03.15.12
CAHY: Innovative meat product (continued, 3)
One of the reasons for the blog’s interest in “pink slime” comes from experience working with microorganisms that produced collagenase, an enzyme that degrades the connective tissue protein, collagen.
To do rapid qualitative screening for collagenase production, or just to quickly and cheaply assay for the presence of the enzyme in samples, we used large amounts of fetal calfskin collagen.
And the way it was prepared is not too dissimilar from how Beef Products, or corporate America, processes garbage into a food product of marginal value.
Our collagen source had to be replenished once every year and a half so. That involved getting the hide from a freshly slaughtered fetal calf.
A local slaughterhouse provided them, free, I think. Maybe it’s all used as profit margin now.
The fetal calf hide would be put in a plastic bucket of water with a small amount of microbial growth inhibitor thrown in. It would be allowed to sit for a day or two. This would loosen it up, making the hair easier to debride.
We let it rot a little, so to speak.
Everytime the lab did this there would be a new batch of student assistants and one would be “volunteered” to help prepare it.
The hide would be taken out of the vat, put on an aluminum table/sink, and the hair removed with scrapers. If it was the first time you ever did it, you gagged a lot. The smell was not pleasant and you either got used to it, or breathed through your mouth, or suffered until your gag reflex got burned out for the day, or something like that.
Scraping the hair off the hide and rinsing it took about an hour.
Another couple hours were spent cutting the hide — now looking like what it was, pink flesh — into strips. Then the strips were slowly fed into a coarse meat grinder to make chunks. The work took most of the morning, or afternoon, depending on when you started.
The chunks were thrown into big vats of acetic acid. The acetic acid vats were then kept in a cold room for years, serving as the reservoir of collagen which was, when it started, in the flesh.
Acetic acid rendered the collagen into a slow-flowing gel after a week or two. When one needed a quantity for lab work, one took a beaker, dipped it into the vat of chunks, took out some, and squeezed the chunks through a cheese cloth.
The collagen gel was expressed, caught in another beaker, the remnants of the acetic acid dialyzed away with phosphate buffer.
When the gel collagen was ready you could pour it into a glass or plastic petri dish and put it in an incubator at body temperature. There it would firm up into a solid white layer of what sort of looked like very white, slightly quivering shiny flesh. It would have been great in horror movies.
Typically, one could put little round assay pads on the plate, impregnate the pads from samples drawn from liquid growth medium from bacterial samples of interest, and wait for a couple hours.
If collagenase was present the collagen would clear (dissolve, actually) into protein fragments and water around the pads, leaving a halo.
If you left the collagen plate in the incubator long enough, it dried out, leaving a fairly tough circle of dried insoluble cross-linked collagen which, to the touch, felt a bit like paper.
“Boneless Lean Beef Trimmings,” or “pink slime” reminded me of fetal calfskin collagen. It was not a food but it was also, loosely speaking, a meat trimming.
The marine bacteria with which we worked found it very nourishing. And the acetic acid, like ammonia with “pink slime,” kept it microbe free before use.