Conditioning reduces kernel damage when impact shelling almonds

Abstract

Abstract Almonds can be classified based on their shell characteristics from soft to hard shell varieties. The majority of Australian and Californian varieties have soft shell properties. Most Spanish almond varieties have hard shells. Although having a hard sealed shell protects the kernel from insect damage it affects their processability. Common commercial almond processing equipment simultaneously compresses and shears the almonds and this creates a high percentage of damaged kernels from the broken shell being forced into the kernel, particularly for hard shell varieties. This paper shows that for the soft shell variety ‘Nonpareil’ and the three hard shell varieties of ‘Marcona’, ‘Tarraco’ and ‘Vyro’ that conditioning by soaking in water and resting before processing improves the recovery of undamaged kernel when shelling using impact. The impacts were applied by feeding the almonds into a rotating impellor and throwing them onto a stationary outer wall. An effective conditioning process resulted in the kernel moisture content increasing from 6% to 14% for hard shell and to 11% for ‘Nonpareil’ varieties. The conditioning process was measured to reduce the amount of scratched, chipped and broken kernel, and hence increased the recovery of undamaged kernel. After shelling, the conditioned kernel needed to be dried back to a 6% moisture content to be suitable for storage. Hence, the industry would be able to increase its recovery of undamaged kernel by changing to an impact shelling process using suitably conditioned almonds.