THE INFLUENCE OF DRYING CONDITIONS ON THE EFFECTIVE MOISTURE DIFFUSIVITY AND ENERGY OF ACTIVATION DURING THE HOT AIR DRYING OF RED BEETROOT

The main goals of the present work are the influence of drying characteristics on red beetroot, effective moisture diffusivity determination and the activation energy. The drying characteristics of red beetroot were investigated theoretically and experimentally by convection drying at different air temperatures, ranging 50 – 80ºC and relative humidity 30,6 – 53,8%. Red beetroot samples were dried from moisture content of 88,84±0,35% until 9.88±0.5%. The results have shown that, increasing the drying air temperature causes shorter drying times from 450 min to 240 min. Moisture transfer from red beetroot samples was described by applying the Fick’s diffusion model. The effective diffusivity coefficient of moisture transfer varied from 1,471x10-8 to ,.8145 x10-8 m2 /s in first stage and 6,0094 x10-8 to 1,19x10-7m2 /s in second stage of drying process, over the temperature range analised. The temperature dependence of the diffusivity coefficients was described by Arrhenius type relationship and was found to be 22,33 kJ/mol in first stage and 19,85kJ/mol in second stage of drying process. The research aimed to establish the kinetics of the drying process of red beetroot, in order to investigate the optimal drying parameters for this vegetabl

A Complex Characterization of Pumpkin and Quince Purees Obtained by a Combination of Freezing and Conventional Cooking

Two main sources of fibers and bioactive compounds represented by pumpkin (Cucurbita maxima L.) and quince (Cydonia oblonga Mill.) were selected for the present study. The current changes in consumers behavior oblige manufacturers to develop new assortments of ready-to-eat products, considering their nutritional characteristics. Hence, this study aimed to process free sugar pumpkin and quince puree using a combination of freezing (−15 °C) and cooking at 95 °C for 20 min. Four variants of purees were obtained by using different combinations between pumpkin and quince (pumpkin puree, quince puree, and pumpkin and quince puree in ratios of 1:1 and 3:1). The samples were characterized in terms of complex interconnected analysis, which could provide further information for the added-value products. Thus, highest values of β-carotene content were attributed to pumpkin puree (P −5.34 ± 0.05 mg/g DW) and pumpkin and quince puree 3:1 (PQ 3:1 −3.78 ± 0.014 mg/g DW). These findings are also supported by the values of ABTS inhibition, which was registered as 71.32% for the P sample and 76.25% for the PQ 3:1 sample. The textural analysis revealed firmness values of 1.27 N for pumpkin puree and 2.33 N for quince puree. Moreover, the structural changes were minimum, while the cellular structure and some tissues were preserved intact

Three Types of Red Beetroot and Sour Cherry Based Marmalades with Enhanced Functional Properties

The importance of bioactive compounds such as betalains and anthocyanins was highlighted in the present study by the valorization of red beetroot and sour cherry as an attempt to develop healthy products. The aim of the study was to obtain and characterize three types of marmalade based on red beetroot, sour cherry and both in 1:1 combination, obtained by heating at 95 °C for 30 min. Changes in total phenolic content, total flavonoids, betalains, anthocyanins and antioxidant activity were evaluated before and after the thermal treatment. Several other analyses such as color, rheological and textural analyses and confocal laser microscopy were performed to provide further information about the quality of the added-value food products. A significant decrease of 34% in betalains content was registered in the red beetroot marmalade due to the chemical changes in bioactives induced by the temperature. A satisfactory ABTS radical scavenging activity of 8.12 ± 0.38 mMol Trolox/g dry weight (dw) was obtained for the red beetroot and sour cherry based marmalade. The gelled structure was validated by the rheological and textural characteristics. The results highlighted the potential use of red beetroot and sour cherry as food raw materials, due to their particular profile of bioactive compounds