I worked as sous chef in a latin themed restaurant where customer consumption of guacamole had me prepping upwards of 100 avacados daily to make the next days guac. The acid you use can range from tomatoes to vinegars to lemons/limes. Regardless of your preference, it must be added immediately to stave off oxyidzation; the reason guac browns. Simply sealing the guac in a tupperware/rubbermaid container will not stop the oxydization because of the air present in the container http://www.officialbruinsprostore.com/Authentic-Phil-Esposito-Jersey itself. To stop this process, put a piece of cling wrap directly on the surface of the guacamole after it's put in the container, then put the top on. This will keep quac green for days.
The simplest remedy is to cover your prepared Phil Esposito Jersey guacamole tightly with plastic wrap. Make sure to press the plastic wrap tightly against the surface of the guacamole to minimize exposure to air.
Also, consider using Saran Wrap instead of other plastic wraps. Saran Wrap officialbruinsprostore.com/Authentic-Terry-Oreilly-Jersey tends to be a bit more expensive than most other plastic wraps, but it's the only brand made of polyvinylidene, which is less permeable to oxygen than other types of plastic wrap.