Acid Neutralization to Retain Chlorophyll
The addition of alkalizing agents to canned green vegetables can result in improved retention of
chlorophylls during processing. Techniques have involved the addition of calcium oxide and sodium
dihydrogen phosphate in blanch water to maintain product pH or to raise the pH to 7.0. Magnesium
carbonate or sodium carbonate in combination with sodium phosphate has been tested for this
purpose. However, all of these treatments result in softening of the tissue and an “alkaline” flavor.
Blair [10] in 1940 recognized the toughening effect of calcium and magnesium when added to
vegetables. This observation led to the use of calcium or magnesium hydroxide for the purpose of
raising pH and maintaining texture. This combination of treatments became known as the “Blair
process.” Commercial application of these processes has not been successful because of the inability
of the alkalizing agents to effectively neutralize interior tissue acids over a long period of time,
resulting in substantial color loss after less than 2 months of storage.