|Troy D. Fishler||University of Wisconsin|
|Amber M. Gotch||University of Wisconsin|
|Paul C. Bethke||USDA ARS and University of Wisconsin|
Chip and fry processing potatoes that produce excellent products from storage are highly valued by growers and processors. Potato breeders and industry cooperators evaluate new clones for their ability to produce attractive chips and French fries. For many of those evaluations, potatoes are put into crates and stored in humidified, refrigerated lockers. Trials with storage volumes that simulate commercial practice are conducted late in variety development efforts. Differences in processing quality have been observed between potatoes stored in crates and bulk piles or pallet boxes, but the contribution of stored potato volume to those differences has not been investigated systematically. The effect of storage volume on tuber sucrose and glucose content and fried product color was evaluated for 5 chip processing lines and one fry processing line. For each evaluation, 90,000 kgof freshly harvested potatoes were placed into bulk storage to a height of 6 m. Subsamples collected as bulk bins were filled were pooled and a subset of 450 kg was placed in a ventilated pallet box and multiple 20-kg samples were put into crates and held in refrigerated lockers. Tubers were preconditioned at 13 °C, treated to prevent sprouting and ramped slowly to storage temperature. Sugar content of triplicate 6-tuber samples and post-fry product color were quantified monthly. Evaluations continued until potatoes were shipped for commercial processing. In 5 of 6 comparisons, tuber sugar contents and product color were similar at all scales of storage. In one comparison, potatoes in bulk storage began senescent sweetening earlier than those in crates. Overall, these data suggest that storage volume had a small effect on sugar content and fried product color. Differences in processing quality that have been attributed to differences in storage volume may have been caused by differences in scale of production or differences between potato samples.