Diversity profiling and rapid detection of spoilage yeasts in a typical fruit juice bottling factory

Abstract

Spoilage caused by yeasts is a constant and widespread problem in the beverage industry which can result in major economic losses. Fruit juices provide an environment which allows the proliferation of yeasts, leading to spoilage of the product. Some factories do not have the laboratory facilities to identify spoiler yeasts and it becomes a prolonged process if outsourced, which obstructs the planning of corrective actions. This study aimed to establish yeast diversity and apply a rapid method for preliminary identification of spoiler yeasts associated with a small scale fruit juice bottling factory. The yeast population in the factory was determined by isolating yeasts from the production environment, process equipment and the spoiled products. Yeasts were identified by PCR-RFLP analysis targeting the 5.8S-ITS region and sequencing the D1/D2 domain of the 26S rRNA gene. A total of 201 yeasts belonging to ten different genera (Candida, Lodderomyces, Wickerhamomyces, Yarrowia, Zygosaccharomyces, Zygoascus, Cryptococcus, Filobasidium, Rhodotorula/Cystobasidium and Trichosporon) were isolated and identified from the production environment and processing equipment. The overall yeast distribution showed that Candida parapsilosis and Lodderomyces elongisporus were widely distributed in the factory, with Candida parapsilosis being reported as an opportunistic pathogen. Zygosaccharomyces bailii, Zygoascus hellenicus and Saccharomyces cerevisiae were isolated from the spoiled products and are known to be highly fermentative. In addition, Zygosaccharomyces bailii and Zygoascus hellenicus were found to be present inside the refrigerator where the fruit pulp is stored, which makes it a potential point of contamination. The data also provided a yeast control panel which was successfully utilized to identify unknown yeast in spoiled product from this factory using PCR-RFLP analysis.