Answer to Question #10650 in Biochemistry for Raquel Smedley
How do variations in the bread rising process temperature affect the process, and the final product?
The fermentation process is driven primarily by the life cycle of yeast, with bacterial activity playing a supporting role. Too cold or too hot dough can affect yeast activity and enzyme functioning. At temperatures below 50 degrees Fahrenheit, yeast is largely dormant and inactive. It will still rise a dough but it will take much longer. Yeast becomes more active as the temperature rises, peaking between 90-100 degrees. Above 100 degrees, the yeast becomes less active again, and at 138 degrees Fahrenheit, the delicate microorganisms are killed.
Different fermentation temperatures can yield correspondingly different results and a versatile baker can make this decision part of his or her toolbox. A change in fermentation temperature will change the proportions of lactic and acetic acid in a dough resulting in markedly different flavor and physical characteristics. A higher fermentation temperature – 27ºC+ (80ºF) - will cause a noticeable jump in lactic acid production. Lactic acid has a round, mellow flavor that fills the back of the mouth, the flavor you get in buttermilk or yogurt. Breads with a higher lactic acid content taste fuller in the mouth, often have a more open crumb and a thinner, crispier crust. A lower temperature - 22ºC or less (72ºF) - will not affect the acetic acid development but will drop the amount of lactic acid resulting in a more astringent flavor that is tighter and sharper in the mouth, the flavor you get in vinegar. Breads with a higher acetic acid content often have a tighter crumb and a thicker, less crispy, chewier crust.
It is suggested that the final dough temperature does not always have a specific value, but rather, is determined by the type of dough being prepared. For instance:Consistency Water Content Example Temperature For& dry consistency (water content below 50%)& like italian breads farrarese, mantovano the temperature should be 23 C (73.4 F) For soft - 25 C (77 F) For slack douph (water content 60 to 65%) T= 27-28C (80.6-82.4 F)