Here I got the answer when I did google. Like to share with everyone.
. A Wilton representative explained to me that for the code stamped on the bottom, the first number indicates the year, (or currently, the first two numbers, since it's 2010)... then the last three numbers represent the julian calender, which to my understanding is basically the 365 days of the year. so one that I had on the shelf, 8077 means it was made on the 77th day of 2008 (March 17, 200
. It has a shelf life of 18months, so mine needs to be thrown out. A new one I bought says 10168, so it was made on the 168th day of 2010 (June 17, 2010).