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Causes of post harvest discoloration of potato chips from summer potatoes




Clegg, Max DeWayne, author
Chapman, Harold W., advisor
Johnson, Gestur, committee member
Fults, Jess L., committee member

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Early summer potatoes are harvested from the Gilcrest and Rockyford areas in Colorado. Potato chip processors use these newly harvested potatoes and have found them to be erratic in performance, some lots producing light colored chips, others making a dark undesirable product. Information is lacking on the causes of this after harvest darkening. Three plots (a highly fertility, a low fertility and a low fertility plus 120 lbs. of nitrogen) were planted using the variety Irish Cobbler. These plots were located in the Gilcrest early potato producing area. Potatoes were harvested July 7, 11, 18, 25, August 1 and 8, and placed into 50°, 70°, and 90°F storage. An injury treatment was added to the July 25 harvest. At three day intervals over a period of 21 days, respiration, chip color and some chemical analyses were determined. Results show that immature potatoes can not be held in storage for chipping purposes. Delaying the date of harvest will improve the storage capability. Storage at 50°F is detrimental to summer chipping potatoes. Storage at 70°F or above is recommended. The trend of treatment was that potatoes from Treatment II (low fertility, no nitrogen) produce the lightest colored chips. Injury to tubers increases sugar accumulation and results in darker chips. The high non-reducing sugar content of early potatoes may be the main cause of after harvest darkening of potato chips. This high sugar content may be a readily available source of sugar, easily converted into reducing sugars, which in turn causes the potatoes to darken when chipped.


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