OPTIMIZATION OF PROCESS PARAMETERS FOR THE OSMOTIC DEHYDRATION OF BEETROOT IN SUGAR SOLUTION

ABSTRACT Water and sugar transfer were quantitatively investigated during osmotic dehydration of beetroot slices using response surface methodology with the temperature (25–45C), processing time (30–150 min), sugar concentrations (20–60% w/w) and solution‐to‐sample to ratio (5:1–25:1) being the independent process variables. Quadratic regression equations describing the effects of independent process variables on the water loss (WL), solid gain (SG) and water reduction were developed. It was found that immersion time and concentration of sugar solution were the most significant factors affecting the WL during osmotic dehydration of beet root followed by temperature. Effect of temperature and time were more pronounced for SG than the concentration of sugar solution. The osmotic dehydration process was optimized for water loss, solute gain, and weight reduction. The optimum conditions were found to be: temperature 33.64C; immersion time 115.37 min; sugar concentration 27.71%; and solution‐to‐sample ratio 17.5:1. At these optimum values, water loss, solid gain and weight reduction were found to be 53.74 (g/100 g initial sample), 8.34 (g/100 g initial sample) and 45.41(g/100 g initial sample), respectively. PRACTICAL APPLICATIONS Osmotic dehydration is one of the preservation techniques, which increase the shelf life of the food material. The quality of preosmosed beetroots is much superior than the one obtained from the conventional dehydration. The osmotically dehydrated beetroots can be used for cooking asvegetables after rehydration. It is also used for making juice, wine, pickles and as colorants.