Understanding the Differences in Coca-Cola Sugars: From Mexican Coke to American Holiday Editions

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Initial Claim and Scientific Investigation [0:00]

• Previous Video's Claim & Challenges [0:00]
  • The host, George, made a claim in a previous video that Mexican Coke contained no (unhydrolyzed) sucrose.
  • Two chemistry professors challenged this aggressive claim, as George had only measured glucose, not sucrose directly.
• Replication of Tests at Shippensburg University [1:02]
  • George visited Shippensburg University to collaborate with chemistry professors Jeb and John.
  • An undergraduate student, Rebekah, was hired to replicate and expand upon George's initial tests using more precise equipment.

Understanding HPLC and Initial Results [1:10]

• High-Performance Liquid Chromatography (HPLC) [1:15]
  • Rebekah utilized an HPLC machine, a sophisticated instrument capable of separating and identifying individual chemical components within a sample.
  • The process involved sonicating Coke samples to remove carbonation, filtering them, and then running them through the HPLC.
• Interpreting Chromatograms [1:30]
  • The HPLC produces a chromatogram, a graph where the X-axis represents time (retention time) and the Y-axis represents signal (concentration).
  • Each peak on the chromatogram corresponds to a unique chemical compound, with the area under the peak being proportional to its concentration.
  • By running pure compounds (standards), the retention times of glucose, fructose, and sucrose could be identified.
• Comparing American vs. Mexican Coke Sugar Profiles [2:21]
  • American Coke (HFCS) [2:33]
    • The chromatogram for American Coke (sweetened with high-fructose corn syrup) showed a larger fructose peak compared to its glucose peak.
  • Mexican Coke (Cane Sugar) [2:49]
    • The chromatogram for Mexican Coke (listing cane sugar as an ingredient) showed nearly equal peaks for glucose and fructose.
    • Explanation of Sucrose Inversion [2:58]
      • Sucrose (cane sugar) is a disaccharide composed of one glucose unit and one fructose unit.
      • When sucrose is exposed to acid, it undergoes hydrolysis (inversion), breaking down into equal amounts of glucose and fructose.
  • Quantitative Results for Mexican Coke [3:07]
    • The tested Mexican Coke samples contained an average of only 2.8 grams per liter (g/L) of sucrose.
    • This indicated that approximately 97% of the original cane sugar had been inverted into glucose and fructose.

The Sucrose Degradation Experiment [3:30]

• The Challenge of Freshness [3:39]
  • To accurately measure the rate of sucrose inversion, a freshly bottled cane sugar soda was needed, as Mexican Coke could take days to reach shelves, by which time inversion would have already occurred.
• Sarsaparilla Soda Experiment [3:57]
  • The team acquired fresh sarsaparilla soda, sweetened with cane sugar, from a local company (Reading Soda Works).
  • The sarsaparilla soda had a pH of 4.60, significantly higher (less acidic) than Mexican Coke's pH of 2.75 (Mexican Coke is about 71 times more acidic).
  • Controlled Acidification and Storage [4:53]
    • Hydrochloric acid was added to the sarsaparilla soda to match Mexican Coke's pH of 2.75.
    • The acidified soda was then divided into three batches and stored at different temperatures: 3°C (fridge), 22°C (room temperature), and 39°C (hot summer day).
• Sucrose Degradation Over Time [5:26]
  • After just 14 days at 39°C, almost all the sucrose in the sarsaparilla soda had inverted.
  • Even at room temperature (22°C), almost half the sucrose had hydrolyzed after three weeks.
  • The cold (3°C) sample showed minimal sucrose degradation.
  • This confirmed that Mexican Coke's acidity, combined with typical storage and transport temperatures, leads to significant sucrose inversion before consumption.

The Unexpected Discovery: Oligomers in American Coke [6:12]

• Revisiting High Fructose Corn Syrup (HFCS) Composition [6:12]
  • When examining the chromatogram of pure high-fructose corn syrup (HFCS), a small, previously overlooked peak was identified.
  • This peak corresponded to other sugars, such as maltose, maltotriose, and maltotetraose, which are glucose oligomers.
• Presence in American Coke, Absence in Mexican Coke [6:37]
  • Upon closer inspection, this small peak was consistently present in samples of regular American Coke.
  • Crucially, this peak was not present in Mexican Coke samples.
  • This indicates a subtle, but chemically distinct, difference in the sugar composition between American Coke (HFCS) and Mexican Coke (inverted cane sugar).
  • The host speculated that this small concentration of maltose might contribute to a discernible taste difference.

The "Holy Grail" and Blind Taste Tests [8:32]

• Discovery of Cane Sugar American Coke [8:32]
  • Jeb unexpectedly found a "Holiday Edition" American Coke bottle in a store that listed "CANE SUGAR" in its ingredients, rather than HFCS.
  • This was a significant discovery as it presented a true American Coke with cane sugar, allowing for a controlled comparison with regular HFCS American Coke, free from other differences like sodium content or country of origin.
  • The sugar profile of this Holiday Edition Coke showed a high, intact sucrose peak, much like freshly bottled cane sugar soda, unlike the inverted Mexican Coke.
• Blind Taste Tests with NPR's Planet Money [11:10]
  • To test if people could taste the difference between cane sugar and HFCS in American Coke, George conducted a blind taste test with NPR's Planet Money hosts, Jeff and Kenny.
  • Kenny, one of the hosts, was able to correctly identify the cane sugar American Coke as different from the HFCS American Coke twice out of three attempts.
  • This suggested that, contrary to George's initial dismissal, some individuals might be able to taste this subtle difference.
• Economic Context of Sugar Choices [12:15]
  • The Planet Money hosts explained that US cane sugar prices are artificially inflated due to government tariffs and subsidies, making high-fructose corn syrup a much cheaper alternative for beverage manufacturers like Coca-Cola.
  • Introducing a cane sugar "Holiday Edition" allows Coca-Cola to appeal to consumers who prefer "real sugar" without incurring the higher costs for their main product line or directly validating the taste preference implied by Mexican Coke.