[Pro_bity]

Good article, although his use of the word "chemicals" as a negative is pretty silly. Particularly, in this sentence "Fermentation and curdling involve hundreds of chemical reactions that produce a multitude of complex flavor compounds with a depth that can't be replicated by chemicals."

[abeppu]

Given that the paragraph you've quoted from is followed with a description of how acids denature proteins, I think the author probably understands that all the other stuff he's working with are "chemicals" too.

However, I think this works as a reasonable shorthand for non-specific synthetic food additives in this context. Laypeople like myself understand that butter substitutes include artificial flavors to attempt to recreate some of the flavor of butter, but they fall short. The author can favorably compare his curdling approach to the fake butter flavors of those familiar commercially available products without stopping to specify them, because it doesn't matter which specific chemical additives he's comparing to. If he instead said " ... a depth of flavor that can't be replicated by adding acetoin or diacetyl" (which wikipedia says are the common fake butter additives) what would that really add for his readers?

[ubernostrum]

Well, obviously chemicals can't replicate the chemicals produced by the chemical reactions among the chemicals in butter. I don't see what's so hard to understand about it.