Antifungal activities of three different Lactobacillus species and their production of antifungal carboxylic acids in wheat sourdough

Abstract

This study was undertaken to assess the antifungal performance of three different Lactobacillus species.Experiments were conducted in vitro and in situ to extend the shelf life of wheat bread. Standard sourdough analyses were performed characterising acidity and carbohydrate levels. Overall, the strains showed good inhibition in vitro against the indicator mould Fusarium culmorum TMW4.2043. Sourdough bread fermented with Lactobacillus amylovorus DSM19280 performed best in the in situ shelf life experiment. An average shelf life extension of six more mould-free days was reached when compared to the non-acidified control bread. A range of antifungal-active acids like 3-phenyllactic acid, 4-hydroxyphenyllactic acid and 2-hydroxyisocaproic acid in quantities between 0.1 and 360 mg/kg were present in the freeze-dried sourdoughs. Their concentration differed greatly amongst the species.However, a higher concentration of these compounds could not completely justify the growth inhibition of environmental moulds. In particular, although Lb. reuteri R29 produced the highest total concentration of these active compounds in the sourdough, its addition to bread did not result in a longest shelf life. Nevertheless, when the artificial compounds were spiked into a chemically acidified dough, it succeeded in a longer shelf life (+25 %) than achieved only by acidifying the dough. This provides evidence of their contribution to the antifungal activity and their synergy in concentration levels far below their single minimal inhibition concentrations under acidic conditions.

Identification and quantification of antifungal compounds produced by lactic acid bacteria and propionibacteria

“…These organic acids have been highlighted in previous studies as antifungal compounds produced by LAB and therefore could be of interest to extend bakery product shelf-life (Axel et al, 2016a, b). Dal Bello et al (2007), Lavermicocca et al (2000) and Magnusson et al (2003) reported the production of phenyllactic acid in antifungal lactobacilli isolated from different sources.…”

Control of Zymoseptoria tritici cause of septoria tritici blotch of wheat using antifungal Lactobacillus strains

“…The analysis was carried out using a Waters Quattro premier XE UPLC system as described by Axel et al . (). The LC‐MS/MS method was operated in negative electrospray ionization mode to detect the antifungal compounds.…”

A Review 'Clean Labeling': Applications of Natural Ingredients in Bakery Products

“…The use of natural preservatives would enable bakeries to market the so called "clean label" or "label friendly" products [40]. Thus, the "free-from" trend leads the bakery industry to reconsider traditional preservation methods and replace chemical preservatives with natural alternatives to guarantee a clean label [41].…”

“…reuteri R29 produced the highest total concentration of these active compounds in the sourdough, its addition to bread did not result in a longest shelf life. However, the chemical application of the antifungal carboxylic acids succeeded in a longer shelf life than achieved only by acidifying the dough (+25 %), which is an evidence of their contribution to the antifungal activity and their synergy [51].…”

“…Food labels of such products have claims such as "no preservatives" or "natural" [41]. Thus the inclusion of 'clean label' continues to drive health-focused new product developments.…”