Effect of Water Activity on the Sensory Crispness and Mechanical Deformation of Snack Food Products

Potato chips, popcorn, puffed corn curls, and saltines were equilibrated to various water activities (a_w) over saturated salt solutions. Sensory panels determined the crispness and textural hedonic quality of the humidified products by the magnitude estimation technique coupled to a verbal concept scale. Critical water activities (a_c), where the products became organoleptically unacceptable, generally fell in the 0.35–0.50 a_w range. Instron analyses showed that the force‐deformation curve changed distinctly near the a_c for saltines and puffed corn curls, while the curve changed more gradually with increasing a_w for popcorn. Potato chips did not produce a consistently shaped force‐deformation curve. The cohesiveness value of popcorn was found to be a good indicator of its sensory crispness.