Is regular sugar greener than high-fructose corn syrup?

Illuminating answers to environmental questions.
May 19 2009 11:59 AM

May Cause Earth Decay

Is regular sugar greener than high-fructose corn syrup?

(Continued from Page 1)

The researchers found that, on average, fossil fuel use, greenhouse gas emissions, and the release of acidifying substances seemed highest with corn sugar, while water usage was highest for cane sugar. The differences arose, in large part, because each crop has very different yields. While individual corn kernels are more densely packed with sugar than beets or cane (producing about four times as much by weight), cornfields themselves are relatively sparse. One U.S. acre produces about 4tons of corn, while an acre of Australian sugar cane field produces 38tons of cane and a U.K. beet field 22 tons of beets. As a result, a single acre can produce about 5.4 tons of sugar from sugar cane versus 3.4 tons from sugar beets and only 2.5 tons from corn.

A big wild card here is that making sweetener from any of these crops returns some useful byproducts that can offset some of the environmental burdens. Beet pulp, for example, can be used as animal feed, as can the corn protein and gluten meal that get separated out during the corn wet-milling process. Sugar cane probably gets the biggest plus in this category, as its waste fiber, known as bagasse, makes an efficient fuel source: Many sugar mills—where cane stalks from the field are converted into raw sugar—run entirely on bagasse, cutting out the need for additional fossil fuels.

Advertisement

So sugar cane seems to be the most efficient producer of sugar and potentially the lightest user of fossil fuels, even though its significant water requirements can't be ignored.

But to truly compare table sugar with HFCS, we need to look at the later stages of processing. We do know that evaporating cane and beet juice into dry, raw sugar—the least-processed variety—requires significant amounts of energy. A report from 1985 estimates that it takes 3,380 kilocalories and 5,660 kilocalories, respectively, to process a kilogram of crystalline sugar from cane and beets—quite a bit, considering that kilogram of sugar provides 3,850 kilocalories of food energy. It's unclear whether that figure pertains to raw or refined sugar, however. Producing the finer stuff not only requires several more steps—evaporating, spinning, melting, chemical decolorizing treatments—it also means more food miles, since these steps occur in a separate facility.

Meanwhile, to turn simple corn syrup into high-fructose corn syrup, enzymes are used to convert 90 percent of the glucose molecules into supersweet fructose before the resulting solution gets blended back with simple glucose syrup. It's unclear just what kind of additional burden these final steps account for, but we do know that the entire corn wet-milling process takes a whole lot of energy—according to the consulting firm FTI, it's the most energy-intensive food-manufacturing industry in America, meaning it spent the most on electricity and fuel per dollar-value of shipments made. Sugar beet processing comes in at No. 2; sugar cane mills and refiners, collectively, are No. 3.

As your mom, your dentist, and the Lantern has told you time and time again, take all things in moderation and you'll probably be fine—that goes for sugar and high-fructose corn syrup, as well. And cutting down on our overall sweetener intake makes a lot more sense than simply switching one for the other. After all, if we all boycotted HFCS and instead ramped up our consumption of cane sugar, where would we find enough hot, humid land to put all those additional cane fields? Are you willing to gobble up the rest of Florida, Louisiana, Hawaii, and Texas just to avoid corn in your Coke?

Is there an environmental quandary that's been keeping you up at night? Send it to ask.the.lantern@gmail.com, and check this space every Tuesday.

Nina Shen Rastogi is a writer and editor, and is also the vice president for content at Figment.

  Slate Plus
Working
Dec. 18 2014 4:49 PM Slate’s Working Podcast: Episode 17 Transcript Read what David Plotz asked a middle school principal about his workday.