Abstract
Food drying is one of the most ancient techniques employed to preserve specific perishable commodities, enhancing preservation, minimizing packaging needs, and decreasing shipping weight. This study aimed to assess the impact of oven, sun, and room drying techniques on the nutritional quality of onions. Proximate and mineral constituents were examined in both fresh and dried onion samples utilizing established analytical methodologies. The proximate analysis results indicated a considerable reduction in moisture content (P<0.05) in onions dried by all techniques compared to fresh onions. Conversely, the amounts of ash, crude protein, crude fiber, and carbohydrate significantly increased (P<0.05) in onions subjected to all drying procedures compared to fresh onions. Crude lipid content considerably (P<0.05) increased in sun-dried onion and decreased in room-dried onion, but no significant (P>0.05) difference was observed in oven-dried onion compared to fresh onion. A considerable increased (P˂0.05) in mineral content was detected during drying, with the exception of magnesium, which maintained the same concentration post-drying. Sodium, potassium, calcium, and phosphorus were the primary macronutrients present in all samples. The concentrations of magnesium and zinc considerably increased (P<0.05) during drying, with the greatest values recorded for room drying (0.13±0.00 to 0.33±0.00 and 0.17±0.00 to 0.36±0.00, respectively). The concentrations of aluminum, iron, and copper ranged from 0.21±0.01 to 0.92±0.02, 1.57±0.81 to 8.05±1.07, and 0.01±0.00 to 0.02±0.00, respectively, across all drying procedures. The study showed that drying methods (sun, oven, and room) eliminated more than 70% of the total moisture content while preserving and enhancing the concentration of both organic and mineral elements, with room drying yielding the most favorable results. Oven and sun drying may be better for desiccating onions having the duration time between 48hrs-8days.

Key words: Allium cepa L, desiccation, proximate analysis, mineral content