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Modeling of Thermal Properties of Persian Walnut Kernel as a Function of Moisture Content and Temperature Using Response Surface Methodology
Author(s) -
Mamani Imanali
Publication year - 2015
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/jfpp.12527
Subject(s) - thermal diffusivity , water content , response surface methodology , thermal conductivity , moisture , thermal , central composite design , materials science , thermal effusivity , thermodynamics , composite material , mathematics , thermal resistance , statistics , engineering , physics , geotechnical engineering , thermal contact conductance
Response surface methodology–central composite rotatable design was used to model and optimize the effect of moisture content (5.86–34.14% dry basis [d.b.]) and temperature (18.79–61.21C) on the thermal properties of walnut kernels, including specific heat, thermal conductivity and thermal diffusivity. A second‐order polynomial model was adequately fitted for each response parameter using multiple linear regression analysis ( R 2 = 0.973–0.988). The linear function of moisture content in all reduced models had the most significant effect ( P < 0.0001). The values of thermal parameters increased with enhancing moisture content within the studied temperature range. The optimum levels of moisture (14.03% d.b.) and temperature (25.86C) as independent variables lead to the target value for the specific heat (2.5 kJ/kg·C), thermal conductivity (0.11 W/m·C) and thermal diffusivity (1.28 × 10 −7 m 2 /s). A close agreement between experimental and predicted data under optimal conditions of thermal parameters was found. Practical Applications Knowledge of the thermal characteristics of agricultural and food products support sizing the thermal equipment and understanding the food transformation. Designing the process heating systems by modeling the main thermal parameters will successfully provide an opportunity for the food industry to produce a dried product with high quality. As there is no available information about the optimization of thermal properties of Persian walnut kernels, the current study employed response surface methodology as a powerful tool for modeling the possible relationship between the different thermal parameters and environmental conditions in this strategic and nutritive crop.