Lactobacillus strains isolated from Danbo cheese as adjunct cultures in a cheese model system

Abstract

Isolates of Non-Starter Lactic Acid Bacteria (NSLAB) from six ripened Danbo cheeses of different ages and of different brands were examined. Special emphasis was on the genus Lactobacillus with the aim of investigating their role in cheese maturation. Thirty-three isolates were typed by the PCR-based method, Randomly Amplified Polymorphic DNA (RAPD). Ten RAPD types were found and 70% of the isolates were of RAPD types found in more than one cheese. The different RAPD types were identified to species level by Temporal Temperature Gradient Gel Electrophoresis (TTGE). Most of the isolates were identified as Lactobacillus paracasei (76%), but also Lactobacillus curvatus, Lactobacillus plantarum, Lactobacillus rhamnosus and some taxa originating from the starter culture were detected. In one cheese, no lactobacilli were found . One strain of the most frequent Lactobacillus RAPD type from each of the five cheeses with a Lactobacillus flora was used as adjunct cultures in a cheese model system. Four of the five adjuncts were re-isolated during ripening. Two adjunct containing model cheeses received higher flavour scores than the control while two other were associated with off-flavours. The two model cheeses with off-flavour had a similar microflora and both were after 13 weeks of ripening dominated by a strain identified as L. plantarum.