Progress 08/15/07 to 08/14/09
Outputs
OUTPUTS: Sweet potato (Ipomoea batatas) is an important root crop in Caribbean Basin and the southeastern part of the United States. Some properties of this crop such as starch, sweetness and volatile contents are main properties ruled public acceptance of sweet potatoes. However, these properties are very variable. Similar contents of starch were detected in sweet potato cultivars on this study; however during baking starch losses were different among cultivars. Transformation of starch to glucose by the enzymatic activity was related to sweetness and also to the rate of releasing of volatile compound during cooking. This is probably due differences in starch composition among varieties. The rate of transformation could be determinant in public acceptances for certain sweet potato varieties. The activation energy of degradation of starch to glucose ranged from -0.19 to -13.5 kJ/K-mol. Our data suggest activation energy for starch degration was related to cultivar sweetness after baking but also could be related to taste. Starch was related to alcohol insoluble solids (AIS) through the following equation: Starch = 0.7 x % AIS - 18.49. Where, the intercept of 18.49 was the percentage of insoluble solids which are neither sugars nor easily hydrolysable starch. Correlations of starch with maltose and starch with the sucrose's index indicated starch and then AIS are good indexes for selection of sweet potato for sweetness, but not for taste and texture. Sensorial analyses did show overall acceptability of above mentioned cultivars was not dependent of sweetness. Thus, volatile index could be good criteria for cultivars selection. Benefit of volatile index is to get a selection index for taste, but volatile index require great efforts to develop. Therefore, association of activation energy of starch degradation to units of glucose and volatile composition of cultivars need further studies in order to develop a criteria for taste selection among sweet potato cultivars. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
. Flavors in sweet potato germplasm are very variable; thus, identification of flavor-related compounds is necessary to improve selection criteria for breeding programs. In this study light-fleshed sweet potatoes types shows significant correlations between AIS and maltose, and between AIS and sucrose's index. However, there was relatioship between about parameters mentioned and overall acceptability of the cultivars. Benefit of volatile index as cultivar selection criteria is that it could be a semi-quantitative manner of ranking public acceptability without requiring a sensorial panel. However, creation of volatile index is difficult to implement because the extraction and analysis of volatiles are costly. A simple procedure for evaluate the activation energy of starch degradation to glucose and its relation with volatile releasing must evaluated. This project allowed the recognition of sweetpotato cultivars by aroma pattern by Solid Phase Micro Extraction (SPME).
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The tropical type sweet potatoes (white or yellow pulp) is intermediate in sweetness after cooking as compared to the sweetness of orange-flesh (Gem). This less sweet characteristic is the market's preference in the American tropics. For fresh market, sweet potato quality is defined in terms of attractiveness, taste and flavor after cooking. Taste is primarily related to sweetness. There are studies that suggest that volatile compounds (VC) may increase or decrease the intensity of sweetness. Carbohydrates are the major constituents in sweet potato flesh, and it is well known that carbohydrates are able to retain VCs by physical adsorption. Knowledge of the volatile composition of tropical type sweet potatoes is scarce and has been evaluated in this study. Forty-five VCs have been identified by dynamic headspace from sweet potato flesh. Physical and chemical properties of sweet potato flesh have been measured in this study in order to better understand their relationship to VC release and good eating quality. Starch, total protein content and other chemical and physical properties of sweet potato flour have been studied. Contribution of this research to the breeding program is better understood by considering that the VC index will be contributing to the selection of the best varieties. In addition, this research will allow us to increase our knowledge of the chemical and physical properties of sweet potatoes, to assess off-odor compounds which are responsible for the non-good qualities of some varieties. This assessment is important because off-odor compounds may affect commercial success for some sweet potato varieties. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Strong markets for fresh roots of tropical-type sweet potato exist within the Caribbean Basin and in the Northeastern United States. Flavors in sweet potato germplasm are variable; thus identification of flavor-related compounds is necessary to improve selection criteria for breeding programs. Most of the research concerning flavor in sweet potato has been done on orange-fleshed types. In this study light-fleshed sweet potato types show significant correlation between AIS and maltose, and between AIS and sucrose index. Benefit of volatile index is to get a selection index for taste. This project will allow aroma pattern recognition from baked tropical type sweet potato (light-fleshed types) by Solid Phase Micro Extraction (SPME).
Publications
- Dumas, J. A. and C. Ortiz. 2007. Characterization and level of desorption of volatile compounds released from boiling sweet potato pulp (Ipomoea batatas) Pulp. In: Proc., 42nd Annual Meeting Caribbean Food Crops Soc. 373-379.
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