Development of antifungal ingredients for dairy products: from in vitro screening to pilot-scale applications

Key words: antifungal activity, screening, bacteria, molds, dairy productsIntroductionIn dairy products, bioprotective cultures and their metabolites represent an interesting alternative to chemical preservatives. The aim of this study was to develop dairy ingredients with antifungal properties, active against a large diversity of spoilage fungi and to test their efficiency and organoleptic impact in real products. Materials and methods First, the biodiversity of spoilage fungi in a large variety of dairy products was investigated using molecular methods in order to select the most appropriate fungal targets. Then, the antifungal activity of fermentates obtained from 698 lactic acid bacteria, propionibacteria and fungal strains were screened in vitro using a novel high-throughput method in a cheese mimicking model. After optimizing fermentation conditions to improve antifungal activity, the best fermentates were tested at a pilot scale in uncooked pressed cheese (UPC) and sour cream to evaluate their antifungal activity using challenge and durability tests and their impact on organoleptic properties using sensorial analysis.Results The in vitro screening allowed selecting antifungal ingredients that were also active in situ. Durability tests revealed that a Lactobacillus rhamnosus fermentate had a promising activity in sour cream. For UPC, a Propionibacterium jensenii–based ingredient could be used instead of natamycin delaying Mucor racemosus and Penicillium commune for up to 16 days. Conclusion These approaches led to the development of new antifungal dairy-based ingredients that might replace natamycin in UPC