I'm thinking anxiety!
Chewing is (among other things) a way of alleviating stress. Even though the dogs aren't called Goofy Goldens for nothing, I think maybe you have a worried puppy there. He can't talk to you about his worries, so he chews.
It's hard on him because he's still sort of a kid, and his leader (that's you!) is gone a good part of the day, and he needs guidance and attention. Not that you don't have anything else to do, but showing leadership is a must for owners of pups! Can you work a good walk back into his daily schedule? Or two short ones, morning and evening, when you can't do a longer one? Set aside some time to play with him a couple of times a day, too - just five or ten minutes could do the trick. If he has a superabundance of energy, he really NEEDS good walks every day, and even hikes on weekends if your family can do it.
If you can't trust him in the kitchen when you're not there, can you gate it off with baby gates?
Instead of rawhides (one gulp and they're gone), look in your pet store for the hard bones that have filler in them. The bones are made so they won't splinter, and they're great for a heavy chewer. When he gets the insides licked out, you can put peanut butter inside instead. You can put them in the freezer and then he'll find them even more fun. He'll chew on the bones, too, and when they get too ugly you can toss them (but they last a long time). Kong toys are good, too. (Our dogs always like anything with peanut butter in or on them.)
Another thing to do is to take him to obedience classes. It gives you something to do together - including the homework - it gives him a chance to socialize with other dogs, and he may learn some obedience, too. While you're there, ask the teacher to tell you what other indications of stress to look for. You'll be surprised what they are.