Ohmic heating has been shown to affect the drying rate and texture of foods. This research was designed to determine the effect of ohmic heating on rehydration, color and texture properties of sweet potatoes. Three combinations: 60Hz, 40V, 60Hz, 60V and 1Hz, 40V were applied to ohmically heat sweet potato cubes. The ohmic treated cubes and untreated cubes or controls were stored for six days in four different %relative humidities of 11.15%, 32.73%, 57.70% and 75.32%. Results showed that there was no significant difference in the rehydration properties of ohmic treated samples and control samples. The % moisture gain varied between a minimum of 0.1% and a maximum of 40.7% in the case of ohmically treated samples and 0.71% to 32.41% for control samples. The color lightness values increased with increase in storage time for both ohmically treated and control samples. The 60Hz, 40V ohmically treated samples had less increase compared to control samples. The degree of redness (a*) and degree of yellowness (b*) values were significantly higher for ohmically treated samples during storage. A significant loss of color pigments into rehydrating water was observed during rehydration for ohmically treated samples. The 60Hz, 40V treated samples retained color and appearance compared to other treatments. Texture analysis showed that the ohmic treated samples (60H, 60V) had higher hardness, springiness and chewiness values than the control samples. At lower humidities the firmness or hardness values increased with increase in storage time. Positive correlations were obtained between the moisture content of the samples after rehydration and the hardness and chewiness values. This study demonstrated that ohmic heating played a pivotal role in retaining rehydration properties, color attributes and some of the texture attributes of the sweet potato samples when appropriate combinations of frequency and electrical field strength were used.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-04122004-150752 |
| Date | 15 April 2004 |
| Creators | Bhattiprolu, Sireesha |
| Contributors | Marybeth Lima, Steven G. Hall, Witoon Prinyawiwatkul |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-04122004-150752/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0022 seconds