title: Antifungal sourdough lactic acid bacteria as biopreservation tool in quinoa and rice bread.
abstract: The use of sourdough fermented with specific strains of antifungal lactic acid bacteria can reduce chemical preservatives in bakery products. The main objective of this study was to investigate the production of antifungal carboxylic acids after sourdough fermentation of quinoa and rice flour using the antifungal strains Lactobacillus reuteri R29 and Lactobacillus brevis R2Δ as bioprotective cultures and the non-antifungal L. brevis L1105 as a negative control strain. The impact of the fermentation substrate was evaluated in terms of metabolic activity, acidification pattern and quantity of antifungal carboxylic acids. These in situ produced compounds (n=20) were extracted from the sourdough using a QuEChERS method and detected by a new UHPLC-MS/MS chromatography. Furthermore, the sourdough was applied in situ using durability tests against environmental moulds to investigate the biopreservative potential to prolong the shelf life of bread. Organic acid production and TTA values were lowest in rice sourdough. The sourdough fermentation of the different flour substrates generated a complex and significantly different profile of carboxylic acids. Extracted quinoa sourdough detected the greatest number of carboxylic acids (n=11) at a much higher concentration than what was detected from rice sourdough (n=9). Comparing the lactic acid bacteria strains, L. reuteri R29 fermented sourdoughs contained generally higher concentrations of acetic and lactic acid but also the carboxylic acids. Among them, 3-phenyllactic acid and 2-hydroxyisocaproic acid were present at a significant concentration. This was correlated with the superior protein content of quinoa flour and its high protease activity. With the addition of L. reuteri R29 inoculated sourdough, the shelf life was extended by 2 days for quinoa (+100%) and rice bread (+67%) when compared to the non-acidified controls. The L. brevis R2Δ fermented sourdough bread reached a shelf life of 4 days for quinoa (+100%) and rice (+33%). However, the shelf life was similar to the chemically acidified control indicating that the preservation effect of the carboxylic acids seems to have a minor contribution effect on the antifungal activity in gluten-free breads.
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Ireland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Axel
authors.affiliation: Mass Spectrometry Research Centre (MSRC) & Team Elucidate, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
authors.forename: Brid
authors.initials: B
authors.lastname: Brosnan
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Ireland.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Zannini
authors.affiliation: Mass Spectrometry Research Centre (MSRC) & Team Elucidate, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
authors.forename: Ambrose
authors.initials: A
authors.lastname: Furey
authors.affiliation: Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland.
authors.forename: Aidan
authors.initials: A
authors.lastname: Coffey
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Ireland. Electronic address: e.arendt@ucc.ie.
authors.forename: Elke K
authors.initials: EK
authors.lastname: Arendt
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000935:Antifungal Agents / Q000494:pharmacology*; D061046:Biological Control Agents / Q000494:pharmacology*; D001939:Bread / Q000382:microbiology*; D002208:Caproates / Q000378:metabolism; D027465:Chenopodium quinoa / Q000382:microbiology*; D005285:Fermentation; D005433:Flour / Q000382:microbiology*; D005520:Food Preservatives / Q000494:pharmacology*; D061353:Food Storage; D005658:Fungi / Q000187:drug effects; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D007778:Lactobacillus / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism / Q000382:microbiology; D053719:Tandem Mass Spectrometry
chemical_list: D000935:Antifungal Agents; D061046:Biological Control Agents; D002208:Caproates; D005520:Food Preservatives; D007773:Lactates; C017648:3-phenyllactic acid; D019344:Lactic Acid; C019419:alpha-hydroxyisocaproic acid; D019342:Acetic Acid
keywords: Antifungal compounds; Bioprotective cultures; Lactobacilli; Shelf life; UHPLC-MS/MS