Bread

Bread wheat (Triticum aestivum, genome BBAADD) is a young hexaploid species formed only 8,500-9,000 years ago through hybridization between a domesticated free-threshing tetraploid progenitor, genome BBAA, and Aegilops tauschii, the diploid donor of the D subgenome. Very soon after its formation, it spread globally from its cradle in the fertile crescent into new habitats and climates, to become a staple food of humanity. This extraordinary global expansion was probably enabled by allopolyploidy that accelerated genetic novelty through the acquisition of new traits, new intergenomic interactions, and buffering of mutations, and by the attractiveness of bread wheat's large, tasty, and nutritious grain with high baking quality. New genome sequences suggest that the elusive donor of the B subgenome is a distinct (unknown or extinct) species rather than a mosaic genome. We discuss the origin of the diploid and tetraploid progenitors of bread wheat and the conflicting genetic and archaeological evidence on where it was formed and which species was its free-threshing tetraploid progenitor. Wheat experienced many environmental changes throughout its evolution, therefore, while it might adapt to current climatic changes, efforts are needed to better use and conserve the vast gene pool of wheat biodiversity on which our food security depends.

Humans have relied on sourdough starter microbial communities to make leavened bread for thousands of years, but only a small fraction of global sourdough biodiversity has been characterized. Working with a community-scientist network of bread bakers, we determined the microbial diversity of 500 sourdough starters from four continents. In sharp contrast with widespread assumptions, we found little evidence for biogeographic patterns in starter communities. Strong co-occurrence patterns observed in situ and recreated in vitro demonstrate that microbial interactions shape sourdough community structure. Variation in dough rise rates and aromas were largely explained by acetic acid bacteria, a mostly overlooked group of sourdough microbes. Our study reveals the extent of microbial diversity in an ancient fermented food across diverse cultural and geographic backgrounds.

Sourdough fermentation by lactic acid bacteria is commonly used in bread baking, affecting several attributes of the final product. We analyzed whole-grain wheat and rye breads and doughs prepared with baker's yeast or a sourdough starter including Candida milleri, Lactobacillus brevis and Lactobacillus plantarum using non-targeted metabolic profiling utilizing LC-QTOF-MS. The aim was to determine the fermentation-induced changes in metabolites potentially contributing to the health-promoting properties of whole-grain wheat and rye. Overall, we identified 118 compounds with significantly increased levels in sourdough, including branched-chain amino acids (BCAAs) and their metabolites, small peptides with high proportion of BCAAs, microbial metabolites of phenolic acids and several other potentially bioactive compounds. We also identified 69 compounds with significantly decreased levels, including phenolic acid precursors, nucleosides, and nucleobases. Intensive sourdough fermentation had a higher impact on the metabolite profile of whole-grain rye compared to milder whole-grain wheat sourdough fermentation. We hypothesize that the increased amount of BCAAs and potentially bioactive small peptides may contribute to the insulin response of rye bread, and in more general, the overall protective effect against T2DM and CVD.

PurposeBread is a global staple with large variations in carbohydrate quality. The role of bread for weight regulation has been controversial and few studies have investigated associations of bread consumption with long-term weight changes. Therefore, our objective was to investigate the associations of baseline intake of bread, different types of bread, and whole grains as well as plasma alkylresorcinol - a biomarker of wholegrain wheat and rye intake - with weight changes during a follow-up covering the 6th and 7th decades of life.MethodsThe current analyses were conducted in 1764 men and women (47.4 ± 0.6 years at baseline) participating in the second and third wave of the Hordaland Health Study. A food frequency questionnaire was used to estimate baseline bread and wholegrain intake. Baseline plasma alkylresorcinol concentrations were determined in blood samples. The outcome was weight change (kg) during the 20-year follow-up. Multivariate linear regression models were applied.ResultsParticipants gained on average 2.1 ± 7.4 kg during follow-up. While total bread intake at baseline was not associated with weight change, a higher white bread intake was associated with weight gain (0.017 kg/g white bread/day, 95% CI: 0.002, 0.032 kg/g white bread/day). Wholegrain consumption - but not wholegrain bread - was inversely associated with weight gain (-0.013 kg/g whole grain/day, 95% CI: -0.026, 0.000 kg/g whole grain/day). Accordingly, plasma alkylresorcinols were inversely associated with weight gain (-0.004 kg/nmol/L alkylresorcinol, 95% CI: -0.007, -0.002 kg/nmol/L alkylresorcinol).ConclusionThe current study suggests that weight regulation is associated with the carbohydrate quality of breads, i.e., refined versus wholegrain breads. Wholegrain intake, based on both self-reported dietary data and objective biomarkers, may improve weight regulation from middle to late adulthood.