The sourness issue is just another confidence thing in angling. How many times do we hear that people have turned up to a match with rank casters and done well? What do carp anglers add to their boilies/stick mixes? Butyric acid, which stinks of bably vomit.
I have used pellets that have been repeatedly frozen and thawed for over a year and had success on them, framing in matches. Of course, you might say that with fresh ones I may have won some of them, but who can tell; I may not have even got in the frame.
The short answer is yes, you can freeze them, but it’s up to you to experiment with how many times.