![]() ![]() Cottage cheese has a shelf life of 21 to 28 days, although there is often considerable loss of quality during this period 13. ![]() Permeability to O 2, CO 2, and water vapour transmission rates for packaging films are among the most essential factors in determining the package atmosphere composition, which may influence the product’s deterioration rate12. Opaque or semi-opaque packaging materials, most usually containing a white pigment such as TiO 2, are normally used for yogurt 11.ĭifferent types of packaging concepts are also required for various types of cheeses. For long-life, heat-treated drinking-yogurt products, composite materials made with: plastic/Alu-foil/paperboard with good water vapour, O 2, and light barrier properties are also often used. A good O 2 barrier packaging will help to protect the product from oxidation, and a good light barrier will help to delay fading of light-sensitive colours and avoid light-induced oxidation.ĭrinking-yogurt products are packaged in PE-HD bottles sealed with either aluminium foil laminate heat-seal closures, or with PE-LD caps. For these products, a low water vapour transmission rate (WVTR) is required to prevent the product from losing water during shelf life. For pasteurised, spoonable yogurt products, barrier laminated materials are desirable if a long shelf-life is needed, with some having shelf lives of 4–6 months at ambient temperatures. The most popular material in current use for fresh yogurt is thermoformed TiO2 pigmented high impact polystyrene (PS-HI), with either an aluminium foil/plastic laminate or a paper/plastic laminate heat-seal lid or closure. 10 AA concentration degraded in the UP-PET bottled milk after 60 days of refrigerated storage, while sensory evaluation of the milk remained without noticeable change. 8 reported a total loss of AA in UHT milk packed in C-enamelled tinplate cans after 30 days of storage at 3☌. Losses of ascorbic acid (AA) during milk storage have been reported for UHT milk storage at various temperatures durations of storage and with different packaging materials, such as C-enamelled tinplate cans 8 brown glass bottles 9 and aseptic multilayer containers 5. Pigmented PET enhances its versatility by protecting the food from light, which in turn helps to protect food flavour against light-induced lipid oxidation 5, 7. Polyethylene terephthalate (PET) is another plastic material used for milk packaging. ![]() Although the product had been exposed to light, the researchers had used multi-layered plastic bottles with a high barrier. Under these conditions the stability was only five days. The product was stored at 4☌ with exposure to fluorescent lighting. 6 evaluated the influence of the packaging material on the shelf life of commercialised pasteurised milk in Greece. Based on the results of the study, high-density polyethylene (PE-HD) bottles were better for storing pasteurised milk compared with that of a low-density polyethylene (PE-LD) pouch (Table 1, see below). 4 evaluated the influence of storage temperature on the microbiological stability of homogenised whole pasteurised milk packaged in different polyethylene (PE) monolayer materials, pigmented with titanium dioxide (TiO 2). The dairy industry is able to achieve a 45-day shelf life through the use of ultrapasteurisation (UP) processes, while ultra-high temperature (UHT) processed products achieve a shelf life of three months to one year with no refrigeration 5. ![]()
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