Frying of potato for French fries production is a complex process including a combined heat and mass transfer. Evaporation of water, starch gelatinization, fat uptake, crust formation and colour development are key aspects that are affecting the sensorial attributes and that are controlled by process parameters as well as by material properties. Mass transfer is occurring in the potato tissue as water is transferred to and evaporating at the surface and oil is absorbed. Hence, affecting this parameter may affect the frying behaviour and quality attributes of the French fries. Pulsed electric field (PEF) technology can be used as a pre-treatment in order to achieve cell disintegration within plant raw materials by cell membrane electroporation. The resulting enhancement of mass transfer processes was shown for several applications such as extraction or drying already. A pre-treatment of potato by PEF was investigated in order to determine its effect on frying behaviour and quality of French fries. For PEF pre-treated samples, a faster transfer and removal of water was observed during frying resulting in lower moisture content at earlier stages of the frying process. As a consequence, the crust formation was found to be more intense and texture analysis revealed a harder crust texture. A reduced fat-uptake was found for PEF pre-treated samples during finish-frying. Less browning of the French fries was observed due to a promoted release of reducing sugars from disintegrated cells at the product surface. In a similar study, an ultrasound assisted frying process was investigated focusing on microstreaming effects generated in the oil during frying. Some results on heat and mass transfer modifications will be discussed and compared with the frying behaviour of PEF pre-treated samples in order to further elaborate underlying mechanisms. The PEF pre-treatment of potato prior to frying showed a promising potential to reduce the fat uptake of French fries and to modify the colour as well as the crust formation.

Affecting the frying behaviour and quality characteristics of French fries by PEF pre-treatment

APICELLA, PIETRO;BARBA, Anna Angela;LAMBERTI, Gaetano;
2011

Abstract

Frying of potato for French fries production is a complex process including a combined heat and mass transfer. Evaporation of water, starch gelatinization, fat uptake, crust formation and colour development are key aspects that are affecting the sensorial attributes and that are controlled by process parameters as well as by material properties. Mass transfer is occurring in the potato tissue as water is transferred to and evaporating at the surface and oil is absorbed. Hence, affecting this parameter may affect the frying behaviour and quality attributes of the French fries. Pulsed electric field (PEF) technology can be used as a pre-treatment in order to achieve cell disintegration within plant raw materials by cell membrane electroporation. The resulting enhancement of mass transfer processes was shown for several applications such as extraction or drying already. A pre-treatment of potato by PEF was investigated in order to determine its effect on frying behaviour and quality of French fries. For PEF pre-treated samples, a faster transfer and removal of water was observed during frying resulting in lower moisture content at earlier stages of the frying process. As a consequence, the crust formation was found to be more intense and texture analysis revealed a harder crust texture. A reduced fat-uptake was found for PEF pre-treated samples during finish-frying. Less browning of the French fries was observed due to a promoted release of reducing sugars from disintegrated cells at the product surface. In a similar study, an ultrasound assisted frying process was investigated focusing on microstreaming effects generated in the oil during frying. Some results on heat and mass transfer modifications will be discussed and compared with the frying behaviour of PEF pre-treated samples in order to further elaborate underlying mechanisms. The PEF pre-treatment of potato prior to frying showed a promising potential to reduce the fat uptake of French fries and to modify the colour as well as the crust formation.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/3094005
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