ENGINEERING STUDIES ON LEMON FRUIT DRYING WITHELECTRIC OVEN

Abstract

The present study aimed to assess the drying kinetic usingan electric oven dryer for drying lemon fruits using thin layer models. The drying behavior was investigated and simulated using four different thin layer drying models (Newten, Page, Modified Page, Henderson and Pabis's equations). The experimental work was conducted under two different levels of oven temperature (80 and 110°C) and, whole fruit, whole fruit with (1% NaOH) pretreatment and three different thickness (4, 5 and 6 mm). The variations in lemon moisture content was recorded versus drying time until reaching of 14.28 and 8.10 (% d.b) for whole fruit without pretreatment at (80 and 110°C), respectively, whilst it reaches (14.15, 12.86 and 14.15% d.b) at 80°C and (12.86, 14.15 and 16.82% d.b) at 110°C for lemon slices of 4, 5 and 6 mm, respectively. The whole lemon fruit with NAOH pretreatment recorded higher percentages of total crude fats (from 1.599 to 1.622%), total soluble sugar(from 6.40 to 6.80%), citric acid (from 5.95 to 6.21%) and ascorbic acid, vitamin c, (from 44.21 to 44.98 mg/100g) in comparison with the whole lemon without pretreatment and sliced lemon. Allstudied models could describe the drying behavior of whole lemon fruits and slices satisfactorily. However, the Page and Modified page models considered more proper for describing the drying behavior and predicting the changes in moisture content of both forms of lemons due to the higher values of coefficient of determination R2 (0.9896).