Optimization of Hydrothermal Treatment Conditions for Pear Puree Using the Response Surface Methodology

Abstract

This study analyzed the quality characteristics of pear puree by varying the hydrothermal treatment temperature (50, 70, and 90°C) and time (15, 30, and 45 min) and sought to determine the optimal hydrothermal treatment conditions through the response surface methodology. A total of nine experimental points were studied according to the central composite design. The temperature and time were set as independent variables, and the redness, ΔE value, aerobic bacteria, coliform group, polyphenol oxidase (PPO) activity, total polyphenol content (TPC), and total flavonoid content (TFC) related to the quality characteristics were set as dependent variables. The redness and the ΔE value were measured as −0.38∼1.20 and 0.97∼11.88, respectively, and the R 2 value was 0.9754 and 0.9818, respectively. The R 2 value of viable cell counts were 0.9849 and 0.9714 in the aerobic bacteria and coliform groups. The PPO activity was 122.57∼235.13 g/min, and the R 2 value was 0.8616. The TPC and TFC as active ingredients of pear puree were in the range of 19.33∼24.54 and 4.56∼5.78 GAE mg/100 g, respectively, and the R 2 values were 0.9181 and 0.9097, respectively. Based on this, the contour map was superimposed to set the optimal hydrothermal treatment conditions. The optimum points derived were 74.6°C and 20.7 min. When the predicted and the experimental values were compared to verify the reliability of the model, all the experimental values of each of the response variables were within the 95% confidence and prediction intervals, confirming the suitability of the model.