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Title: ALKALI-NEUTRALIZATION PROCESS MAINTAINS THE FIRMNESS AND SENSORY QUALITY OF CANNED SWEETPOTATO PIECES

Author
item Walter Jr, William
item SYLVIA, KARINA - NCSU
item TRUONG, VAN-DEN - NCSU

Submitted to: Food Quality Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/1997
Publication Date: N/A
Citation: 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 developed a process which has the potential to eliminate this problem. Sweetpotato pieces are treated with a trisodium phosphate solution, blanched, treated with a dilute acid solution, and canned in 30% sugar syrup. Using sweetpotatoes which had been stored for ten months before canning, product prepared using our process was several times as firm as, did not disintegrate as much as, and was preferred by sensory panelists to sweetpotatoes stored for ten months but canned using a conventional process. This new process will permit processors to prepare a product of consistent firmness and wholeness, regardless of the post-harvest 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: Textural properties of canned sweetpotatoes (SP) depend on the length of time the roots are stored before canning. SP are canned for only a few months each year because those canned after longer storage tend to soften and disintegrate. If the length of the canning season is to be extended, the wholeness and firmness of SP canned after long-term storage must be retained. In this report we discuss the use of an alkali infusion neutralization process to accomplish this goal. Jewel cultivar SP stored 1, 5, and 10 months after harvest were peeled, cut into pieces, treated, and canned in 15 deg and/or 30 deg Brix syrups. Samples were evaluated for degree of disintegration (wholeness), firmness (shear force), chemical composition, and sensory acceptance. Untreated samples (controls) disintegrated as storage time prior to processing increased, while treated samples remained intact, and that firmness and sensory texture scores also declined with increasing storage time. Treated samples were significantly firmer than controls throughout the study, and, although shear force declined over time, sensory panelists did not detect any texture change. Overall sensory acceptance at 10 months was greatest for phosphate-treated samples in 30 deg Brix syrup. Thus, the alkali-neutralization process retains firmness, wholeness, and sensory quality of SP canned after long-term storage. This process will permit commercial processing of SP roots stored for up to 10 months.