For the marmalade, I would modify the mesh itself. The edges look too clean and crisp where it touches the bread. If your modeling package supports sculpting, subdivide it several times and sculpt it to look better. Also, too glossy, maybe even try some SSS (and Fresnel, like mentioned above)?
For the apple, your UV doesn't look very good, I can see stretching along the texture, If you have to, just make it so there is no stetching from this view and dont worry about the other sides of the apple. The apple is also too smooth, they generally have very small divets and irregularities, use a subtle displacement map and it should help that out (hold an apple up to a light and look at how the light falls on it, you will see those small irregularities).
The coffee could probably use more roughness because the reflection is fairly crisp (not sure about this, look at how actual coffee looks and see how the reflection would look). Plus, the coffee/cup looks too clean, maybe get a texture that has some foam/bubbles or add them in the mesh. make sure your coffee isnt a flat plane, it should have a meniscus.
Are you using an HDRI? if not, try to get an image that is actually inside a room (maybe even a kitchen/dinning room). it looks like there is too much white being reflected.
It's also looking a bit grainy, try rendering at 2x-4x the resolution you rendered this at, then reduce the size. It will give you a much crisper image.
Hope these suggestions help, looking forward to some revisions
