Sourdough starters also produce lactic and acetic acids, further contributing to flavor. The baker's yeast enzyme maltase converts maltose into glucose, invertase converts any added sucrose to glucose and fructose, and zymase converts glucose and fructose to carbon dioxide gas which makes the dough rise, and alcohol which gives the baked bread flavor. Specifically, the grain enzyme diastase begins to convert starch in the grain to maltose. Enzymes in the flour and yeast create sugars, which are consumed by the yeast, which in turn produce carbon dioxide and alcohol. įermentation typically begins when viable baker's yeast or a starter culture is added to flour and water. While this sugar may be sucrose or table sugar, instead it may be glucose or maltose. Typically 60 ml ( 1⁄ 4 cup) water at 40–45 ☌ (105–115 ☏) and 2 g ( 1⁄ 2 teaspoon) of sugar are used, or expressed differently, a sugar weight of about 3.5% of the water's weight. Yeast viability can be tested by mixing yeast in warm water and sugar, and following a short rest period during which the cells first accommodate to the environment and then begin to grow, a layer of foam is developed by the action of the yeast, a sign of primary fermentation and live yeast. The minimum weight of water required may be calculated: yeast weight x 4 = water weight. ' Proofing the yeast' is a hydration process that occurs when dry yeast is mixed with warm water and allowed to rest for a short time. The autolyse is credited to Raymond Calvel, who recommended it as a way to reduce kneading time and thereby improve the flavor and color of bread. This rest period allows for better absorption of water and helps the gluten and starches to align. This refers to a period of rest after the initial mixing of flour and water, a rest period that occurs sequentially before the addition of yeast, salt and other ingredients. Some breads begin mixing with an autolyse. Proofing, also sometimes called final fermentation, is the specific term for allowing dough to rise after it has been shaped and before it is baked. Particular rest periods include, but are not limited to, autolyse, bulk fermentation and proofing. Work periods are typically followed by rest periods, which occur when dough is allowed to sit undisturbed. Some work periods are called mixing, kneading, and folding, as well as division, shaping, and panning. Work periods occur when the dough is manipulated by the baker. The process of making yeast-leavened bread involves a series of alternating work and rest periods. If the yeast is still alive, it will feed on the sugar and produce a visible layer of foam on the surface of the water mixture.įermentation rest periods are not always explicitly named, and can appear in recipes as "Allow dough to rise." When they are named, terms include "bulk fermentation", "first rise", "second rise", "final proof" and "shaped proof". Proofing can also refer to the process of testing the viability of dry yeast by suspending it in warm water with carbohydrates (sugars). In contrast, proofing or blooming yeast (as opposed to proofing the dough) may refer to the process of first suspending yeast in warm water, a necessary hydration step when baking with active dry yeast. During this rest period, yeast ferments the dough and produces gases, thereby leavening the dough. In cooking, proofing (also called proving) is a step in the preparation of yeast bread and other baked goods in which the dough is allowed to rest and rise a final time before baking. Bread covered with linen proofing cloth in the background.
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