Fresh, homemade guacamole is free of color-preserving chemicals.
Ask multiple cooks keep guacamole from turning brown and you are likely to get multiple answers. But conquering the tricky culinary problem requires understanding the science behind the chemical reaction that causes the color change. Enzymatic browning occurs naturally when the internal cells of certain produce are exposed to oxygen. The enzyme, polyphenoloxidase, reacts by forming melanins or brown pigments on the flesh. But home chefs can control the color change by reducing the exposure to oxygen and changing the pH level of the dip by adding citric acid.
Instructions
1. Assemble the ingredients for your favorite guacamole recipe. Juice a fresh lime or measure about 2 tbsp. of bottled lime juice into a bowl. Slice and pit the avocado. Scoop the flesh from the skin and place it into the juice, coating each piece. Chop and prepare all the other ingredients.
2. Drain the lime juice off the avocado and set aside, and mash the pieces with a potato masher. Add the other ingredients according to your recipe. Add 1 tbsp. of lime juice and mix well. The citric acid in the lime juice lowers the pH of the guacamole, as the polyphenoloxidase works ideally in a pH environment of 5.0 to 7.0. The lime juice, with a pH of under 3.0, lowers the overall level and slows the browning.
3. Cover the guacamole with a sheet of plastic wrap. Press the wrap against the surface of the dip. Do not simply cover the bowl - air should not be able to touch the guacamole.
4. Store the guacamole in the refrigerator until ready to serve. Allow the dip to come to room temperature before serving to enhance the flavors, but do not uncover it until the last minute. Promptly refrigerate unused portions.
Tags: lime juice, citric acid, color change, other ingredients