Drying rate of onion (Allium cepa L.) drying using air dehumidification with silica gel

Onions (Allium Cepa L.) is one of the most popular seasoning in the world. Besides of its seasoning function, onion contains several vitamins, such as vitamins B, vitamin C, iron, calcium, and other chemical compounds. Drying using air dehumidification can be option to enhance the storage life of onion during harvest season. In this study, the onion was dried from initial moisture content 83% wet basis to 17% wet basis using tray dryer equipped with silica gel as the air adsorbent. The onion was sliced and then was dried for 120 minutes under various drying temperatures (40-70°C) and the air velocity is 6.5 m/s As the response, the moisture content and anthocyanins content were observed. The onion drying was conducted using sun drying as the comparison. The experimental data was then used for calculating the drying rate and the drying time. Result showed that the higher drying temperatures and higher air velocity speed up the drying time. The sun drying needs longer drying time, up to 8 days. The anthocyanin content was affected by the drying temperature.