antimicrobial property by the diffusion ability method from the well showed that the most sensitive bacterium was Staphylococcus aureus (20 mm) in front of the ultrasonic extract. Regarding the ability of Pseudomonas aeruginosa bacteria, there was no significant difference between the extracts (p<0.05) and none of the extracts had antibacterial power against Pseudomonas aeruginosa bacteria. The highest ability of Candida albicans (36 mm) was with ultrasonic extract, and in the investigation of the growth of Aspergillus niger after spraying for 8 days, the lowest growth rate was obtained with ultrasonic extract (9 mm) and then 70% ethanol extract (10 mm). Based on this, the amount of phenolic, flavonoid, antioxidant and antimicrobial compounds was 70% more than the 20% ethanol extract, and in the ultrasound, method based on Hurdel technology, a large number of active compounds were found in the 20% ethanol solvent in a short period of time.