An enzyme is essentially a catalyst. That is, it takes two or more materials and converts them into something else through a chemical reaction process. Your digestive system does this on a regular basis with food. However, it's also performed in labs and in food-making to take a kernel of corn and turn it into the ubiquitous sweetener known as high-fructose corn syrup. Food manufacturers use enzymes in a few steps in the process --- first to separate starch from the corn and then to convert part of the sugary mix from one kind of sugar to another.
Overview of High-Fructose Corn Syrup Production
It takes a lot of work to produce a sweetener from a corn kernel. First, food manufacturers must wet mill corn to get the starch out. This is a process that separates starch from other parts of the corn, including its protein, oil and fiber Corn starch is basically a long chain of glucose molecules. Enzymes help free starch in one step and convert sugars in another step. After that, the ingredients of high-fructose corn syrup go through a refining process to make them suitable for use in commercial products.
From Dust to Glucose
The process for creating high-fructose corn syrup was patented by Japanese researchers in the 1960s. They refined a system already in use as processed food makers worldwide searched for alternatives to regular table sugar when the prices of raw materials increased. Early attempts were made to simply sweeten starch extracted from corn, but the results were often too bitter, unstable and discolored. However, the introduction of an acid-enzyme conversion process changed things. After wet milling, the starch is now "washed" in a bath of mineral acids, which also contains a set of enzymes, including alpha- and beta-amylase. Think of this process as a kind of demolition: alpha-amylase makes structural breaks in the starch backbone and beta-amylase releases various forms of sugar molecules as it breaks down the starch with water. This process results in liquid mix comprised almost entirely of glucose.
From Glucose to Fructose
The next step in creating high-fructose corn syrup is using another set of enzymes to convert part of the glucose into fructose. Contrary to what you might think, high-fructose corn syrup is not all fructose. Some of the glucose remains. In addition, the ratio of fructose to glucose varies based on how the sweetener will be used. The enzymes used in this step can convert the glucose to fructose in proportions of 42, 55 and 90 percent. This is called enzymatic isomerization. The enzymes are conveniently found in several types of bacteria like Actinoplanes missouriensis, Bacillus coagulans, Flavobacterium arborescens, and Streptomyces. Makers of processed food products like bread, cereals and condiments use the lowest fructose ratio, called HFCS-42, while HFCS-55 is favored among soft drink makers. HFCS-90 is rarely used alone, but is often mixed with HFCS-42 to create HFCS-55.
Economics versus Epidemics
The way enzymes are used in the production of high-fructose corn syrup made it economically more viable than table sugar, also known as sucrose. Food and beverage makers began a wholesale abandonment of sucrose in the 1970s and 1980s. By 2005, sucrose had a sweetener market share of roughly 3.7 percent whereas it had a near-monopoly before the rise of high-fructose corn syrup, according to HealthCommentary.org. HFCS's meteoric rise ascent has not been without controversy. Although no other food product has seen such an increase in use -- nearly 1,000 percent between 1970 and 1990 -- public health authorities can't help but notice the trends that parallel its increased use. These include obesity, diabetes, hypertension and metabolic syndrome. In the late 2000s, high-fructose corn syrup was becoming more of a food pariah than a welcomed alternative to sugar. Sales slumped 11 percent between 2003 and 2008, according to a June 2010 report from MSNBC. And in 2009, the three major producers in the United States experienced another 9 percent drop, reports Melanie Warner in The New York Times (May 1, 2010).
References
- "American Journal of Clinical Nutrition"; Manufacturing, Composition and Applications of Fructose; L. Mark Hanover and John S. White; Nov. 1993
- UCDavis COSMOS; The Making of High-Fructose Corn Syrup; Kevin Ha; July 24, 2010
- Elmhurst College Virtual Chembook: Corn Syrup; Charles E. Ophardt; 2003
- U.S. Food and Drug Administration: Code of Federal Regulations Title 21: Sec. 184.1866 High Fructose Corn Syrup
- HealthCommentary.org; Is High-Fructose Corn Syrup the Next Trans Fat?; Mike Magee
- "San Diego Union Tribune"; High-Fructose Corn Syrup Friend, Foe?; Ed Blonz; July 30, 2008
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