Acta Chimica Slovaca (ACS) publishes papers on fundamental and applied aspects of chemistry, biochemistry, chemical technology, chemical engineering and process control, biotechnology and food technology. Welcome are also topics which include chemical aspects of materials, physical chemistry and chemical physics, analytical chemistry, macromolecular chemistry and biomedical engineering.

Batch drying of sliced tomatoes at specific ambient conditions

Mohammad Jafar Royen *, Abdul Wasim Noori, Juma Haydary a

Institute of Chemical and Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, 81237 Bratislava, Slovakia
Faculty of Chemical Technology, Kabul Polytechnic University, Kart-e Mamoorin, Kabul, Afghanistan
a Institute of Chemical and Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, 81237 Bratislava, Slovakia

E-mail: *,

Abstract: In this work, drying of tomato slices was studied in a laboratory scale batch dryer working at conditions specific for geographical locations with low ambient pressure and low relative humidity of air. Tomato is a perishable farm product with high moisture content. Despite their high value, tomatoes are subjected to wastage and spoilage during their seasonal period; to last longer after harvested, they need to be treated by drying. Drying is one of the most widely used methods of tomato preserving for a longer period of time. This study involves experimental work on tomatoes drying in a tray laboratory batch dryer with the dimensions of (490 × 330 × 310) mm, a load cell-force sensor (range: 0—5 kg), fan (speed: 0—2500 rpm), air flow sensor (0—150 l/min) and a temperature and humidity monitoring system. This study was aimed at the development of a suitable drying method for the production of dehydrated agricultural products under specific air properties and climate conditions such as low ambient pressure and low relative humidity. During the experiment, the average ambient pressure was 82 kPa, and the average relative humidity of air was 20 %. Drying characteristics of tomato slices were determined at three temperature levels, namely: 50 °C, 60 °C and 70 °C,and three air flow rates: 30 l/s, 40 l/s and 50 l/s, for each temperature level. In this study, the effect of temperature, air flow rate, and ambient conditions on the drying rate of tomato slices were studied. The results indicate that during the experiments, tomatoes were dried to the final moisture content of 32.2 % from 92 %. Drying time at 50 °C, 60 °C and 70 °C, and air flow of 30 l/s was 17.80 h, 15.80 h, and 14.08 h, respectively. For the air flow rate of 40 l/s, the drying time was 15.0 h, 12.9 h and 11.7 h and for the air flow rate of 50 l/s, the drying time of tomato slices was 14.0 h, 11.6 h and 10.2 h, respectively.

Keywords: Batch drying, upland condition, sliced tomatoes, drying temperature, humidity

Full paper in Portable Document Format: acs_0310.pdf

Acta Chimica Slovaca, Vol. 11, No. 2, 2018, pp. 134—140, DOI: 10.2478/acs-2018-0019