I do not know what cheese makers would do nowadays without the
hot iron to guide them in evenly maturing curd. It is one of the
most essential attributes of making. It should, of course, be most
judiciously used.
In 1845, Mr. L. M. Norton, of Goshen, Conn., discovered that the acid
in curd could be gauged by stringing threads from a heated iron. He
kept the discovery a secret for a long time but at last divulged it.
To supply yourself with a handy instrument for testing acid, take
a three-quarter inch bar of iron a foot long and set one end into
a ferrule on a wooden handle. It can then be conveniently handled
without burning the fingers. Heat the metal a little hotter than
desired and then thrust for a moment into a bucket of water, to
thoroughly clean the surface. Holding it in the left hand, take a
piece of curd squeezed dry of whey and press against the iron. If it
does not adhere at all, the curd is perfectly sweet, no matter how it
may smell to you. If it clings slightly, you may be assured that acid
is beginning to develop, so keep close watch of it. Curd ought never
to string out threads more than one-fourth of an inch long before
whey is drawn, and oftentimes less is desirable.
Have the iron at just the right temperature or you cannot make an
accurate test. A right temperature implies that the iron is so hot
that the curd will fry around the edges when pressed against it, but
not so hot that it will scorch over.
Tainted and floating curds will often string threads six inches and
more in length, and then not be fitted to grind and salt. As soon
as acid has overcome the gaseous condition of such curd so that the
inflation will subside, it is ready to grind, but not before. Cheese
makers should not be afraid of souring and airing such curd too much.