Q: Sometimes when I cook chicken, there is a white residue, kind of like cooked egg whites, that comes out. What is it and how can I avoid it happening?

This happens frequently with grilled chicken breasts or kabobs.  What you are seeing is protein from the meat, dissolved in water either from the meat or added during processing, which has leaked out and then cooked to form a gel.

After evisceration, chicken can retain up to as much as 8% of its total weight in water used during cleaning and handling.  Some of this water leaks out during cooking, carrying protein with it.  Some of the protein is found between the cells of the meat.  When chicken is frozen, cellular damage may cause more water and more protein to leak out.  As described in the "Custards and Sauces" posting, between 120°F (50°C) and 180°F (82°C) proteins in solution begin to unravel and bond with each other, trapping the liquid in which they are floating.  This is called coagulation.

There are a few things you can do to avoid this happening.  First, use fresh chicken wherever possible.  As mentioned, freezing may increase the chances of this happening.  If you are using frozen chicken, make sure that it was flash frozen, since this reduced cellular damage, and keep it at below 0°F (-18°C) until you are ready to use it.  Thaw slowly in the refrigerator allowing about 5 hours per pound or 10 hours per kg.

Second, buy from a reliable source.  While some water must be used to clean the poultry, the range of retained water appears to be between 4% and 8% of the total package weight.  Some packers may allow more water to be retained than is truly necessary, thus increasing profits.

Finally, dry off any excess water before cooking.

While these suggestions may help, I find that the "goop" still happens from time to time.  If it does, just clean it off as best you can before serving.