Review ArticleThermal analysis of pre-boiling regime in frying experiments at several sample orientations and gravity levels

•Pre-boiling frying regime: estimation of heat transfer coefficient.•Heat transfer rates are well predicted from one dimensional heat conduction model.•Dependence of heat transfer coefficients on a variety of experimental conditions.

The focus of this work is on the extraction of heat transfer coefficients from experimental data during the pre-boiling regime of potato frying by employing a specially designed device. Knowledge of these coefficients is necessary for the estimation of temperature spatial profiles at the inception of frying. In this way, not only understanding but also modeling of the frying process is facilitated. Heat transfer coefficients are estimated based on a one dimensional heat conduction model through matching theoretically predicted with experimentally measured temperature evolutions at three distinct distances below, but close to, the surface of the fried item. The tests cover a variety of experimental conditions regarding the initial oil temperature, fryer geometry, frying surface orientation, type of fried item, and level of gravitational acceleration. The dependence of heat transfer coefficients on the above experimental conditions is discussed.

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