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Explain how preservative methods interfere with enzymatic activity canning heating freezing pickling soaking in acetic acid salting?
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How are frozen peas increased in shelf life?
Freezing peas performs one of two functions: - It prevents bacterial activity - It prevents enzymatic activity (natural degeneration) By reducing the temperature of peas to zero or below zero degrees Celsius, the water molecules in the peas are reduced to zero percent activity; effectivley they become ice. Water molecule activity is essential for the functioning of the naturally-occurring enzymes in the peas, so this is how the enzymatic activity is reduced. Bacterial activity is also another cause of deterioration in the quality of peas, however most bacteria cannot function or multiply in freezing conditions, so any damage they might do is then made impossible. In summary, by freezing peas, or most other foods you are slowing down (though not preventing) the natural process of degeneration. Eventually peas will go stale in the freezer, but freezing them is a great way of ensuring they're at optimum quality for more than a few days on end.
How does ethanol act as a preservative?
Ethanol has many properties that make it an excellent preservative at high enough concentration. It is antimicrobial, it is stable and does not easily react, and it readily penetrates and diffuses through tissues and entire organisms,
How does freezing temperature affect mocroorganisms and enzymes?
Freezing temperature make ice of the water in bacteria and completely stop there metabolic activity. Enzymes do not work at freezing temperature as they have no scope for movement in solid ice. So there activity halted.
What does blanching a vegetable mean?
Blanching is most commomly used to prepare vegetables for freezing. It is simply scalding, boiling or steaming a vegetable briefly - a couple of minutes - to stop enzymatic action before freezing, but without actually cooking the vegetable.
What is the effect of freezing on water activity?
The water molecules will slow down.
Why does pressure change the freezing point of water?
restricts molecular activity
Why does freezing help preserve peas?
Mostly the bacteria that would feed on the peas, or whatever organic material you've frozen, can't survive in freezing temperatures.
What are the effects of freezing on enzyme activity?
When an enzyme is frozen, it only slows down activity. Unlike boiling an enzyme, it does not stop it from working.
Could reanimation be possible?
Not at this time. There are many problems that accompany cell death, freezing, and attempts at reanimation.When speaking of freezing people and then reviving them, the problem is that ice crystals form in tissues, and those crystals destroy cell membranes, killing the cells (often the case in frostbite). That is why flash-freezing with liquid nitrogen is necessary. However, replacing water in plasma with antifreeze-like fluid (not antifreeze itself, which is toxic, but rather glycerol or dimethyl sulfoxide) so that it can perfuse throughout tissues, allows for the body to be frozen quickly to slow cellular activity, preventing oxidative stress and destruction of cell structures and enzymes.The biggest problems come from the actual reanimation process itself, as you have to replace those fluids and reheat the body in sufficient time so that enzymatic activity, metabolic activity, nerve activity, etc. are restarted at the same time so that the cells don't begin to breakdown. Since there are many mechanisms in place in cells that chemically/enzymatically detect cellular impairment, such states usually trigger apoptosis, whereby the cell destroys itself. On the whole, this results in tissue death.If you could solve the above problems, then it could, in theory, be possible to slow cellular/enzymatic activity enough to preserve someone...and then reheat the body and restart these processes to allow them to continue without excessive cell/tissue death. However, at the moment, this is not possible.
Why is salt is put on the roads on icy weather?
This is called a colligative property. Salt lowers the freezing point of water. Why? Because the molecules (formula units) of the salt interfere with the formation of ice crystals by getting in their way. The more salt, the lower will be the freezing point.
Do I need to wash salmon before freezing it?
No. I disagree. I clean my fish before freezing. There can still be microbial activity in frozen food. That is all the more likely in a fish that is still full of fecal matter.
Does freezing a enzyme affect it?
When an enzyme is frozen, it only slows down activity. Unlike boiling an enzyme, it does not stop it from working.
