title: Volatile compounds and changes in flavour-related enzymes during cold storage of high-intensity pulsed electric field- and heat-processed tomato juices.
abstract: BACKGROUND
  The effects of high-intensity pulsed electric field (HIPEF) processing (35 kV cm(-1) for 1500 micros, using 4 micros bipolar pulses at 100 Hz) on the production of volatile compounds and flavour-related enzymes in tomato juice were investigated and compared with those of thermal processing (90 degrees C for 30 or 60 s).
  
  
  RESULTS
  Tomato juice treated by HIPEF showed lower residual lipoxygenase (LOX) activity (70.2%) than juice heated at 90 degrees C for 60 s (80.1%) or 30 s (93.2%). In contrast, hydroperoxide lyase (HPL) was almost completely inactivated when the juice was subjected to 90 degrees C for 60 s, whereas roughly 50% of the control tomato juice was depleted after HIPEF treatment or thermal processing at 90 degrees C for 30 s. A slight decrease was observed in the initial LOX activity of treated and untreated samples during storage, whereas initial HPL activity was strongly affected over time.
  
  
  CONCLUSIONS
  HIPEF-treated juice exhibited higher levels of compounds contributing to tomato aroma than untreated and heat-treated juices throughout storage. Thus HIPEF processing can preserve flavour quality and stability of tomato juice compared with conventional thermal treatments.
authors.affiliation: Department of Food Technology, TPV-XaRTA, University of Lleida, Rovira Roure 191, Lleida, Spain.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Aguiló-Aguayo
authors.forename: Robert
authors.initials: R
authors.lastname: Soliva-Fortuny
authors.forename: Olga
authors.initials: O
authors.lastname: Martín-Belloso
mesh_terms: D000446:Aldehyde-Lyases / Q000378:metabolism; D001628:Beverages / Q000592:standards*; D003080:Cold Temperature; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004560:Electricity; D004798:Enzymes / Q000378:metabolism*; D005511:Food Handling / Q000379:methods; D005519:Food Preservation / Q000379:methods*; D005638:Fruit / Q000378:metabolism*; D006358:Hot Temperature; D008084:Lipoxygenase / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism*; D013649:Taste; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D004798:Enzymes; D055549:Volatile Organic Compounds; D003577:Cytochrome P-450 Enzyme System; D008084:Lipoxygenase; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase