Does Yoshi eating apples do anything?

In super mario world, yoshi can eat apples that are in the bushes.

Does eating these apples do anything?

There are three types of Berries (apples) that Yoshi can eat with varying effects. In all cases, any berry eaten will add one coin to the player's coin count and can cause the coin counter to rollover. (giving the player a 1-up as a reward.)

• Red - The most common of berries. Eating 10 of these in the same stage will cause Yoshi to produce an egg that hatches into a Super Mushroom. Using or holding any other form of power-up will not affect this though, as it will always be a Super Mushroom. In the Remake (Super Mario Advanced 2), the egg will create a power-up based on the Yoshi Color.
• Pink - An uncommon berry that found in a few stages. Eating 2 of them in the same stage will produce a small smiling cloud that floats around like Lakitu. The cloud will rain coins slowly as it floats forward. Collecting all the coins will cause the cloud to throw a 1-up mushroom as a reward!
• Green - The least common of the berries, it only shows up in one level as part of level design. ¹ Each berry you eat will add 20 seconds to the game timer. Yoshi will eat the berry much like an enemy, and will not produce an egg.

As noted, the Red and Pink berry requires you to eat them in the same stage, and will not roll over their counts to any other stage. ²

1: There's one stage where green berries can be found which is named Funky in the Special World. There's one other stage where a green berry can be found, but it's not as important as it is in Funky.

2: Needs testing, but if I recall, the berry count WILL roll over between lives. Eating 8 red berries, then restarting the stage due to a death will still keep 8 in memory. So you would only need two berries for a egg at that point. I can recall this from the SNES version, but need to test before confirming for this answer.