Yeast and mold get a bad rap, which is understandable in most cases. If yeast and mold appear in foods where they don’t belong, it can be a sign of a problem in the manufacturing process, or it could simply mean that you left your strawberries in the fridge for too long. No matter the case, there are some food and beverage items that we would not have without the aid of yeasts and molds.

These groups of organisms deserve our thanks for providing us with the following three foods:

1) Bread – What is better than walking into a bakery and smelling delicious, freshly baked, yeasty bread? Nothing! While it is true that not all bread has yeast as an ingredient, most breads use yeast to leaven the dough. The yeast consumes the sugars in the dough and then releases gas in the form of carbon dioxide and alcohol in the form of ethanol as byproducts. The carbon dioxide inflates air bubbles in the dough and makes the dough rise. Once the dough is baked, you are left with a gorgeous, delicious, airy bread.

However, while yeast helps bread rise, mold in bread spells trouble. According to the United States Department of Agriculture, some molds found in grain crops can produce mycotoxins, which are poisonous and can cause people who eat them to become sick. If your bread has a moldy spot on the surface, the roots of the mold could extend deeper than the eye can see. It’s recommended that moldy bread be thrown out, even if it only appears to be moldy on the surface.

2) Kombucha – I will admit, kombucha is not for everyone, as the tart, acidic beverage can be an acquired taste. But for those of us who can’t get enough of the fermented drink, we owe it all to fungi and bacteria! To make kombucha, you start with a Symbiotic Culture of Bacteria and Yeast (SCOBY). This bacteria and yeast culture functions similarly to the yeast in bread. The bacteria and yeast use the sugars found in sweetened, brewed tea for food. The digestion of the sugars creates byproducts in the form of alcohol, carbon dioxide and organic acids, including gluconic, acetic and others. The combination of all of these elements transforms the tea into a tart, bubbly, delicious kombucha.

Most consumers buy commercially-available kombucha at the grocery store, but there are also many homebrewers around the world. Both commercial brands and home brewers beware – kombucha is another food susceptible to mold growth. To prevent contamination, brewers should ensure that their equipment and environments are sterile. If your SCOBY grows mold, it’s time to throw it out and start a new batch using a different one.

3) Blue Cheese – Blue cheese is another item that people either seem to love or hate. The distinguishing veins in blue cheese can actually range in color from gray to green or from black to blue. No matter the color, it’s mold that you have to thank for the marbled hue and distinctive taste of blue cheese. The most widely used mold to put the “blue” in this type of cheese is Penicillium Roqueforti, which is safe to eat. This mold is usually introduced after the cheese curds have been drained and put into their molds (no pun intended).

After the mold is introduced, the cheesemaker “needles” the cheese to allow air to reach the mold and enable it to grow within the cheese, which creates the veins we are familiar with. The blue cheese-making process can vary greatly, so it produces many possible results. The type of milk used, what the animal ate prior to milking and when the mold is introduced all contribute the various textures and flavors of the cheese. But, while no mold at all means no blue cheese, other types of harmful molds can grow within the cheese when it exceeds its shelf life.

Whether you are a fan of these foods and drinks or not, it is undeniable that yeasts and molds play an important role in the food industry. However, the presence of yeast and mold in a product is not always a good sign. Yeast and mold often signal spoilage in a product and should be addressed immediately. These organisms can be present in the food itself, but they can also be found on food contact surfaces, such as conveyor belts or food packaging. It is important to take precautions to limit the presence of yeast and mold in your production environment. An effective environmental monitoring program can enable food manufacturers to prevent and track mold within their facility.

Yeast and mold grow in a wide range of conditions in raw materials and finished products, making growth difficult to manage and control. If you are concerned that you have potentially harmful yeasts and molds in your production environment or product, partner with Mérieux NutriSciences to help strengthen your environmental monitoring program. Our new microbial identification services using MALDI-TOF enable us to identify the specific yeast or mold causing spoilage issues. Learn more about how Mérieux NutriSciences can help transform your EMP to prevent unwanted contamination today!


Meet the Author

Katie Schott
Product Specialist, Mérieux NutriSciences

Katie Schott is a Product Specialist supporting Chemistry and Microbiology business initiatives at Mérieux NutriSciences. She received her Bachelor of Science in Public Health from Purdue University in 2013. In her free time, Katie enjoys reading, traveling, weightlifting and taking her dog for long walks by the lake.

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