CHLOROPHYLL

Almost everywhere we look in this world, we find green plants. We learned in school that “chlorophyll” makes plants green.  It should therefore be easy to extract a natural green color.  If only it were that simple!  Chlorophyll is a large, complex, ringed molecule.  In the center of the molecule is a magnesium atom.  For the chemists who might be reading this article, the magnesium atom is held in place by an ionic bond, not a covalent bond.  As a result, the magnesium atom is only weakly held in place in the center of the chlorophyll ring.  When the chlorophyll molecule is heated in water, the added thermal energy easily displaces the ionic bond holding the magnesium atom.  The magnesium atom separates from the chlorophyll molecule, thereby creating a new molecule called “pheophytin.”

Chlorophyll (with a magnesium atom) is bright green, but pheophytin (without a magnesium atom) is a dull, drab, olive green.  In time, pheophytin breaks down further and turns muddy brown.  This is how you know you overcooked your vegetables!  They turn brown.  This is also why professional chefs blanch vegetables: they are trying to prevent the magnesium atom from separating from the chlorophyll molecule, leaving their blanched vegetables bright green.  In a restaurant, professional chefs can blanch vegetables.  In a food processing plant however, food technologists do not have such a luxury.  As a result, food technologists searched for many years for a way to preserve the magnesium atom, but to no avail.

Preparation:

There are two major crop sources for chlorophyll: alfalfa in Europe and mulberry in Asia.  Both crops permit the extraction of chlorophyll with its magnesium atom intact.  The crops are dried, ground, and immersed in oil.  Chlorophyll is naturally oil soluble.  A strong alkali is applied to the oil in the presence of copper salts.  This chemical process is known as saponification (or more commonly known as the “soapmaking” process).  Saponification is an exothermic chemical reaction – it creates heat.  The resultant heat separates the magnesium atom from the chlorophyll, making pheophytin.  Pheophytin molecules immediately bond to the copper in solution and become bright green, heat-stable molecules.  Sodium or potassium are next added to further stabilize the new molecule in water.  Water soluble sodium copper chlorophyllin … E141 in the EU ... is produced in this manner.

Application:

In the EU, sodium copper chlorophyllin may be used in foods generally.  It can be found in soups, sauces, and dressings, in hard and soft candies, in ice cream and in pet foods.  In the EU, sodium copper chlorophyllin can also ne found in personal care products such as moisturizers, hand creams, and soaps.  At present (2020), the use of sodium copper chlorophyllin is limited in the US to a “… citrus-based dry beverage mixes in an amount not exceeding 0.2 percent in the dry mix.”  Although this use restriction is very limiting, in the US sodium coper chlorophyllin has also found usage in aloe vera personal care products, pet snacks, mouthwash, and toothpaste.  It is not clear if or when FDA might allow sodium copper chlorophyllin in foods generally.