Because of my poor English, I'm not sure about what do you mean with "blanching"...maybe you plunge for few seconds in boiling water the basil leaves?
If so, I'm doubtful about this procedure. Green pesto gets its flavour and taste mainly from the absolute freshness and good quality of the basil it's made with. You're supposed to wash it the less you can and to drain it until perfecly dry before processing in the blender (or, better, into a mortar). Basil ends up in nothing when cooked, and all its flavour goes away...
To preserve the brilliant green color of the fresh leaves, the best way is adding to it some grains of cooking salt while processing. This is the procedure traditionally used by the Ligurian housewives.
Hope this helps!
Blanching basil leaves is a successful technique used by many chefs and food stylists. It does a very good job of maintaining the bright green color and also stablizing the flavor. You must, however, only blanch the leaves for 1-2 seconds AT THE MOST! In and out of boiling water, then plunge into cold water (not iced). Ice water will, most assuredly, turn the leaves black. I've had great results when making pesto with the end of the season plants growing in my garden.
Sorry to say...but I'm still doubtful. I live in the Country of Pesto, have made pesto many times, know lots of people making their own pesto and have read lots of recipes, but have never heard about anyone plunging the basil leaves in hot water to "stabilize" the flavour. Maybe the American basil, which is pretty different from the Ligurian one, requires this procedure...but our basil has a wonderful, intense flavour that doesn't need to be stabilized in any way, only it must be preserved from any damaging procedure before using for pesto.
As for the brilliant color, I'm not a "food stylist" and don't care too much about this point, but as far as I know the cooking salt technique I quoted above is effective enough.
That's a good question; is the Italian (Ligurian) basil different from our domestic variety?
I know that ours varies in flavor depending on the growing season (early, middle, late) and the green house basil sold in winter is different again.
I do not blanch the basil. In the processor with the garlic, pine nuts and S/P. It doesn't last long enough to loose it's color.
I had no intention of insulting you Pongi, only to offer a functional answer to the original question posed by 9hundred. I have found no drawbacks to making pesto with this technique.
There are many varieties of basil available here in the US---from the stalky, large leafed variety popular with Italian cooks to smaller, more delicate leafed bush basil and Thai basil. I've used this technique with all these varieties. Blanching the leaves as I described in my previous post (1-2 seconds only!) just wilts the leaves. You will find that the blanching water takes on very little color. The essential oils (or flavor agents) and the chlorphyll are locked within the leaves and thus remain stable throughout continued processing. The color and flavor will then hold up to chopping, cooking (which usually turns fresh basil black), encorporating into baked goods like pastry dough, and freezing of basil pesto. If you do not blanch the basil when making pesto, with in a day or two, it will invariably turn a greyish-green color and loose it's bright flavor due to oxydation. Salt or no salt, oxydation will happen.
I learned the technique from Tom Colicchio, chef of Gramercy Tavern and Craft here in NYC. If there was ever a fussy chef regarding maintaining the flavor profile of any ingredient, it would be Tom.
Give it a try, you'll be happy with the results.
Don't worry foodnfoto...I don't feel insulted, only love to discuss and have a "hot" temper...mainly when you speak about something I've grown up with! Do you remember the thread about the originality of recipes? Well...when speaking about Pesto, I am just "the native"!
As for basil, we have also had a thread about this point here one month ago and you can check it for more information. Briefly, the basil I have tasted in US is completely different from ours, both for the shape and texture of the leaves (which are much more hard and crunchy) and for the taste, which is too aromatic and mint-like for my italian palate. This is not only due to the different varieties (in Italy we have basically two edible basils, the "Ligurian" and the "Neapolitan") but also to the environment where basil is grown. The Italian Riviera has an unique environment due to its weather and soil, and the basil which grows here is also unique-I'm not saying it's necessarily THE BEST, but it's the one Ligurian Pesto was born with, and it's the only one the Italian Pesto producers use (I mean that you cannot use, in example, the Neapolitan Basil).
Being the american basil so different, probably the blanching procedure is necessary to give it a flavour and a texture more similar to ligurian basil and make it suitable for pesto...
Apart from that, I'd like to add just a couple of things:
The first way to prevent basil oxidation is to avoid the use of blades. Basil should be NEVER chopped with a knife or a food processor, because the contact with a metal makes it immediately oxidyze and change its taste. This is the reason why all the Pesto recipes recommend the use of the mortar. Of course, nowadays also in Italy most people use the food processor to spare time...but you must know that it's wrong and that your pesto cannot be the best.
When ready and put into the jar, pesto is covered with olive oil just to prevent oxidation. To my experience, freezing does not alter significatively its features, unless you keep it into the freezer for many months. I always freeze my pesto with good results. As for cooking...why do you want to cook Pesto? Apart from Baked Lasagne, pesto is supposed to be added raw to any dish...
More, I hope YOU don't feel insulted if I add another consideration. I don't want to generalize, but I had an american Pesto ( in a renowned Italian restaurant in SF) and it did not resemble to our Pesto more than I resemble to Claudia Schiffer. I don't say it wasn't good...but it was not Pesto, it was something else, an American style basil sauce. To tell the truth, I must say that it has been often the same when I tried to eat Pesto here in Italy, but out of Liguria. You also may have the same problem with commercially available Italian pestos, which are sometimes full of odd ingredients (parsley-nuts-butter-spinach and so on) which aren't included into the original recipe (which I posted in January under a thread called "Ligurian Pasta Sauces"). This is the reason why Pesto producers are asking for the "Denominazione d'Origine Controllata" (sorry for the Italian but I can't translate this) for the Ligurian Pesto.
Finally...I must apologize for my "hot" and talkative defense! I hope nobody has felt insulted from my point of view...if so, please forgive me! Like Americans, sometimes also we Mediterraneans can be good patriots!
Oh...I forgot to say something. As you can imagine, I'll keep on making Pesto as I've always done, but I'll also be glad to try blanching basil for other purposes. All considered, also here in Genoa basil doesn't mean only Pesto, and I'm sure that foodnfoto advice will work great also with Italian recipes!