Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2005
Publication Date: 8/1/2005
Citation: Mcconnell, R.Y., Truong, V., Walter, W.M., McFeeters, R.F. 2005. Physical, chemical and microbial changes in shredded sweetpotatoes. Journal of Food Processing and Preservation. 29:246-267. Interpretive Summary: The International Fresh-cut Produce Association reported that fresh-cut produce has been a fast growing commodity in grocery stores during the last 10 years. Therefore, there is a substantial potential for creating new value-added market opportunities for fresh-cut products from sweetpotatoes, a highly nutritious vegetable. This study examined the effect of various packaging materials and modified atmosphere packaging (MAP) conditions on quality changes and microbial growth in shredded sweetpotatoes under refrigerated storage. The quality of shredded sweetpotatoes packed in air could be maintained for 7 days at 4 deg C, but extended up to 14 days with a MAP of 5% oxygen, 4% carbon dioxide and 91% nitrogen in moderately oxygen-permeable film (e.g., Cryovac PD 961), and refrigeration at 4 deg C. The MAP-stored samples had consistently lower total aerobic bacteria counts than the samples stored in air. Yeasts, molds, lactic acid bacteria, color, beta-carotene, and sugars of all stored samples did not change significantly, regardless of treatments. Application of this minimally processing technique to fresh-cut sweetpotatoes could result in increasing profits for farmers by using all grades of roots and providing consumers with convenient and nutritious food products.
Technical Abstract: With the increasing demand for fresh-cut vegetables, substantial potential exists for developing minimally processed sweetpotato products. This study was undertaken to determine the effects of semi-permeable polymeric materials and modified atmosphere packaging (MAP) on quality changes and microbial growth in shredded sweetpotatoes under refrigerated storage. Shredded sweetpotatoes from two major commercial cultivars, Beauregard and Hernandez, were packed in low and medium oxygen permeability bags and flushed with gas composed of 5% oxygen, 4% carbon dioxide, and 91% nitrogen. Quality changes and microbial growth were monitored in comparison to the samples packed in air using high oxygen permeable films. The quality of shredded sweetpotatoes could be maintained for 7 days at 4 deg C in air, but extended up to 14 days with MAP. Considering the parameters measured in this investigation, the best results were obtained by MAP using moderately oxygen permeable film (7,000 cc/atm/m2/24 hr). Shredded sweetpotatoes stored in MAP showed less changes in tissue firmness, dry matter, ascorbic acid, and starch than samples stored in air. The MAP-stored samples had consistently lower total aerobic bacteria and enteric bacteria compared to the samples stored in air. Yeasts, molds, lactic acid bacteria, color, beta-carotene, and sugars of all stored samples did not change significantly, regardless of treatments. Higher ethanol levels were generated in the MAP-stored samples after 10 days, but the off-odor was not detected in any of the samples.