THE EFFECTS OF ULTRAVIOLET LIGHT APPLICATION In BATCH SYSTEM ON THE MOLD GROWTH AND THE MOLD INACTIVATION OF YOGHURT
Project no. 1356 · Status: Kapanmış · 2018
Summary
Ultraviolet-C light; has a lethal effect on microorganisms such as mold, yeast, bacteria and algae. Disinfection effect is available at many application points. Variations such as enzymatic activity, oxidation and dehydration, which lead to quality loss, mostly begin on the food surface. Therefore, surface applications are important to eliminate or control microorganisms on the food surface. In addition, UV irradiation initiates the oxidation process of lipids, which can lead to off flavor perception. In this study, it was aimed to determine the effects of UV-C light application with laboratory type ultraviolet light sterilizer on the surface of yoghurt both in mold inactivation and lipid oxidation during and after storage. The research was carried out in two stages. In the first stage, 0,321-19,26 kJ/m2 doses of UV-C lights (254nm) were applied on yoghurt surfaces with the batch system. And their effects on mold inactivation, lipid oxidation level and sensory properties were determined. In the second stage, UV-C light was applied to yoghurt surfaces at the doses determined in the previous stage (0,321-1,926 kJ/m2). The effects of UV-C light application on the shelf life of yoghurts were determined by evaluating mold growth, lipid oxidation and sensory properties during 21 days of storage. As a result, UV-C light application was found to be effective on the mold count and 2,18 log decrease was obtained compared to the control group in yoghurt by application of 1,926 kJ/m2 dose. During the storage period, the most effective UV-C light dose was found to be 1,926 kJ/m2 in surface mold count, but sensory foreign flavor was determined at this dose. With UV-C light application, it was revealed that surface moldiness problem can be significantly reduced in yoghurts however high doses of UV-C light applications cause lipid oxidation and sensory foreign flavor.