Whole Wheat Sourdough Research Articles

Screening and Application of Novel Homofermentative Lactic Acid Bacteria Results in Low-FODMAP Whole-Wheat Bread

FODMAPs are fermentable oligo-, di-, monosaccharides, and polyols. The application of homofermentative lactic acid bacteria (LAB) has been investigated as a promising approach for producing low-FODMAP whole-wheat bread. The low-FODMAP diet is recommended to treat irritable bowel syndrome (IBS). Wheat flour is staple to many diets and is a significant source of fructans, which are considered FODMAPs. The reduction of fructans via sourdough fermentation, generally associated with heterofermentative lactic acid bacteria (LAB), often leads to the accumulation of other FODMAPs. A collection of 244 wild-type LAB strains was isolated from different environments and their specific FODMAP utilisation profiles established. Three homofermentative strains were selected for production of whole-wheat sourdough bread. These were Lactiplantibacillus plantarum FST1.7 (FST1.7), Lacticaseibacillus paracasei R3 (R3), and Pediococcus pentosaceus RYE106 (RYE106). Carbohydrate levels in flour, sourdoughs (before and after 48 h fermentation), and resulting breads were analysed via HPAEC-PAD and compared with whole-wheat bread leavened with baker’s yeast. While strain R3 was the most efficient in FODMAP reduction, breads produced with all three test strains had FODMAP content below cut-off levels that would trigger IBS symptoms. Results of this study highlighted the potential of homofermentative LAB in producing low-FODMAP whole-wheat bread.

Effect of Staphylococcus aureus Contamination on the Microbial Diversity and Metabolites in Wholewheat Sourdough.

Wholewheat sourdough products are becoming increasingly more popular, and Staphylococcus aureus is a common opportunistic pathogen in dough products. The effects of S. aureus contamination (102 cfu/g) on metabolites as well as titratable acidity (TTA), pH, and microbial diversity of sourdough were investigated. S. aureus contamination significantly decreased the content of mannose while increasing the sorbitol in sourdough (p < 0.05). The S. aureus contamination significantly reduced the number of lactic acid bacteria (LAB), such as Lactobacillus curvatus, and the TTA values (p < 0.05). Furthermore, S. aureus contamination significantly reduced the content of most esters and acid flavor compounds while significantly increasing the content of 2,4-decadienal (p < 0.05), which is a compound that could have a negative impact on the flavor of sourdough. The PCA model developed based on volatile metabolites data could be used to distinguish contamination of S. aureus in sourdough cultured for 4 h. Sorbitol, 2,3-dimethylundecane, 1-pentanol, and 3-methylbutanoic acid were newly found to be the characteristic metabolites in S. aureus-contaminated sourdough.

Effect of the fermentation temperature on the degradation of phytic acid in whole-wheat sourdough bread

Whole-wheat bread is commonly consumed all over the world, in part because of its high nutritional content. These breads have high levels of phytic acid, which can chelate divalent minerals. In this study, lactic acid bacteria (LAB) were isolated from sourdoughs to screen for extracellular phytase activity and to determine the strains showing the highest activity for use in sourdough preparation. Phytase-active LAB strains were identified by 16S rRNA sequencing. The highest extracellular phytase activities were determined to be 803.95 U/mL and 797.88 U/mL, observed with Lactobacillus brevis HEB33 and Lactobacillus plantarum ELB78, respectively. Sourdough fermentation was performed at 25, 30 and 35 °C in order to determine the optimum temperature for the degradation of phytate. To investigate the temperature and strain effects on bread quality parameters, specific volume, texture, color and sensory analyses were performed along with analyses of the phytic acid and mineral contents. The highest phytate degradation was found in sourdough bread prepared with both Lactobacillus brevis HEB33 and Lactobacillus plantarum ELB78 fermented at 25 °C. The addition of spontaneously fermented sourdough at all tested temperatures, as well as the fermentation of sourdoughs at 35 °C, had negative effects on the quality parameters and sensory evaluation of the bread samples.

Application of the selected antifungal LAB isolate as a protective starter culture in pan whole-wheat sourdough bread

In vitro antifungal activity against Aspergillus niger was used to screen the lactic acid bacteria (LAB) isolated from whole wheat sourdough. Sequencing results of the PCR products led to the identification of Lactobacillus reuteri as the selected isolate. The LAB isolate had a proper anti-aflatoxigenic capability, and it reduced the amount of B1, B2, G1 and G2 aflatoxins, based on the results of HPLC analysis. n-Decanoic acid, 3-hydroxydecanoic acid and 3-hydroxydodecanoic acid were also identified as the bioactive ingredients using gas chromatography/mass spectrometry in the antifungal fraction obtained from preparative thin-layer chromatography of the L. reuteri culture filtrate. Furthermore, it was revealed that the sourdough fermented with the selected LAB isolate had a significant influence (P < 0.05) on the quality of the produced pan bread in terms of hardness, specific volume and phytic acid content. The growth of A. niger on the produced bread was also remarkably decreased using the controlled sourdough (containing the selected LAB isolate) in comparison with the spontaneous sourdough and control bread. Based on these findings, techno-functional properties of the selected LAB isolate were clarified, and therefore this isolate can be used successfully as a potent protective starter culture for sourdough bread processing.