Optimizing drying time of potatoes by food dehydrator and Koster Moisture Tester

Monday, July 21, 2014
Exhibit Hall AB (Kansas City Convention Center)
Richard J. Norell , University of Idaho, Idaho Falls, ID
J. Benton Glaze Jr. , University of Idaho, Twin Falls, ID
Mireille Chahine , University of Idaho, Twin Falls, ID
Nora L. Olsen , University of Idaho, Kimberly, ID
Abstract Text:

Cull potatoes lose moisture over time when stacked outdoors in a pile.  Measuring dry matter content on a frequent basis is therefore important for effectively managing potato feeding rates for cattle.  In this study, different sample processing methods were compared for drying potatoes.  In trial 1, drying time (DT) and dry matter content (DM) were evaluated for four potato sample sizes in food dehydrators and a lab oven7 mm thick horizontal slices (THICK), 3.5 mm thick horizontal slices (THIN), 7 mm square fries (LFF), and 3.5 mm square fries (SFF).  The dehydrators were 500 watt, Nesco brand, FD-60 with 4 trays and each tray had a plastic insert to prevent sample movement between trays.  Operating temperature was set at 68 C for the dehydrator and the lab oven was set at 55 C.  Four lots of potatoes were used with a single lot analyzed each test day.  Forty potatoes per lot were cleaned and 10 were randomly selected for each processing method.  A 100 g subsample from each processing method was then randomly assigned to an individual tray within dehydrator.  Drying time was significantly different between potato processing methods (p<0.001) with THICK requiring the longest time (459 min), LFF (264 min), SFF (225 min) and THIN (205 min).  DM differed between processing methods with THICK slices having higher DM (p<0.053) than the other three processing methods.  DM was 0.8% lower (p<0.05) in the lab oven than in dehydrator.  In trial 2, DT and DM were evaluated for potatoes processed into THICK and LFF with two Koster Moisture Testers, lab oven, and eight potato lots.  Twenty potatoes were cleaned from each lot with 10 randomly assigned to each processing method.  Three 100 g subsamples from each processed lot were randomly assigned to a Koster tester or lab oven.  LFF reduced DT (P<0.001) by 101 min compared to THICK.  DM did not differ between the two processing methods (p<0.13) nor between lab oven and Koster (p<0.16).  This study indicates that drying time is optimized by reducing potato particle size for both the food dehydrator and Koster Moisture Tester without reducing accuracy in estimating potato dry matter.


potatoes, drying methods, sample processing