My doctor has told me to drink fresh apple juice in the morning. I am finding it difficult to drink fresh fruit juice daily.
Is there anything available in the market which I can keep in the refrigerator and drink?
The nutritional value should be the same or less but not much less.
I have heard that normal apple juice from the market has no [nutritional?] value to drink.
If your physician recommended the fresh apple juice specifically (and not, for example, bottled apple juice or eating apples, or just eating more fruit), you should ask him or her what the reasons for that recommendation are, and what reasonable alternatives you can use if you are finding it difficult to comply with the recommendation.
Fresh apple juice is an oddly specific recommendation given that apples are not known for having juice. Cider is traditional (and seasonal), although it tends to come from apples specifically grown for cider. Unless you have a juicing machine, I am not even sure what fresh apple juice would refer to.
No, you cannot substitute fresh apple juice.
Some of the compounds found in apple juice are very volatile. They evaporate a few minutes after the juice is made, or are broken down by still-active enzymes or oxygenation. These processes don't happen in the whole apple, because these compounds don't come into contact with the wrong enzymes or oxygen before juicing. But they start as soon as the juice is made.
As the enzymes would change the juice too much, and as a measure against bacteria, you cannot keep pressed apple juice in the refrigerator for more than a few hours. It would perish too soon to be brought into the market. Thus, apple juice sold in the market is pasteurized, which means heated. The heating destroys further compounds in the juice, which weren't destroyed by the enzymes and oxygen. Many vitamins can be destroyed during the pasteurization, and possibly other "healthy" compounds.
What is left is still rich in nutrients. The fructose and malic acid stay there for certain, as well as lots of aromatic components (but not all of them). Some vitamins will also remain after the pasteurization, but not all.
So, if you really need the fresh stuff, you cannot substitute it. Even juicing it yourself the night before will reduce its quality. But as SAJ14SAJ said, we don't know why the doctor prescribed you fresh juice, maybe all you need is the quickly available fructose. You can ask him if the pasteurized juice from the market will do. Another option is, if pressing juice is logistically too hard for you early in the morning, to ask if you can eat the whole apple. Again, this depends on what you need the juice for, so we cannot answer here, only the doctor can.
