OULAI Dehegnan Penan Patricia^1,, TOURE Naka¹, LIBRA Michel Archange¹, NIAMKE Lamine Stébastien²

Onions, grown and consumed in many countries around the world for their nutritional, therapeutic, and economic qualities, are prone to storage problems due to their high water content. Processing this fruit vegetable could be a solution to reduce post-harvest losses during periods of abundance. To this end, the influence of two drying methods (sun drying and shade drying) on the biochemical, microbiological, and organoleptic characteristics was studied. The onions were pretreated with boiling water and steam for 5 minutes, then dried for 7 days at an average temperature of 33°C in the sun and at room temperature (22 ± 2°C) in the shade. The results of biochemical analyses reveal that drying significantly reduces the water content of fresh yellow onions from 89.90% to 22.50%. There is also a variation in ash content (1.50 to 4.84%), titratable acidity (20.05 to 44.37 mEq/100g), total polyphenol content (81.97 to 340.37 mg EAG/g), flavonoid content (24.97 to 326 mg EQuer/g), and minerals Ca (4961±2 to 7399±0.5), Fe (147.1±1 to 476.9±0.6), Mg (734±1 to 294.6±0.6), Zn (29.6±0.6 to 46.6±1.40). The microbiological characteristics indicate the presence of mesophilic aerobic bacteria (5.55 × 10³ to 6.25 × 10⁴ CFU/g), total coliforms (4.35 × 10³ to 5.2 × 10³ CFU/g), fecal coliforms (4.65 × 10³ CFU/g), and an absence of yeasts and molds, E. coli, and ASR. The results of sensory analyses show that samples blanched with steam and dried in the shade were more appreciated by tasters for their color, taste, and smell. All these results constitute added value for the onion and will serve to reduce post-harvest losses.

Onion, post-harvest losses, drying, pre-treatment, preservation, Korhogo