PRY (Preservative Resistant Yeast Broth) is a membrane filtration medium with a low pH selective for detection of spoilage microorganisms resistant to acetic acid PRY medium is used for the detection of preservative resistant yeast in beverages such as beer bottled water cider soft drinks sport drinks and wine It is selective for Zygosaccharomyces species The medium prevents growth of other yeasts such as Saccharomyces cerevisiae that are tolerant to lower levels of commonly used food preservatives Spoilage resulting from growth of the yeast Zygosaccharomyces is widespread and causes significant economic losses to the food industry