Published July 1, 2010. From Cook's Illustrated.
When most brands garner comments like “sour, old, sad,” we just had to ask: What does it take to produce good canned diced tomatoes?
Unlike most kinds of canned produce, which pale in comparison to their fresh counterparts, a great can of diced tomatoes offers flavor almost every bit as intense as ripe, in-season fruit. For this reason it’s one of the most important staples in our pantry. We rely on diced tomatoes for everything from pasta sauce to chili to soups and stews. We even use them to make quick salsa when good fresh tomatoes are in short supply.
Supermarket shelves are teeming with different brands of diced tomatoes, and in recent years most have come out with “petite diced” versions as well. To make sense of the selection, we gathered 16 widely available styles and brands. There was only one way to start the process of identifying the best: Open the cans, pass around some spoons, and hold a blind tasting of plain, unheated tomatoes. When the tomatoes were sampled this way, potential flaws would have nowhere to hide.
To our surprise, nearly half of the brands fell short. And that’s putting it nicely: The lowest-rated tomatoes were flat-out awful, eliciting slams like “mushy, gruel-like texture” and “tastes like wet socks.”
Although we asked our tasters to consider a range of factors (natural sweetness and texture, for example), they homed in on fresh flavor as their primary criterion for loving—or loathing—a tomato. “Nothing tinny here,” wrote tasters about the favorite tomato in this round. The runner-up was similarly praised as “fruity” and “fresh-tasting.”
After the first taste test, we were down to nine brands. For the next round, we used the samples to make a simple garlic-and-olive-oil-laced tomato sauce. Our two favorites from the initial round came out on top again, with comments like “beautiful texture” and “pleasing” tomato flavor. What made the difference between these two and the remaining seven brands, half of which had nothing to recommend them, even when disguised by other ingredients and flavorings?
Rarely have we struggled so much to nail down the reasons for liking what we liked. Appearance, for example, had no bearing on quality: Some tomatoes boasted an appealing bright red color yet tasted stale and washed out. Others, with noticeably more seeds, green pieces, and even cores, tasted quite nice. Did size matter? No. While some brands’ petites scored lower than their regular cuts, others scored higher.
The companies themselves were no help—for the most part, they told us any information was proprietary. It was only when we turned to food scientists, including Sheryl A. Barringer, a professor of food science and technology at Ohio State University, and Diane Barrett, fruit and vegetable products specialist in the department of food science and technology at the University of California-Davis, that we got some answers. According to these experts, great diced tomatoes start with the tomatoes themselves. Some companies experiment constantly to grow not only the best-tasting varieties but also the firmest fruit, with thick “walls” that will stand up to mechanical dicing. Others choose to use thin-walled tomatoes and cook them longer for a softer consistency, which our tasters did not care for.
But even a seemingly perfect tomato may not taste great. “There are tomatoes that come off the vine tasteless, and it doesn’t get better if you process them,” Barringer said. Geography may also be a factor. Our top-ranked tomatoes were grown in California, source of much of the world’s tomatoes, where the dry, hot growing season leads to sweet, complex flavor. The bottom-ranked brands came from the Midwest and Pennsylvania.
How much does the peeling procedure affect flavor? we wondered. Barringer explained that diced tomatoes are peeled either with lye, a caustic chemical, or by exposure to hot steam followed by a drop in pressure, which literally blows the peels off. But the peeling process has little effect on flavor. More important, she explained, is to process ripe tomatoes quickly, before they rot. “This can happen fast in the hot weather,” she noted. Our tasters called some brands “moldy” and “fermented,” reflecting that perhaps processors hadn’t moved fast enough.
After peeling, the tomatoes are machine-diced and canned. The juice is handled separately, heated and treated with calcium chloride (a firming agent), salt, and citric acid (to boost bright flavor and lower pH). The juice is then added to the cans, which are sealed, heat-sterilized, and rapidly cooled to prevent the tomatoes from overcooking. The timing and temperatures of these steps, said our experts, can mean the difference between preserving fresh flavor and boiling it to death.
The additives can also affect quality: We tasted tomatoes that were too sweet or too acidic (from not enough or too much citric acid) or bland from lack of salt. In fact, the tomatoes with the least amount of salt—125mg per serving compared with a chart-topping 310mg in the top-rated brand—ranked last. We encountered tomatoes so unnaturally firm from too much calcium chloride, they were like “chewing on a wet blanket.” Other brands could have used an extra jolt, with fruit so mushy that tasters likened it to “nursing home food.”
Differences in processing and additives (or even tomato variety) could also help explain why our tasters had polar-opposite reactions to products that came from the same company. For example, tasters praised Del Monte Diced Tomatoes for being “firm and meaty” while decrying its sister brand for a “Styrofoam city” tomato texture. A spokesperson from Del Monte confirmed that the tomatoes canned under its various labels (which also include S&W) are “different” but without revealing how. Another lesson from this tasting is that we can’t count on the results to hold up indefinitely. Our experts told us that companies experiment continually with different varieties and processing methods—so that a canned tomato we like this year might not be the same one we like a few years down the road.
For now we can say that two brands stood out for bright, fresh tomato flavor. Our winner boasted a balance of sweet and tart, along with a “beautiful” firm-ripe texture. Our runner-up was a little sweeter, with a slightly less consistent texture. But we won’t wait too many years before tasting diced tomatoes again—just to be sure these two favorites have still got the formula right.