Cake shelf life

hi every one. I have question about cake shelf life. we produce vanilla cake but after a while ( about 1 month) their color change to yellow!! can you help me about this matter?

whats the recipe you are using? That give indication about the fault…

If youre unwilling to show the recipe to see where the fault originates, then it will be difficult to solve the problem by just using your cursory statements.

hi Roy we generally use for cup cake about
28 % wheat flour
18% whole egg
10 % moisturizer(polyol)
13 % oil
and…flavor …

Incomplete information to learn something abnormal.
If youre unwilling to show your cake recipe and process then its very difficult to see the issue.