Diet Friendly Fast Food

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).