On this occasion, we will address a fundamental topic for owners or managers of businesses in the dairy industry: the refrigeration of dairy products. Milk, cheeses, yogurts, and other dairy products are essential elements in the daily diet of most people. But have you ever wondered why preserving these products in refrigeration is so crucial? What does the preservation of dairy products in optimal conditions depend on? Allow us to explain some key points.
Refrigeration of Dairy Products: What Does the Preservation of Dairy Depend On?
To begin with, milk is a complete food, and when secreted from a healthy udder, it is virtually sterile. This is due to natural milk inhibitors such as lactoferrin and lactoperoxidase, which prevent a significant increase in bacteria in the first hours after milking when it is at room temperature. So, what is the key to maintaining the original quality of milk? Cooling to a specific temperature, 4°C, during this critical period is the preferred method to ensure a high-quality product suitable for further processing and consumption.
The milk cooling process can be achieved through mechanical refrigeration or cooling tanks. However, what is truly essential is maintaining the milk at a sufficiently low temperature and for a limited time to ensure its quality and safety. But what factors determine the effectiveness of dairy product refrigeration for preservation? Here are the key fundamentals:
In order to slow down the growth of bacteria, it is essential to cool the milk to a temperature between 3 and 4°C. Following international recommendations, most countries set a storage temperature for milk at 4°C. In fact, this standard is considered the most effective for controlling bacterial proliferation. However, it is important to note that a temperature below 3°C could lead to freezing phenomena that would adversely affect the composition and quality of the milk.
In addition to the storage temperature, it’s important to consider that as the storage period increases, bacterial growth also increases. Maintaining strict control over the duration of milk storage is essential for dairy product refrigeration to be effective in preserving its quality.
Initial Product Contamination
On the other hand, the quantity of germs present in the milk at the time of milking is a critical factor. Maintaining high hygiene standards from the milking process to storage is essential for obtaining milk with good bacteriological quality. The malfunctioning of the refrigeration tank is not always to blame for unsatisfactory quality.
Another aspect that influences the total germ count is the speed at which milk cooling begins. Almost instantaneous cooling is more beneficial than a longer duration. In the first few hours after milking, bacterial growth is slow and then increases rapidly. Utilizing this period to cool the milk to the storage temperature is indispensable.
Storage in Dairy Product Refrigeration
Of course, the preservation of dairy products doesn’t end with the initial cooling of the milk. Once it has been cooled, it is essential to maintain it under the proper conditions to preserve its quality and food safety. The key here lies in the use of cold, a fundamental ally in the dairy industry.
Undoubtedly, cold plays a leading role in food preservation, as it slows down the speed of chemical, enzymatic processes, and the proliferation of microorganisms. In other words, by reducing the temperature, a delay in the indicative deterioration changes that occur in dairy products is achieved. This delay is more pronounced as the temperature decreases. However, it is pertinent to highlight that, even at low temperatures, some microorganisms can survive. Therefore, maintaining the cold chain is imperative to ensure the integrity of dairy products.
There are various methods in which cold is utilized for the refrigeration of dairy products:
Freshly milked, milk typically has a temperature close to 37°C, making it a breeding ground for various types of bacteria present on the farm, especially those from the soil or manure. To prevent the proliferation of these microorganisms, the milk must be cooled immediately to reach a temperature between 3 and 4°C. This process will inhibit the development of bacteria and result in a high-quality product. Cooling is the most relevant initial process for the processing of most foods, and in the case of dairy, it is critical to ensure hygiene, food safety, shelf life, taste, and nutritional quality of the milk.
Currently, advanced technology such as stainless steel tanks equipped with refrigeration systems is used to achieve effective cooling. Additionally, cooling is also employed in other processes, such as inducing fat crystallization or improving cream formation.
Actual Dairy Product Refrigeration
Once dairy products have been cooled, it is necessary to maintain them in a temperature range between 0 and 5°C. To increase the efficiency of this method and extend the shelf life of these foods, it is common to combine it with pasteurization, a process that uses heat to reduce the initial microbial load of the milk. Refrigeration is a common practice in the dairy industry to preserve cheeses, yogurts, and other fresh dairy products.
Specifically, freezing is a method used in the production and preservation of specific products, such as ice cream. The latter is stored at temperatures as low as -30°C and is maintained at -18°C during distribution and sale. Although freezing is occasionally used to concentrate milk, this is a costly and limited process compared to concentration by evaporation. It is also not common to use this process to delay the deterioration of fresh milk or liquid dairy products. Some types of creams are marketed frozen, especially for industrial use in the production of ice creams and butter.
Maintaining the Cold Chain: The Purpose of Dairy Product Refrigeration
The cold chain is a critical concept in the dairy industry and the handling of perishable foods in general. Its main objective is to ensure the preservation of fresh foods, either through refrigeration or freezing, to preserve their organoleptic properties and ensure food safety.
As mentioned, in the case of dairy products, hygiene at the time of milking and subsequent storage are key factors that influence the quality of the final product. Bacterial reproduction is very slow in the two hours following milking, so it is essential to take advantage of this time to refrigerate the milk at a temperature of approximately 4°C.
At this point, European regulations stipulate that the maximum cooling temperature for raw milk should be 8°C if milking is daily and 6°C when the frequency is lower. When the milk is intended for the production of other products such as yogurt, cheese, cream, or butter, it must be kept at a maximum of 6°C until the transformation process is complete.
Storage temperature is a critical factor in the cold chain and the refrigeration of dairy products in general. Lower temperatures delay germ growth. However, it is important to avoid temperatures below 3°C, as, as mentioned, they could cause the freezing of the milk, altering its composition and quality. In particular, freezing can significantly affect certain liquid dairy products, destabilizing the composition of fats and proteins. Therefore, most dairy products are preserved by refrigeration at temperatures ranging from 2 to 5°C.
As dairy products are perishable foods, storage time is another essential factor to consider. For example, raw milk has a shelf life of approximately 72 hours, while products like cheese spread can be preserved for 15 days. Similarly, yogurts and cream cheese have a shelf life of 21 days, and other cheeses, such as cottage cheese and mozzarella, expire after 30 days.
We provide solutions for the refrigeration of dairy products at all stages of the process.
At Intersam, we design and develop customized industrial and commercial refrigeration and air conditioning systems, both within and outside of Spain, since 1995. Our equipment and installations cover all stages of various processes that require cold. If you are a manager of a company that uses milk as a raw material for its products, contact us and share your dairy product refrigeration needs with us. Make your brand a guarantee of quality, safety, and durability!