Yeasts are tiny living organisms that allow us to transform natural raw materials into fermented products. For example, yeasts use sugar to enable bread dough to rise. Without yeasts, we would have flat bread. Yeasts can also transform the sugar present in grape must or beer wort into ethanol and carbon dioxide thus producing alcoholic beverages. Without yeasts, there would be no wine, beer or alcohol.

Yeasts can be found in many environments, from the grape to the bottom of a bread pan, from the surface of our skin to the legs of various insects, such as bees or fruit flies. Yeasts are “nice” microorganisms that contribute to the quality of fermented products and to the ecological equilibrium of our world. The role of the Lallemand Company is to find new ways to produce these microorganisms naturally and in great quantity, thereby making them readily available to several end-users such as bakers, winemakers, and brewers.

Did you know that from only one gram of yeast, the Lallemand Company can obtain several tons of fresh yeast?

Yeasts can multiply quickly if they are given the right food. To live, yeast needs water, energy, and nutrients. I Read More

Yeasts are tiny living organisms that allow us to transform natural raw materials into fermented products. For example, yeasts use sugar to enable bread dough to rise. Without yeasts, we would have flat bread. Yeasts can also transform the sugar present in grape must or beer wort into ethanol and carbon dioxide thus producing alcoholic beverages. Without yeasts, there would be no wine, beer or alcohol.

Yeasts can be found in many environments, from the grape to the bottom of a bread pan, from the surface of our skin to the legs of various insects, such as bees or fruit flies. Yeasts are “nice” microorganisms that contribute to the quality of fermented products and to the ecological equilibrium of our world. The role of the Lallemand Company is to find new ways to produce these microorganisms naturally and in great quantity, thereby making them readily available to several end-users such as bakers, winemakers, and brewers.

Did you know that from only one gram of yeast, the Lallemand Company can obtain several tons of fresh yeast?

Yeasts can multiply quickly if they are given the right food. To live, yeast needs water, energy, and nutrients. In fact, at Lallemand, the yeasts are fed with molasses! They are also provided with nutritional supplements such as vitamins and minerals, nitrogen and phosphate. The yeast is produced in large vats called fermenting tanks.

A wide variety of yeasts exist, but the most famous one is most certainly Saccharomyces cerevisiae.


© Armand-Frappier Museum, 2008. All rights reserved.

Saccharomyces cerevisiae

Lallemand

© Lallemand


Yeast – Why Your Bread Is Fluffy

To make the bread you eat every day, bakers must of course use flour, water and salt, but they also have to add something to make the dough rise. This "something" is usually yeast, a microscopic fungus which gives bread its flavour and lightness.
Yeast – Why Your Bread Is Fluffy

To make the bread you eat every day, bakers must of course use flour, water and salt, but they also have to add something to make the dough rise. This "something" is usually yeast, a microscopic fungus which gives bread its flavour and lightness.

© Armand-Frappier Museum, 2008. All rights reserved.

Bread making

To make bread, one starts by mixing flour and water. Yeast is then added to the resulting dough.

Yeast is a microorganism consisting of a single cell. There are different types of yeasts, but the one that is generally used is called Saccharomyces cerevisiae.

The dough is then sent for kneading which is a particular way of folding the dough on itself in order to distribute the cells uniformly in the bread dough.

The dough is then left to rest: this is the incubation period during which the yeasts reproduce in the dough.

During a few automatic steps, the bread is given the desired shape.

It is then placed in bread pans and sent to the ovens for baking.

Yeasts feed on maltose, a sugar that is found in flour. When the yeasts degrade the maltose to feed on it, they liberate alcohol and carbon dioxide. This process is called alcoholic fermentation. The carbon dioxide bubbles push against the dough and this gives it volume and forms visible bubbles in the bread.

During baking, the yeasts are killed and the alcohol is burned, which gives the bread its good taste.

When the bread is cooked and golden brown, it is sliced and individually wrapped.

The fresh bread is finally ready to be delivered to the stores where we can purchase and then savor it.

Bon appétit!

Production Cinémanima inc. and Armand-Frappier Museum

© Production Cinémanima inc. and Armand-Frappier Museum


To make yeast breads, microorganisms must be allowed to multiply and exert their effect before baking. To distribute the microorganisms throughout the dough, bakers knead the dough. The most popular bread-making yeast is Saccharomyces cerevisiae.

Illustration : Cinémanima inc.

© Illustration : Cinémanima inc.


Kneading gives the dough the necessary consistency, and prevents it from becoming too sticky to be easily shaped.

Illustration : Cinémanima inc.

© Illustration : Cinémanima inc.


The dough is set aside for some time, to allow the yeast to multiply. Yeast digest maltose, the sugar in flour, and transform it into carbon dioxide, which is a harmless gas, and alcohol. Here we can see the effect of allowing the bread to rise: the volume of the dough has increased by a factor of 5!

Illustration : Cinémanima inc.

© Illustration : Cinémanima inc.


As the bread bakes, most of the yeast is killed. The alcohol is almost completely burnt off, but leaves behind a pleasant taste.

Illustration : Cinémanima inc.

© Illustration : Cinémanima inc.


Carbon dioxide is responsible for the small air bubbles that give bread its light texture.

Illustration : Cinémanima inc.

© Illustration : Cinémanima inc.


If It Wasn’t For Bacteria…We Wouldn’t Have Any Yogurt!

The transformation of milk into yogurt depends on the action of two bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus. Both these bacteria consume lactose (milk sugar) and transform it into lactic acid, which causes the milk to coagulate and gives yogurt both its solid texture and its characteristic sour taste. The acidity also helps preserve yogurt, as it prevents certain harmful bacteria from multiplying.

When Lactobacillus bulgaricus and Streptococcus thermophilus are both active, it takes less time to coagulate the milk. One of these species releases substances that favour the growth of the other. Once a certain level of acidity is reached, bacterial growth slows down, and if the temperature is low enough, stops. Yogurt thus contains a certain number of live bacteria... in fact, about five hundred thousand per gram!

Yogurt Production, Step By Step

Preparation of the milk : pasteurisation, addition of sugar (if necessary), and topping up of the fat content.

Read More

If It Wasn’t For Bacteria…We Wouldn’t Have Any Yogurt!

The transformation of milk into yogurt depends on the action of two bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus. Both these bacteria consume lactose (milk sugar) and transform it into lactic acid, which causes the milk to coagulate and gives yogurt both its solid texture and its characteristic sour taste. The acidity also helps preserve yogurt, as it prevents certain harmful bacteria from multiplying.

When Lactobacillus bulgaricus and Streptococcus thermophilus are both active, it takes less time to coagulate the milk. One of these species releases substances that favour the growth of the other. Once a certain level of acidity is reached, bacterial growth slows down, and if the temperature is low enough, stops. Yogurt thus contains a certain number of live bacteria... in fact, about five hundred thousand per gram!

Yogurt Production, Step By Step

Preparation of the milk : pasteurisation, addition of sugar (if necessary), and topping up of the fat content.

Incubation : addition of fermenting agents (Lactobacillus bulgaricus and Streptococcus thermophilus) to the milk in incubation vessels. The bacteria are allowed to act for 14 to 16 hours, with the exact duration of incubation determined by the desired final acidity. The yogurt's fat and water content, as well as the presence of unwanted bacteria, are monitored throughout the incubation period.

Packaging : this step is highly automated in industrial facilities. Fruit jams are added to the yogurt, containers filled, aluminum foil sheets applied, covers put on, and best-before dates printed—all by a single machine operating at breakneck speed under the watchful eye of an operator.

Other bacteria that may also be present in yogurt: Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum.


© Armand-Frappier Museum, 2008. All rights reserved.

Streptococcus thermophilus

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Lactobacillus acidophilus

Miloslav Kalab, Agriculture and Agri-Food Canada, Ottawa

© Miloslav Kalab, Agriculture and Agri-Food Canada, Ottawa


Yogurt making

In yogurt making, the first step is to pasteurize the milk, then to adjust the desired quantities of sugar and fat. The ferments, i.e., the bacteria, are then added.

Yes, it’s the bacteria that convert the milk into yogurt!

The bacteria feed on lactose, a sugar that is found in milk. By degrading this sugar, the bacteria produce lactic acid; this is what gives yogurt its slightly sour taste and specific texture, in addition to helping to preserve it.

After an incubation period of about 16 hours, the yogurt containers are filled on an assembly line and fruit jams and flavors are added to the bottom of the containers. This step is entirely automated, ensuring that quantities are precisely calculated, and getting the job done much more rapidly.

The final packing consists of applying an aluminum film that will be glued to the container to seal in the product. After this step, it is finally time to apply the plastic covers. Generally, the expiration date is stamped on the cover at the very end of the packaging steps.

The bacteria present in yogurt, such as Lactobacillus bulgaricus and Lactobacillus acidophilus, are probiotic. This means that they can help to keep us healthy.

Yogurt is so tasty and so good for you; why deprive yourself?

Production Cinémanima inc. and Armand-Frappier Museum

© Production Cinémanima inc. and Armand-Frappier Museum


Learning Objectives

The learner will:
  • familiarize himself with the vocabulary used in microbiology;
  • explain the relationship between developments in imaging technology and the current understanding of the cell;
  • identify which microorganisms are infectious, how the immune system fights against them, and the reinforcements of modern medicine;
  • describe the benefits of microorganisms .

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