Improvement in Texture of Pressure-Assisted Thermally Processed Carrots by Combined Pretreatment using Response Surface Methodology

The effect of pretreatment pressure (0.1 to 400 MPa), temperature (25 to 75 A degrees C), and calcium chloride concentration (0 to 1.5%) and their complex interaction on hardness, residual pectinmethylesterase (PME) activity, and diffused calcium content of pressure-assisted thermal processed (PATP, 700 MPa, 105 A degrees C for 15 min) carrot have been studied using response surface methodology. Predicted values of carrot hardness, calcium content, and residual PME activity were found to be in good agreement with experimental values as indicated by the high R (2) values of 0.98, 0.96 and 0.96, respectively. The optimum processing conditions, namely, calcium chloride concentration 1.0%; pretreatment pressure ranging from 286 to 314 MPa; pretreatment temperature varying from 53.8 to 58.3 A degrees C, fulfill the conditions to obtain the PATP carrot with hardness a parts per thousand yen145 N, calcium content a parts per thousand yenaEuro parts per thousand 2.5 mg/g, and residual PME activity a parts per thousand yenaEuro parts per thousand 70%. These conditions resulted in more than tenfold increase in the hardness of PATP carrot (14.08 to 145 N) as compared to PATP carrot without any pretreatment. The study demonstrated that response surface methodology can be used for modeling carrot quality parameters of PATP.