Influence of process variables on colour changes, carotenoids retention and cellular tissue alteration of cherry tomato during osmotic dehydration

Osmotic dehydration is an appropriate technique for preserving nutritional components that are naturally present in different vegetables. In order to quantitatively evaluate changes induced by osmotic treatment in CIEL*a*b* colorimetric parameters and lycopene and β-carotene content, cherry tomato in halves (L. esculentum var. cerasiforme cv. Cocktail) were osmotically treated by immersion in different solutions (a 20% w/w, NaCl solution, a 55 Brix sucrose solution and a ternary solution (10% NaCl and 27.5% sucrose)) at 30, 40 and 50 °C for 24 h. The alteration suffered by the cellular tissue was also analysed by means of microscopic observations. The obtained results showed a general increase in a* and b* coordinates resulting from the concentration of the liquid phase and a decrease in lightness as a consequence of the enhancement in sample opacity. Regarding carotenoids content, an increase in lycopene and β-carotene was observed in samples osmotically dehydrated at moderate temperatures (30 °C and 40 °C) with the solutions that include sucrose on its composition. In addition, microscopic observations revealed a direct relationship between the integrity of the cellular matrix and the preservation or even synthesis of lycopene and β-carotene.