Chlorophylls stability

Schwartz, S.J. and Lorenzo, T.V., Chlorophyll stability during continuous aseptic processing and storage, J. Food Sci., 56, 1059, 1991. 

Since Woodward s work on the synthesis of chlorophyll a (60JA3800) it is known that the intrinsic unstable thioformyl moiety can be stabilized by the delocalization effect of heterocyclic systems. Recently the synthesis of 2-amino- and 3-aminothioformylthiophenes (and furans) and the corresponding benzo derivatives (Scheme 19) has been reported (96S1185). These compounds exist as amino tautomers (91S609 96S1185). 

Commercially produced metal-substituted chlorophylls such as copper chlorophylls and copper chlorophyllins that can be obtained by chemical modification of natural chlorophylls have better stability, solubility, and tinctorial strength, but they cannot be considered natural food colorants and will be discussed later. 

A second potential area to be explored may be biochemical encapsulation of chlorophylls to protect and prolong their stability. New techniques of encapsulation produce a milieu capable of quenching active forms of O2 (radicals and 02) that mimic the protective enviromnent of chlorophylls in the thylacoid membranes. 

In recent years, metallo-chlorophylls and metaUo-chlorophyllins have been considered alternatives to their natural chlorophyll counterparts due to their enhanced color potency, and greater stability against moderate heat, dilute acids, and oxidative agents in general, not to mention their alleged biological activities. 

Commercially available stable green metallo-chlorophyU colorants could be produced and in 1984 Segner et al. patented the process to preserve the green color in canned vegetables under the Veri-Green trade name. Some years later, the formation and stability of these complexes were found to be dependent on the type of metal, pH, ionic concentration, temperature, and chlorophyll species — which could explain the unpredictable color changes observed in the beginning. ... 

Kaur, B. and Manjerkar, S.P., Effect of dehydration on the stability of chlorophyll and P-carotene content of green leafy vegetables available in northern India, J. Food Sci. TechnoL (India), 12, 321, 1975. 

The research into the biological activities of chlorophylls developed over the past 20 years is also important although very few in vivo assays concerning then-potential health benefits have been performed. Far fewer studies have focused on chlorophylls in comparison to carotenoids. Efforts to stabilize chlorophylls in pro-... 

Magnesium has its role intimately intertwined with phosphate in many phosphoryl transfer reactions, as Mg-ATP in muscle contraction, in the stabilization of nucleic acid structures as well as in the catalytic activity of ribozymes (catalytic RNA molecules). It also serves as a structural component of enzymes, and is found as the metal centre in chlorophylls, which absorbs light energy in photosynthesis. 

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