<p> VCE FOOD TECHNOLOGY Unit 3 outcome 1 Primary and secondary processing of dairy products</p><p>Most of the food that we eat today has undergone some form of processing. There are two types of processing that food may be subject to.</p><p>Primary processing</p><p>This is the initial stage of processing that a food undergoes after harvest. The food retains its essential qualities. Foods may undergo primary processing to make them safer to eat, easier to transport, more appealing to consumers or more convenient to use. Examples of primary processing are the milling of wheat and rice, refining of sugar, extraction of corn kernels from the cob and pasteurisation and homogenisation of milk.</p><p>There is also subcategory of primary processing:</p><p>Post harvest treatment</p><p>This is merely preparing food for sale after harvest or slaughter. Post harvest treatments do not alter the physical appearance of the food significantly. It literally allows the food to be saleable and ready to undertake further preparation. Examples include waxing apples, removing the feathers from a chicken and washing and grading eggs.</p><p>Secondary processing</p><p>Secondary processing of food occurs after primary processing to create food products that are significantly different from the original raw ingredients that form the product. It subjects the food to processes such as heating, mechanical force and the additional of chemicals and flavourings. During Food and Technology classes, much of the practical work undertaken could be seen as secondary processing. Examples include cooking fried rice from Jasmine rice, muffins from flour and yoghurt, cheese, custard or ice cream from dairy products. VCE FOOD TECHNOLOGY Unit 3 outcome 1 The table below describes the stages in the primary processing of whole milk. Fill in the table with the relevant information. </p><p>Stage Description of process Effect of process Milking  Mechanical milking  The milk is collected from machines draw milk from the the cow twice per day cow’s udder using suction cups  The milk temperature is attached to the teats brought down from the  The milk is transported to temperature of the cow to a stainless steel vats via large safer temperature outside the pipes, where it is refrigerated Temperature Danger Zone  The milk is then transported (TDZ) of around 2°C from the farm to the dairy Testing  On arrival at the dairy, the  Milk is an unstable food raw milk is tested to ensure that and may contain high levels of it is clean and free of high levels harmful bacteria; these will be of harmful bacteria identified during the testing  If it is fit for consumption it stage. If levels are too high, it passes through to large storage will be discarded tanks  The low storage temperatures reduce the rate at which milk spoils by keeping it outside the TDZ Pasteurisation  The milk passes through  Harmful bacteria and food heat exchange pipes and is spoilage enzymes are heated to 72°C for 15 seconds deactivated. The milk is now  It is then rapidly cooled to safer to consume <4°C  The flavour of the milk changes slightly – it takes on a mild ‘cooked’ flavour Homogenisation  The liquid is forced through  The mixture is now a tiny nozzles under pressure homogenous mixture – the fat  The force causes an increase globules become more stable in the surface area of the fat and will not consolidate and globules and they no longer rise to the top of the milk as clump together cream  The milk has a creamier mouth feel and thicker texture than before homogenisation  The milk is whiter than before homogenisation Packaging and  The pasteurised,  The pasteurised, transport homogenised milk is packaged in homogenised milk is ready for sterile plastic or cardboard sale through retail and containers wholesale outlets  The milk is then transported  It is now in a safe, to wholesale or retail outlets in convenient form for use in a refrigerated trucks, where it is variety of recipes or as a stand- stored at >4°C until sale alone product VCE FOOD TECHNOLOGY Unit 3 outcome 1</p><p>The table below describes the stages in the secondary processing of whole milk into yoghurt. Fill in the table with the relevant information.</p><p>Stage Description of process Effect of process Additional protein is  Extra protein is added to the milk  The protein content of the added to milk milk becomes higher  This protein is in the form of casein, the natural thing for in  This allows yoghurt to set protein found in milk to a firm consistency Heating of the milk  The milk is cooked for 30  The protein is denatured minutes at 85°C or at 90°C for 10 and the end product has better minutes consistency Live bacterial cultures  Once the milk has been  The quantity of ‘good’ introduced heated, it is cooled to the desired bacteria is significantly temperature and live bacterial increased cultures are introduced Milk held at 40°C  The milk is held at a stable  The lactic acid produced temperature of 40°C for 2-3 during fermentation creates a hours or at 30°C for 18 hours. sour taste and acidic pH levels Fermentation occurs during the in the yoghurt. stage.  The milk solidifies into curd.  This causes the protein When the curd is distributed strands in the milk to mesh (e.g. by placing a spoon in the together and the milk becomes yoghurt) the whey may seep solid out of the product and separate Flavouring, packaging  The yoghurt is cooled rapidly  The yoghurt is transformed and transport to stop any bacteria multiplying with a variety of textures,  Additives such as colouring, flavours and colours thickening or preserving agents  The market share of the may be introduced. Other manufacturer may be increased ingredients may be added such due to a wider range of products as sugar fruit puree or fruit available pieces, cereals and nuts  The yoghurt is then placed into sterilised containers and sealed  It is stored at a temperature of <4°C  The yoghurt is then transported to wholesale or retail outlets, where it is stored until sold</p>