Tuesday, March 2, 2010

Green Tomato Sauce

Once again I have a have a pile of unripe green tomatoes. All different varieties, in various states of perfection.

Green tomato sauce.

The concept is simple, the same basic method and recipe as for an ordinary home-made tomato sauce (or any chutney really): fruit, vinegar, sugar, spices. Cook.

What I wanted, desperately, was an iridescent green sauce, vibrant and neon. A sauce that does justice to the fresh tartness of the tomatoes. That invokes green fruit on green vines. A green colour that is dripping with the adjective ‘piquant’.

The sauce tastes beautiful – spicy and tangy with a strong sweet flavour just off-set by the bitterness of the unripe capsicums and tomato. But to my surprise, as the sauce cooked down, it gradually changed colour from the bright and dark greens of the fresh fruit to a murky military greenish khaki.


I have a couple of theories.

1 – The toffee theory

This sauce basically relies on cooking fruit for a long time with added sugar – ie, a kind of chunky sophisticated caramel. In other caramel culinary adventures I have observed that when heated sugar tends to darken in colour, achieving a certain toffee-like colour.

I felt this theory had some persuasive elements, but not enough to explain the whole phenomenon... Back to the lab.

2 – The chlorophyll theory.

Basically, plants, particularly the leafy part of plants, produce chlorophyll.* Chlorophyll is what makes the green part of plants green. And it is present in green (ie, unripe) fruits – like tomatoes and capsicums, as well as in green leafy vegetables and herbs such as spinach and parsley.

When you cook leafy greens (peas or beans, for example) too long they go grey. This is because something in the heating process starts to leech the chlorophyll out of the plant (actually what happens is that the heating somehow removes magnesium from the cells and replaces it with hydrogen, and the chlorophyll changes into something called pheophytin, molecularly speaking). Interestingly, this process also occurs during exposure to acid – ie vinegar.

So – observe: simmering green tomatoes and capsicum in vinegar for 2 hours. A change in colour.

Could the combination of vinegar and heat be responsible? I think yes.

I understand that practitioners of the dark arts of molecular gastronomy and food technology play with chlorophyll, using extracted essence of green to both flavour and colour foods. Theoretically I could use a kind of chlorophyll extract to ‘restore’ the green colour to my sauce.

But I think I’ll leave it the way it is. I think a sleight of hand to give a semblance of the colour these tomatoes once were wouldn’t do justice to them. My sauce is an icky brown colour because that is what happens when you turn home-grown mismatched tomatoes into spicy sticky sauce.

* Amazingly, chlorophyll enables plants to convert sunlight into food – that is the plant is able to turn the energy present in waves of light into useful energy for growth. The extra cool part? Light is technically like a rainbow – all different colours. Plants only ‘eat’ a certain part of the rainbow – the green part (or it could be the blue and yellow parts ... it’s all a bit tricky ...).

Green Tomato Sauce

1.5 kg green tomatoes, chopped (for ordinary tomato sauce, use ripe red tomatoes)
200 g chillies, chopped
3 brown onions, finely chopped
3 green capsicum, finely chopped (use red ones if making red sauce!)
6 cloves garlic, chopped
2 cups sugar
2 cups white vinegar
½ tsp fennel seeds
½ tsp mustard seeds
½ caraway seeds
1 teaspoon ground nutmeg
1 teaspoon cloves, whole
Sea salt to taste
In a large pot, bring chopped tomatoes to the boil, simmer until starting to soften and collapse, about 10 minutes. Add the chopped chilli, capsicum and onion and simmer until soft.
Add ¾ of the sugar and all the vinegar and bring to a simmer for another 10 minutes. Taste – if too sharp or too powerfully vinegary, add remaining sugar.

Then add the spices and simmer gently for a couple of hours until it thickens.

Cool, puree with a bar mix and strain through a sieve.

Bottle and refrigerate (keeps about 1 month).

Eat with cheese, cured meats, barbequed sausages, hamburgers or poached eggs.

1 comment:

  1. I lean toward your chlorophyll hypothesis.

    Since you're using homegrown tomatoes, show off your dish in our "Grow Your Own" roundup this month. To participate, find the details here: