How Humidity Affects Baking Yeast and Leaveners

Bakeries, breweries and those who appreciate bread owe a debt of gratitude to this single-celled fungus that feeds on sugars to produce alcohol and carbon dioxide gas – raising dough!

Yeast can be purchased as either compressed cakes or dry granules and stored properly can last two years; their effectiveness depends on factors like temperature, humidity and other environmental considerations.

Temperature

Yeast, the single-celled organism Saccharomyces cerevisiae that gives bread its rise and flavor, requires warmth and moisture for its survival. When these conditions exist, yeast releases carbon dioxide gas that causes dough to rise while improving texture, grain size, color and eating quality. Furthermore, yeast breaks down complex sugars present in flour and water into simple sugars more easily absorbed by its cells, as well as producing alcohol and other organic compounds which impart unique flavors into baked goods.

Chemical leaveners (baking soda and powder) are combinations of an alkaline and acid that react when mixed with liquids and heated in an oven, producing gas when heated. Since these leaveners don’t contain their own acid components, they rely on ingredients in recipes like buttermilk, fruit juices, vinegar, molasses or brown sugar that contain acids to trigger them into release the gas then again when heated by heat from an oven reactivates them again. Also providing leavening are egg whites which also contain natural acids which also leavened the bread or cookies produced. An imbalance between acid to leavener ratio can result in flat or overly chewy loaf of bread or cookies produced in an overly acid/leaven ratio could result in flat or overly chewy loaves or cookies produced.

To test whether active dry or rapid rise yeast is still active and ready to use in recipes, mix one teaspoon of sugar with 1/4 cup warm water (100 to 110AdegF) and see if the mixture bubbles up within five minutes – if so, your yeast is alive and can be added directly into any recipe!

Humidity

Humidity impacts many physical, chemical and biochemical processes involved with baking such as volume expansion, crust formation, yeast inactivation, protein coagulation, enzyme activities and gelatinization of starch. Furthermore, humidity controls heat transfers through convection, radiation and conduction. Furthermore, humid environments promote mold growth and spoilage of stored foods.

Yeast is an essential leavening ingredient, producing dough’s characteristic texture and rising properties. Produced by Saccharomyces cerevisiae bacteria, yeast also transforms sugars into carbon dioxide and ethanol during fermentation to add depth of flavor in bread products with either fruity or nutty notes depending on fermentation time and baking conditions.

Baker’s yeast comes in either compressed cakes or dry granules that must be mixed with warm water before use, both types being sensitive to temperature and humidity fluctuations and having different properties depending on which recipe it’s being used for. Both forms should be stored somewhere cool, dry and heat resistant – such as in a closet or cabinet for optimal conditions; when exposed to humidity spikes like humid or rainy seasons it could quickly deteriorate, leading to indoor relative humidity levels exceeding 60% and leading to mold growth.

Moisture

Yeast and leaveners are integral ingredients to baking breads, rolls, cakes, pastries, cookies and other food that require rising. They do so by releasing carbon dioxide gas during fermentation, expanding and increasing dough volume as it rises, while adding unique flavors to baked goods.

To produce leavening action in dough, yeast feeds on sugar from the dough and transforms it into a form that supports cells and structures within. As its cells consume this sugar for energy, they then release alcohol and carbon dioxide as waste products – similar to what happens when making yogurt or kombucha beverages.

As yeast’s microbial activity is stimulated by other bacteria present, as well as heat from an oven, for optimal leavening results it should be stored in an environment with plenty of air flow and plenty of cool, dry space with access to plenty of oxygen.

Fresh yeast can be purchased in liquid or compressed forms. Liquid yeast is easy to measure and dissolve into dough, while compressed forms often lose effectiveness over time even in the refrigerator; they must therefore be rehydrated prior to use; more modern versions, such as instant yeast granules containing both live and dried yeast cells do not require this step.

Sugar

Yeast is a single-celled organism that uses fermentation to make bread rise. By digesting the sugar found in dough and turning it into energy for itself, yeast releases carbon dioxide and alcohol as waste products that give yeast-raised products their airy structure and distinct taste and texture.

Bakers use Saccharomyces cerevisiae yeast, a species of fungus. To survive and reproduce effectively, yeast requires food in various forms including pure sugar, molasses, honey or natural sweeteners; along with certain fruit juices.

Sugar not only supplies yeast with energy for cell division and fermentation processes, but it also adds sweetness to baked goods and acts as a leavening agent – producing carbon dioxide during fermentation which allows dough to expand into light airy crumb shapes.

Commercial yeast comes in various forms designed for different uses. Cream yeast is a suspension of live yeast cells in liquid used frequently by commercial bakeries with professional dispensing and mixing equipment, and stored either in the fridge or freezer. Compressed yeast is a dry form of active yeast with its liquid removed for industrial and home use. While it can be stored in a refrigerator, before use it must first be reconstituted by adding warm sugar water before being consumed. Instant yeast resembles active dry yeast but is used without needing to rehydrate before use. Stored at room temperature, instant yeast won’t last as long as its compressed counterpart which can last up to one year when refrigerated or frozen.