Milk Type And Its Packaging And Shelf Life Introduction

Milk is rich in nutrients, and people like to drink it, but it is also easy to breed bacteria. Untreated raw milk can be stored for 48 hours at 0°C, 24 hours at 10°C, 6 hours at 25°C, and only 3 hours at 30°C. With the development of transportation, cold chain technology and sterilization technology, various type of milk are produced and also make it possible for the milk to enter thousands of households and become an important source of supplementary nutrition for people.

The packaging of milk must have the functions of oxygen, light and moisture barrier, fragrance preservation and odor prevention. This requires packaging to ensure that external bacteria, dust, gas, light, moisture, etc. cannot enter the packaging container on one hand; on the other hand, the packaging material must have good stability, not absorb the peculiar smell, and components cannot be decomposed and migrated, which affects the quality of milk; There is also to ensure that the water, oil, and aroma components contained in the milk do not penetrate outward.

Milk is packaged on a filling machine, which from an industrial point of view requires good smoothness, stretchability, and heat-sealing performance for milk packaging. The challenge of cold and heat is also faced in storage and drinking. Liquid milk packaging must be able to withstand pasteurization or hydrogen peroxide sterilization and high-temperature treatment requirements to make all milk products have stable shelf life.

Today we will give a brief introduction to common milk types, their packaging and  shelf life:

In many developed countries, unpasteurized raw milk is the most popular among consumers, but it is also the most expensive. Freshly squeezed milk contains antibacterial active substances such as lysozyme, which can be stored at 4°C for 24 to 36 hours. This kind of milk does not need to be heated, and is not only rich in nutrients, but also retains some trace physiologically active components in milk, which is very beneficial to the growth of children.

The raw milk after pasteurization needs to be refrigerated at 4°C-10°C throughout the whole process, which is more popular and preserves the nutrients in milk to the greatest extent. The milk with a short shelf life is mostly pasteurized “homogeneous” milk. It is one of the most advanced milk sterilization methods in the world. Conventionally, pasteurized milk can be stored for about 7 days at 4°C, but there is another type of pasteurized milk called HTST, which has a higher pasteurization temperature. Therefore, after HTST pasteurized milk is filled into gable top cartons or glass bottles, the shelf life can reach 15-30 days at 4°C.

It is also known as normal temperature milk, adopts ultra-high temperature sterilization method, which can kill all harmful bacteria, and prolong the shelf life to 6-12 months. It does not need refrigeration, but the nutrients will be greatly lost. Usually, this normal temperature milk needs to be filled into aseptic containers after UHT sterilization.

It is made from milk powder and water. Some companies import large quantities of milk powder from abroad and add water to reconstitute it. The cost of reconstituted milk is relatively low, and the nutritional value will decrease slightly, because the reconstituted milk has undergone the process of processing the milk into milk powder at high temperature. The reconstituted milk shelf life is more than 12 months after UHT sterilization.

Flavor milk is not as high in nutritional value as pure milk, but because of its rich taste, they are very popular with children. In order to have a better taste, some spices are usually added to milk beverages. Milk beverages can usually be prepared with fresh milk or milk powder and other auxiliary materials. They need to be sterilized before and after filling. The sterilized products can be stored at room temperature for about 1-2 years.