Modern fruit is bred to be a lot sweeter so I imagine it’s primarily the sugars that increase appetite or food noise. Mandarin oranges are a prime example of this.

It’s so sweet these days that often times they can’t even be fed to frugivorous or omnivorous animals because the sugar content puts them in poor health. (Diabetes usually)

The purpose of eating fruit seems to be for hydration with the added bonus of vitamins, minerals, and antioxidants. It also offers an instant energy source at that, so likely very useful to our ancestors whilst they were persistence hunting.

Certainly would have been in your best interest to eat as much fruit as possible as it is a fleeting resource (rots quickly and desirable to other animals) so that likely influenced how much we gravitate to sweet things as a species. I don’t believe the food noise would have been nearly as intense though, not being purposely bred for sweetness and all.

I’m careful about the fruit I eat because so much of it is pure sugar. I usually pick things with high fibre to counteract the appetite stimulating effects of sugar and I always eat the skin and seeds if they are edible. Things like granny smith apples, pears, berries, underripe kiwis and bananas.

I’ve been really enjoying korean melons as the whole plant is edible (rind and seeds) and it doesn’t give any food noise for me as its only mildly sweet. If anything it quells my fruit and by extension sugar craving. Hydration is a plus during the summer.