Industrial-scale application of Lactobacillus reuteri coupled with glycerol as a biopreservation system for inhibiting Clostridium tyrobutyricum in semi-hard ewe milk cheese

The suitability of the biopreservation system formed by reuterin-producing L reuteri INIA P572 and glycerol (required for reuterin production) to prevent late blowing defect (LBD) was evaluated in industrial sized semi-hard ewe milk cheese contaminated with Clostridium tyrobutyricum INIA 68, a wild strain isolated from a LBD cheese. For this purpose, six batches of cheese were made (three with and three without clostridial spores): control cheeses with lactococci starter, cheeses with L. reuteri as adjunct, and cheeses with L. reuteri and 30 mM glycerol. Spores of C tyrobutyricum INIA 68 germinated during pressing of cheese curd, causing butyric acid fermentation in cheese after 30 d of ripening. The addition of L. reuteri, without glycerol, enhanced the symptoms and the formation of volatile compounds associated with LBD. When glycerol was added to cheese milk contaminated with C tyrobutyricum, L. reuteri was able to produce reuterin in cheese resulting in cheeses with a uniform cheese matrix and a volatile profile similar to cheese made with L reuteri and glycerol (without spores). Accordingly, L reuteri INIA P572 coupled with glycerol seems a novel biopreservation system to inhibit Clostridium growth and prevent LBD by means of in situ reuterin production. (C) 2017 Elsevier Ltd. All rights reserved.