I just quickly googled the effects of copper in cheese production, and got this article. I will do some more in depth research and get back to you, but I think I won't be buying copper for my home cheesemaking...
http://www.izsler.it/izs_bs/ftp/doc/CREF%20latte/pubblicazioni/cessione%20rame.pdfI here is a translation of the "introduction" section, which pretty much summarizes what copper's chemical (in very basic terms) effects are on the cheese:
INTRODUZIONE – La presenza di tracce di metalli in prodotti lattiero caseari assume particolare
importanza poiché per diversi elementi è stata dimostrata una elevata biodisponibilità per l’uomo se presenti
in tale categoria di prodotti [1]. Per quanto riguarda i due più importanti formaggi D.O.P. nazionali
preoccupazioni sono destate dalla lavorazione caldaie di rame, metallo essenziale, ma ad alte concentrazioni
potenzialmente tossico. Anche le ricadute tecnologiche dovute alla presenza di rame sono rilevanti. Il
metallo, infatti, può modificare il metabolismo di diversi ceppi batterici [2] potendo favorire la crescita di
alcuni ceppi a scapito di altri. Concentrazioni di rame a livelli particolarmente elevati possono anche indurre
modificazioni delle caratteristiche organolettiche del prodotto finito, fino a produrre un inverdimento del
prodotto [3; 4]. Il rame può, inoltre, promuovere fenomeni di ossidazione delle frazioni lipidiche del
formaggio con produzione di molecole dall’odore sgradevole, oltre ad ossidazione del colesterolo con
formazione di ossidi promotori del processo di aterosclerosi [5]
INTRO: The presence of trace metals in dairy products become of great importance as various examples of these elements have demonstrated a high bioavailability to humans when present in this category of products (dairy). As far as the two most important national DOP(Denomination of protected origin) cheeses go, worries have arisen in regards to the use of copper cauldrons in the production process, as it is an essential metal, but at high concenctrations is potentially toxic. Even the technological effects as a result of the presence of copper are relevant. The metal, in fact, can modify the metabolism of various bacterial strains, with the ability to favor the growth/development of certain strains, at the expense of others. Particularly high copper concentrations can actually cause a modification to the organoleptic qualities of the finished product, or can even cause the product to turn green. Copper can also promote oxidation of the lipids present in the cheese, resulting in the production of foul smelling molecules, in addition to the oxidation of cholestorol with the formation of oxides which promote the process of atherosclerosis.
I am no translator, so I hope you can get the gist.
My scientifically ignorant conclusion is that copper leeches into the milk, and thus changes the environmental qualities in which we process the milk, so it would in fact result in a change in the acidifying process. This is based of of one quick article that I found in 5 minutes though. I am sure there is tons of info on the subject out there.