4.3 Sweeteners and sugar alternatives

Types of Sweeteners

Nutritive and Non-Nutritive Sweeteners

The most fundamental way to classify sweeteners is by whether they contribute calories.

Nutritive sweeteners provide calories and energy. The most familiar examples are sucrose (table sugar), fructose (fruit sugar), and glucose. These are the traditional sugars you encounter throughout food science, typically providing about 4 kcal per gram.

Non-nutritive sweeteners provide no significant calories. They're used as sugar substitutes in food products to reduce calorie content. This category includes both artificial sweeteners (aspartame, sucralose, saccharin) and natural sweeteners (stevia). Because they're so much sweeter than sucrose, only tiny amounts are needed, which is why the calorie contribution is negligible.

Sugar Alcohols and Artificial Sweeteners

Sugar alcohols (also called polyols) are a special type of nutritive sweetener with a chemical structure that resembles both sugars and alcohols. They don't fit neatly into either the "nutritive" or "non-nutritive" category because they fall somewhere in between:

• They provide fewer calories than regular sugar, typically around 1.5–3 kcal per gram instead of 4
• They have a lower glycemic index than sucrose, meaning a slower blood sugar response
• Common examples: xylitol, sorbitol, erythritol, and maltitol
• One drawback: sugar alcohols can cause gastrointestinal discomfort (bloating, gas, laxative effects) when consumed in large amounts, because they're incompletely absorbed in the small intestine

Artificial sweeteners are synthetic compounds designed to mimic the sweetness of sugar without providing significant calories. They're commonly found in processed foods, beverages, and as tabletop sweeteners (think of the colored packets). Examples include aspartame, sucralose, and saccharin.

Stevia as a Natural Non-Nutritive Sweetener

Stevia stands out because it's both non-nutritive and naturally derived. It comes from the leaves of the Stevia rebaudiana plant, native to South America. The sweet taste comes from compounds called steviol glycosides (primarily stevioside and rebaudioside A), which are extracted and purified for commercial use.

Stevia is widely used as a sugar substitute in food products and beverages. Some people notice a slight bitter or licorice-like aftertaste, which is why manufacturers often blend stevia with other sweeteners to improve the flavor profile.

Properties of Sweeteners

Glycemic Index and Blood Sugar Response

The glycemic index (GI) measures how quickly a food raises blood sugar levels after consumption. It's scored on a scale where pure glucose = 100.

• High-GI foods cause a rapid spike in blood sugar
• Low-GI foods produce a slower, more gradual rise

Non-nutritive sweeteners generally have a GI near zero, since they aren't metabolized as carbohydrates. This makes them useful for individuals with diabetes or anyone looking to manage blood sugar levels. Sugar alcohols fall in between, with GI values that vary by type (erythritol has a GI of essentially 0, while maltitol's GI is around 35).

Relative Sweetness Compared to Sucrose

Relative sweetness compares how sweet a substance tastes relative to sucrose, which is set as the reference point at 1 (or 100%).

Because non-nutritive sweeteners are hundreds of times sweeter than sucrose, only very small quantities are needed to reach the desired sweetness in a product. This is why a single packet of Splenda can replace a full teaspoon of sugar.

Common Non-Nutritive Sweeteners

Aspartame

Aspartame is an artificial sweetener made from two amino acids: aspartic acid and phenylalanine, joined by a methyl ester bond. It's approximately 200 times sweeter than sucrose.

• Found in diet sodas, sugar-free chewing gum, and many low-calorie food products
• Not heat-stable: it breaks down at high temperatures, so it's unsuitable for baking or prolonged cooking
• Products containing aspartame must carry a warning label for individuals with phenylketonuria (PKU), a rare genetic disorder in which the body cannot properly metabolize phenylalanine

Sucralose

Sucralose is made from sucrose through a process that replaces three hydroxyl groups with chlorine atoms (selective chlorination). This modification makes it approximately 600 times sweeter than sucrose while rendering it essentially non-caloric, since the body doesn't recognize or metabolize it the same way.

• Heat-stable, making it suitable for baked goods and cooked foods (unlike aspartame)
• Sold commercially as Splenda
• Commonly used across a wide range of low-calorie and sugar-free food products and beverages
• Passes through the body largely undigested, which is why it contributes virtually no calories