Validation of Pasteurisation Temperatures for a Tomato–Oil Homogenate (salmorejo) Processed by Radiofrequency or Conventional Continuous Heating

Abstract

Salmorejo is a viscous homogenate based on tomato, olive oil and breadcrumbs commercialised as a “fresh-like” pasteurised–chilled purée. Due to its penetration, dielectric heating by radiofrequency (RF) might improve pasteurisation results of conventional heating (CH). The objective was to val-idate the pasteurisation temperature (70–100 °C, at 5 °C intervals) for salmorejo processed by RF (operating at 27.12 MHz for 9.08 s) or conventional (for 10.9 s) continuous heating. The main heat-induced changes include: orangeness, flavour homogenisation, loss of freshness, thickening, loss of vitamin C and lipid oxidation. Both CH and RF equivalent treatments allowed a strong re-duction of total and sporulated mesophilic microorganisms and an adequate inhibition of the pectin methylesterase, peroxidase and, to a lesser extent, polyphenol oxidase but did not inhibit the pol-ygalacturonase enzyme. Pasteurisation at 80 °C provided a good equilibrium in levels of microbi-ological and enzymatic inhibition and thermal damage to the product. Increasing this temperature does not improve enzyme inactivation levels and salmorejo may become overheated. A “fresh-like” good-quality salmorejo can be obtained using either conventional or radiofrequency pasteurisers.