Application of ozone in preventing the growth of Aspergillus niger and Penicillium notatum in Low-fat set yoghurt

Abstract

Abstract Introduction: Yoghurt is a popular fermented dairy product in the world. Although molds are naturaly associated with the spoilage of cheese, the majority of the fungal species can grow in the acidic yoghurt environment and cause spoilage in it. Interest in ozone applicate has expanded in recent years due to consumer demands for ‘greener’ food additives, and acceptance. Ozone application is an environmentally friendly technology that may be used to control spoilage molds in the manufactured yoghurt. The aim of this study was to use the higher concentration and time the ozonation to obtain the maximum desired result in reducing fungal contamination in low-fat set yoghurt. Methods: The ozone stream at a concentration of 20 ppm for 60 minutes was applied to the surface of contaminated yoghurt samples in order to decrease airborne spoilage microorganisms including Penicillium notatum and Aspergillus niger. The samples were then stored at 4-5°C for 28 days and examined on days 1, 7, 14, 21 and 28 days for microbial, physicochemical, and sensory characteristics. Results: There was approximately 2.83 Log CFU/g and 0.12 Log CFU/g reduction in Penicillium notatum and Aspergillus niger counts respectively in ozonated yoghurt samples in comparison to the control samples by the end of the monitoring period. However, some sensorial alterations were observed and taste and acceptance characteristics were low in Ozonated yoghurt Compared with control yoghurt (p <0.05). Conclution: It was concluded that, Ozone was effective in reducing penicillium notatum but was not effect on Aspergillus niger. However, ozonation could be a promising approach to the production of safe dairy products. Keywords: Ozone, Yoghurt, Penicillium notatum, Aspergillus niger