The Martian and Space Taters

With the new trailer for The Martian out I was thinking about it and I remembered something that bothered me when I read it last year.

Our cast away astronaut endeavors at one point to grow food from potatoes that the crew had in stock for a holiday meal. So I can accept that NASA stocked a number of real potatoes for this one meal for crew moral, but I if NASA did do that I can't imagine them doing it without irradiating the potatoes first. Since the 70's NASA has blasted all astronaut food with Gama rays to kill any possible pathogens. This would certainly have rendered our space taters inert.

Don't get me wrong, the science in this book is really strong, I just wish a little hand waving had been done to explain away this one point.