Fight your way down the snack aisle of any American supermarket and the obsession with crunch is manifest—in fact, it's a global obsession. The ratios of sugar, salt, and fat may vary, but crunch prevails. One theory about the ascendancy of crunch concerns evolution. Crispy-crunchy texture often signals freshness in fruits and vegetables, and, one supposes, in bugs. But the obvious fact is this: Crunch rings a gong in our brains very near to our deepest food-pleasure centers. We all crave crunch. The conundrum was this: Could we make favorite crunchy foods healthier, with less fat and sugar?