Osmotic and membrane distillation for the concentration of tomato juice: Effects on quality and safety characteristics
The aim of this study was to evaluate the utilization of osmotic distillation, membrane distillation, and coupled operation of these systems as an alternative to the conventional thermal evaporation (CTE) technique for the oncentration of tomato juice. Some physicochemical characteristics of the products obtained by different techniqueswere determined. The samples concentrated bymembrane systemsweremore advantageous bymeans of many parameters investigated, especially for color, hydroxymethylfurfural (HMF) and furan formation.HMF and furan contentswere increased up to three to four times after CTEwhile therewas no statistical change aftermembrane concentrations.Ascorbic acid and dehydroascorbic acid levelswere decreased significantly after all concentration operations. Nonetheless, as total vitamin C content, membrane systems were more advantageous compared to CTE. Sensorial evaluation also showed that, except consistence, products obtained by membrane techniques gained higher scores than thermally concentrated products. Industrial Relevance: The quality of tomato paste is dependent on process conditions used to convert the tomato pulp into paste. Conventional thermal evaporation may result in the deterioration of product quality by damaging heat sensitive tomato juice components as well as inducing color changes. Moreover, some mutagenic and carcinogenic compounds such as furan and HMF may be formed. Concentration of tomato juice usingmembrane systems can be proposed as the promising alternative to the CTE sincemost of the characteristics, especially color, are preserved, and HMF and furan formations are reduced significantly by these processes. © 2015 Elsevier Ltd. All rights reserved.