Purple Bowtie Pasta
Simmer chopped red cabbage in water for 8 minutes, lift the cabbage out, then boil bowtie pasta in that violet water. The anthocyanin pigment from the cabbage dyes the pasta purple with no food coloring at all. Add lemon and it turns pink, add baking soda and it turns blue-green. Serves 4 in about 20 minutes of cooking.
Our daughter went through a stretch of eating nothing green, nothing leafy and nothing that looked like a vegetable. Purple pasta got past all three rules, mostly because she watched the water change color in the pot.
This is a real recipe, not a novelty. The cabbage goes into the sauce too, chopped small enough that it cannot be picked out.
How does red cabbage turn pasta purple?
Red cabbage gets its color from anthocyanins, water-soluble pigments in the same family that colors blueberries, black grapes and jamun. They dissolve readily into hot water, so a few minutes of simmering pulls a deep violet out of the leaves, and they survive heat better than most natural pigments, so the color does not cook away.
Boil pasta in that water and the starch on its surface swells, taking the pigment with it. No dye, no beet powder, nothing from a bottle.
Why does the color change with lemon or baking soda?
Anthocyanins are a pH indicator. The molecule changes shape depending on how acidic or alkaline its surroundings are, and each shape reflects a different color. It is a standard first chemistry demonstration.
| What you add | Roughly | Color you get |
|---|---|---|
| Lemon juice or vinegar | Strongly acidic, pH 2 to 3 | Bright pink to red |
| Nothing | Mildly acidic, around pH 5 | Purple, as in the raw cabbage |
| Plain tap water | Near neutral, pH 7 to 8 | Violet drifting toward blue |
| Baking soda | Alkaline, pH 8 and up | Blue, then teal, then yellow-green |
The demonstration takes two minutes and children remember it. Pour the purple water into three clear glasses: leave one alone, squeeze lemon into the second, stir a pinch of baking soda into the third. Three colors, one pot.
Do not drink the baking soda glass, and do not put baking soda into the pasta water itself. Alkaline water makes pasta slippery and faintly soapy.
Ingredients
Serves 4. Prep 8 minutes, cook 20 minutes, total 28 minutes.
For the purple water
- 1/2 medium head red cabbage, about 12 oz (340 g), roughly chopped
- 8 cups water
- 1 tbsp salt, added after the cabbage comes out
For the pasta and sauce
- 12 oz (340 g) farfalle (bowtie pasta)
- 2 cups finely chopped red cabbage, about 5 oz (140 g), from the other half of the head
- 3 tbsp butter, or olive oil
- 2 cloves garlic, minced
- 1/2 tsp salt
- 1/4 tsp black pepper
- 1/2 cup grated parmesan, plus more to serve
- 1/2 cup reserved pasta water
- Optional: 1 lemon, cut into wedges
- Optional: 1/4 tsp chilli flakes
Method
- Make the color (8 minutes). Put the roughly chopped cabbage in a large pot with the water. Boil, then simmer 8 minutes, until deep violet. Do not salt it yet.
- Lift the cabbage out with a slotted spoon, or strain and return the water to the pot. Now add the 1 tbsp salt.
- Boil the pasta (11 minutes). Bring the purple water back to a rolling boil and cook the farfalle al dente, 10 to 11 minutes. Reserve 1/2 cup of the water, then drain. Do not rinse, which washes the color off.
- Make the sauce (while the pasta boils). Melt the butter in a wide pan over medium heat. Add the garlic, cook 30 seconds, then add the finely chopped raw cabbage, salt, pepper and chilli flakes. Cook 5 to 6 minutes until softened and shrunk by half.
- Bring it together. Tip the drained pasta into the pan. Add the reserved water and the parmesan and toss over low heat 1 to 2 minutes, until the sauce coats every bowtie. Serve with more parmesan and a lemon wedge.
Yield: about 6 cups, roughly 1.5 cups per person.
How does the color actually behave?
- It is strongest the moment you drain it, then dulls to grey-lavender as it cools
- Butter and cheese keep it purple, being close to neutral
- Tomato sauce kills it. Acid turns the pasta a muddy magenta-brown. Serve it on the side
- Lemon on the plate turns it pink. Give each person a wedge and let them watch their own bowl change
- It stains wooden spoons, plastic colanders, light grout and white shirts. Use metal or glass and wipe spills immediately
- Reheated leftovers look duller but taste the same
The kitchen will smell of cabbage while the water simmers. Eight minutes gives full color and keeps that mild, since sulfur notes build the longer it boils.
How do you get picky kids to actually eat the cabbage?
The color gets the bowl accepted. The chopping decides whether the vegetable gets eaten.
- Chop it fine. Long shreds get wound onto a fork and set aside. Anything smaller than a bowtie disappears into the sauce
- Cook it soft, not crisp. Crunch is what a child objects to
- Let them run the experiment. A child who explained the color to someone else is invested in eating it
- Keep the sauce familiar. Butter, garlic and parmesan is a flavor they already trust. One new thing at a time, and here it is the color
In our house it goes on the table with whatever else is being served, and chilli flakes on the adult bowls make it dinner rather than a kids’ plate. Ghee instead of butter works too.
Frequently asked questions
Will the pasta taste like cabbage?
Faintly, and less than you expect. Eight minutes pulls out mostly pigment, and the butter, garlic and parmesan sit on top. The chopped cabbage in the sauce is the stronger flavor, and it cooks down sweet rather than sharp.
Can I use a different pasta shape?
Yes. Farfalle, fusilli and penne all hold color well. Whole wheat starts brown and ends dull maroon, so use white pasta if color is the point.
Can I make the purple water ahead of time?
Yes. Strain it into a sealed jar and refrigerate up to 3 days. Bring it back to a full boil, salt it, and cook the pasta as usual. A day ahead turns a 28 minute dinner into a 15 minute one.
Is red cabbage water safe for children to play with?
The plain water and the lemon glass are just food. Keep the baking soda out of mouths, since a spoonful is unpleasant to swallow. Treat the glasses as something to look at, not drink, and rinse hands afterward.
Why did my pasta come out blue instead of purple?
Your tap water is slightly alkaline, common with hard water, and harmless. For a warmer violet, add a teaspoon of lemon juice before the pasta goes in. If you like the blue, leave it, since blue food is rare and children find it more interesting.
Does this work with green cabbage?
No. Green cabbage has no anthocyanin, so the water stays pale yellow. You need red or purple cabbage. Butterfly pea flower behaves the same way if you come across it.
