Pineapple, kiwi and papaya all contain proteolytic enzymes, in other words enzymes capable of breaking down protein molecules. And gelatin, the substance that makes Jell-O gel, is a protein. Gelatin doesn鈥檛 actually occur in nature, it is made from collagen, a protein in great abundance in animal tissues, bones and skin. When bones, hides or hooves are treated with either acid or alkali, the intertwined protein chains that make up collagen unravel and set up the three-dimensional partially cross-linked structure of gelatin. Gelatin dissolves in warm water but as the water cools, the gelatin molecules form a network that traps water, resulting in a gel.
Of course should the gelatin molecules be broken down, no three dimensional array can form and there can be no gelling. Bromolain in pineapple, papain in papaya and actinidin in kiwi are all enzymes capable of breaking down proteins, hence the warning that these fruits cannot be used in Jell-O. But canned fruits are fine because the pasteurization process they undergo destroys the proteolytic enzymes. Interestingly, there is another way to destroy these enzymes. Add chilli pepper to the mix! A chemical in chilli, possibly capsaicin, has the same effect on enzymes as does heat. So you can make pineapple Jell-O with fresh fruit as long as you don鈥檛 mind a little chilli flavour. Probably wouldn鈥檛 go over well with the kids.
While we want to avoid the action of proteolytic enzymes in making gelatin desserts, we welcome this activity when it comes to tenderizing meat. A time-honoured way of softening tough meat is to wrap it in papaya leaves. Papain from the papaya breaks down collagen and softens the meat. Meat can also be tenderized by sprinkling it with a commercial preparation of papain or bromolain or by marinating it in pineapple juice. Of course in this case the pineapple juice cannot be pasteurized. Jell-O is an all American dessert, first patented in 1845 by Peter Cooper but it took some fifty years for this easy 鈥搕o-make dessert to find its way into the hearts of the public. It also found its way into serving dishes on Ellis Island, the entry place for many immigrants into the U.S. The newcomers were served a bowl of Jell-O as an introduction to America. One wonders what they thought of this curious mix of water, sugar, gelatin, adipic acid, artificial flavour, disodium phosphate, sodium citrate, fumaric acid and red dye number 40. Welcome to America!
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