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Green asparagus from the fridge and  from the market are not created equal - at least not when they finally end up on your plate after a short bath in hot water.

You just have to watch one of the consumer report shows on television to hear it: "Frozen veggies are way better than their reputation would suggest." Actually, here in Germany this sentence has been repeated to soften that Ive even heard people say theyd buy the frozen broccoli because it contained "more vitamins and the other good stuff, you know." And you know what? For some veggies like spinach, for example, this may actually be the case. For others, like broccoli or peas, the nutrient status of the frozen and the raw uncooked vegetable appears to be more or less identical (Favell. 1998). But thats something you cannot say for the green asparagus stems, zucchini and green beans in a recent study from the Università degli Studi di Parma in Italy.

I am not an asparagus expert and can still tell that the cell structure of the Transverse  sections boiled (C - from raw | D - from frozen) is profoundly messed up compared to the raw (A) and blanched (B) variety | legend: c = collenchyma; vp = vascular bundle; p = parenchyma; f = fissure.

In the corresponding experiment, the Italian researchers bought Green asparagus stems (Asparagus officinalis L., var. Grande), zucchini (Cucurbita pepo L., va Quine) and green beans (Phaseolus vulgaris L., var. Giamaica) from a local producer and processed them within 24 hours from harvesting. For each of the veggies four samples were prepared: Raw/uncooked  (R), raw/boiled  (B), blanched (BL) and industrially frozen/boiled (FB)

The raw (ten kilograms of each vegetable), blanched (five kilograms of each vegetable) and industrially frozen  samples  (five  kilograms  of  each  vegetable) had been transported were  transported  to  the  University of  Parma laboratories  under  adequate  refrigerated conditions to avoid the exuberant nutrient loss that occurs upon inadequately slow (re-)freezing.
If you "freeze" your veggies in the freezer compartment of your fridge, this will make the cells blast, so that even before they are cooked, and the nutrients flow out. It is generally assume that the latter would not happen, if the veggies are shock-frosted.

Figure 1: Total antioxidant capacity of green asparagus, zucchini and green beans raw, blanched, boiled and frozen and boiled (Paciulli. 2014); as the data tells you frozen veggies with similar  icy grease on them like you see on the right may not really be a better source of antioxidants than fresh veggies from the farmers or even the supermarket.

If we look at the data in Figure 1, though, it would appear that the cells may have "cracked" already so that they are more susceptible to the subsequent heat assault and the frozen + boiled samples end up having consistently lower total antioxidant (Figure 2) and feric acid reducing capacity than their raw + boiled counterparts.

For a similar reason (nutrient retention), the blanched samples have been cooled immediately after blanching in an ice-water bath for 3 min before they have been transported to the laboratories, where their analysis shows that only the Zucchini lost a small, but significant amount of their total antioxidant activity.
References:

• Paciulli, Maria, et al. "Impact of the industrial freezing process on selected vegetables Part I. Structure, texture and antioxidant capacity." Food Research International (2014).

Dont obsess about "optimal" antioxidant contents, just eat your veggies!

Over the past couple of weeks, ... no actually over the past years I have repeatedly written about the concept of (mito-)hormesis and its consequences for the well-established, but not necessarily accurate free radical theory of aging (and for some people everything else). ROS, i.e. reactive oxygen species, have been established as an important signalling molecule that is - among other things - heavily involved in the insulin sensitizing effects of exercise. "Inflammation" makes muscles grow and burns body fat and the "what doesnt kill me makes me strong" principle appears to reign everywhere you look.
That being said, the latest study from the Institute of Health and Environmental Medicine in Tianjin, China, opens another "anti-antioxidant" Box of Pandora. One that puts a huge questionmark behind the implications of hundreds of thousands of scientific studies, when it says in its title, already: "No correlation is found for vegetables between antioxidant capacity and potential benefits in improving antioxidant function in aged rats"

"Skin of Grape Tomatoes Contains Max. Amount of Antioxidants" - You can find this and dozens of other daily updated SuppVersity Science News on www.facebook.com/SuppVersity

This is a title that may in fact change the way we look at study results like those of a recent study by Valdez-Morales, et al. (2014) investigating the "best" = highest antioxidant tomato, the results of which you are about to find among the ~20/day SuppVersity Facebook News @ www.facebook.com/SuppVersity - dont forget to like it, or youll miss out on the latest science news!

If the results of the study can be confirmed by an independent team for vegetables other than lotus root, rape or cucumber and if there is an identical mismatch between the in-vivo anti-oxidant capacity and the potential benefits in improving antioxidant function in (aged) humans.

This would be big and highly consequential news for nutrition experts, scientists and average Joes and Janes like you and me. Why? Well,...

• any ranking of "superfoods" that was based even partly on in vitro data derived with the good old ferric reducing antioxidant power (FRAP) assay would be invalid, ...
• every scientist who has been following up on "promising" data from FRAP assays would have been wasting his time, ...
• and you may have been eating all the wrong foods for years...

... hell no, as long as you ate your veggies over the past years, I wouldnt worry if you may have made a "suboptimal" selection (which would be different based on whatever new criteria you select).

Figure 1: FRAP value, vitamin C and vitamin E content and total amount phenolics in the powdered vegetables that were added to the rodent diets in the study at hand (Ji. 2014)

Honestly, Id hope that you didnt select your foods only based on the orthorexic principle of maximal antioxidant content, anyways. 

Never forget the three principles of veggie eating: Variety, seasonality, colorfulness

Against that background Id recommend you keep eating your lotus roots, if you like them, although, they have a significantly lower beneficial effect on SuperOxide Dismutase (SOD, a group of antioxidant enzymes) than rape and cucumber.

Figure 2: Serum markers of anti-oxidant status / oxidative damage after 6 weeks on the three experimental diets (Ji. 2014)

Moreover, if you look closely at the data in Figure 1+2, you will realize that lotus may suck at SOD and its ability to reduce hemolysis (the destruction of red blood cells), but will have the most profound beneficial effects on the levels of malondealdehyde (MDA), a marker of lipid oxidation, and the amount of plasma carbonyls, which have - just as in cellular regulation, aging, and disease (Levine. 2002). Just like their similarly radical cousins, carbonyls will thus play a dual role so that in the end, their reduction may not be beneficial in each and every case.
Reference: 

• Ji, Linlin, et al. "No correlation is found for vegetables between antioxidant capacity and potential benefits in improving antioxidant function in aged rats." Journal of Clinical Biochemistry and Nutrition 54.3 (2014): 198-203.
• Levine, Rodney L. "Carbonyl modified proteins in cellular regulation, aging, and disease^{2, 3}." Free Radical Biology and Medicine 32.9 (2002): 790-796.
• Valdez-Morales, Maribel, et al. "Phenolic content, and antioxidant and antimutagenic activities in tomato peel and seeds, and tomato by-products." Journal of Agricultural and Food Chemistry (2014). Accepted Manuscript.