First Report of Hanseniaspora guilliermondii as a Spoilage Yeast in Greek Yogurt with Mixed Berries in Egypt

The purpose of this study was to investigate the causative agent of a spoilage incident of Greek yogurt with mixed berries produced by one of the largest dairy manufacturing companies in Egypt. For this purpose, 5 samples from the affected batch were randomly collected and tested for sulfite-reducing bacteria growing under anaerobic conditions, coliforms, yeasts, and molds. The results of enumeration of sulfite-reducing bacteria and coliforms were below the detection limit, while yeasts and molds agar plates showed growth of yeast. From each sample, a yeast isolate was selected and identified by 5.8S-ITS rRNA analysis and sequencing. The yeast species was identified as Hanseniaspora guilliermondii in all the examined samples. This study is the first to report the association of H. guilliermondii with the spoilage of yogurt. This study highlights the importance of controlling non-Saccharomyces yeasts in yogurt production. Further research on the specific spoilage mechanisms of H. guilliermondii in dairy products is recommended.