Funded by The Department of Agriculture, Food and Marine (DAFM) - Project reference number: 15/F/731 

Abstract

Yeast contamination is a problem in a wide range of food products. Yeast growth, leading to spoilage, is an important cause of economic losses in food industry. The sensorial changes that appear in spoiled food result in consumers’ complaints. Vacuum-packed cheeses and other foods/beverages stored under similar anaerobic conditions are particularly susceptible. The overall objective of this project is to characterise the anti-yeast activity of compounds either produced by protective lactic acid bacteria (LAB) or plant-derived compounds identified as defensins. We have previously identified a strong anti-mould LAB strain and the strain has been patented and licensed to Industry. As yeast inhibition was not investigated previously, the proposed project aims to isolate and characterise potential anti-yeast compounds from LAB strains including those previously shown to have anti-mould traits. These anti-yeast compounds would be chemically synthesised to unravel their inhibitory concentrations against selected yeasts. In parallel, antimicrobial peptides known as defensins would also be investigated. These are present in diverse organisms (plants, humans, insects etc). Some defensins in the scientific literature have already been shown to have inhibitory activity against yeast, and indeed one anti-yeast defensin has already been identified in our laboratory where it has been subjected to preliminary investigation against other microorganisms. Here, we propose to mainly focus here on plant defensins that can be easily extracted from seeds and or/chemically synthesised. The inhibitory activity of anti-yeast compounds from LAB and the plant defensins will be assessed both in vitro and in a range of food products (dairy, cereal products and beverages). In addition, the impact of these compounds on a wide range of product parameters will be measured. Special emphasis will be placed on product safety aspects. Challenge tests will be performed on the food products and cytotoxicity assays will be carried out as well. A comprehensive dissemination and product protection plan will be an integral part of the project.