Antifungal activity of propolis in four different fruit juices

Fruit juices and soft drinks are targets for spoilage yeasts, moulds and bacteria. The aim of this study is to examine the antifungal effect of ethanolic extract of Turkish propolis (EETP) treatments in four nonpasteurized fruit juices including apple, orange, white grape and mandarin against 6 different yeasts isolated from the corresponding spoiled juices. These isolated yeasts include: Candida famata, C. glabrata, C. kefyr, C. pelliculosa, C. parapsilosis and Pichia ohmeri. Minimum Irihibitory Concentration (MIC) ranges were determined responding to the National Committee for Clinical Laboratory Standards (NCCLS) M27-A that were slightly modified with broth microdilution method. In this study, the presence of propolis in apple (pH=3.9), orange (pH=3.7), white grape (pH=3.8) and mandarin (pH=3.4) juices ranging from 0.01 to 0.375 mg/mL inhibited the growth of all spoilage yeasts at 25 degrees C. MIC ranges of propolis were 0.02-0.375, 0.04-0.375, 0.01-0.185, 0.02-0.185 and 0.04-0.375 mg/mL in mandarin, apple, orange, white grape juices and RPMI medium, respectively. MIC ranges of Na benzoate, which was used as positive control, were 80-320, 80-320, 40-640, 40-80 and 320-1280 mu g/mL in mandarin, apple, orange, white grape and RPMI medium as blank control, respectively. In terms of MIC ranges, propolis showed greater antifungal activity than Na benzoate. As a result, propolis had significant antimicrobial activity against the yeast isolates from spoiled fruit juices. It was concluded that propolis is worthy to study further as a natural preservative for foods prone to fungal spoilage