Antifungal activities of three different Lactobacillus species  and their production of antifungal carboxylic acids in wheat  sourdough.
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.
School of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland.
Claudia
C
Axel
Mass Spectrometry Research Centre (MSRC) and Team Elucidate, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
Brid
B
Brosnan
School of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland.
Emanuele
E
Zannini
School of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland.
Lorenzo C
LC
Peyer
Mass Spectrometry Research Centre (MSRC) and Team Elucidate, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
Ambrose
A
Furey
Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland.
Aidan
A
Coffey
School of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland. e.arendt@ucc.ie.
Elke K
EK
Arendt
D000935:Antifungal Agents / Q000378:metabolism* / Q000494:pharmacology*; D001939:Bread / Q000382:microbiology*; D002264:Carboxylic Acids / Q000378:metabolism* / Q000494:pharmacology*; D005670:Fusarium / Q000187:drug effects* / Q000254:growth & development; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D014908:Triticum / Q000382:microbiology
D000935:Antifungal Agents; D002264:Carboxylic Acids