how and why the nutrients in the food are lost?
Answers
Answer:
The nutrient value of a food is retained when it is frozen. Any nutrient losses are due to the processing prior to freezing and the cooking once the frozen food is thawed.
Vitamin C is not actually destroyed during boiling. It just get to the water as it’s water soluble. Vitamin C complete disintegration temperature is about 180 degrees of celsius, so it’s far more then boiling temperature of 100 degrees of celsius. It will degrade still, but gradually - not all at once.
The most temperature unstable are actually:
•│vitamin B1│
AFAIK about 40–60 degrees of celsius
•│vitamin B9│
Also above 100 degrees of celsius ( under temperature of boiling )
•│vitamin B12│
Around 100 degrees of celsius AFAIK, so it’s not completely destroyd during boiling.
But there is more then only temperature. Vitamins might be more stable or more prone to destroyed in certain pH. Vitamin C “likes” low pH, but vitamin A is easily damaged in such low pH ( prefer neutral / alkaline pH ). It also depends on oxygen and light access.
Most of vitamins are quite resitant to temperature, and at the same time most of them are very sensitive to sunlight… So, exposing them to sulight or oxygen causing more degradation then cooking alone.
The rest of vitamins are pretty stable at boiling temperature.
All of these vitamins are water soluble so they rather leach into the water then being destroyd. The best way of cooking to preserve vitamins in food are boiling, steaming, microwave ( even 90% more vitamin C then other methods ), slow cooking and pressure cooking.
Frying or baking is made in higher temperature as fat can get very hot on plate, so it’ll destroy much more vitamins.