Puratos (Belgium)

Abstract Background: In nature, microbial communities undergo changes in composition threatening their resilient behaviour. Here, we interrogated sourdough, a natural cereal-fermenting metacommunity, as challenging ecosystem, where players undergo continuous environmental and spatiotemporal stimuli. Results: Inspecting meta-genomes and -transcriptomes, spontaneous sourdoughs harboured dominant, sub-dominant and satellite players differently engaged in functional pathways. The highest microbial richness bared the highest number of gene copies per pathway. Merging meta-24 omics data or using the same microbiota of a spontaneous sourdough, we de novo reconstructed two synthetic microbial communities, respectively, SDG and SMC-SD43. In vitro, the KEGG number of dominant players in SDG was not affected by single player depletion; that of sub-dominants and satellites fluctuated but showed unique contributions. Compared to SMC-SD43, SDG ensured broader transcriptome redundancy. After in situ long-time back slopping, SDG kept stable, with constant volatilome. SMC-SD43 lost many members. Dominant, sub-dominant and satellite players altogether ensured gene and transcript redundancy. Conclusions: Our study demonstrates how starting from spontaneous sourdoughs and by reconstructing the synthetic community it was possible to unravel the metabolic contribution of individual players. To be resilient and performing, the sourdough metacommunity had to comprise dominant, sub-dominant and satellite players, which, only altogether, ensured gene and transcript redundancy. Overall, our study changed the paradigm and introduced theoretical foundations for steering food fermentations.

The main sponge cake ingredients are flour, sucrose, eggs and leavening agents. Exogenous lipids (e.g., monoacylglycerols) are often used to increase air–liquid interface stability in the batter. There is a consumer trend to avoid foods containing such additives. We here reasoned that egg yolk may be an alternative source of surface-active lipids and set out to study the role of egg yolk lipids during sponge cake making. This was done by relocating or removing them prior to batter preparation using ethanol treatments and examining how this affects cake (batter) properties and structure setting during baking. Most egg yolk lipids occur within spherical low-density lipoproteins (LDLs) which were disintegrated by the ethanol treatments. Results showed that egg yolk lipids impact air–liquid interface stability and less so cake structure setting. To prepare high-quality sponge cakes by multistage mixing preferably intact LDLs or, alternatively, their components are needed to incorporate sufficient air during mixing and to stabilize it after mixing. It was also shown that the batter contains intact LDLs in the continuous phase and disintegrated LDLs at air–liquid interfaces. Sponge cake contains intact LDLs in the cake matrix, disintegrated LDLs at air–crumb interfaces and disintegrated LDLs incorporated into the protein network.

SummaryAlthough the impact of heat on molecular properties of wheat gluten is well understood, changes in its microstructure have rarely been studied. Here, formation of the thermoset gluten network in a model system relevant for bread baking was studied with confocal laser scanning microscopy and protein network analysis. From 65 °C onwards, gluten converts from thick aligned protein strands in a highly branched and homogeneous network of small thin protein threads. Neither gliadin incorporation in the network nor application of aqualysin 1, the thermo‐active serine peptidase from Thermus aquaticus which recently has been reported to hydrolyse gluten proteins in dough only at temperatures exceeding 80 °C, impacts on the gluten microstructure. As starch causes structure setting itself and thereby decreases protein mobility, molecular scale changes in the gluten network at temperatures exceeding 80 °C brought about by aqualysin 1 do not impact its microstructure.

Abstract There is an increasing interest in vegetable lecithins because of their broad usage in many food and cosmetic applications. In this research, the chemical variability of commercial lecithins from soy, sunflower and rapeseed were mapped. The acetone insoluble matter, total phospholipid content and their compositions were determined. Significant correlation coefficients were observed between phosphatidylcholine and phosphatidic acid (−0.84), phosphatidylethanolamine and phosphatidylinositol (−0.86), monounsaturated fatty acid and polyunsaturated fatty acid (−0.97). Principal component analysis was used to group the lecithins according to their sources. Rapeseed lecithin was found to be the most different product compared to soy and sunflower lecithin.