Effect of Ohmic Heating on Color, Rehydration and Textural Characteristics of Fresh Carrot Cubes
Carrot cubes were ohmically heated with 2 different frequencies 1 Hz and 60 Hz to evaluate change in color, texture and rehydration properties. Carrot samples were stored under 4 different relative humidity (RH) conditions 11.1 %, 32.7%, 55.7 % and 75.3 %. Experiments were conducted to monitor the textural parameters of hardness, fracturability, adhesiveness, cohesiveness and chewiness and color changes in terms of CIE color values. Results showed that the hardness, fracturability and adhesiveness of 1- Hz samples stored at 75.3 % RH were different from those at 55.7 % RH. The adhesiveness, cohesiveness and chewiness of 1-Hz samples were different from the control at 55.7 % RH. There was significant correlation between cohesiveness and chewiness and moisture content of the rehydrated samples. For the moisture content after ohmic heating a negative correlation was observed with properties of chewiness, hardness and adhesiveness. Color lightness (L*) values of rehydrated carrots decreased (i.e. became darker) with the increase in storage time. At both 1-Hz and 60-Hz the difference in the L values of fresh and rehydrated carrots was significantly different from that of the control. The degree of redness (a*) of 1-Hz rehydrated samples after 1 Hz treatment were different from the control stored at 55.7 % RH. The water absorption capacity values decreased throughout the six-day storage period for both the treated and control carrot samples. Thus there exists a great potential to enhance mass and heat transfer properties in food process engineering using ohmic heating, particularly because ohmic treatment has been shown to significantly alter rehydration, texture and color efficiencies. This study demonstrated that ohmic treatment significantly affects color, texture and rehydration properties of carrots stored under different RH environments.
Advisor:Marybeth Lima; Witoon Prinyawiwatkul; Steven G. Hall
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Keywords:biological agricultural engineering
Date of Publication:03/04/2004