Changes in quality traits of "Hoshi-imo" steamed and dried slice of sweet potato during process and varietal differences
2006
Kuranouchi, T.(National Inst. of Crop Science, Tsukuba, Ibaraki (Japan)) | Nakamura, Y. | Tamiya, S. | Nakatani, M.
Steamed and dried sweet potato slices called "Hoshi-imo is an important agricultural product in Ibaraki prefecture in Japan. In recent years, a large amount of Hoshi-imo is imported, and improvement of the quality of domestic Hoshi-imo is critical to survive competition. Here, we investigated the changes in quality factors such as toughness and brix of Hoshi-imo during the drying process to improve the processing technique and to breed high-quality lines. The luminosity and yellowness of steamed slices decreased and became reddish as they dried. The color characteristics of the slice just after steaming distinctively differed among lines, and the difference was evident even after drying though the difference in luminosity decreased with time. The toughness and brix of Hoshi-imo differed among lines throughout the drying process. These results indicate that it is possible to predict market quality of Hoshi-imo just after the steaming process and to select breeding lines without drying. The moisture content of Hoshi-imo fell to below 30% after drying in all the lines tested. The term of drying should be shortened in some lines because they become too tough during the drying process. A negative correlation existed between toughness and brix of Hoshi-imo among the lines and cultivars of sweet potato studied, suggesting that temperature should be gradually raised in the steaming process to promote saccharification and to obtain high quality products.
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