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Thermal diffusivity is an important transport property needed in modeling and computations of transient heat transfer in basic food processing operations. In addition, the prediction of nutritional and microbial changes occurring in food during thermal processing requires knowledge of thermal diffusivity of foods. The objectives of this study were to develop a new nonisothermal and nonlinear determination method of thermal diffusivity and to measure the thermal diffusivity of low-moisture foods using that new method. Thermal diffusivities of 5 kinds of low-moisture foods (almond meal, corn meal, wheat flour, chocolate fudge, and peanut butter) were estimated using an inverse technique. Samples were canned and heated at the surface in a water bath at about 70 °C. The 1-dimensional transient heat conduction problem for radial coordinates was solved with a finite-difference model. The thermal diffusivity of each of the 5 samples was determined by the ordinary least squares and sequential estimation methods, respectively. Predicted and observed temperature matched well, with maximum residuals of 0.9 °C. The thermal diffusivity values of the samples ranged from 9.8 × 10 to 1.3 × 10 m /s. The advantages of this method are that the device and the estimation method are simple, inexpensive, rapid, and can handle large spatial temperature gradients, such as those experienced during heating of low-moisture foods. The results obtained in this study will be useful in the design of equipment and in calculations for the thermal processing of low-moisture foods.

Anthocyanins (ACY) and colour changes in cherry pomace under non-isothermal processing were investigated. Pomace at moisture levels of 70% (MC-70), 41% (MC-41) and 25% (MC-25) was heated at 126.7°C in a retort for 25, 40 and 60 min. Total ACY, Hunter colour values, total colour difference (DE), chroma, hue angle (h°) and browning index (BI) were analysed. Thermal degradation kinetics for colour parameters were determined using zero-and first-order models. ACY degradation increased with heating time and ranged from 34 to 68% for 25 and 60 min heating, respectively. The half-life of ACY was 38, 33 and 27 min for MC-70, MC-41 and MC-25 pomace, respectively. The DE increased with increasing heating time, whereas BI exhibited an inverse trend. Except for ΔE for MC-70, the zero-order kinetic model showed better fit (R 2 = 0.85-0.97) to experimental data than the first-order kinetic model for Hunter colour b values and ΔE. International Journal of Food Science and Technology 2013Cherry pomace anthocyanins and colour changes I. Greiby et al. International Journal of Food Science and Technology 2013Cherry pomace anthocyanins and colour changes I. Greiby et al. 1,2,3 MC-70, MC-41 and MC-25 represent cherry pomace with 70%, 41% and 25% moisture, respectively. Values represent average of triplicate AE standard error. Means with different letters (a-c) in rows and (A-D) in columns are significantly different (P 0.05). International Journal of Food Science and Technology 2013Cherry pomace anthocyanins and colour changes I. Greiby et al. International Journal of Food Science and Technology 2013Cherry pomace anthocyanins and colour changes I. Greiby et al. International Journal of Food Science and Technology 2013Cherry pomace anthocyanins and colour changes I. Greiby et al.