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Dairy Research

Extending cheese shelf life

John Lucey

John Lucey, director of the Wisconsin Center for Dairy Research at the University of Wisconsin-Madison, contributes this column for Cheese Market News®.

The dairy industry is facing a challenge that is unprecedented. Due to COVID-19, schools and dine-in restaurants have closed. A big part of the foodservice industry has essentially stopped. This isn’t good news for the dairy industry since about 40% of all cheese goes into foodservice. Sure, you can still get food from many restaurants via delivery, pickup or drive-thru, but the bottom line is that foodservice has essentially come to a halt for the time being.

Unfortunately, the result is that some cheese plants and foodservice buyers are going to have a lot of extra cheese on their hands. At the Center for Dairy Research (CDR), our staff has been fielding many questions from numerous dairy processors all over the country. Companies that supply foodservice want to know what they can do to protect their product.

Therefore, in this column, I want to share a couple of strategies that can be used to hold cheese or extend the shelf life of cheese.

Before I describe these strategies, I want to point out that some of the information and research conducted on these topics was developed for cheese to help with exports. At CDR, we’ve been doing a lot of work on how to extend the shelf life of cheese so that it can be shipped anywhere in the world and still have good body and functionality when the end consumer purchases it. It goes to show that you never know when or how research might be used. Much of this research was funded through dairy farmer dollars from the dairy checkoff program and industry support.

• Freezing cheese

Depending on the cheese type, cheese can be held frozen for up to a year. The general rule of thumb for freezing cheese is to freeze the cheese as quickly as possible and thaw the cheese as slowly as possible (under refrigeration over a week’s time). Thawing properly is important because it allows the moisture in the cheese to re-equilibrate into the cheese matrix.

As I mentioned, many cheeses freeze well (Cheddar, Muenster, Mozzarella, Colby, Colby Jack, Provolone, Brick, cheese curds and hard Italian cheeses), but you have to keep in mind the end use of the cheese. For instance, Cheddar can be frozen, but it will not slice well once thawed, if it has been frozen for a long period. However, Cheddar that has been frozen can be used in frozen entrees or for further processing.

One of the dangers of freezing cheese is the formation of large ice crystals, which can result in damage to the cheese texture and, ultimately, functionality and sensory acceptance. High-moisture cheeses like Ricotta, and low pH cheeses like cottage and cream cheese, are damaged when frozen (crumbly texture).

If a cheese is expected to be sold within about six months, it is probably more advantageous to hold it in low temperature storage (see next section) rather than freezing. If the cheese needs to be held longer than six months, freezing may be the best option.

• Low temperature ‘super-chilling’ storage

Holding cheese in low temperature (around 28-32°F) is probably the best option for most cheeses as they can be held in low temperature storage for about six months with minimal impact on body and functionality.

The biggest advantage for low temperature storage is that the cheese is not freezing. Because of the moisture and salt content in cheese, it doesn’t freeze until under 28°F. Since the cheese is not actually freezing, we don’t need to worry about the damage that might occur when the cheese undergoes the process of freezing and then thawing.

Research at CDR has found that holding cheese at temperatures around 32°F results in the cheese almost being in suspended animation and having very slow body breakdown. This strategy extends the shelf life of cheeses like low-moisture, part-skim Mozzarella and Cheddar by 3-6 months compared to typical storage temperatures (when low temperature storage is combined with alterations in the cheesemaking recipe).

Low temperature storage also works well for shredded or sliced cheeses. This is also the method of choice for cheese varieties, such as Ricotta or cream cheese, that cannot be frozen because of catastrophic changes to the body and texture of the cheese after freezing and thawing.

• High pressure processing (HPP)

Another option is high pressure processing (HPP) systems that apply and then release high amounts of hydrostatic pressure by the compression of a fluid medium, typically water. The process of applying and releasing pressure induces physical, chemical and biochemical changes in microorganisms, including the inactivation of foodborne pathogens, spoilage organisms and enzymes. It is widely used for food safety purposes as it can destroy pathogens in meats and a range of food/beverage products.

HPP can be used to extend cheese shelf life by several months (3-6 months demonstrated for some varieties). The food product (cheese) is in its final packaging when it goes through the HPP system. After the treatment, the cheese can then be stored under normal refrigeration temperatures.

CDR research found HPP can extend the shelf life of low-moisture, part-skim Mozzarella, Cheddar and block Gouda. By altering the cheese make procedure, as well as using HPP, CDR researchers were able to produce low-moisture, part-skim Mozzarella that still had good body, shreddability and functionality on pizza even after nine months of refrigerated storage. HPP might also be an option for those cheeses that can’t be frozen (cream cheese, Mascarpone, Ricotta, etc.).

However, one issue may be cost, although these costs are decreasing as HPP systems increase their throughput and the technology evolves.

• Increase stretching temperature of curd for Mozzarella

A current CDR research project is finding that when making low-moisture, part-skim Mozzarella, higher stretching temperatures for the curd can inactivate or destroy most residual rennet. By destroying these enzymes, the proteolytic activity of the cheese is greatly decreased, resulting in a longer performance shelf life.

A downside is that by increasing the cook temperature, more fat is lost in the cooker water. Some early research at CDR indicates the waterless cookers may help to reduce fat loss when increasing stretching temperatures. CDR research indicates that increasing the curd temperature from typical values around 130-140°F up to 150-160°F helped to extend the shelf life by 3-6 months depending on the specific curd temperature used. Another option is to produce processed Mozzarella by adding some emulsifying salts in the make which also helps to control functionality and reduce fat losses.

• CDR is here to help

At CDR, we know that this is a very difficult time for the dairy industry. And, while this is a quick overview of some options to slow down aging and extend cheese shelf life, know that you can reach out to CDR at any time for help and technical advice: www.cdr.wisc.edu/.

CMN

The views expressed by CMN’s guest columnists are their own opinions and do not necessarily reflect those of Cheese Market News®.

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