Bread Flower

Nasturtium Loaf

This is a 100% whole wheat loaf, made with nasturtiums (Tropaeolum majus) from my garden.

The idea of eating a flower is strange for a lot of folks who have been taught since childhood to avoid them.  But violets, nasturtiums and marigolds have long been used in salads.  Nasturtiums have a nice peppery taste when you chew on the leaves and flowers, so they lend an interesting spice to a salad, or when I'm just wandering through the garden to get some vegetables.  We like to plant them every year, they are easy to grow and they look nice.  If you don't use them, however, they can get fairly weedy.  At this time of season, they are in fact getting a bit out of hand, in some cases climbing out of their beds, and over the lawn, making for new land to conquer.  They walked across a path, and beneath our grape vines and climbed all over a certain variety of heirloom tomatoes that I had neglected.

I picked a few nasturtiums for a bread.  I've used nasturtiums before, most recently in Lou Preston's Garden Tomato bread, and I thought I could taste them there, but in those loaves I also had other garden ingredients.  This time, the nasturtiums had to carry the day, so I picked 50 flowers and 50 leaves.  That didn't even begin to put a dint in our crop.  The total weight of the flowers, leaves, ants and earwigs was 136g (prior to my washing it).

You've got to watch those earwigs.  They like to hide in the flowers.  Rather disconcerting if you slice into your bread and find half an earwig.  It could happen.

I chopped the leaves coarsely, but left the flowers whole, and just kneaded them into the dough at the same time I added salt and the final 50g of water.  Very pretty.  Didn't seem to effect the properties of the dough too much, I was still able to do a full set of stretch and folds, in the Tartine style.  I took this bread to 77% hydration, and it worked nicely.

• 1000g ww flour
• 720g + 50g water
• 20g salt
• 50g wheat germ
• 136g nasturtium flowers (50 flowers & 50 leaves) 

About nasturtiums

The complexity of the pathway by which various plants synthesize mustard oils has suggested to plant biologists and geneticists that they share a common evolutionary ancestor, and are thus related.  The taxonomy debate is as hot as mustard, but if the evolutionary argument holds, nasturtiums belong to the mustard family of plants, Brassicaceae, and are thus related to plants as diverse as broccoli, brussel sprouts, cabbages and papaya.

A number of web sites have some info on nasturtium nutrition, but I don't really trust all of them.  You have to be careful, because some of the info seems to be quoting studies about watercress (which is Nasturtium official), and sometimes its about horseradish (Nasturtium armoracia).

This nasturtium is out-of-hand, climbing up over my neglected tomatoes

The flower and leaves and seeds and root of the garden plant nasturtium are edible, and Barnes PDR for Herbal Medicines seems to think it is fairly benign.  The plant parts have antioxidant properties: they contain Vitamin C, and oxalic acid.  It also contains spilanthol, glucosinolates*, volatile oils, flavonoids, carotenoids, and it is loaded with enzymes (some of them unique to the plant's own specific peptides; nasturtium has drawn curious scientists for its levels of myrosin, an enzyme that hydrolyzes the glucosinolate sinigrin, also found in cabbage, which has received some favourable press recently due to its anti-cancer properties).  In "The Art of Fermentation," Sandor Katz recommends the use of nasturtium leaves in some of his vegetable fermentation recipes, both as a spicy addition, and because of its anti-molding properties.  The anti-bacterial nature of the leaves has long been recognized, and the plant has been used effectively in herbal remedies to expel phlegm, and improve sinusitis. Its use against sinusitis, respiratory inflammation, and urinary tract infection, has been studied, its antibiotic and antiviral efficacy conjectured.  The seeds have been used as a purgative.  The plant has folk-uses, and since 1684 when it was first brought to France, folk medicine has used it as a remedy for the flu.

Kintzios and Barberaki (Plants that fight cancer) say that benzyl glucosinolate from nasturtium, when it undergoes hydrolysis via enzymes creates BITC (benzyl isothiocyanate) which destroys several different kinds of cancer cells, at least in vitro.

The confectionary industry has taken an interest in nasturtium seeds as a source of nasturtium's xyloglucans, which can be developed into new edible gums and gels (similar to the way pectin is used).

But some (Carlson, K., and Keiman, R. (1993) Chemical Survey and erucic acid content of commercial varieties of nasturtium, Tropaeolum magus L., JAOCS, 70(11). pp. 1145 - 1148) have proposed that nasturtiums could be farmed on an industrial scale to harvest its erucic acid, the same way rapeseed and mustard are.  This sort of oil is not generally used for human ingestion, but more for lubricating, emulsifying, plasticizing, coating, and as an ingredient in rubber -- on an industrial scale.

Just to put this into perspective: when some studies with rats found erucic acid to be toxic, plant growers rushed to create a rapeseed with much less of it, so the negative study wouldn't affect the sales of their oil.  They called the new plant based on rapeseed canola:  so, canola has less than 2% erucic acid in its oil, and is considered edible, but rapeseed grown for industrial uses still contain 45-50% of erucic acid in the total oil of the seed.  Here's the kicker: nasturtium contains about 80% erucic acid in the oil of its seed.  The seeds are often eaten in recipes that otherwise might use capers or peppercorns.  I haven't been able to find out how much erucic acid (if any) remains in the flower and leaves, which are more commonly eaten. 

Erucic acid is an omega-9 monounsaturated fat, and it is said to lower blood platelet counts and morphology of the platelets themselves.  Furthermore, some studies consider high levels of erucic acid  dangerous because it tends to pile up in heart tissue.  Apparently animal studies suggest one would need high levels of it for this to happen.  Still, its use is generally discouraged, and laws are set up to limit the amount of it you should eat -- especially for children and pregnant women.**   

(Kitts, Toxicity and Safety of Fats and Oils).

While he reports some dangers for mustard oil from the black mustard plant, including skin irritation, possible ulcers, goiter and nephrosis, James Duke the author of "Handbook of Medicinal Herbs (2002) seems to poo-poo the idea that nasturtium's mustard oil content is dangerous.  

That's what I've learned about nasturtiums.  You can eat it in your salad, crush the seed into mustard, or preserve that seed in vinegar like capers -- or you can use leaves and flowers in your bread like I've done here.  I suppose in the small amounts I've used here, any negative effects are going to be small indeed.  But I think you should still be aware that the seed at least contains erucic acid and of course triglycerides.  In the small amounts humans would ingest, I don't see a problem, but it never hurts to know more (Harlow R. et al. (1996) "Gas-liquid chromatography of triglycerides from erucic acid oils and fish oils" Lipids 1(3). pp 216-20). 

Bread Results

A nice loaf, but not as peppery as I'd imagined it would be.  The crumb is colourful, but would be much more colourful in a white bread, i.e. if it wasn't a whole grain bread.

Of course, I'm not going there.

Once in a while, it is nice to have a nasturtium loaf.  I wouldn't want it all the time.

Notes to Myself

• * Glucosinolates are compounds comprised of nitrogen, and sulphur bound to glucose, and linked to oxygen.  Many predator insect species consider the resultant volatile oils a deterrent.  Gardeners have noted that it keeps greenfly under control, and grown at the trunk of fruit trees, it deters aphis.  Some organic gardeners will grind up nasturtiums and spray it on leaves, too.
• ** More on erucic acid:  Curiously, part of the metabolic pathway for other omega-9 fats (oleic acid, for example) may lead to the creation of erucic acid internally.  When oleic acid is elongated by the elongase enzyme it will eventually metabolize to erucic acid.  (Enig, M. (2000) Know your fats: the complete primer for understanding the nutrition of fats, oils and cholesterol)
• Apparently "nasturtium" refers to the way the taste twists your nose.
• Why not just use pepper in a loaf?  Well, because pepper is a carcinogen.