Lactic acid bacteria bioprotection applied to the malting process. Part II: Substrate impact and mycotoxin reduction Pedro Oliveira a , Brid Brosnan b , Fritz Jacob c , Ambrose Furey b , Aidan Coffey d , Emanuele Zannini a , Elke K. Arendt a, * a School of Food and Nutritional Sciences, National University of Ireland, University College Cork, College Road, Cork, Ireland b MSRC, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland c Forschungszentrum Weihenstephan für Brau- und Lebensmittelqualit€ at, Technische Universit€ at München, Alte Akademie 3, 85354 Freising-Weihenstephan, Germany d Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland article info Article history: Received 24 April 2014 Received in revised form 2 November 2014 Accepted 7 November 2014 Available online 15 November 2014 Keywords: Fusarium culmorum Antifungal Lactobacillus reuteri Phenyllactic acid Wort Deoxynivalenol abstract Lactic acid bacteria (LAB) with antifungal activity can be applied to the malting process in order to improve the microbial stability and safety of malt. The main objectives of this project was to evaluate the influence of the antifungal activity of LAB cell-free-supernatant (cfs) in the malting process and to investigate antifungal effects of selected LAB towards the mould growth and mycotoxin production of Fusarium culmorum. The impact of substrate concentration on the production of LAB antifungal com- pounds and the changes in the malt quality attributes was also investigated. Barley grains infected with F. culmorum were used in the malting trials. Lactobacillus amylovorus and Lactobacillus reuteri cfs were generated in a wort based substrate and applied in the early stages of malting. F. culmorum growth was quantified and the mycotoxin deoxynivalenol (DON) was detected in the malted grains. The various supernatants were characterized based on their sugar and organic acid composition. Antifungal me- tabolites were quantified using a QuEChERS and HPLC-UV/PDA method. Standard EBC methods were used to evaluate the malt quality attributes. Results show that L. reuteri R29 cfs produced in 3  P substrate successfully inhibited Fusarium growth by 23% and mycotoxin DON by 83%. Using a 3  P wort substrate concentration, 68% of the phenyllactic acid (PLA) was produced, when compared to the 12  P substrate. PLA plays an essential role in the supernatant antifungal activity. Malt quality attributes resulted in highly modified grains, lower pH, higher colouration, and higher extract yield. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Lactic acid bacteria (LAB) have been of great interest to the cereal/beverage industry due to their potential to improve the safety as well as the quality of cereal/beverage products. Malting is defined as the limited germination of cereal grains. During this process simple sugars and enzymes are generated. Steeping is the first stage of malting and is considered the critical stage for development of the microbiota. During steeping, soaking and air stages, with high moisture levels (over 95% RH), and with a temperature ranging between 14 and 16  C, optimal conditions for the grain to grow are generated. The subsequent germination takes place for 4e6 days applying the same humidity conditions. Following the germination step, the third malting stage is called kilning, where the green malt grains are dried to reach moisture levels of 3e4% (Kunze, 2010). The above described malting process provides the optimal conditions for fungi, naturally present in grains, to proliferate (Rabie, Lübben, Marais, & Van Vuuren, 1997). Contaminated cereal grains containing pathogenic filamentous mould, can lead to mould proliferation during the malting stages. Fungi colonize healthy grains and produce mycotoxins, even if present in small concen- trations (Oliveira, Mauch, Jacob, Waters, & Arendt, 2012). These mycotoxins can accumulate in processed cereal-based food or * Corresponding author. Tel.: þ353 21 490 2064; fax: þ353 21 427 0213. E-mail address: e.arendt@ucc.ie (E.K. Arendt). Contents lists available at ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont http://dx.doi.org/10.1016/j.foodcont.2014.11.011 0956-7135/© 2014 Elsevier Ltd. All rights reserved. Food Control 51 (2015) 444e452