Taste-Off: The best sugar-free root beer — and the fizzy duds

We tasted through eight brands of diet root beer, from A&W to Barq's and Stewart's, to find the ones that taste great -- and the awful ones to avoid.

Frothy, sweet and deliciously complex, root beer is the kind of bubbly libation that’s exactly right on a hot day. It’s refreshing straight out of the can or bottle — and an instant treat poured over vanilla ice cream.

Since that jolt of spice mixed up with vanilla, caramel, nutmeg and more typically comes with a landslide of calories, we decided to check out diet and zero-sugar options, including a few trendy prebiotic brews that have a few calories, but far fewer than the usual hit of 180 to 200 per can of regular root beer.

While at least a dozen companies make a diet version of their root beer, we settled for the eight brands easily found at local stores. Tasting the root beers was both fun and surprising, as the flavor profiles of the beloved drink can be vastly different. Some are creamy and vanilla-forward, while others lean into cinnamon, anise and cherry. Some are deep brown and extra foamy; others are clear with hardly any bubbles at all.

Achieving exactly the right level of sweetness is clearly a challenge, as many brands don’t get it right. Some rely on a single sweetener such as aspartame, stevia or Sucralose. But the most successful incorporate several sweeteners, using them to create a careful balance.

Great zero-sugar root beer is foamy and rich. It hits the sweet note just right and pings the palate with bursts of vanilla, caramel, nutmeg, cinnamon, honey and anise. Bad diet root beer is flat, watery, sour or has so much sweetener that it tastes like chemicals.

Here’s the scoop on zero sugar root beers that are just as delicious as the full-sugar versions, and the insipid pours not worthy of a glass — much less the ice cream to dress it up. Nutrition info refers to 12 ounces and is included only in the sodas that have calories.

Mug Root Beer

The signature sweetness of full-sugar root beer plus a nice hit of traditional root beer flavor makes this just plain terrific. It’s a gulp of childhood so good, it’s hard to believe it has no sugar. $9.98 for 12 12-ounce cans at Raley’s. (4 stars)

Stewart’s Diet Root Beer

Those who like a slightly less sweet soda may fall hard for this rich, caramelly version. Sweetened with aspartame, it’s refreshing and has loads of interesting flavors. $6.49 for four 12-ounce bottles at Total Wine & More. (4 stars)

A & W Zero Root Beer

A pleasant hit of vanilla, extra-smooth flavor and lots of root beer froth explain why this brand earns a spot on every soda aisle. It’s good. $4.49 for 6 16.9-ounce bottles at Target. (3½ stars)

Barq’s Zero Sugar Root Beer

It’s not awful, but this pour is significantly less flavorful than the top contenders. The use of aspartame as the primary sweetener is a good choice, but it’s extremely sweet and lacks both aroma and flavor. $9.99 for 12 12-ounce cans at Safeway. (2½ stars)

Olipop Classic Root Beer

Fans of kombucha may enjoy this unusual, creamy flavored root beer made from a wide array of botanicals. It’s minimally sweet and has a distinct sour note thanks to a dose of prebiotics and a hit of cider vinegar. 35 calories. $2.99 for 12 ounces at BevMo. (2 stars)

Zevia Root Beer

There’s a right way and a wrong way to use stevia. This brand gets it wrong, as the flavors of root beer are all but smothered in sweetener, giving it an unappealing flavor reminiscent of chemicals. $6.99 for eight 12-ounce cans at Target. (1 star)

Poppi Root Beer

Infusing a soda with gut-enhancing ingredients is a great idea, but the tart kick of prebiotics makes this taste more like cola than root beer. 25 calories. $2.55 for 12 ounces at Raley’s. (1 star)

Virgil’s Zero Root Beer

This insipid, sour liquid has little flavor and no fizz. $6.49 for four 12-ounce cans at Raley’s. (No stars)

Reviews are based on product samples purchased by this newspaper or provided by manufacturers. Contact Jolene Thym at timespickyeater@gmail.com. Read more Taste-off columns at www.mercurynews.com/tag/taste-off.