I’ve long been a fan of Coca-Cola. That’s pretty well-known in my immediate circles, and, many years ago, by the people who used to frequent the alt.food.cocacola Usenet group.
By now, most of us know that in 1985 Coca-Cola changed the formula of their flagship product and the backlash against “New Coke” resulted in the re-introduction of the “original formula” as Coca-Cola Classic.
But all was not the same. Pre-“New Coke” Coca-Cola was sweetened with sugar, and “Coca-Cola Classic” is sweetened with High Fructose Corn Syrup, as you see here. HFCS is significantly cheaper than sugar.

During Passover, people who follow the Ashkenazi Jewish tradition are forbidden from consuming products containing certain grains, including corn. Therefore, the Chicago Coca-Cola Bottling Company produces a limited amount of Coca-Cola Classic sweetened with sugar, which is sold in grocery stores in areas with larger Jewish populations.
Here’s the delightful ingredient list:

You can identify Kosher Coca-Cola here in the Chicago area by looking for the seal of the Chicago Rabbinical Council on the can:

The cans in these photos have the same UPC code, so there’s no way of differentiating the product at the scanner. If you’re seeking the Kosher stuff, look for the identifiers I’ve shown above.
Now, to further confuse the situation, many foodies claim that Coca-Cola made in Mexico, which is available at many Mexican grocery stores in our area, tastes the same as “original” Coca-Cola. It certainly contains sugar, as you see:

But the last time I had a Mexican Coke (in Mexico a couple of years ago), it seemed to taste more like “New Coke” (or “Coke II”) than the original, pre-1985 formula.
That brings us to today’s experiment.
The three containers shown in the photo at the top of this page hold, from left to right, Kosher Coca-Cola, HFCS-sweetened Coca-Cola Classic, and a Coca-Cola (note the absence of the word “Classic”) bottled in Mexico.
My experiment was to identify which drink came from which source, and to note the differences between each. I would take three clean glasses and have my lovely assistants pour equal amounts of each product into each of the three glasses. No ice. The cans and bottle were all kept next to each other in the refrigerator for several hours prior to the test and were opened at the time of the experiment.
And the results:
I was able to identify the HFCS-sweetened Coke Classic, but I confused the Mexican and Kosher Cokes. They both tasted very similar, which leads me to believe the “New Coke” taste of the Mexican product is a thing of the past.
Anyway, I now have a couple of six-packs of the Kosher stuff in my pantry, ready for when I want “The Real Thing.”