By [Your Name/Journalistic Staff]
July 17, 2026
From: Culture Cheese Magazine, Summer 2026 Edition

New York, NY – Behind every delectable wedge of cheese, from the pungent blues to the creamy bries and the sharp cheddars, lies an intricate, invisible world teeming with life. Microbes, often misunderstood or overlooked, are the true artisans, sculpting the very essence of what makes cheese so captivating. Josh Windsor, the esteemed affineur and Senior Caves Manager at Murray’s Cheese in New York City, stands at the forefront of this microbial exploration. In a recent insightful breakdown, published in Culture Cheese Magazine’s Summer 2026 issue, Windsor peels back the layers of complexity, illuminating how these microscopic organisms define a cheese’s identity, safety, and sensory profile.

Windsor’s expertise, honed through years of nurturing some of the world’s most celebrated cheeses—including the ACS "Best in Show" winner Stockinghall Clothbound Cheddar and the World Cheese Awards "Best American Cheese" winner Greensward—extends beyond the aging cave. His active involvement with Genspace, a community biology lab, allows him to delve into the microbial genomics of cheese rinds, bridging the gap between traditional craft and cutting-edge science. His unique perspective underscores a fundamental truth: cheese is not merely a product of milk and rennet, but a living ecosystem, constantly evolving under the guidance of its microbial inhabitants.

The Unseen Architects of Flavor: Microbes in Cheesemaking

At its core, cheese is a magnificent testament to microbial activity. The nuanced flavors, the intoxicating aromas, and the diverse textures that differentiate one cheese from another are direct outcomes of specific microbial populations at work. It’s a symphony of microscopic life, where each species plays a crucial role in transforming simple milk into a complex culinary masterpiece.

Windsor emphasizes that the "specific diversity of the microbiota inhabiting the milk" is paramount. This microbial fingerprint dictates not only the eventual character of the cheese but also its fundamental safety. For instance, the characteristic holes and nutty flavor of Swiss-style cheeses are the work of Propionibacterium freudenreichii, which ferments lactic acid into propionic acid, acetic acid, and carbon dioxide gas. The pungent, earthy notes of blue cheeses come from molds like Penicillium roqueforti, while the sticky, orange-hued rinds of washed-rind cheeses like Limburger or Époisses are cultivated by bacteria such as Brevibacterium linens, known for producing sulfur compounds that contribute to their distinctive "stinky" aroma.

The entire cheesemaking process, from the initial milking to the final aging, is a meticulously choreographed sequence of ecological shifts. Each stage creates a unique environment—an ecological niche—that favors certain microbial species while suppressing others. As the milk undergoes these transformations, its microbial diversity evolves, progressively shaping the character and complexity of the dairy product. Understanding this dynamic interplay is key to appreciating the depth and artistry of cheesemaking.

From Udder to Aging Cave: A Microbial Journey

The microbial journey of cheese begins long before the milk ever reaches the vat, originating directly from the source: the udder of the dairy animal. This initial environment sets the stage for the entire microbial narrative.

The Udder’s Ecosystem and the Farm’s Terroir

Like human skin, the udder’s surface hosts a complex biome, a diverse community of microorganisms present from birth and continually acquired from the surrounding environment. For a ruminant, this environment is rich and varied, introducing a constant influx of newcomers from bedding, feed, manure, dust, soil, and interaction with other animals. If the conditions—specifically time and temperature—are favorable, these new microbes can survive, multiply on the teat, and eventually be transferred into the milk during milking.

This initial microbial contribution is critical, as it often includes many "technically functional" bacteria, such as beneficial Lactobacilli, essential for cheesemaking. The concept of "terroir," often associated with wine, is equally relevant here. The unique microbial fingerprint of a specific farm, influenced by its soil, climate, feed, and animal husbandry practices, can impart distinctive characteristics to the raw milk, and subsequently, to the cheese. This farm-specific biome is a cornerstone of artisanal raw milk cheesemaking, contributing to flavors that are impossible to replicate elsewhere.

Milking, Cooling, and the Rise of Psychrotrophs

As soon as milk leaves the warmth of the udder, it begins to cool. Modern dairy practices accelerate this process through refrigeration, primarily to inhibit the rapid growth of spoilage microorganisms and extend shelf life. However, this cooling, while beneficial for preservation, also introduces another layer of microbial dynamics. Longer storage times and colder temperatures favor the proliferation of psychrotrophic (cool-loving) bacteria.

While many of the "functional" bacteria vital for cheesemaking may become dormant at these colder temperatures, psychrotrophs remain active. These cold-tolerant microorganisms, such as certain species of Pseudomonas, Flavobacterium, and Bacillus, can produce enzymes like lipases and proteases. Even in small quantities, these enzymes can subtly alter the milk’s proteins and fats, influencing the flavor and texture development of the cheese, sometimes even before the cheesemaking process officially begins. This subtle enzymatic activity can be both a blessing and a curse, contributing to complexity in some cases, or leading to off-flavors if not properly managed.

Heat Treatment: Defining Raw, Pasteurized, and Thermized Milk

Following collection and initial cooling, milk often undergoes heat treatment, a critical step that fundamentally alters its microbial landscape. The United States legally distinguishes between two primary types of milk based on this treatment: raw and pasteurized.

• Pasteurization: This widely adopted process involves heating milk to a specific temperature for a defined period to destroy significant populations of microorganisms. The primary goal is to eliminate pathogens—disease-causing bacteria—thereby enhancing food safety. Common pasteurization methods include High-Temperature Short-Time (HTST), where milk is heated to 161°F (71.7°C) for 15 seconds, or Low-Temperature Long-Time (LTLT), involving heating to 145°F (62.8°C) for 30 minutes. While highly effective at safeguarding public health, pasteurization is indiscriminate; it destroys both harmful and many beneficial, "technically functional" microbes that contribute to flavor development. The result is a largely sterile canvas for the cheesemaker.

• Raw Milk: In contrast, raw milk is any milk that has not met the requirements for pasteurization. For many artisanal cheesemakers and enthusiasts, raw milk is prized for its "living" qualities and its potential to produce cheeses with unparalleled complexity and depth of flavor. The untouched microbial diversity of raw milk, directly reflecting the farm’s unique terroir, is believed to be crucial for developing intricate aromatic and textural profiles that are difficult to achieve with pasteurized milk. However, raw milk also carries inherent risks due to the potential presence of pathogens like E. coli, Salmonella, and Listeria monocytogenes, necessitating stringent hygiene practices and careful aging protocols.

• Thermization: Occupying a middle ground, thermization involves heating milk to temperatures below full pasteurization standards, typically around 135-149°F (57-65°C) for 15-20 seconds. This process is designed to reduce the overall microbial load without completely sterilizing the milk. It effectively targets some dangerous strains, such as E. Coli, and extends the shelf life of the raw milk before cheesemaking. Crucially, thermization aims to preserve a significant portion of the beneficial flora, allowing for more complex flavor development than fully pasteurized milk. However, as Windsor notes, thermization is generally "not hot enough to kill Listeria," meaning thermized milk is still classified as raw milk in the U.S. and requires careful handling and aging. Many European cheesemakers utilize thermization to balance safety with the preservation of microbial diversity.

Post-Treatment and the Evolution of Cheese

After heat treatment, the microbial journey continues its dynamic course. For pasteurized milk, the largely sterile liquid must be repopulated. This is primarily achieved through the deliberate introduction of "starter cultures" by the cheesemaker—specific strains of bacteria (e.g., Lactococcus lactis, Streptococcus thermophilus) chosen for their ability to acidify the milk and initiate flavor development. Additionally, microorganisms present in the creamery environment—in the air, on surfaces, and within the aging caves—contribute to the developing microbial community.

As the cheesemaking process unfolds, from coagulation and cutting to pressing and salting, the internal environment of the cheese changes dramatically. Factors like pH, moisture content, salt concentration, and oxygen levels create successive ecological niches, favoring the growth of certain microbial populations over others. This process continues relentlessly throughout the life of the cheese, especially during the critical aging phase. Rind development, whether bloomy (like Brie), washed (like Gruyère), or natural (like aged Cheddar), is a direct result of surface microbes flourishing and interacting, breaking down proteins and fats into a cascade of aromatic and flavorful compounds.

Supporting Data: The Science Behind the Scenery

Modern scientific advancements have provided unprecedented insights into the microbial world of cheese, transforming our understanding from anecdotal knowledge to empirical data.

Key Microbial Players and Their Contributions

The cheese microbiome is a complex consortium, but certain genera and species are particularly renowned for their contributions:

• Lactic Acid Bacteria (LAB): This broad group, including Lactobacillus, Lactococcus, and Streptococcus species, are the workhorses of cheesemaking. They convert lactose (milk sugar) into lactic acid, which lowers the pH, initiating coagulation, expelling whey, and inhibiting spoilage organisms and pathogens. Beyond acidification, LAB also contribute significantly to flavor development through proteolysis (breaking down proteins) and lipolysis (breaking down fats).
• Propionibacteria: As mentioned, Propionibacterium freudenreichii is responsible for the characteristic holes (eyes) and sweet, nutty flavor of Swiss-type cheeses.
• Molds: Penicillium roqueforti gives blue cheeses their distinctive veining and pungent flavor. Penicillium candidum creates the soft, bloomy white rind on cheeses like Brie and Camembert, contributing to their creamy texture and mushroomy notes.
• Yeasts: Often found on the surface of cheeses, yeasts like Debaryomyces hansenii can metabolize lactic acid, raising the pH and creating a more hospitable environment for subsequent bacterial growth, especially for washed-rind cheeses. They also contribute to flavor and aroma.
• Brevibacterium linens: This bacterium is a primary driver of the characteristic pungent, savory, and sometimes "stinky" aromas of washed-rind cheeses. It produces sulfur-containing compounds that are key to these profiles.

Microbial Succession and Modern Research

The concept of "microbial succession" is central to cheese aging. Different microbial groups thrive at various stages, creating a dynamic ecosystem. For example, early in ripening, LAB dominate. As lactic acid accumulates, yeasts and molds may colonize the surface, metabolizing lactic acid and raising the pH, which then allows acid-sensitive bacteria (like Brevibacterium) to flourish. This sequential growth creates layers of flavor and texture.

Modern research techniques, particularly genomics and metagenomics, have revolutionized our ability to study these complex communities. By sequencing the DNA of entire microbial populations within a cheese, scientists can identify all present species, even those that are difficult to culture. This allows for detailed mapping of cheese microbiomes, revealing previously unknown interactions and providing a deeper understanding of how specific microbes contribute to desired characteristics or potential spoilage/pathogen risks. This data empowers cheesemakers to better control and optimize their processes.

Official Responses: Navigating Safety and Tradition

The inherent microbial diversity of milk, particularly raw milk, presents a delicate balance between preserving traditional flavors and ensuring public safety. Regulatory bodies worldwide grapple with establishing guidelines that protect consumers while acknowledging the cultural and culinary value of artisanal cheese.

U.S. Regulations and the 60-Day Rule

In the United States, the Food and Drug Administration (FDA) imposes strict regulations on raw milk cheese. The most notable is the 60-day aging rule, which mandates that raw milk cheeses must be aged for a minimum of 60 days at a temperature of at least 35°F (1.7°C) before being sold. The rationale behind this rule is that the extended aging period, combined with factors like salt and low pH, provides sufficient time for potential pathogens (which generally do not thrive in such environments) to die off. While this rule offers a measure of safety, it effectively restricts the production of many traditional, softer, younger raw milk cheeses that are common in Europe. Critics argue that the 60-day rule is an arbitrary blanket policy that doesn’t fully account for varying cheesemaking practices and hygienic controls.

European Approaches and HACCP

In contrast, many European countries, particularly those with a rich history of raw milk cheesemaking like France, Italy, and Switzerland, often adopt a more nuanced approach. While public health remains paramount, their regulations frequently emphasize stringent hygiene practices throughout the entire production chain—from farm to creamery—rather than solely relying on aging periods or pasteurization. Systems like Hazard Analysis and Critical Control Points (HACCP) are widely implemented, requiring cheesemakers to identify potential hazards and establish control measures at every stage. This approach allows for the production of a wider variety of raw milk cheeses, including fresh and soft varieties, provided that the cheesemaker can demonstrate robust safety protocols.

The debate between raw milk advocates, who champion flavor complexity and traditional methods, and public health authorities, who prioritize pathogen elimination, remains ongoing. Organizations like the FDA, USDA, and state dairy boards continuously review and update their guidelines, seeking a balance that supports both innovation and consumer protection.

Implications: The Future of Flavor and Safety in Cheese

Josh Windsor’s insights highlight that the character of cheese is the result of an "interconnected system" where "no single thing is solely responsible for the outcome." While pasteurization significantly alters the microbial composition of milk, it is but one factor among many. Refrigeration, storage time, farming practices, milking techniques, and creamery sanitation are "equally important" in determining a cheese’s ultimate identity. This holistic perspective carries profound implications for the future of cheesemaking, for consumers, and for public health.

For Cheesemakers: Innovation and Consistency

A deeper understanding of the cheese microbiome empowers cheesemakers to innovate with greater precision. By consciously manipulating factors like starter cultures, environmental conditions in aging caves, and even the initial farm environment, cheesemakers can create novel flavor profiles or replicate traditional ones with greater consistency. This knowledge also enhances safety protocols. When cheesemakers understand which microbes are beneficial and which are harmful, they can implement targeted hygiene and control measures, reducing the risk of contamination while still fostering the desirable microbial communities that define their cheeses. The ability to "curate" a cheese’s microbiome is becoming a hallmark of cutting-edge artisanal production.

For Consumers: Appreciating Complexity and Informed Choices

For consumers, Windsor’s breakdown enriches the experience of eating cheese. It moves beyond a simple raw-vs.-pasteurized dichotomy, encouraging a more nuanced appreciation for the complex interplay of factors that contribute to a cheese’s unique character. Consumers can make more informed choices, understanding that a cheese’s safety and flavor are a product of its entire journey, not just a single heat treatment. This deeper understanding can foster a greater connection to the producers and the craft.

For Public Health: Balancing Tradition with Modern Safety

The challenge for public health officials is to evolve regulations that are science-based, flexible, and supportive of diverse cheesemaking traditions. Instead of blanket rules, there’s a growing recognition that risk assessment should be specific to the type of cheese, the production methods, and the hygiene controls in place. The goal is not to eliminate all risk (an impossibility in any food system) but to manage it effectively, allowing for the flourishing of artisanal raw milk cheeses while ensuring robust safety standards. This requires ongoing dialogue and collaboration between scientists, cheesemakers, and regulators.

Sustainability and Future Innovations

Microbial understanding can also contribute to sustainability in cheesemaking. By optimizing microbial processes, cheesemakers might reduce waste, improve efficiency, or even develop new cheeses from byproducts. Furthermore, research into the specific enzymes produced by cheese microbes could lead to novel applications in other food industries or biotechnology.

Josh Windsor, through his work at Murray’s Cheese and Genspace, embodies this forward-thinking approach. His dedication to exploring the microbial world of cheese rinds and sharing his knowledge through teaching underscores a crucial message: cheese is a living food, a testament to the intricate dance between nature, craft, and science. The future of cheese lies in continuing to unravel the secrets of its unseen architects, ensuring both its safety and its endless capacity for flavor.

About the Author:

Josh Windsor is an affineur and the Senior Caves Manager at Murray’s Cheese in New York City. He actively nurtures and ages the Cave Aged line of specialty cheeses, including the 2019 American Cheese Society (ACS) “Best in Show” winner Stockinghall Clothbound Cheddar and the 2022 World Cheese Awards “Best American Cheese” winner Greensward. Always curious about how cheese ages, Josh is an active member of the community biology lab, Genspace, where he explores the microbial world of cheese rinds. Josh shares his love of all things dairy by teaching cheese appreciation, science, and history at Murray’s Cheese and sensory evaluation at Cornell University’s cheese short courses.