Rise and shine with yeast

by Sanjeev Kapoor

The aroma that emanates from the oven when a bread is being baked is something that is difficult to describe in just a few words. It has more than just the power to make your mouth water. According to a new study, it can also make you a kinder person. While other studies have connected pleasant smells to better moods in the past, the new study sought to make a concrete tie between aromas and good deeds. But this aroma comes only when the bread rises. And what makes the bread rise? It is a leavening that is added to the bread dough. This leavening is yeast.

What is yeast

There are quite a few leavening agents besides yeast. Like baking powder, baking soda, eggs, etc. Let us first study the role of leavening agents. It makes the product soft, chewy and also light. So, it is very necessary to take the role of a leavening agent seriously. Remember, they can make or mar our breads, cakes, cookies and all that we add the leavening to.

Do we really take bread for granted? Yes we do and no we should not. How easy it is to pick up a loaf bread from the shop shelf but did you know that we have been eating raised breads for the past six thousand years? Yet the secret of the raising or leavening agent has been disclosed just a few centuries ago. Now we know that it is the gas-producing metabolism of a particular kind of fungus which is yeast.

Origin of yeast

It can be said that yeast is man’s oldest industrial microorganism. Probably it was being used even before the written language was developed. It is said that ancient Egyptians were using yeast and the process of fermentation to produce alcoholic beverages and to leaven bread over 5000 years ago. They did not understand the working of yeast but thought it to be a mystery or magic.

As referred in Bible ‘Leaven’ was a soft dough-like medium, a small portion of which was used to leaven each new bread dough. Over the years the use of these starter cultures helped to select for improved yeasts by saving a “good” batch of wine, beer or dough for inoculating the next batch. For hundreds of years, it was traditional for bakers to obtain the yeast to leaven their breads as by-products of brewing and wine making. As a result, these early bakers have also contributed to the selection of these important industrial microorganisms.

How does yeast work

When added to dough, yeast ferments simple sugars and produces carbon dioxide and alcohol. The fermentation begins slowly and increases in speed with time. The increase in speed is due to two conditions in the dough: yeast multiplies and its enzymes become more active while the dough is being kneaded while the sugar for fermentation gradually liberates from starch in the dough by the action of natural flour enzymes.

The gas bubbles get distributed in the elastic dough prior to baking. The difference between delicate structure of the leavened dough and that of the baked dough can be clearly seen. While the baking process starts, the heat kills the yeast and inactivates its enzymes thus stopping further fermentation and release of carbon dioxide. But the bubbles already formed enlarge under the influence of the heat due to expansion of carbon dioxide, expansion of the entrapped air and conversion of water into steam. Yeast activity is dependent on temperature; they act best at about 35ºC.

Types of yeast

Yeast comes in many forms but for you and me, the packets of active dry yeast with expiry date stamped on them are the answer. The expiry date is valid for the packet kept at room temperature otherwise it can be stored for longer periods in the freezer.

You also get fresh yeast. But remember that dry yeast is nearly twice as strong as fresh yeast. Which means if you are using fresh yeast use double the amount of dry yeast. Fresh yeast is used in industrial bakeries which have special high-volume dispensing and mixing equipment. It is available in cake yeast which is soft, solid and beige in colour.

How to use yeast

It is very important to know that you should use just the amount that is recommended in the recipe – not more not less. Knead together the required amount of flour, water, some butter and active yeast and then leave the dough covered in warm place so that the dough rises and doubles in volume.

There is a way to prepare the yeast to be added to the dough. Add a quarter teaspoon of sugar to half a cup of warm water, stir and then sprinkle a teaspoon of yeast granules and cover instantly. The yeast will froth and that is when you add it to the flour. But if it does not become frothy, it means the yeast is inactive and is fit to be thrown away. You may well ask why was sugar added? That is because sugar feeds the yeast.

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MasterChef Sanjeev Kapoor

Chef Sanjeev Kapoor is the most celebrated face of Indian cuisine. He is Chef extraordinaire, runs a successful TV Channel FoodFood, hosted Khana Khazana cookery show on television for more than 17 years, author of 150+ best selling cookbooks, restaurateur and winner of several culinary awards. He is living his dream of making Indian cuisine the number one in the world and empowering women through power of cooking to become self sufficient. His recipe portal www.sanjeevkapoor.com is a complete cookery manual with a compendium of more than 10,000 tried & tested recipes, videos, articles, tips & trivia and a wealth of information on the art and craft of cooking in both English and Hindi.