I save slices and pieces of lemon or orange in my freezer.
They're handy for spiking fish, soup, veggies or baked goods.
Today I was gifted with five nice peaches. Along with the sliced, peeled peaches and some sugar I added a slice of frozen lemon to the bowl. Tossed to stir and into a freezer bag.
Just enough acidity to retain color, but not too much to detract from the flavor of the peaches. Yummm! 
Just the right amount for a single serving.
bw