Q3. Freshly collected cow’s milk spoils within a few hours at room temperature but
the milk packed in a tetra pack stays fresh for a longer period of time. Give reasons
Answers
Answer:
The microbiological phenomenon takes place here.
Fresh Milk:
Freshly collected cow milk have thousands of bacteria in it. The presence of that bacteria is through a source like soil, dirty utensil in which milking is done, unclean cow udder, etc.
Now, these bacteria are responsible for the deterioration of milk. Normal room temperature is between 35-37 degree Celsius. And milk that comes from the udder has a temperature of 37.2-degree celsius. This is the best suitable temperature for bacterial growth and it makes milk acidic.
Packed /Sachet Milk:
Packed Milk comes from the dairy industry which they procure from the farmer. This is the same milk that we talk above but the reason behind it stay for long is pasteurisation on treatment.
Pasteurization is a process where every particle of milk is heated to 73-degree celsius for 15 seconds and suddenly it chilled to less than 4-degree celsius where it kills all pathogen or harmful bacteria. Now, this milk is kept for refrigeration (under 5 degree Celsius temperature) and this temperature is not suitable for bacteria to grow. So, it stays long for over 2 days at refrigeration temperature.
Beyond 2 days there are some microbial changes observe in milk again as there are some bacteria that grow at refrigeration temperature slowly.
Answer:
Explanation:
The freshly collected cow’s milk has some bacteria and that is why it gets spoiled in a few hours unless it is boiled and cooled. After boiling and cooling, the milk stays good for a few more hours. If boiled, cooled and kept in the fridge, it stays good for a few more days.
Milk packed in sachets actually have a life of about 7 or 8 days because they have been pasteurised, packed in fairly aseptic packing and of course kept refrigerated all through till they are delivered to the consumers.