Bread flavor

The composition of the volatile fraction of bread depends on the bread ingredients, the conditions of dough fermentation and the baking process. This fraction contributes significantly to the desirable flavors of the crust and the crumb. For this reason, the volatile fraction of different bread types has been studied by several authors. Within the more than 280 compounds that have been identified in the volatile fraction of wheat bread, only a relative small number are responsible for the different notes in the aroma profiles of the crust and the crumb. These compounds can be considered as character impact compounds. Approaches to find out the relevant aroma compounds in bread flavors using model systems and the odor unit concept are emphasized in this review. A new technique denominated "aroma extract dilution analysis" was developed based on the odor unit concept and GC-effluent sniffing. It allows the assessment of the relative importance of the aroma compounds of an extract. The application of this technique to extracts of the crust of both wheat and rye breads and to the crumb of wheat bread is discussed. 

During the last four decades, economic pressures have forced changes in bread manufacture and distribution. Hence, as a consequence of the sensitivity of bread flavor to changes in technological procedures, the bread produced in a modern way is often somewhat deficient in odor and taste compared to bread produced and distributed by traditional methods. 

To improve the quality of bread produced by modern methods, it is necessary to understand the chemistry of bread flavor. Therefore many studies have been undertaken to clarify the composition and formation of the flavors of different types of bread (1-5). 

Figure 1. Proposed heterocyclic key compounds of bread flavor...

Shortened fermentation or baking steps during bread making often result in bread of poor flavor quality. To improve the flavor of bread produced by modern technology it is necessary to gain information about precursors and reaction routes leading to important bread flavor compounds. 

Thiele, C., Ganzle, M.G., Vogel, R.F. 2002. Contribution of sourdough lactobacilli, yeasts, and cereal enzymes to the generation of amino acids in dough relevant for bread flavor. Cereal Chem 79 45-51. 

Flavor Descriptors Roasted, Bread Crust Occurrence Coffee, Cooked Pork, Wheat Bread Flavor Threshold 0.04 ppb... 

It has long been known that the lack of certain substances in our diet brings about serious conditions known as deficiency disease. To these substances the name vitamines has been given. Yeast is the chief source of these. marvelous, substances without which life would The in-ipngsiKla. The rich bread flavor of which man never tires is the result of the interaction of the products of yeast fermentation and its importance cannot be overestimated. ... 

The richness of bread is directly associated with the fermentation of the dough. The rich bread flavor is supposed to be due to split-protein products produced during fermentation. The flavor of flour is a very different thing from the flavor of rich bread. The bread flavor is something very complex and delicate as shown by the fact that any small change in manipulation changes the flavor of the bread. 

Bread flavor. White bread During the baking process the impact substances 2-acetyl-1 -pyrroline and 2-ace-tyl-A (A )-tetrahydropyridine form in the crust, on storage their concentrations decrease rapidly. Precursors are metabolites of yeasL Also of importance are ( )-2-nonenal (see alkenals), 3-methylbutanal (see al-kanals), 2,3-butanedione, and methional. In bread crumbs, degradation products of linolic acid such as ( )- and (Z)-2-nonenaJ and ( , )- 2,4-decadienal predominate. 

Importance Pro is able to participate in a-helices to a much lower extent than other amino acids. It is thus a helix breaker of particular importance for the structure of proteins. Rotation about the amino peptide bond of proline is especially hindered the correct folding of Pro-containing proteins thus appears to be catalyzed by peptidylprolyl cis-fra/u-isomerases (rotamases, EC 5.2.1.8 see FK-506). On account of its presence in gluten, Pro is involved in the Maillard reaction resulting in the typical bread flavor. The inner salt (betaine) of I, l-dimethyl-P. is a widely distributed pyrrolidine alkaloid in plants, e.g., in woundwort (Stachys spp., stachydrin). 

WLP Bredie, M Boesveld, G Budolfsen, L Dybdal. Modification of bread flavor with enzymes. Poster presented at the American Association of Cereal Chemists annual meeting, Minneapolis, 1998. 

Sourdoughs contain significant amounts of Lactobacillus plantarum, L san francisco, L fermentum, L brevis, Leuconostoc mesenteroides, and Streptococcus thermophilus, which act synergistically with yeast to enhance bread volume and the typical bread flavor. 

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