Batch drying of sliced tomatoes at specific ambient conditions

Abstract

In this work, drying of tomato slices was studied in a laboratory scale batch dryer working at conditions specifi c 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 fl ow 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 specifi c 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 fl ow rates: 30 l/s, 40 l/s and 50 l/s, for each temperature level. In this study, the effect of temperature, air fl ow 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 fi nal moisture content of 32.2 % from 92 %. Drying time at 50 °C, 60 °C and 70 °C, and air fl ow of 30 l/s was 17.80 h, 15.80 h, and 14.08 h, respectively. For the air fl ow rate of 40 l/s, the drying time was 15.0 h, 12.9 h and 11.7 h and for the air fl ow rate of 50 l/s, the drying time of tomato slices was 14.0 h, 11.6 h and 10.2 h, respectively.

Experimental Study and Mathematical Modeling of Convective Thin-Layer Drying of Apple Slices

“…Sliced apples were placed on perforated trays in the tunnel of the load cell; the balance and load cell were connected to the control interface box and data acquisition software with balance calibration option. A more detailed description of the experimental set-up is given in our previous work [26]. Each batch comprised 300 ± 2 g of apples.…”

Monitoring Temperature Profile and Drying Kinetics of Thin-Layer Banana Slices under Controlled Forced Convection Conditions

“…To represent and explain the single-layer drying of fruits and vegetables, the researchers created theoretical, semi-theoretical, and empirical equations [4] for bananas [25][26][27], tomatoes [28], and garlic [29].…”

An active indirect solar system for food products drying

“…Drying is the most used and most suitable method for agricultural products preservation (Srisittipokakun et al, 2012). The most popular and current techniques for agricultural products dehydration include open sun drying (Akpinar, 2010), solar drying (direct and indirect) (Mohamed et al, 2008), convective drying (Royen et al, 2018), drum drying (Mujumdar, 2014), spray drying (Sormoli and Langrish, 2016), fl uidized-bed drying (Senadeera et al, 2013), freeze drying (Kudra and Mujumdar, 2009), microwave drying (Pu et al, 2016), osmotic drying (Karam et al, 2016), vacuum drying (Sagar and Kumar, 2010), ultrasound drying (Mulet et al, 2003), etc. However, drying is generally an energy-intensive operation and it can signifi cantly affect the cost of the product.…”