Candied or made into preserves might save the fruit for food. Less so for vitamin C. If the concern is less food for energy and more vitamin C to hold off scurvy I think your best bet is to invest in vitamin C in the form of pills, or bulk powder. I like the unsweetened, non-chewable, 500mg tablets.

If you want a chuckle give the non-chewable tablets to someone used to the heavily sweetened chewable version. Vitamin C is quite sour. Chewing the non-chewable sort sort will give you a pucker all the way down to your toes. Fun to watch. Cheap thrills.

I assume the preservation of the citrus is intended to preserve the vitamin C to prevent scurvvy, correct? While the preserves would add nice variety to what could otherwise be a very bland diet, why not try a Native American remedy for scurvvy: pine needle tea? Not attempting to hi-jack the thread, just asking and offering up another alternative.

Thanks for the post, and you are right about use of evergreen needles.

Actually I just started some urban foraging and thought learning to preserve the harvest of citrus this time of year in California would be a further step in my efforts to be "equipped to survive" both short- and long-term. I intend to use the same technology to preserve the wild edible foods I have been learning about, including mushrooms. Once the initial canning and dehydrating stuff cost is absorbed, and given the markedly good quality of homemade stuff, you also wind up stretching your preparedness dollar.