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CECLU, Liliana; BERBEC (CTRCHELAN), Ana; NISTOR, Oana Viorela; RUDI, Ludmila. Effect of drying conditions on the physical properties of red beetroot samples. In: Microbial Biotechnology. Ediția 3, 12-13 octombrie 2016, Chișinău. Chișinău, Republica Moldova: Institutul de Microbiologie şi Biotehnologie, 2016, p. 97.
Ediția 3, 2016
Conferința "Microbial Biotechnology" |
Chișinău, Moldova, 12-13 octombrie 2016
Drying is an important unit operation and one of the oldest ways of food preservation. The main objectives in drying food products is the removal of water up to a certain level, at which microbial spoilage and deterioration chemical reactions are greatly minimized, weight and volume reduction, intended to decrease transportation and storage costs. Hence, this study aims to evaluate the influence of different drying methods on the drying kinetics and physical properties of red beetroot slices (Beta vulgaris L. var. Cylindra). Drying behaviour of red beetroot samples was investigated by free convection method (at different temperature ranging between 50°C and 70°C) and microwave combined method (a triple combination consisting of the free convection followed by forced convection simultaneously with microwave at different powers). Convection redices drying time from 360 min to 270 min as the air temperature increased from 50 to 70°C. While drying time of combined method, was reduced from 147 min to 126 min, once with increasing microwave power. The drying characteristics curves were evaluated against the Page, Henderson and Pabis, and the Logarithmic mathematical models but the Page model best described the drying process of red beetroot slices. The effective moisture diffusivity coefficient increased with increasing drying temperature (at 50°C - 3.59x10–8m2 s-1, at 60°C - 4.55x10–8m2 s-1, at 70°C - 6.58x10–8m2 s-1) and microwave powers (at 105W - 1.45x10-V s-1, at 210W - 2.64x10–7m2 s-1, at 315W - 4.68x10–7m2 s-1) with activation energy for moisture removal of 27.60 kJ mol-1 (for convection drying process) and 11.591 W g-1 (for microwave combined method).