Investigation of effective thermal conductivity kinetics of crust and core regions of potato during deep-fat frying using a modified Lees method

Effect of Potato Orientation on Evaporation Front Propagation and Crust Thickness Evolution during Deep‐Fat Frying

“…Orientation has a direct effect on potato texture since it is observed that the crust at the horizontal top (θ= 0 o ) and the vertical side surface (θ= 90 o ) is crispy, compact, and very dry, whereas the crust at the horizontal bottom surface (θ= 180 o ) is soft, pliable, and not so dry. This is in accordance with the findings of Ziaiifar and others (2009). The crust features for bottom surfaces should be attributed to the formation of a gas layer which acts like an insulator preventing high heat fluxes, and therefore, the formation of a very dry rigid crust.…”

“…Southern and others (2000) while performing preliminary tests in order to decide which potato chip orientation suits them best for their main experiments, that is, horizontal or vertical; concluded that the vertical position results in a faster moisture loss rate compared to the horizontal position. Recently, Ziaiifar and others (2009) measured both the bottom and the top crust thermal conductivity of single potato samples (0.05 × 0.05 × 0.006 m) fried at isothermal conditions (170 °C). They found that the top crust conductivity is lower than the bottom crust, which implies structural differences between the top and the bottom crust and they suggested that the lower conductivity corresponds to a drier crust because of the different heat transfer coefficient values.…”

On the capacity of a crust–core model to describe potato deep-fat frying

“…Sahin et al (1999) stated that the thermal conductivity of food materials depends on their porosity, structure and chemical constituents. Recently, Ziaiifar, Heyd, and Courtois (2009) measured for the first time both the crust and the core thermal conductivity, k co , of single potato samples fried at isothermal conditions (170°C). It must be noted that these authors measured the crust's and the core's thermal conductivity separately after removing the crust from the core's flesh at a temperature range from 20 to 32°C, which is far from the frying conditions and they concluded that:…”

Investigation into the dehydration process of oily sludge by fry‐drying method

“…Therefore, fry‐drying is more energy efficient than hot air drying. The food frying process has long been the subject of many investigations , but few studies have used this method for oily sludge dehydration. Ohm et al .…”