Abstract

The influence of a radio-frequency heating process on some quality parameters of tomato puree during pasteurisation was investigated. The innovative process uses radio-frequency electric fields (27.12 MHz) in combination withdeionised water as dielectric coupling medium. The stability of both colour and L ascorbic acid as well as the formation of5-hydroxymethylfurfural (HMF) during radio-frequency heating were compared to those during conventional heating of tomato puree in a water bath and a stirred reactor. The results suggest that radio-frequency heating has a positive impact on the nutritional quality of tomato puree by preserving endogenous antioxidants and colour characteristics. The high retention of the thermally unstable L-ascorbic acid and the minor formation of HMF after radio-frequency heating indicate a gentlepasteurisation process. This new rapid heating technique bears a large potential to reduce thermal load during food processing and to improve nutritional quality.