I have an ice cream recipe from Madeleine Kamman with a basic cooked custard base. The recipe gives a shelf life of only 5 days. Why when frozen?

Probably the flavor and maybe texture are best up to 5 days. The ice cream should be fine beyond that but probably not as good as it would have been if you had consumed it quickly. I find that's the case with homemade ice cream.

It should be fine for much longer. But unless you just end up having it left over, I wouldn't polan to make it too far in advance. Home made ice cream has a shorter "optimum time" than commercially made because it lacks stabilizers, and it might take on ice crystals. That said, Mme Kamman is the fussiest cooking teacher/chef I've ever encountered, so I would take her 5 days with a grain of salt. ;)

Thanks Chef June and HalfPint...I have not met or worked with Mme Kamman but I sometimes laugh at just the tone of her writing in her cook books but that said I so respect her knowledge and her expertise of technique. And she also knows her food history so what more can I say. Thanks again!