Development of a Mechanical Undercutting System to Minimize Sweetpotato Skinning during Harvest

• Published in: Applied engineering in agriculture Vol. 30; no. 3; pp. 355 - 360
• Main Authors: Hayes, Bradley H, Ward, Jason K, Davis, Jeremiah D, Shankle, Mark W, Arancibia, Ramon A
• Format: Journal Article
• Language: English
• Published: American Society of Agricultural Engineers 01.05.2014
• Subjects: cutting; engineering; experimental design; fresh market; fungi; growers; harvesting; industry; markets; postharvest losses; pruning; root growth; roots; shrinkage; skinning; sweet potatoes; vines; weight loss; Mississippi
• ISSN: 0883-8542; 1943-7838
• DOI: 10.13031/aca.30.10330

Sweetpotatoes have been an important high-value crop in Mississippi and future market growth is expected. Industry demand has created the need for a continuous supply of sweetpotatoes throughout the year. Therefore, managing the harvest process and postharvest storage environment is critical to maintaining a year-round supply of quality sweetpotato roots. This has been a challenge in Mississippi and growers have been experiencing postharvest losses due to excessive root shrinkage (weight loss) and bacterial and fungal rots. These losses are directly related to damage during harvest procedures that cause cuts and abrasions (skinning) to the delicate skin of the sweetpotato root. De-vining sweetpotatoes prior to harvest is a commonly used method to halt root growth and begin toughening of the skin. This method is viable for producers using manually-assisted harvesting for the fresh market. Producers using bulk harvesting prefer to leave vines on to reduce the amount of foreign material going into storage. A new method of halting plant growth and allowing the root to cure in the ground prior to harvest is needed. The objective of this study was to design and test a mechanical root pruning blade to halt plant growth and initiate skin set prior to harvest of sweetpotatoes and to quantify the effects of undercutting sweetpotatoes on skin strength relative to de-vining. The hypothesis was that cutting the deep root of the sweetpotato plant would allow this process to begin. Therefore, two different undercutting implements were designed and fabricated. These implements were tested in experimental plots and the skin strength was directly measured. Root skin strength was measured at three days and six days after treatment. Results indicated that at three days after treatment, undercutting had no significant effect on skin strength for both vine conditions (vine-on and de-vined). At six days after treatment, undercutting with the newly developed implement significantly increased skin strength for roots in which the vine had been left on.