Osmotic dehydration of bell peppers: influence of high intensity electric field pulses and elevated temperature treatment

Osmotic dehydration of bell peppers using sucrose and sodium chloride as osmotic agents as influenced by moderate thermal treatment (25-55 degreesC) and high intensity electric field pulses at varying field strengths (E = 0.5-2.5 kV/cm) was Studied. Two product quality indicators (vitamin C and carotenoids) were evaluated. Increasing temperature resulted in water loss from 32% to 48% and increasing field strength resulted in water loss from 36% to 50% of initial moisture content. Both conditions enhanced solid gain during osmotic dehydration of bell pepper. Air drying reduced vitamin C to approximately 5% of initial concentration while increasing temperature (25-55 degreesC) during osmotic dehydration decreased residual vitamin C concentration after osmotic dehydration from 20% to 4% and high intensity electric field (2.5-0.5 kV/cm) decreased it from 13% to 7% of initial value. Carotenoids reduced from 80% to 55% as a result of temperature increase and from 74% to 62% of initial fresh content as a result of high intensity electric field pre-treatment. Results obtained at field strength 2.5 kV/cm were comparable and in some cases better than those at elevated temperature of 55 degreesC suggesting high intensity electric field as an attractive alternative to conventional thermal processing. (C) 2002 Published by Elsevier Science Ltd.