Fresh-cut fruits and vegetables are popular value-added convenience foods widely available worldwide. Consumption of fresh-cut produce has grown at a rapid pace during the last 10 years and new product development is still occurring (United Fresh Produce Association, pers. comm., 2007). Fresh-cut products are substituting for frozen items in certain cases. A wide variety of fresh-cut products are now commercially available for direct consumer use or for further processing by restaurants and fast-food chains. Many consumers of fruit and vegetables base their purchasing decisions on product convenience and quality.
Fruits and vegetables are rich sources of phenolic compounds, which can act as antioxidant or free radical scavengers in the human body to reduce the risks of certain types of cancer, diabetes, and cardiovascular diseases (Scalbert et al., 2005). The role of phenolics as antioxidants in the human body has prompted researchers to determine how their content and activity are affected by postharvest processing and storage conditions. Previous studies indicated an increase in total phenolic content and antioxidant activity in fresh-cut carrots, potatoes, jicama roots, and lettuce (Aquino-Bolanos et al., 2000; Cantos et al., 2001, 2002; Cisneros-Zevallos, 2003). Sweetpotato roots are chilling-sensitive and controlled abiotic stress treatments such as wounding and storage of fresh-cut products at chilling injury (CI)-inducing temperatures may enhance the nutraceutical value or health benefits through an increase in secondary metabolites such as phenolics (Dixon and Paiva, 1995). However, a recent study has indicated that the phenolic content and antioxidant capacity after wounding may decrease or increase depending on type of fruit and vegetable tissue and cultivar (Reyes et al., 2007).
Sweetpotato roots are a major staple food widely consumed in developing countries and rank as the third most important starchy food crop in the world (Food and Agriculture Organization of the United Nations, 2007). Like other vegetables, sweetpotato roots can also be consumed as a fresh-cut product and different style cuts have recently been marketed on a small scale. However, there is considerable potential for further market expansion of fresh-cut sweetpotato products. Minimally processed sweetpotato products such as shredded, sliced, or French-fry cuts may decrease preparation time for use in restaurants and other food service facilities. Sweetpotato roots have been reported to contain phenolic antioxidant compounds such as chlorogenic acid, caffeic acid, and dicaffeoylquinic acids with different antimutagenic effects (Walter et al., 1979; Yoshimoto et al., 2002). The increase in phenolic content and antioxidant activity was observed when whole sweetpotato roots were stored at CI-inducing temperatures (Padda and Picha, 2008a). Reyes et al. (2007) indicated the total phenolics and antioxidant capacity in shredded sweetpotatoes stored for 2 d at 15 °C increased by 17% and 12%, respectively. However, information pertaining to the effect of temperature and storage on the total phenolics, individual phenolic acids, and antioxidant activity of different style fresh-cut sweetpotatoes was not presented. More detailed research on phenolic composition and antioxidant value of different style fresh-cut sweetpotatoes will be of increasing commercial importance as the demand for fresh-cut sweetpotato products increases. The purpose of this study was to quantify the changes in the phenolic composition and antioxidant activity in different style fresh-cut sweetpotatoes held at different temperatures and storage durations.
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