Modeling and Evaluation of the Osmotic Pretreatment of Tomatoes (S. lycopersicum) with Alternative Sweeteners for the Production of Candied Products

Abstract

The aim was to study the effect of alternative sweeteners on the mass transfer of osmodehydrated (OD) tomato before a traditional candying process. During OD pretreatment, osmotic solute type (sucrose S, oligofructose O, sucrose and oligofructose SO, palatinose (isomaltulose)/polydextrose and steviol glucosides and oligofructose PSO/ISO, palatinose (isomaltulose)/polydextrose and steviol glucosides and maltodextrin PSM/ISM), concentration (65–75 °Brix), and temperature (75–95 °C) effect were investigated. A multivariate analysis was conducted by means of principal component analysis (PCA) and a polynomial model was proposed, to investigate the main effects of OD on mass transfer and water activity, aw as a function of the process variables. The increase of temperature and solute concentration favored, in most cases, the increase of mass transfer. Sucrose and oligofructose were the most effective osmotic solutes for solid gain (SG)-water activity (aw) decrease and water loss (WL), respectively. To achieve increased mass transfer, SO, ISO, and PSO could be used followed by PSM and ISM. When oligofructose is used, SG and aw changes are more pronounced (desired for candying). In the contrary, when introducing maltodextrin in OD solutions, milder mass exchange phenomena are observed, in all process conditions. The total or partial substitution of sucrose with alternative sweeteners (isomaltulose, steviol glucosides) and ingredients with health benefits (oligofructose) could add significant advantages to the osmodehydrated candied product. Nonetheless, the final aw of all dehydrated tomatoes ranged from 0.80 to 0.96 indicating that OD did not lead to microbiologically stable products, and thus another processing step (e.g., air-drying) should be complimentary applied.