Combined effect of crude herbal extracts, pH and sucrose on the survival of Candida parapsilosis and Zygosaccharomyces fermentati in orange juice

Abstract

The purpose of this study was to evaluate the antimicrobial activity of crude extracts of cinnamon and clove compared with potassium sorbate against food spoilage yeasts isolated from orange juice (Candidaparapsilosis and Zygosaccharomyces fermentati). The ethanolic extract of both cinnamon and clove showed activity against C. parapsilosis and Z. fermentati with minimum inhibitory concentrations (MIC) of 1.0 and0.5 mg/ml by agar dilution method, respectively. While potassium sorbate showed activity against both yeasts with MIC 0.4 mg/ml. The combined effect of pH, concentration of sucrose and cinnamon extract or cloveextract or potassium sorbate in orange juice on the survival of the isolated yeasts were studied using Response Surface Methodology. The pH of orange juice and the concentration of cinnamon or clove extracthad the most significant (P<0.05) effect on the survival of C. parapsilosis and Z. fermentati while concentration of sucrose had the least effect. Survival of C. parapsilosis and Z. fermentati was mostly affected by theconcentration of potassium sorbate but pH and the concentration of sucrose did not have significant effect on the survival of Z. fermentati.

Keywords

• orange juice
• sucrose
• herbal exacts
• cinnamon
• clove
• potassium sorbate