Abstract: A method for making an expandable half-product or pellet suitable for cooking by microwave oven (or other method such as frying) that results in a non-uniform, random design, while having a distinct pattern or style. The half product design is achieved by inducing stress cracks in the half product. The stress cracks are created by a controlled drying process whereby extruded half-products are first case hardened to create an outer skin that requires an internal build-up of pressure to penetrate. After creation of the outer skin, by drying in an oven or in ambient air, the half-product is heated to permit the vapor pressure of the moisture inside the half-product to break through the outer skin and escape. Such escape points induce stress cracks in random places in the half-product. The general pattern of the stress cracks can be varied by manipulation of the time-temperature profile of the case hardening and stress cracking steps.

Abstract: A method for making an expandable half-product or pellet suitable for cooking by microwave oven (or other method such as frying) that results in a non-uniform, random design, while having a distinct pattern or style. The half product design is achieved by inducing stress cracks in the half product. The stress cracks are created by a controlled drying process whereby extruded half-products are first case hardened to create an outer skin that requires an internal build-up of pressure to penetrate. After creation of the outer skin, by drying in an oven or in ambient air, the half-product is heated to permit the vapor pressure of the moisture inside the half-product to break through the outer skin and escape. Such escape points induce stress cracks in random places in the half-product. The general pattern of the stress cracks can be varied by manipulation of the time-temperature profile of the case hardening and stress cracking steps.