Influence of surface coating with xanthan gum on heat transfer during deep‐fat frying of potato strips
2012
KIM, DEOK NYUN | MIN, BOCKKI | Lee, Sung-Ho | LEE, SUYONG
Potato strips were coated with xanthan gum solutions (0.3, 0.6, 0.9%, w/v) which exhibited shear‐thinning and weak gel‐like characteristics. Then, the effects of the surface coating on heat transfer during deep‐fat frying of the potato strips were investigated as a function of concentration of xanthan gum solutions. Deep‐fat frying of surface‐coated potato strips exhibited sigmoidal temperature profiles which were shown to be dependent on the concentration of xanthan gum solutions. Heat transfer coefficients were also determined to be between 215 and 254 W/m² K. The use of higher concentration of xanthan gum led to a distinct decrease in heat transfer coefficients during frying of potato strips, which were shown to be highly correlated to the viscosity of xanthan gum solution (R² = 0.99). It thus suggested that the surface coating of potato strips with xanthan gum might create an insulating layer, consequently reducing the rate of heat transfer during frying. PRACTICAL APPLICATIONS: Coating and batters in the frying industry are the common methods to reduce the oil uptake of fried foods. However, few experiments have been carried out to investigate the changes in the heat transfer during frying when a food matrix is coated or battered. In this study, a food matrix coated with hydrocolloid solutions was subjected to deep‐fat frying during which heat transfer coefficients were investigated. Our results obtained in this study can provide a fundamental understanding for the mechanisms of heat transport in coated (or battered) fried food systems, consequently helping optimization and control of a frying process.
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