If congress wants to delegate details to experts they could explicitly state that in the law, and create their own organization of experts to do the job. Giving the president more power is not a requirement, and enforcement should remain separate. But even then, regulations shouldn't be ambiguous. The laws should state something like "food purity should be within %x of yada yada, where x is updated yearly by the appropriate agency" Then it's up to the courts to decide if the law was broken or not.
In the short term this could be a nightmare as companies flaunt all sorts of regulation, but I think overall it is a good thing.