We’ve all had those green vegetables served to us that looked like they’ve died a thousand deaths. Drab olive army green. A color that’s perfect if you’re trying to camouflage yourself, but not so pleasant on a dinner plate. Which brings us to the obvious question…what can you do to make and keep your green vegetables a bright beautiful green?
Chlorophyl: The Color Green
The green and green-blue tones that we find in our fruits and vegetables come from Chlorophyl, the pigment that enables plants to absorb energy to build tissues. There are two types of chlorophyl:
- Chlorophyl – a: Bright blue-greens, typical in items like broccoli.
- Chlorophyl – b: muted olive-green found in items like artichokes, broccoli stems, older vegetables.
As plants ripen and mature, chlorophyl levels decrease because of oxidation As a result, other pigments are revealed. This is why peppers turn red, orange, yellow, etc. as they ripen from green, and why tomatoes go from green to red.
When Things Go Badly
Chlorophyl is the most fragile and water soluble of all pigments. Cooking some vegetables enough to soften without killing the color can be a challenge. When green vegetables are boiled or blanched, cell walls burst and oxygen inside is released. The release of oxygen bubbles is what makes the green color appear more intense. Oxygen in the cells blocks the full color of the chlorophyl.
Too much heat will cause a magnesium ion at the center of the cells to be replaced by a hydrogen atom (present in all acids). This is the cause of the drab brown-green color. This usually happens when boiling and blanching vegetables because they are submerged directly in water where there’s an abundance of hydrogen.
Recipe Suggestion: Green Onion & Parsley Grits
To Keep Greens Bright Pay Attention to Time, Temperature, and Acidic Conditions:
Time & Temperature:
- Chlorophyl loses its bright green color after about 7 minutes of cooking. Cut sturdier vegetables into smaller pieces so they cook within this time.
- Cook quickly with high heat. Roast vegetables around 425-450 degrees (400-425 convection) for a short time.
- When roasting vegetables, cut and toss with seasonings (salt, pepper, etc.) and oil and let sit on baking sheet for 30 minutes before roasting. Salt draws moisture out of the cell walls and the high heat will help them to steam-roast. Steam will help keep the temperature low enough to not brown the vegetables while the high heat softens the pectin and lignin fibers to soften the structure of the vegetable.
- Heavily salting water for blanching green vegetables also speeds up cooking. Sodium ions replace calcium ions which are responsible for sturdiness in cell walls.
- When boiling, par-cook a short time in a large volume of rapidly boiling water without a lid. Lids trap steam which contains acids that have entered the water from the vegetables.
Acid is the Enemy:
- DO NOT add baking soda to water. In the past, many cooks espoused adding baking soda to water to create a more alkaline condition for boiling vegetables. While acidity is reduced, it quickly breaks down cell walls resulting in a soft mushy texture and flat flavor.
- Don’t cover green vegetables tightly when keeping them warm. Condensation contains ascorbic acid from the vegetables themselves and forms on the cover. The acidic nature of the condensation affects the color of pigments as it drips back on to the vegetables. Instead, leave a corner or edge cracked open for steam to escape.
- When tossing green vegetables with dressings, leave them raw if they’re tender enough. The cells will be sturdier and stand up better to the effect of the acid. They will remain a brighter color longer (just not as bright as if they’d been blanched).
- Toss green vegetables with acidic elements at the very last minute. The less time they are in contact with the dressing, let longer they’ll stay bright.
- Instead of using lemon juice on asparagus and broccoli, use lemon zest alone. Lemon zest supplies a bright pop of lemon flavor without acid.