I made a no-oil sponge cake for a swiss roll. I filled it with fresh whipped cream and then stored the cake in the fridge. It has gone moldy within 4 days of filling it. Since filling it, it has been stored in the fridge. Why did it go moldy so quickly?
Oil acts as a preservative which slows down the growth of mould in the cake. Because you've removed a preservative, the bacteria grows at it's normal pace. Chilling it slows it down, but not as much as the oil would.
When I make bread I tend to put honey in it as this is a natural preservative and this works for me, gets another day out of the bread.