Specific gravity and cultivar effects on potato tuber impact sensitivity

This work investigated the influence of specific gravity on the impact sensitivity of individual potato tubers from three cultivars (Russet Burbank, Snowden and Atlantic). Specific gravity and impact sensitivity are both important quality measures in the potato industry. The two impact sensitivity measures used were: constant-height multiple-impacting (CHMI) of whole tubers to determine bruise volume, bruise energy, and bruise resistance; dynamic axial compression (DAC) of tuber tissue samples to determine failure stress, failure strain, shockwave speed, and predicted bruise threshold using a static prediction equation. The experiment was repeated the following year using only Russet Burbank tubers, with similar but less definitive results. That specific gravity variation in these experiments was natural and not achieved through dehydration. The results show that higher specific gravity tubers were more sensitive to impacts in the Russet Burbank and Atlantic cultivars, which showed lower bruise resistance and lower bruise thresholds with increasing specific gravity. Snowden showed higher bruise threshold, but lower bruise resistance with increasing specific gravity. A recently developed mathematical model was used to predict bruise threshold from tissue failure properties, tuber size, and tuber radius of curvature at the impact point.