How the unique life cycle of your favorite produce affects its flavor and nutrition.
Cruising through the produce section at the grocery store, you may think of the whole foods on display as little more than inert merchandise, no different from all the boxed foods in the center aisles. But the amazing truth is that the kale, cucumbers, apples, and peaches you buy and eat are actually living, breathing entities.
Like other living things, they have quirks and quibbles. They are prone to bumps and bruises. They get injured when they’re mishandled and even pant in the heat. Each has a complex internal chemistry — and a short lifespan.
“Fruits and vegetables are not manufactured, static items,” says Russ Parsons, author of How to Pick a Peach: The Search for Flavor from Farm to Table. “They develop and adapt and age just like the rest of us.”
Indeed, from the beginning of their existence, veggies and fruits change in response to their environments. “Plants react to wind and temperature, soil, and stars,” says biodynamic beekeeper and farmer Gunther Hauk, author of Toward Saving the Honeybee. To illustrate, Hauk explains that seeds sown three days before a full moon have a higher germination rate than seeds sown three days before a new moon.
Left to their own devices, plants will do everything they can to satisfy their basic need for light and water: following the sun with their branches, tilting their leaves to catch rainfall, pushing their roots down and out into the soil in search of nutrients.
Given this special “intelligence,” it shouldn’t be a surprise to discover that how a piece of produce lives its life — how it is raised, nurtured, handled, and marketed — dramatically affects its flavor and nutrient profile. Understanding the inner workings of your favorite veggies and fruits can help you enjoy them while they’re in their prime.
Strength and Vulnerability
Just as we have stem cells that develop into the different cell types needed to support our growth and healing, plants have meristematic cells for the same purpose. Found in meristem tissue, these cells can morph into flowers, fruits, roots, or whatever the plant needs.
“When you remove a tip or shoot, say by pruning, the plant responds by releasing hormones,” says Preston Andrews, PhD, emeritus professor of horticulture at Washington State University. Those plant hormones signal meristem tissue in buds near the pruned site and tell the cells to transform into new shoots or flowers.
Plants also have skeletons, made of cellulose instead of bone. Cellulose can take many forms, from the bell-shaped flesh of a red pepper to a foot-long crunchy stalk of celery. It has a hollow, matrix-like structure that is strong and flexible; this helps plants resist hailstorms and wind gusts.
More importantly, the honeycombed cellulose walls protect delicate fluid-filled vacuoles inside the plants’ cells. Like microscopic piñatas, these vacuoles contain a brew of compounds that give veggies and fruits their flavor, aroma, and color, as well as their antioxidants and phytonutrients.
One of the most vital of these compounds is chlorophyll. Responsible for absorbing sunlight for photosynthesis (and giving plants their colorful hues), the chemical constituents of chlorophyll are similar to the heme structure of hemoglobin in human blood. Once we ingest them, these chemicals act as powerful detoxifiers of our blood and tissues.
Resilient and powerful though these plants are, they can also be vexingly delicate. Plant skin is vulnerable to infection. The smallest nick or puncture wound on the surface can become a festering sore. Yeasts and molds lurking on the surface speed to the cut to feast on whatever juices, sugars, and organic acids leak out.
Cuts on the surface of fruit can also lead to enzymatic browning. Most produce — especially apples, pears, bananas, and artichokes — contain substances that, when exposed to oxygen, change the flesh color to brown. The browning itself doesn’t affect the taste or nutrients, but it does affect a fruit’s commercial appeal.
Surface nicks aren’t a fruit’s only worry. Too much pressure can bruise delicate produce, squashing cell walls and sending fluids flooding into damaged tissue. Unlike bruised human tissue, however, bruised produce flesh doesn’t heal. A blemish on a piece of fruit can accelerate ripening and dehydration, which leads to premature death.
Even vibrations caused by trucking produce to market can be harmful. Vine-ripened tomatoes, for instance, must be carefully packaged to ensure the gel around the seeds isn’t shaken to the point that it falls out of the fruit the moment it’s cut, explains James Gorny, PhD, vice president of food safety and technology for the Produce Marketing Association. He notes that upward of 25 percent of all vegetables and fruits picked in the United States are lost to such damage.
Rough handling doesn’t just make for less-attractive produce; it can also lower its nutrient content. A bruised tomato loses roughly 15 percent of its vitamin C.
The Saga of Ripening
Similar to people, edible plants owe their aging — or ripening — to a surge of hormones. Instead of testosterone and estrogen, plants rely on a powerful hormone called ethylene.
Ethylene triggers cell walls, rigid with cellulose, to soften. It also dissolves pectin, the glue that binds plant cells. Exposed to enough ethylene, a plant’s cell walls become more pliable and permeable. In fruits, this eventually promotes the mingling of compounds that create their juice and soften their skin.
“Ripeness is not a fixed point but a process,” explains Parsons. “It begins with pollinated flowers forming fruit and it ends with rot.”
As fruit ripens, its flavor becomes fuller and more complex; the flesh sweetens as simple sugars and starches (both of which contain glucose) morph into more-complex fructose and sucrose.
Vegetables ripen more slowly than fruit, meaning they live longer and are less fragile. And unlike fruit, a vegetable releases its flavor (and often its smell) only when its cells are crushed — when chewed, diced, or cooked. (See “Optimize Your Onions”.)
Veggies are usually ripe when you buy them, but fruits like apples, bananas, melons, and mangoes are often picked early due to their fragility, which puts the onus on either the seller or the consumer to see them through the last step. The savvier you are about this ripening process, the better you’ll be able to take advantage of the fruit’s peak moments of taste and nutrition — and avoid a soggy, fly-infested fruit bowl.
Fruits that ripen after picking, such as pears, bananas, and tomatoes, are called climacteric; nonclimacteric fruits, such as strawberries, mandarins, and grapes, refuse to ripen after being removed from their parent plants. (For insights on what you can do to ripen and extend the postharvest life of veggies and fruits, see “Protect Your Produce,” below.)
Ripening is a formidable hurdle for growers who want to get their produce to consumers at the height of flavor. Some commercial producers blast their fruit with ethylene gas at the warehouse, forcing it to ripen on demand. That will cause fruit to soften and change color, but it can’t add sugar or any of the other chemicals that add up to a complex flavor, explains Parsons.
“Picked at just the right moment and ripened this way, a tomato can be adequate, but it will never be great.”
Living, Breathing Produce
When so much of the food we buy is packaged in cardboard and plastic, it can be easy to forget that much of it came from living plants.
Empty a package of instant oatmeal into a bowl and try to visualize the graceful stalks of grain that produced it. It’s a stretch. But take one look at a bright-red apple or chubby purplish-black eggplant, and the magnificent transformation of energy from sun to plants to people is undeniable.
Whether you appreciate veggies and fruits for the complex science they represent, the surprising consciousness they embody, or the nutritious and delicious eating experience they deliver, having insight into their secret lives may just help you view them with newfound respect.