On Food and Cooking

Apple Air and Texture Apples differ from
pears in having as much as a quarter of their
volume occupied by air, thanks to open spaces
between cells in the fruit. (Pears are less than
5% air.) The air spaces contribute to the
typical mealiness of an overripe apple: as the
cell walls soften and the cell interiors dry out,
biting into the apple simply pushes the largely
separated cells apart from each other rather
than breaking the cells and releasing pent-up
juices. Air cells become a factor in baking
whole apples; they fill with steam and expand
as the apple cooks, and the skin will split
unless a strip is removed from the top to
release the pressure.
Both apples and crabapples are good
sources of cell-wall pectins (p. 265) and make
excellent jellies. For the same reason, a
simple puree of apples has a thick, satisfying
consistency when briefly cooked into apple-
sauce, or slowly reduced to “apple butter.”