Century Cactus Source of Great Natural Sweetener

April 7, 2007
A cactus for the centuries makes more than tequila - it makes a great natural sweetener with inulin.

Long before anyone heard of artificial sweeteners, or the obesity epidemic or which soft drink had the coolest commercials, there were desert plants called agave as many as 300 species of them throughout the Americas.

Known to native populations in Mexico and Central America as the "century plant" because of the length of time it takes to flower, agave is truly a survival plant for indigenous populations living in harsh environmental conditions. A mature agave plant may grow up to 12 feet in diameter with leaves up to eight feet long.

The many species of agave provide medicine, tools and food. The leaves yield fiber and are used as an herbal beverage; the tough stems have been used to make writing utensils, nails and needles; juice from the succulent leaves provide water, carbohydrates and micronutrients.

Closely related to aloe, and sporting similarly thick, fleshy leaves, agave also is the source for such classic fermented beverages as tequila and mezcal. But the sap of the flower recently has processors taking notice.

Agave tequilana (blue agave), and Agave salmiana and a few other agave species are now exploited to yield a healthy sweetener called agave syrup. Although marketed as a sugar substitute, that designation is somewhat misleading. Agave syrup is a sweet, fructose-rich liquid similar in color to honey and a little less viscous, which means it has a slightly greater water content (20 percent for honey vs. about 30 percent for agave syrup).

Agave syrup is a sugar substitute only in the sense that we've become accustomed to refined sucrose as our staple source of sweet carbohydrate. Because of its high fructose content (between 74 and 85 percent), agave syrup is sweeter than sugar, which means formulations may be able to use 25 to 40 percent less agave than table sugar. That savings translates to a lower calorie product. In this manner it is distinct from sugar substitutes created in a lab to imitate the taste of sugar. Agave syrup doesn't imitate anything; as a sweetener, it's a natural.

Maple Syrup of the Dessert

In one sense, agave syrup is analogous to maple syrup, a similar product of a far different environment. Both are derived from the sap of a plant. In both instances, the sap is collected and processed by heat to create syrup that runs about 70 percent sugar. But there are also distinct differences.

The first and most obvious differences are the plant source, and the type of sugar. Maple syrup is the boiled down sap of the maple tree. Maple sap starts out as 1.95 percent sucrose. Slow boiling brings this concentration to about 70 percent sucrose by evaporating most of the water.

Agave plants are crushed, and the sap collected into tanks. The sap is then heated to about 140°F for about 36 hours not only to concentrate the liquid into a syrup, but to develop the sweetness. The main carbohydrates in the agave sap are complex forms of fructose called fructosans, one of which is inulin, a straight-chain fructose polymer about ten eight to 10 fructose sugar units long. In this state, the sap is not very sweet.

When the agave sap is heated, the complex fructosans are hydrolyzed, or broken into their constituent fructose units. The fructose-rich solution is then filtered to obtain the desired products that range from dark syrup with a characteristic vanilla aroma, to a light amber liquid with more neutral characteristics.

Dark agave syrup retains more minerals, whereas the light syrup goes through a fine filtration process to remove some natural solids. The advantage of the lighter syrup is that it can be used in a large variety of applications without altering the taste of the foods or recipes.

Agave syrup can be used to sweeten fresh fruits, fruit smoothies, fruit juice beverages, coffee, tea, baked goods, ice cream, yogurts, salad dressings, jams and jellies and other prepared foods. Another advantage is that agave has a long shelf   up to three years   and will not crystallize. The light viscosity makes it easier than honey to physically handle and pour, and the high fructose content means many foods made with it will stay moist do to the hygroscopic (water drawing) nature of fructose.

Sweeter than the Scale

Sucrose is 50 percent each of glucose and fructose. Honey is about the same, plus much fructose in free form. High-fructose corn syrup is 55 percent fructose.

Better than Its Hype

Most fruits are rich in fructose. Pure glucose yields the highest glycemic response of any carbohydrate, and is therefore the standard by which glycemic index is judged. The Glycemic Index is a system of measurement of glucose response for persons with diabetes but has lately been misused and misrepresented as a diet plan.

According to proponents of glycemic index for reasons both sound and unsound, carbohydrates that result in a slow glycemic response are more satisfying and considered less of a health risk because they do not cause a rapid insulin response. Fructose-rich agave, with its low glycemic index, should be healthier and less prone to be stored as fat.

However, in 2004, Nielsen and Popkin in the American Journal of Clinical Nutrition, argued the opposite in reference to high-fructose corn syrup (HFCS). The authors proposed HFCS, which has replaced much of the sucrose in the American diet over the last few decades, is at the heart of the epidemic of obesity because: 1) fructose is more easily converted to fat than glucose (therefore eating the same amount of calories will make you fatter) and 2) fructose is less satisfying than glucose because it doesn't stimulate a rapid insulin response and increase cravings for sugar. By that argument, agave syrup would not be very satisfying, and would put us at risk for obesity, just as HFCS.

But it is inconsistent to argue that low glycemic foods are satisfying in one case and not so in another.

The reliability of glycemic index as a determinant of carbohydrate value was called into question in a 2000 study by Regina McDevitt, also published in the American Journal of Clinical Nutrition. The researchers overfed subjects in a metabolically controlled setting, keeping total calories fixed. They found no difference in the distribution of excess calories as fat, whether excess calories came from glucose, fructose or sucrose. Apparently, something as boring as overeating is the main culprit in obesity.

The value of agave should not be called into question by questionable marketing. The primary strengths of agave are that it is a relatively unrefined sugar that retains micronutrients, is pleasant to taste and easy to use. Plus, it's sweeter than table sugar because its sweetness derives from fructose allowing for lower calorie formulations and lower overall calorie intake without sacrificing the pleasure of eating.

Agave syrup is a healthful, natural carbohydrate, similar to honey, maple syrup, molasses, sorghum and other natural sweeteners that have been with us for centuries -- long enough for a few agave flowers to bloom.

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