Packaging dried milk products

Each step in the processing and packaging of dry milk products can influence the properties of the finished product. The total heat treatment (i.e., time x temperature) for each step during the manufacture of milk powder is important in determining its properties. The method of heating and the total heat exposure influence protein denaturation, oxidation of the fat and the subsequent shelf-life of the powder. 

Packaging is the largest user of adhesives because every day each home uses 10 different packages of food products bottles of various drinks water, milk, juices, bier, wine, several other packs of meat, fish, frozen foods, dry foods, rice, noodles, and many other food packaging, each pack may only use less than one gram but each of us probably uses several grams of adhesives each day in all those packaging. 

Other processes (except milk drying) require the finished product to be cooled to a suitable storage temperature, usually 4°C or thereabouts, and kept cool until the point of sale. Conventional-type cold stores can be used for mixed dairy products, since all of them will be packaged and sealed after manufacture. 

The use of wooden sticks for ice cream and water ice products dates back to 1921. For many years, most stick products were ice lollies, and most bars were couverture coated ice creams ( choc ices ). Today the variety is much greater and ice cream, water ice and milk ice are sold in a number of different formats. For example, premium chocolate-coated ice creams are now often produced as stick products, and water ices are sold in tubes. Two main processes, moulding and extrude and cut are used to produce stick products. Tubes use the package as the mould and bars are made by extrude and cut. Bars and stick products are often coated with chocolate or couverture, and sometimes also dry pieces such as nuts. 

Full-cream milk powder has traditionally been packaged in tinplate cans evacuated before closure. The oxygen content of the headspace can increase to 5% over the first week of storage due to release of trapped air. Oxygen concentrations such as these can severely limit the shelf-life (Abbott et al., 1961). Milk powder is given heat treatment on spray-drying in order to increase the thiol concentration in the casein to provide the natural antioxidant. Heat treatment increases the chance of forming cooked milk flavour in the reconstituted product. 

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