Cheese & Dairy

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What causes cheese to turn pink?

Various attributes of a cheese, including both flavor and appearance, contribute to the final quality of the product. During the production of some cheeses, microbial processes can cause strange quality defects, often with colorful outcomes. Researchers in University College in Cork, Ireland identified the microbial culprit behind a notorious pink cheese defect. In this Science Digested, Adam Shutes from the Boston Cheese Cellar explains what they found.

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Cheese mites, gophers of cheese rinds

Next time you buy a piece of cheese with a mottled natural rind, such as a clothbound Cheddar or Tomme de Savoie, take a close look at the rind with a magnifying glass. If you look long enough, you will see tiny pieces of the rind are moving! These specks are microscopic arachnids known as cheese mites. Gophers of the cheese world, these tiny mites can both impart flavors as well as cause headaches for cheese producers.

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Geotrichum candidum: A yeast holding on to its moldy past

Have you ever noticed those goat’s milk cheeses with the wrinkly surface at the cheese shop? They look like a fuzzy white brain or a dusty grey coral and they smell like sweet, buttery flatulence. Those aesthetics and aromas come from the growth of the fungus Geotrichum candidum. Using in-depth genomic sequencing, French scientists recently unlocked the evolutionary history of this important cheese microbe and revealed a fungus with an identity crisis.

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Microbe guide: Chrysosporium sulfureum

If you’ve ever spotted yellow fluff on the surface of a cheese rind, you were probably looking at the mold Chrysosporium sulfureum. Considered a typical fungal species on the rinds of many classic French cheeses including Tomme de Savoie and Saint-Nectaire, this cave-loving fungus is widespread, but enigmatic. Here’s a summary of the little that we do know about this cheese fungus.

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Can good viruses keep bad bacteria out of fermented foods?

Food scientists have developed a diverse toolkit to help food producers keep pathogens out of fermented foods, including pasteurization, raw ingredient and end-product testing, and the addition of natural preservatives. Over the past decade, a new technology using viruses that attack pathogenic bacteria (bacteriophages), has emerged on the market as a potential addition to this food safety toolkit. Here we explain the science of using good viruses to kill bad bacteria in fermented foods.

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Dissecting the Microbial Diversity of Kefir

Kefir is a thick, sour, and sometimes slightly spritzy fermented milk drink produced through the action of the bacteria and fungi within kefir ‘grains’, a classic example of a SCOBY (Symbiotic Community of Bacteria and Yeasts). Despite a history that dates back several millennia, kefir and the microbes that produce it remain little-understood. Two recent papers from China and Ireland set out to explore the microbial diversity of kefir samples collected from a wide geographical area. One also provides insight into the physical structure of the kefir grain, and the distribution of yeast and bacteria across it. [click to view the full story]

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Microbe Guide: Yarrowia lipolytica

From biofuels to fish food to gold nanoparticles, Yarrowia lipolytica is all the rage these days as a powerful workhorse for biotechnology. But this yeast also has important roles in the flavor development and appearance of some traditional fermented foods. Here’s all you need to know about this versatile and beautiful yeast. [click to view the full story]

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Wooden Boards for Cheese Aging: Reviewing the Science

Wooden boards are widely used for aging cheese in Europe and America. While their use has an established track record for utility and safety, it has also been the subject of debate. Food safety regulations on both sides of the Atlantic require food contact surfaces to be sanitizable, and wooden boards are rough and porous, and therefore difficult to disinfect. [click to view the full story]

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Surveying cheese rind microbial diversity

What happens when you collect 137 cheeses from around the world and sequence their DNA? You end up eating a ton of cheese. But more importantly, you learn a lot about what bacteria and fungi live in a typical cheese rind, that sea salt may be a previously unrecognized source of cheese microbes, and whether the notion of ‘microbial terroir’ holds up in artisan cheeses. In this Science Digested, I provide a digested version of recent research that used new DNA-sequencing approaches to broadly survey the microbial diversity of artisan cheese rinds.

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Microbe Guide: Sporendonema casei

If you’ve ever spotted bright orange patches on the rind of a cheese, there’s a good chance it was Sporendonema casei. While orange may instill a sense a fear, this orange mold isn’t out to get you. It’s a benign mold species that contributes unique aesthetics and flavors in cheese rind ecosystems. [click to view the full story]