People have made good suggestions about the heat and not being down totally to nutrition. However in terms of nutrition I like the SIS Isotonic energy gels a lot especially on hot days as they can be taken without water. I also highly recommend Nuun tablets for water as sometimes you cannot drink anymore water because it lacks the other nutrients that your body won't get from just water but have lost. I have also in the past used powdered coconut water but at that time they didn't have them in tablets so the powder tended to get outside moisture and turn into hard chunks (which were quite tasty but not what I wanted in water) Anything where you can get hydrated and replace things is important.
For actual food, certainly gels like the Clif Gels or GU are great for quick energy and chews like Clif Shot Bloks or ProBar Chews or if you are into it Floyd's of Leadville CBD chews are quite similar. Though if you want more food I have found the Clif savory pouches to be great and fairly easy to put down. Many pro cyclists also use homemade rice cakes (or soigneur made) with different things in them. They are generally easier to digest and if you size them right can work well while riding.
One other good thing is different more odd flavors can be nice. One of my favorite snacks while touring or longer easier paced rides is the Sahale Snacks nuts It isn't one flavor or texture and the Thai Cashews for instance also have soy sauce and spice with the sweet and your palate will thank you for that because it is a delicious shock from eating just sweet stuff a lot or more plain flavored stuff. However sometimes plain flavors can be easier to get down in the heat.
Keep as cool as possible and drink plenty of fluids and stop if you need to. Ain't no winning if you bonk out or feel like hurling at the end. The only podium you should care about is the
Camelbak water bottle holding your water or drink mix equipped water. In summer time sometimes I will wear my sun sleeves which are usually cooling and when I go to bathroom I will usually get them nice and wet while washing my hands for extra cooling (I try to avoid wasting drinking water) or I might wet them beforehand. I also will wear a cycling cap and get that wet as well to keep my head cool.