Riccardo Sabbatini
Marche Polytechnic University, Italy
Title: The potential role of essential oils as preservatives against spoilage yeasts in yogurt
Biography
Biography: Riccardo Sabbatini
Abstract
Contamination of foods by spoilage yeasts could lead to a reduced food product shelf-life due to gas production and undesirable off-flavors and off-odours. Considering the growing consumer’s demand for natural foods without chemical preservatives, the food industry has been induced to research alternative solutions to guarantee the required microbiological standards. A plant-derived natural antimicrobials such as essential oils have emerged as effective compounds against spoilage microorganisms and/or pathogens which could affect food safety and stability. In this context, the aim of this study was to assess the potential role of 7 different essential oils (cinnamon, ginger, lemongrass, mandarin, orange, lemon and lime) as preservatives in yogurt against spoilage yeasts. These essential oils were chosen for their possible positive attribution to yogurt’s flavour and odour. The antifungal activity of these essential oils was evaluated by disc diffusion assay on 75 spoilage yeast strains isolated from yogurts prepared with buffalo milk. The tested yeasts belonged to the genera Candida, Rhodotorula, Debaryomyces, Kluyveromyces and Yarrowia. The best performing essential oils were cinnamon and lemongrass. Therefore, they were selected for further minimum inhibition concentration (MIC) assay using the micro-well dilution method. Based on the obtained results, the potential role of the selected essential oils as preservatives was tested directly in yogurts intentionally contaminated by selected yeast strains in order to confirm their efficiency against yeast spoilage and to evaluate their sensory impact on the final product through a final acceptance test.