Molecular comparisons for identification of food spoilage yeasts and prediction of species that may develop in different food products

Authors: Kurtzman, Cletus

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/4/2014
Publication Date: 9/4/2014
Citation: Kurtzman, C.P. 2014. Molecular comparisons for identification of food spoilage yeasts and prediction of species that may develop in different food products [abstract].

Interpretive Summary:

Technical Abstract: Spoilage of foods and beverages by yeasts is often characterized by objectionable odors, appearance, taste, texture or build-up of gas in packaging containers, resulting in loss of the product. Seldom is human health compromised by products spoiled by yeasts even though some spoilage is caused by species that are opportunistic pathogens. A secondary effect of yeast contamination is metabolism of nitrites and organic acids that are added to products to control growth of food safety bacteria. Detection, identification and source tracing are important aspects of quality control programs, such as the HACCP system, but the success of quality control is dependent on knowing the identity of the spoilage organisms. Once spoilage occurs, it is necessary to identify spoilage species accurately to establish effective quality control. DNA-based methods offer the most rapid and accurate means for species identification. Common approaches for yeasts include sequencing of diagnostics regions, such as ITS or the D1/D2 domains of the LSU rRNA gene, or methods based on these sequences, which may include species-specific primers and probes, RAPD, real time PCR, DGGE and bead-based flow cytometry. Molecular identification has shown that a large number of ascomycete yeast genera cause spoilage, but only a few basidiomycete yeast genera, such as Trichosporon, Rhodotorula, and Cryptococcus, initiate spoilage. Phylogenetic analysis of spoilage organisms has revealed that certain foods, such as those high in sugar or salt, are often spoiled by groups of closely related species. For example, many high sugar products are spoiled by Zygosaccharomyces, Torulaspora and relatives, whereas meat products are often spoiled by species of Yarrowia and Debaryomyces. Knowledge of product composition and species relationships allows prediction of which species are likely to spoil particular products, which can lead to product formulations less likely to undergo spoilage.