Case Study 2 — The Tomato That Lost Its Smell

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Case Study 2 — The Tomato That Lost Its Smell

"In 1965, a winter tomato in a New Jersey grocery store tasted like a tomato. By 1995, it tasted like wet cardboard. By 2015, you could buy a tomato bred so it didn't bruise in transit but had lost its scent in genome-time."

This case study walks through one of the best-documented examples in food science of a deliberate trade-off in plant breeding — and what it cost. The story matters here because every principle in Chapter 18 (cell structure, pigment chemistry, ripening hormones, flavor volatiles) shows up in how the modern grocery-store tomato was redesigned.

The Original Tomato

Tomatoes (Solanum lycopersicum) are South American — domesticated in the Andes and Mexico thousands of years before European contact, brought to Europe in the 1500s, and slowly accepted as food (early Europeans thought they were poisonous because they're in the nightshade family). By the late 1800s, regional varieties had stabilized: Brandywine, Cherokee Purple, San Marzano, Mortgage Lifter, Black Krim, Beefsteak. Each variety had a profile — sweetness, acidity, aromatic complexity, flesh density, color, season.

A summer tomato in Italy or California or New Jersey through about 1960 was, in the language of this book, a climacteric fruit picked nearly ripe. The pectin in its cell walls had begun to soften (Ch 18). Its volatile aromatic compounds had developed in the last week on the vine — these are the green-leaf aldehydes (hex-2-enal and relatives), the smoke-and-pine notes (β-ionone), the sweet-fruity esters. By the time you cut into it, the cell walls released juice and aroma in proportion.

A summer tomato tasted like itself.

The Engineering Problem

By the 1950s, American grocery chains were transitioning from local-supplier produce to regional and national distribution. A truck of tomatoes from Florida to Boston is a 1,500-mile journey at temperatures and pressures designed for the truck, not the tomato. If you pick a fully-ripe tomato in Florida and put it in that truck, it arrives in Boston as a slurry.

The plant breeders' solution: pick tomatoes green, ripen them with ethylene gas in trucks and warehouses, breed varieties with thicker skins, denser flesh, longer shelf life, and resistance to cold storage. The Florida MH-1 tomato, released in the 1960s, was a paradigm. It was bred for "shippability." The trade-off was flavor.

This wasn't accidental. The breeders knew. The economics of 1960s-2000s food distribution rewarded the trade-off. The grocery chains wanted reliable supply year-round. The flavor cost was a externality borne by the eater.

The Specific Losses

Researchers have catalogued exactly what changed. The flagship study is Klee & Tieman's work at the University of Florida (which is, ironically, the institution that created some of the worst shippability tomatoes — and is now also working on fixing them).

Modern shipping-bred tomatoes have lost about 50% of their volatile aromatic compounds compared to heirloom varieties — including the most "tomatoey" volatiles. The losses include:

Hex-2-enal ("fresh-cut grass" aroma): down significantly.
β-ionone (raspberry/violet): nearly absent.
6-methyl-5-hepten-2-one (sweet-fruity): down.
Methyl salicylate (wintergreen-savory): down.
2-isobutylthiazole (slightly meaty/cooked): down.

What remained: high water content, decent acid, lycopene (the red color), some sucrose. What was lost: the aromatic complexity that made you say "this tomato is amazing."

A 2012 study found that one specific gene, uniform-ripening (u), had been bred into commercial tomatoes for cosmetic reasons (uniform red color across the whole fruit). The u gene also disabled a chloroplast pathway that contributed sugars and aromatic precursors during ripening. Breeders selected for prettiness and accidentally selected for blandness.

The Refrigeration Problem

Even the same tomato variety tastes worse if you refrigerate it. Cold storage at 4°C / 40°F (typical fridge) damages the membranes in tomato cells, releasing enzymes that convert flavor volatiles into compounds that taste off. The volatile compound profile shifts from "tomato" to "mealy." After 7 days at fridge temp, even an heirloom variety has lost most of its peak flavor.

This is why food writers all yell at you to keep tomatoes on the counter. They're right. The chemistry is unforgiving.

The Recovery

Starting in the 2000s, plant breeders started selecting for flavor again. Trinity Hardin's work at the University of Florida focused on returning the lost aromatics through breeding (without GMO techniques — just selection from genetic diversity within the species). The results: varieties like Tasti-Lee and Garden Gem retain better aromatic profiles while remaining commercially viable.

Heirloom varieties, meanwhile, are hugely popular at farmers' markets. The slow-food movement, the locavore movement, and the rise of CSAs all rest, partly, on the recognition that the food-distribution system trades away things eaters notice. The economics changed: people are willing to pay $4/lb for an heirloom Brandywine that costs $1/lb to wholesale-ship as a beefsteak.

Why This Story Matters

This isn't just a tomato story. The same dynamic plays out across the produce aisle: - Strawberries lost flavor as they were bred for shipping density and uniform redness. - Apples were bred for storage (Red Delicious is famously textured-bad now, after decades of selection for shelf-stable color). - Potatoes lost variety as Russet Burbank dominated and other varieties were largely abandoned. - Bananas are at risk because the Cavendish variety is genetically uniform and vulnerable to a fungal disease (Tropical Race 4) that's already killing plantations.

The general lesson: modern food choices were shaped by a 60-year industrial system that valued shipping over flavor. What's been lost was lost in genomes; bringing it back requires intentional breeding programs.

Analyze This

The "u" gene story is bittersweet — breeders selected for one trait (uniform color) and got an unwanted side effect (lost flavor). Identify a non-food example of selecting for one trait and unintentionally losing another. Domestication of dogs? Education-system optimization? Drug discovery?
A modern food system could be designed to prioritize flavor. What barriers exist? Who benefits from the current system? Who would benefit from a flavor-prioritizing one?
You read this case study. You go to the grocery store. Tomatoes from Mexico are $1.99/lb. Local heirloom from a farmers' market are $4/lb. Both are exactly the same calorie content. Which do you buy? Why? What does your choice signal?
From a science-pedagogy perspective, how could this case study be used to teach a high-school chemistry class? What would Pat Hammond do with it?
The solution offered in this case study (slow-food movement, intentional breeding, willingness to pay) is one that depends on consumer-side action and free-market choice. What's a different theory of change? What if every big agriculture company committed to flavor-aware breeding by 2030?