Milk is excellent food for bacteria and molds. Left standing during a warm temperature, it
might not last the day before it begins to sour as the result of microbial activity. That’s why milk
is sold pasteurized and refrigerated, or ultra-pasteurized and kept in air-tight containers. It will
depend on the room temperature; cold room will allow the milk for long time then the hot room
Controlling fermentation by microbes leads to the formation of yoghurt and cheeses, which are
ways to preserve milk nutrients without having to worry about them spoiling in unwanted ways.
We can store milk without refrigeration by boiling it at 6-8 hours of intervals. Milk consistency
will thick after 3-4 booking sessions. Add some boil water to adjust the thicknesses before
boiling it again.
Pasteurized milk: if unopened, up to four hours at room temperature. If refrigerated below
4°C (40°F), five to seven days. Pasteurized milk will stay longer without significant souring for
significant more time than raw milk which will go bad far quicker. Pasteurization is that the
process of heating milk for a predetermined time at a predetermined temperature to destroy
pathogens. The thermal destruction process is logarithmic, and bacteria are killed at a rate that’s
proportional to the number of bacteria present. Pasteurization improves a product’s safety and
extends its time period by killing pathogenic and rotting organisms.
Ultra-high temperature milk (UHT): Heated to at least 135ºC (275°F) for 2 to 4
seconds and stored in special packaging, UHT milk can last six months at ambient temperatures
if unopened. If once it opened, it should be refrigerated and treat like fresh milk. UTH milk has a
shelf life of many months and doesn’t need to be refrigerating if it is not opened.
In contrast to bacterial growth, physical, chemical, and enzymatic changes in the milk, such as
browning reactions, cream separation, sediment or gel formation, are what restrict the shelf life
of UHT milk.
Filtered milk: Milk passed through a fine filter to sift out souring bacteria. Filter milk can
keep for 45 days when store at 7 0 C.
Frozen milk: 3 months.
Evaporated/condensed milk: one year at ambient temperatures.
Dried milk: up to 1 year in powdered form.