Icey Techniques: Blanching
Cooking can be seen as a game in which the player has to use different factors, such as time and temperatures to bring each ingredient to its maximum potential.
Several cooking techniques involve ice, for example, to carefully chill stocks and soups.
One technique that includes “playing” not only with heat but also with the cold, is blanching. A widely known technique to prepare vegetables, which leans on the use of ice. But how come, most available information focuses on the hot phase of this cooking process, namely the steaming and boiling temperatures, or the cooking times for each vegetable. These definitely belong to the “need-to-knows” of every kitchen professional.
But how come we oversee the importance of that one key ingredient for this technique: the ice cube. Does it actually make sense to spend a fortune on the best and freshest produce, only to toss it into low-quality ice after boiling?
If you want to know more about how a good ice cube can determine your blanching success, you might want to keep reading…
Why good ice matters...
The bigger, harder, and compact the ice cubes used for the ice bath, the better you can control the temperature. It is these characteristics that determine how quickly the ice melts as soon as steaming hot vegetables are added. It is important to create an environment that can withstand this sudden temperature change to properly halt the cooking process. Counting in the heated ambient temperatures in commercial kitchens, slower melting ice cubes help to maintain an ideal temperature of exactly 0°Celsius. This prevents the ice bath become a lukewarm brew, once the well-drained, but hot vegetables are added’. If you really want to dig into the depth of blanching knowledge, we recommend the following read: Blanching of Foods
What happens behind the cell walls of the vegetable is that a so-called enzyme lipoxygenase (LOX) is inactivated. This enzyme is one of the main factors of “off-taste” development and present in many vegetables. When it comes to taste, there are two main reasons for blanching. One is for taste improvement, for example, to remove certain bitter agents, the other is to retain a certain aroma… In any case, it is crucial to use absolutely tasteless and freshly produced ice, to prevent any type of aroma alteration during the chilling process. One thing to look out for is ice makers that carry the HACCP certificate and are equipped with a filtering mechanism of any sort.
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Vegetables are plant materials that contain pigments, which cause red, green, or purple coloration in fruits or vegetables. The green colour in broccoli, haricots, or brussel sprouts is caused by chlorophyll, while red vegetables, such as carrots contain carotin. Both chlorophyll and carotin are sensitive to heat, quickly breaking down during the heating process. The destruction of these pigments during food preparation can be halted by controlling the temperature within the vegetable, for example by quick-chilling these in a bath full of quality ice. It is important to keep an eye on the size and the ice-to-water ratio of an ice bath. The vessel needs to be big enough to accommodate freely moving vegetables within the ice-cold water, to avoid dents and pressure points, which can cause brown spots.
This is where the correct timings of both cooking and cooling come into play. Depending on the structure, size, colour, sweet and bitter agents, different vegetables require certain boiling or steaming times and temperatures. In an ideal situation, the texture is only affected by the cooking process to the point it is pleasantly chewable and digestible. Missing this point will cause the destruction of cell structures, and the outer layer of the vegetable will start breaking up, taking in too much water, and becoming unpleasantly soft.
The Nutritional Content
In most cases, the nutritional value of plant produce is highest, right after harvest and when it remains unmanipulated. However, some greens, such as beans require heat treatment for safe consumption. Recent research also shows that some bioactive compounds in vegetables can be unlocked and made bioavailable through thermal (steam) blanching. This is caused by the destruction of cell walls and tissue structures, as soon as the vegetable is exposed to heat.