layer of oil (as in a vinaigrette) or butter Old Tricks for Green Vegetables Cooks had worked out the practical chemistry of chlorophyll long before it had a name The Roman recipe collection of Apicius advises, “omne holus smaragdinum fit, si cum nitro coquatur ” “All green vegetables will be made emerald colored, if they are cooked with nitrum.” Nitrum was a natural soda, and alkaline like our baking soda In her English cookbook of 1751, Hannah Glasse directed readers to “Boil all your Greens in a Copper Saucepan by themselves, with a great Quantity of Water Use no iron pans, etc., for they are not proper; but let them be Copper, Brass, or Silver.” Cookbooks of the early 19th century suggest cooking vegetables and making cucumber pickles with a copper ha’penny coin thrown in to improve the color All of these practices survived in some form until the beginning of the 20th century, though Sweden outlawed the use of copper cooking pots in its armed services in the 18th century due to the toxicity of copper in large, cumulative doses And “Tabitha Tickletooth” wrote in The Dinner Question (1860): “Never, under any circumstances, unless you wish entirely to destroy all flavor, and reduce your peas to pulp, boil them with soda This favorite atrocity of the English kitchen cannot be too strongly condemned.” Red-Purple Anthocyanins and Pale Anthoxanthins The usually reddish anthocyanins and their pale yellow cousins, the anthoxanthins, are chlorophyll’s opposites They’re naturally water-soluble, so they always bleed into the cooking water They too are sensitive to pH and to the presence of metal ions, but acidity is good for them, metals bad And where chlorophyll just ... opposites They’re naturally water-soluble, so they always bleed into the cooking water They too are sensitive to pH and to the presence of metal ions, but acidity is good for them, metals bad And where chlorophyll just... until the beginning of the 20th century, though Sweden outlawed the use of copper cooking pots in its armed services in the 18th century due to the toxicity of copper in large, cumulative doses And “Tabitha Tickletooth” wrote in... atrocity of the English kitchen cannot be too strongly condemned.” Red-Purple Anthocyanins and Pale Anthoxanthins The usually reddish anthocyanins and their pale yellow cousins, the anthoxanthins, are chlorophyll’s