Last week, we discussed how milk makes its way from the dairy farm to the dairy processing plant. The next step in our examination of the dairy industry is processing and packaging. This is the step in the dairy manufacturing process where the milk is pasteurized and packaged – and maybe even turned into the cream, butter, or ice cream that the dairy industry is famous for.
We learned in our last blog that milk is delivered to dairy processing plants in large tanker trucks. The first stop for the milk once it is unloaded from the tanker truck at the plant is the separator. A separator is a machine that (as its name suggests) will separate the milk into two parts – the cream (fat) and skimmed milk. You may be surprised to learn that even whole milk goes through this process. In fact, regardless of the level of fat desired in the final product – whether 1%, 2%, or whole milk – this step is needed so that the exact amount of milk fat can be added back to the product. In this way, every time you choose one of these products off the shelf, it has precisely the amount of fat you want and expect.
Did You Know? The difference between skim and whole milk is this: there is no fat added back to skim milk, but whole milk is 3.5% fat.
After the separating process, vitamins A and D are added to the milk product. While vitamin A and some vitamin D naturally occur in whole milk, they are supplemented in low-fat milk products to meet a specific “standard of identity” for milk. According to FDA regulation, 2,000 international units of vitamin A and 400 international units of vitamin D are required for the product to be legally labeled as milk). Vitamin D supplementation is credited with helping to reduce the incidence of rickets and other bone-weakening medical conditions, as vitamin D facilitates the body’s calcium absorption.
After vitamins are added, the milk will be homogenized. Homogenizers are used in many industries to create many products. However, in the dairy industry, the machines use high pressure to pump milk through fine holes, decreasing the globule size in milk fat. Fat is less dense than water; therefore, without homogenization, milk fat will naturally separate and rise to the top of milk. While this is not dangerous or harmful (especially for those who love cream!), most people prefer the consistency of homogenized milk. Homogenization results in a uniform and appealing texture, but it has no effect on the milk’s ultimate nutritional quality.
The last step is pasteurization, during which raw milk is heated to destroy bacteria. Pasteurization requires the milk to be kept at high temperatures for a specific length of time to prevent the serious illnesses, yeasts, and molds that bacteria can cause.
Fast Fact: Traditional pasteurization heats the milk to 161 degrees Fahrenheit for a minimum of 15 seconds. Ultra-high-temperature pasteurization heats the milk to 280 degrees Fahrenheit for a minimum of one to two seconds. Both methods result in milk that is safe to drink – but neither affects nutritional levels.
After pasteurization, the milk is cooled rapidly and packaged into bottles or cartons. During and after packaging, milk is kept cold in refrigerated rooms. Keeping milk cold is vital to delivering a high-quality product to the consumer. In fact, for every degree over 40 that milk reaches, the shelf life is reduced by 24 hours – so keep that in mind when getting home from the grocery store! Milk should be kept below 40 degrees Fahrenheit to remain fresh for as long as possible.
Zwirner Has the Equipment the Dairy Industry Needs
Zwirner Equipment maintains a robust inventory of dairy industry homogenizers and pasteurizers. If you are seeking high-quality reconditioned equipment, call our team today.
