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United States Department of Agriculture

Agricultural Research Service

Title: Textural Properties and Sensory Quality of Processed Sweetpotatoes As Affected by Low Temperature Blanching

Authors
item Truong, Van-Den - NCSU
item Walter, William
item Bett-Garber, Karen

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 3, 1998
Publication Date: N/A

Interpretive Summary: Sweetpotato processors in the United States are able to produce canned sweetpotatoes for only a few months each year. This is because, if this crop is processed after more than a short period of storage after harvest, it becomes soft and disintegrates. The severity of softening and disintegration increases as storage time before processing increases. Our research program has focused on solving this problem, and in this report we describe a second approach to eliminate it. In this process we blanched sweetpotato cylinders in water at 62 deg C for 30 to 45 min., followed by canning in 30% sucrose syrup. The blanching conditions we used gave a canned product 2 to 3 times more intact and 2 to 7 times firmer than sweetpotatoes which were canned without any pretreatment. Sensory panels preferred sweetpotatoes stored 9-12 months and then canned using this newly developed process over sweetpotatoes canned with no pretreatment. This new process will permit processors to prepare a product of consistent firmness and wholeness, regardless of the postharvest history of the sweetpotatoes, and as a result could extend the processing season. In addition, it will provide a market for those sweetpotatoes which now are discarded by shippers after the canning operations have shut down for the season.

Technical Abstract: Sweetpotatoes (SP) stored for 9-12 months after harvest were cut into cylindrical pieces and, following factorial experiments and response surface design, were blanched at 50-80 deg C for 15-274 min. Instrumental textural properties of the samples were measured by uniaxial compression and texture profile analysis. Samples of selected blanching treatments were canned in syrup for textural and sensory evaluations. We found that both blanching temperature and time had significant effects on firmness. Optimal temperature for maximal firmness retention was about 62 deg C. For canned SP, the 62 deg C blanched samples were more intact (2-3-fold) and firmer (2-7-fold) than the controls. Sensory texture and overall acceptability were greatest for samples blanched for 30 and 45 min before canning.

Last Modified: 4/21/2014
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