"Using leftover marinades
It seems a shame to discard that flavorful mixture, but do not be tempted to reuse leftover marinade without first cooking it. During the contact with raw foods, the marinade most likely has picked up harmful bacteria that could make you very ill. For the same reason, it's wise to cook leftover marinade before using it to baste with.
Frugal cooks can put the leftover marinade to use as a sauce, but it must first be boiled for five minutes to destroy any harmful bacteria. Of course, this boiling process will render it useless as a tenderizing marinade, but it can still impart some flavor as a sauce. Alkalines leaked from the first marinated food will interact with the acids to diminish the sharpness or acidity of the original marinade." -- (removed spelled out link per Community Policies