Liquid milk has a high demand because of its nutritional value and pleasant flavour. Milk from
cows has a creamy white appearance, but from goats and other animals has a yellower colour and
a higher viscosity. Milk is sold universally for domestic consumption, for use with other products
(eg. tea, porridge) and for use by other processors (eg. butter, cheese, yoghurt). For small-scale
processors this is a relatively difficult product to produce as the process requires careful control
over hygiene, a relatively high capital expenditure and short distribution channels to good
markets as the shelf life (at 3-5 days) is shorter than most products.
Principles of preservation and methods of processing
The principle of preservation is the destruction of pathogenic and most spoilage bacteria and
inactivation of most enzymes by heat during pasteurization at 63°C for 30 minutes. This time
and temperature combination is described by regulations in some countries and should be
carefully adhered to.
Process flow diagram
Milk is immediately filtered, by use of filtering pads, soon
A surface cooler is used to cool the milk to stop
further multiplication of micro-organisms in milk.
Use batch pasteurizer. Control of temperature and time is very
important for correct pasteurization to give expected shelf life.
The vessel to be used should be fabricated from stainless steel or
aluminium or bought locally from hardware shops. Milk should be
heated with constant stirring to prevent the product
overheating/burning at the bottom.
Cool quickly to temperature below 10oC. Cooling is done by
placing the pan containing the hot product into another vessel
which contains cold water. The product is stirred continuously
until the temperature drops.
Pack into sterilized bottles and seal with sterile lids using
a small filling and capping machine.
Storage should be in either a cooler or a refrigerator at
below 10°C. The milk should not be exposed to sunlight as
this will heat it, promote rancidity of milk fat and destroy
the vitamin riboflavin.
The transportation of milk from the storage room to the
market should be in a refrigerated vehicle if the distance to
be covered is long. But for a short distance which takes less
than an hours drive, refrigeration is not necessary:
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