You need to harden off seedlings before putting them directly in the sun. Start by putting them in full shade for 4-5 days, then gradually introduce them to full sun. It can take a month. I do not know much about pitomba and their sunlight requirements

I think everyone has made that mistake before, usually with tomatoes and peppers. They can also get wind burned. You did correctly and it should recover. You may also put up something to break up the wind if it is windy. The plant may have just come from a greenhouse and is not use to full sun, cold temperatures, or wind. I bought a pitomba and the recent cold weather burn a few of the leaves. But so far it has done well.

Thanks for the tips. I put the little guy under a banana shrub (gives it some protection) and it seems to be perking up. I have my fingers crossed. I really should have known better, but I figured that such a tropical plant would be a-ok in direct light right off the bat. I did the same for my pitangatubas, and they didn't falter at all in full Florida sun; sure fried that pitomba though.