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Lettuce – No oil, No point

  |   Food, Science   |   1 Comment

In fast food meals Iceberg lettuce adds structure, texture and a pale flash of contrasting colour. Crisp, green and low in calories it must be good for you, right? Only if you drench it in oil.

Undressed lettuce is fairly pointless, nutritionally speaking.  A quarter of a head of iceberg weighing roughly 100g, contains about 13 calories/53 kJ, at least 95g of water, a little folic acid and some antioxidants and phytochemicals. But not that many.

The American fast food industry has driven the production and development of today’s ubiquitous  iceberg lettuce because

  • It stacks well as there are no real leaves to crush
  • It retains its crispness for a very long time
  • It needs relatively little care or attention which makes it perfect for minimum waged unskilled food prep staff

 

iceberg_b

 

Vindication in my loathing of iceberg lettuce :

I really do not like it. At All. Chiefly because it is has become a filler rather than a food, fooling the fast food eater in to thinking they are getting goodness through salad. It is an imposter in the salad world and I just don’t trust it. Especially when it is bare.

 

 

A 2005 study compared lipophilic (meaning something that has an affinity with oil or fats) antioxidant activity in Baby Head, Romaine and Iceberg lettuce varieties and came down heavily in favour of the leafy, tufty varieties.

 

leafy-lettuce

Courtesy of Suburban Tomato

 

Romaine, or Cos, lettuce has the greatest level of antioxidant activity, probably because lettuces produce a high concentration of lipophilic antioxidants in the outer leaves as a natural protection against light damage. Therefore, lettuce varieties that are bushy and unfettered and reveal their leaves to the sun contain more nutrients. Ones that are developed to be compact and stackable (ahem, ahem iceberg) are less nutritious.

 

caesarsalad

 

It should come as no surprise that Romaine is chef’s choice for Caesar Salad. The leaves are begging to receive all that luxuriously rich dressing in their rich green crenelations so their antioxidants can rush through the oil matrix and start doing you the world of good. Not so your sun-deprived undressed iceberg. Here’s a recipe for the classic Caesar from Dear Martini (the lipids in the anchovies and egg yolks are creating a six-lane super-biovailability highway.)

 

[divider] All about the bioavailability of carotenoids, of course[/divider]

 

Carotenoids –  antioxidants which include lutein, lycopene, beta-carotene and the unpronounceable zeaxanthin – are associated with a reduced risk of several chronic and degenerative diseases such as cancer, cardiovascular disease and macular degeneration. Everyone knows they are present in fresh fruit and vegetables, however it is the intensity of their uptake, or bioavailability, that really matters.

In 2012 a study at Purdue University in Indiana 2 proved that low fat salad dressings are pointless. The study’s chief chap, associate professor of Food Science Mario Ferruzzi, said that:

  • “If you want to utilize more from your fruits and vegetables, you have to pair them correctly with fat-based dressings. If you have a salad with a fat-free dressing, there is a reduction in calories, but you lose some of the benefits of the vegetables.”

 

Olive-Oil-Bottle

 

 

The study looked at the impact of the amount and type of lipids on the absorption of carotenoids. Blood was taken from subjects who had eaten leafy salads with different kinds and quantities of dressings.

The results showed that 20g servings of salad dressing containing monounsaturated fatty-acid rich oils promoted higher carotenoid absorption compared to 3 and 8 g servings of salad dressing.

Monounsaturated oils include sunflower, canola, olive, hazelnut and good news for Australians: Macadamia nut oil which we grow very well3.

However the type of oil you use has less impact on bioavailability than the quantity you use.  So if you have just plucked the leafiest, greenest lettuce from your patch and you only have non-specific salad oil in your pantry, slosh it on. Just remember to put “cold-pressed monounsaturated oils” on your shopping list. And cross off the “reduced fat salad dressing” because now you know better.

 

Here’s how the French do it

The Vinaigrette emulsion of 3 parts oil and 1 part vinegar with salt and pepper to taste is your classic. Do not be scared of it, you don’t have to produce a permenantly stable emulsion, you really can’t be expected to with that ratio. It is meant to be a coating, a thin, mobile sauce. Just remember to dry the leave as the water will repel the emulsion.

Rather than link back to a recipe, here is a snapshot of how the French do it from the Time-Life series of cookery books, 1980, Salads and Cold Hors-d’Oeuvre. Yes, right over the bowl, with no measuring. It is that simple. Never even contemplate bare salad leaves again. Are we agreed? Good.

how-the-french-do-it

 

 

References:

1. Cano, A. and Marinob, A. ” Hydrophilic and Lipophilic Antioxidant Activity in Different Leaves of Three Lettuce Varieties”, International Journal of Food Properties, 2005, Vol.8(3), p.521-528. DOI: 10.1080/10942910500269584

2. Goltz, S.R., Campbell, W.W., Chitchumroonchokchai, C., Failla, M.L. and Ferruzzi, M.G. ” Meal triacylglycerol profile modulates postprandial absorption of carotenoids in humans”, Molecular Nutrition & Food Research, 2012, Vol.56(6), pp.866-877, DOI: 10.1002/mnfr.201100687

3 This is an unsponsored post, however I want to recommend Macadamia oil from MacNuts WA. It is also excellent for frying fish as it has a smoking point of around 2000C.

 

 

 

 

1Comment
  • Liz | Feb 10, 2014 at 16:34

    Love this post. I am a big dressing devotee and now I can eat it with impunity – its clearly doing me good. I have to admit to quite enjoying iceberg lettuce though but I will say that quietly and perhaps no one will hear me. Sadly (or happily depending on how you see it) I can’t see to grow them so I end up mostly eating the loose leaf varieties which grow easily and prolifically in my garden.

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