The History of Trans-Fats and Crisco
It all starts with the cotton gin which as every school-child knows was invented by Elli Whitney and which made cotton a cheap and usable textile. Because of the cotton gin, the growth of cotton n production expanded from 750,000 bales in 1830 to 2.85 million bales in 1850 and horribly, as grew cotton, so did slavery in America. But that is a different tale than I intend to tell here.
The point of the cotton gin to this discussion is thus: that with the increased production of cotton came the increased production of cotton seed which was a by-product of ginning and which was considered a nuiscance and a waste-product. In 1902 a German chemist named Wilhelm Normann patented a process for "hardening" or hydrogenating liquid plant oils which produced a solid but creamy white lard-like fat that was shelf-stable for up to two years (far longer than the oils from which the product was made). Normann's patent got noticed by the American firm of Proctor and Gamble which bought the rights to the patent in 1909. Proctor and Gamble was smart: they knew that cotton seed was a virtually free waste product that just happened to be filled with lots of liquid oil and armed withthe Normann process that they now owned they were able to convert cottonseed into a brand new product called"Crisco" which they produced for virtually nothing and which they marketed by giving away cookbooks every one of whose recipes just happened to use Crisco. As everyone now knows, Crisco became a household name and a staple of every pantry in America.
Margarine is older than Crisco and was originally a blend of animal and natural vegetable fats and skim milk along with an emulsifier like lecithin, flavoring like butyric acid and coloring. In this form,margarine was a high fat product that was cheaper than butter. Once hydrogenation was perfected however, most margarine came to be made with partially hydrogenated vegetable oils and thus, came to contain trans-fatty acids. For many years, margarine was marketed as a "healthy" alternative to butter because it contained no cholesterol (whereas butter does). This is ironic since margarine contained large amounts of trans fats that were far more dangerous to health than the cholesterol contained in butter. In fairness however it should be noted that butter and cow-meat does contain small amount of a few bacterially-produced trans-fats (this is because cows are "ruminants" whose guts contain bacteria thatdigest cellulose).
What Are Trans-Fatty Acids?
Trans-fats are fatty acids with at least one double carbon-to-carbon bond in the hydrocarbon tail wherein the proximal and distal carbons are oriented on opposite sides of the double bond. This is distinct from the more common "cis" fatty acid.
What Foods Have Trans-Fats
Mostly partially hydrogenated vegetable oils. Fully hydrogenated oils are simply saturated fats without any double bonds, but fats that are partially hydrogenated do contain trans-fatty acids. Trans-fats are an unavoidable consequence of partial hydrogenation because the process temporarily breaks double bonds into single bonds and then back into double bonds again and this allows the sides to "spin" into the lower-energy trans configuration.