Monday, October 24, 2016

The Cheesy Side of Science



Growing up in Wisconsin, I have become well versed in the many flavorful cheese varieties available in the Dairy State. Before working as a science writer, however, I had no idea that cheesemaking was such a highly scientific process. So, today I want to take a moment to share some of the things I’ve learned with our Curious Community. After reading this you’re sure to appreciate that next piece of cheese even more!

*Special Note: This is a fun overview of the cheesemaking process, but this list in no way covers all of the necessary steps or science involved in cheesemaking. Those interested in making their own cheese should contact a professional or a research center for guidance.
Also, while it is appropriate to use cheesemaking or cheese making, have decided to use “cheesemaking” as that is the form preferred by my sources.

The Process:
 Cheesemaking is a fairly complex process. From the addition of starter cultures and rennet to the monitoring of moisture, temperature, pH and more, cheesemakers are both chemists and artists. Though there are a few basic steps required in the cheesemaking process, the possible variations at each step make an exact outline of the process nearly impossible to create. So, instead of exploring each and every step of the cheesemaking process, we will be exploring some of the more interesting scientific processes involved in each of the basic steps of cheesemaking.

Quality Milk:

If we’re going to talk about cheese we have to talk about milk. Every cheesemaker will tell you that the secret to a great cheese is starting with quality milk. That means selecting milk from farms that are passionate about animal care and good sanitation practices.

Once the milk arrives at the cheesemaking facility, many cheesemakers will choose to pasteurize the milk to minimize the number of potential pathogens which might contribute to spoilage down the road. The pasteurization process is generally accomplished through High Temperature Short Time (HTST) processing where the milk is held at temperatures around 161 degrees Fahrenheit for about 15 seconds. For more on this see: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=133.3

Some cheesemakers do choose to utilize raw milk for their cheese. This may be done for a variety of reasons, but regardless of the reasoning, every raw milk cheese made in the United States must be labeled as such and be aged for a minimum of 60 days to ensure food safety. For more on these regulations please see the section on Cheddar Cheese at: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=133.3


Step 2:  Addition of the Starter and the Coagulant

Once the milk is ready for the cheesemaking process it will be transferred into vats and various additions will be made to aid in flavor development, color and coagulation. We won’t go into all of the details here as there are many combinations of enzymes, cultures and such that can be added to create each cheese, but one thing remains the same for all cheese, a coagulant must be added.

So what is a coagulant? Well, the terminology is a bit confusing but essentially, a coagulant is something that causes clotting. In the case of cheese, the term for a clotting agent is rennet. Rennet is then used as an overarching term for all of the enzymes that aid in coagulating milk. While rennet can come from a number of sources, the most common enzyme, or rennet, used in the coagulation of U.S. milk is fermentation produced chymosin.

Chymosin is traditionally known as one of two enzymes that help calves to process their mother’s milk. As ancient cheesemakers looked for ways to preserve milk (i.e. the cheesemaking process), they noticed the clotting power of this enzyme and began using it to jumpstart the processes of preservation.  While chymosin was originally discovered in the stomach of calves, scientists have discovered that by inserting the chymosin gene into bacteria, yeast or fungi cells and then extracting, purifying and standardizing the chymosin enzyme, chymosin can be produced without involving calves. Today it is estimated that 95 percent of American-style cheese is made with this form of fermented form of chymosin. There are, however, several styles of plant rennet that do not involve chymosin at all. The most popular plant-based coagulant or rennet comes from a thistle variety called Cynara cardunculus.


Annatto:

Another fun fact I’ve learned during my time in the food world is that cheese varieties such as Cheddar get their signature orange color from a tropical plant extract called annatto. While the exact reasoning or origins behind the use of annatto are not clear to experts, we do know that annatto has been referenced in the cheese business for more than 200 years. Naturally, cheese is white or yellow in color. In the winter months when cows are not grazing cheese tends to have a pale white tint. In the summer, a yellow tint emerges thanks to the carotenoid in the grass that many cows consume while grazing. Therefore, some people believe that annatto was used as a colorant in order to create a uniform color for the cheese rather than allowing the color to shift with the seasons. Others believe that the colorant was added as a marketing tactic to differentiate cheese in one region from cheese in another. Regardless of the reason, the use of annatto has certainly caught on in the U.S.
            So what is annatto? Annatto is derived from the seed of the plant Bixa Orellana L.  The seeds of this plant are naturally covered in a reddish pigment which is what is extracted and used to create annatto. The amazing thing about annatto is that despite its strong color, it has no flavor, so adding it will not impact the flavor profile of the cheese. Annatto is also very stable so a brand new Cheddar and a seven year old Cheddar colored with annatto should have the exact same coloring assuming that the cheese has not sustained light damage or oxidation.
In terms of regulations, annatto is a natural product but because it is not naturally found in cheese it cannot be labeled as a natural colorant. In terms of safety, annatto has a long history of good food safety and has not been tied to significant allergen issues though in rare cases people do have an allergy to this colorant.

There’s a lot more to learn, so check out page 6 for an article I wrote on the topic: https://www.cdr.wisc.edu/sites/default/files/pipelines/2012/pipeline_2012_vol24_04.pdf
  

The Final Steps: Cutting, Heating, Draining and Salting

            After the addition of the colorant, starters and coagulants, the cheese is left to gel or set. Once the cheese reaches the proper texture, a cheesemaker will begin cutting the curd in order to break the now large coagulated mass of milk into tiny pieces called curds. This curd will then be heated.
During this process the curd will shrink and water will be expelled from the curd.  At the end of this process the curd will be separated from the liquid which is now called whey. At this point, the curd will go on to be further processed per its varsity’s requirements. So, what happens to the whey you might ask? 

                                                         Join us Friday to find out!


Have a question about cheese?  Let me know in the comments section and I will try to find an expert to answer your question. 


Want to learn more about cheesemaking?

·         Read an article: 
·        
           Take a class:  



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