Why food becomes mouldy

Cutting off damaged portions small lesions and spots and using the produce for processing has been a good way to utilize lower quality fruits and vegetables. Overly ripe or damaged produce may suffer from the same issue as above. As acids are converted to sugars, the pH increases.

Therefore, you should follow a current recipe from a reliable source USDA, National Center for Home Food Preservation, OSU Extension fact sheets which will indicate if acidification is needed for products, like tomato-based canned foods, in order to control pH. Additionally, recipes from reliable sources will suggest water bath processing canned foods even after hot-filling since it has been shown to inactivate heat resistant molds. The use of spoiled apples in processed products is particularly noteworthy.

Apples with core rot or spoiled by blue-green molds have been associated with patulin, a mycotoxin, in apple juice and cider. Patulin does not cause symptoms of acute illness, but long-term exposure can result in chronic diseases, notably cancer.

Heat treatments, like pasteurization and canning, do not sufficiently decrease patulin concentrations. Spoiled apples should be discarded unless the final product will be fermented into hard cider or apple cider vinegar. The yeast fermentation decreases patulin activity. The short answer: Remove the molded portion and use the rest of the product. Sauerkraut and pickle ferments can sometimes sprout mold and yeast growth on the surface of the product.

Mold, in particular, grows best in the high-oxygen environment near the surface. For this reason, it is suggested that the vegetables are submerged below the surface of the salt brine to limit oxygen availability and prevent mold growth. If kahm yeast or mold form on the surface, remove quickly but be warned: the spoilage microbes may come back since you are unlikely to remove every cell.

You are at a greater risk for losing the fermentation if the spoilage occurs at the beginning of the fermentation process rather than at the end. Some cheeses and dried meats utilize mold as part of their normal fermentation and development. As such, mold-ripened products e.

Brie cheese are safe to consume. However, spoilage molds on soft cheeses that are not a part of manufacturing e. If spoilage molds are found growing on hard cheeses like cheddar , hard meats like dry-cured salami , and firm vegetables like cabbage, carrots, and peppers , then the affected portion can be cut off and the rest of the product consumed. The goal is to remove the mold itself—a mold filament is called a hypha and can penetrate through the surface of softer products—as well as eliminate any food that may have been contaminated with mycotoxin.

The hard surfaces of these products limits diffusion. Be generous in determining how much of the affected portion to remove—cut at least 1 inch outside of where the mold is growing in order to remove hyphae which may not be visible. Mold growth on beverages can lead to mycotoxin formation which diffuses through the product.

The toxin cannot be eliminated by simply removing the mold and surrounding product, in direct contrast, for example, to hard cheeses. But as consumers' preservative-free demand increases and companies change their preservative policies in response, "mold spoilage will undoubtedly become more prevalent, resulting in increased food waste," Doyle predicts.

The best we can do, then, is try to prevent mold from forming in the first place—and luckily, we can do more to prevent mold growth than gobble up the content of our fridge as fast as possible. As Doyle points out, "molds like to grow in areas that are high in moisture, such as unkempt refrigerators. Keeping foods in the fridge in the first place should also reduce mold growth, as "molds grow especially well in warm, moist environments," Doyle says.

By Jillian Kramer Updated May 25, Save FB Tweet More. All rights reserved. Plants contain a chemical compound called chlorophyll. Chlorophyll makes it possible for plants to capture the energy of sunlight and use it to make food sugars and starches from air and water. Unlike plants, molds and other fungi have no chlorophyll and can't make their own food. The molds that grow in your mold terrarium feed on the bread, cheese, and other foods.

A mold produces chemicals that make the food break down and start to rot. As the food is broken down into small, simple parts, the mold absorbs them and grows. It can be annoying to find moldy food in your refrigerator. But in nature, mold is a very useful thing. Mold helps food and other materials rot, which is an icky but necessary thing. In a natural environment, rotting things return to the soil, providing nutrients for other living things. Mold is a natural recycler. There are thousands of different kinds of molds.

One mold that grows on lemons looks like a blue-green powder. A mold that grows on strawberries is a grayish-white fuzz. A common mold that grows on bread looks like white cottony fuzz at first. If you watch that mold for a few days, it will turn black. The tiny black dots are its spores, which can grow to produce more mold.

Why didn't some foods get moldy? If you used foods that contain preservatives, mold may not have grown very well on them. If you want to experiment more with mold, you can make one mold terrarium using food with preservatives like a packaged cupcake and another using food that doesn't have preservatives like a slice of homemade cake.

Which one grows more mold? You can also experiment with natural preservatives such as vinegar and salt. If you do more experimenting, let us know what you discover!

This and dozens of other cool activities are included in the Exploratorium's Science Explorer books, available for purchase from our online store.