Effects of different drying pretreatments and methods on physicochemical and sensory properties of leek (Allium porrum L.)

In this work, fresh leeks (Allium porrum L.) were performed pre-treatments such as boiled in hot water and boiled in salted hot water and drying process was carried out by using two different drying methods; tray dryer and microwave dryer. In the tray dryer, 60oC temperature, 2 m/s airflow rate, %10 relative humidity and 3cycles/min tray speed was been worked with. In the microwave dryer, because of increasing drying time with reducing amount of water in the content of leek, different microwave power levels were been worked. For the first 70 minutes 3200 W, then the power levels were gradually increased at certain time intervals like such as 4000, 4480 and 5040 W. As a result of the during process, the fastest group in the tray dryer was the control group, the fastest group in the microwave dryer was the boiled in salted water. Pretreatments applied to fresh leek slowed down the drying rate in the tray dryer, while pretreating boiling in salted water in the microwave dryer accelerated drying. Leek samples were applied as moisture, aw, rehydration, total phenolic substance, DPPH, ascorbic acid, pH, titratable acidity and sensory analysis. As results of the analyses, the control group in the tray dryer received the best score in color sensory evaluation. The total amount of phenolic substance was determined in the control groups dried by both drying methods. However, it was found to be lower in pretreated groups. While the amount of ascorbic acid was lower in the pre-treatment groups, the control groups had the highest value after the fresh leeks. In both methods of drying the groups with the best rehydration were pre-treaeted leeks. Dried leeks were subjected to 4 weeks of accelerated shelf life test at 45oC with some physicochemical analyzes.