When the diet calls for low-carb but the dish screams for a bed of rice — no worries. Just substitute a spoonful of cauliflower “rice,” white cauliflower that’s been pulverized into rice-sized bits. A quick cook turns it into a fluffy scoop that mimics grain, with a fraction of the carbs and calories.

Cauliflower rice, introduced a few years ago, has become so popular that it’s stocked in nearly every supermarket, often in both fresh and frozen forms. Some come mixed with other vegetable shreds, others are flavored with lime, herbs, cheese and more. Many of these are pricey at about $5 for less than a pound — but so convenient.

For this taste test, we stuck with the plain versions — and learned that there are vast differences between brands. Surprisingly, fresh did not out-perform frozen. The key to great product, it turns out, has much more to do with the freshness of the vegetable itself and its preparation.

Great riced cauliflower starts with fresh, rock-hard cauliflower that has tight florets, no blemishes and little to no odor. It’s carefully shredded into fairly uniform bits, using primarily the vegetable’s more tender florets. Bad riced cauliflower relies on old, tough, sulfurous cauliflower, and it’s heavy on stalks and stems that are sized so differently they fail to produce an even cook.

Here’s the scoop on the cauliflower rice to crave, and the dirt-flavored crumbles that should never make it to the plate. Nutrition details refer to ¾ cup.

Boulder Canyon Riced Cauliflower

Clean flavor, understated aroma and a touch of sweetness make this the best of the freezer section. The bits are uniformly ground, primarily from florets rather than stalk, making it extra tender. 22.5 calories, 22.5 mg sodium, 2.25 g sugar. $3.79 for 10 ounces at Sprouts. (4 stars)

Trader Joe’s Organic Riced Cauliflower

Fine, uniform shreds about the size of cooked rice make this an impressive, fresh alternative. Bits are tender and have minimal odor, a plus for those who don’t love cauliflower. 28.5 calories, 28.5 mg sodium, 2 g sugar. $2.49 for 1 pound. (4 stars)

Earthbound Farms Riced Cauliflower

The uneven dice of this raw version from the produce aisle appears to include more stem than floret, but it cooks up pleasantly tender, with a hint of sweetness. 25 calories, 25 mg sodium, 2 g sugar. $3.99 for 14 ounces at Safeway. (3½ stars)

Birds Eye Veggie Made Riced Cauliflower

Light flavor and even texture make this frozen option good for those who prefer a par-cooked, salted option. 25 calories, 210 mg sodium, 2 g sugar. $4.99 for 10 ounces at Raley’s. (3 stars)

Earthbound Farm Organic Riced Cauliflower

Found in the freezer aisle, these bits have a touch of salt and much more cauliflower flavor than the fresh version from the produce aisle. It’s also easy to overcook into a mash. 25 calories, 70 mg sodium, 2 g sugar. $4.99 for 10 ounces at Safeway. (2½ stars)

365 Organic Cauliflower Riced

A touch of salt underscores the potent cauliflower flavor, which might work fine for those who love the veg, but the strong odor is unlikely to impress those using it as a rice substitute. Find this in the freezer section. 25 calories, 70 mg sodium, 1 g sugar. $1.99 for 12 ounces at Whole Foods. (2½ stars)

365 Organic Riced Cauliflower

Oh, what a difference word placement makes. It’s also in a different supermarket section from the version above. But while the flavor of this unfrozen version is authentic, it’s too powerful to mimic rice, and the mix of cauliflower crumbs and extra-large pieces are too different in size to cook evenly. 19 calories, 22.5 mg sodium, 1.5 g sugar. $4.99 for 1 pound at Whole Foods. (2 stars)

Green Giant Riced Veggies Cauliflower

No matter how long you cook these frozen bits, they are unpleasantly tough and chewy due to dense, fibrous cauliflower. 20 calories, 22 mg sodium, 2 g sugar. $3.59 for 12 ounces at Raley’s. (½ a star)

Little Giant Little Green Sprout

The fibrous texture is bad enough, but this frozen option is also bitter and grassy — not good at all. 20 calories, 20 mg sodium, 2 g sugar. $4.49 for 10 ounces at Safeway. (½ a star)

Cece’s Veggie Co Organic Cauliflower

One bite of these produce-aisle bits is a reason to hate cauliflower. It smells like garbage and tastes like dirt with a bitter kick — nearly a week before the expiration date. 60 calories, 78 mg sodium, 6 g sugar. $4.99 for a 1-pound tub at Sprouts. (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.