Use of response surface methodology to optimise vacuum impregnation of β-carotene from Daucus carota in Pachyrhizus erosus

Abstract

Consuming carotenoid-rich foods prevent and reduce certain types of cancer and cardiovascular and degenerative diseases. In this work, response surface methodology (RSM) was used to maximise β-carotene (from Daucus carota juice) vacuum impregnation into Pachyrhizus erosus (PEC) cylinders (1 mm diameter by 2 mm length). The impregnation was carried out at 40 °C, an absolute pressure of 51 mm Hg, and a 10 g carrot juice/fresh product ratio. The factors considered were the immersion time (t = 20, 30, and 40 min) and the osmotic agent concentration (C = 20, 35, and 50 °Brix). The polynomial equations obtained to predict solute gain (SG), water loss (WL), total carotenoids (TCs), total soluble solids (TSSs), and water activity (a_w) of the product had R² > 0.846. Increasing the osmotic agent concentration increased SG, TC, and TSS values and decreased WL and a_w values. From the obtained polynomial equations of the analysed responses, a quadratic effect was observed in the processing time due to the saturation of solutes on the product surface. The optimum conditions were t = 31 min and 50 °Brix, resulting in an impregnated PEC with a value of 269 μg of β-carotene/100 g dry base, 19.3 °Brix, and a_w = 0.946. It was possible to incorporate carotenoids in PEC by optimising the vacuum impregnation conditions; however, a drying treatment is necessary to increase the shelf life of the obtained product.