ABSTRACT

Ginger and turmeric rhizomes were collected from Orie Ugba Market in Umuahia Abia State. After washing and slicing, both rhizomes were dried using two drying methods; sun drying (for four days) and oven drying (at temperature 110°C for 1 hr 15 mins). The dried rhizomes were then milled into fine powders before the commencement of diverse analysis. The ginger and turmeric samples where characterized in terms of vitamins, minerals and phytochemicals composition. The antioxidant properties (DPPH scavenging and FRAP reducing power) ofthe extracts were also evaluated. The result of this study shows that drying has significant influence on the vitamin, mineral, phytochemical as well as antioxidant activity of ginger and turmeric. All the parameters ofthe samples evaluated increased on drying except vitamin C and antioxidant (DPPH scavenging and FRAP reducing) activities. For the ginger samples, oven drying technique had a positive effect by retaining and increasing the calcium (57.35mg/100g), potassium (287.5mg/100g), sodium (23.42mg/100g), selenium(0.39mg/100g) and phenol (2.49%) contents ofthe ginger samples, while the Sun-drying technique favoured the vitamin C (5.75mg/100g.), alkaloid (3.63%), saponin (5.54%) and flavonoid (6.43%) contents of the ginger samples. There was no significant difference (P>0.05) between the beta carotene and tannin contents of the oven-dried and sun-dried ginger samples. For the turmeric samples, oven drying method had a positive effect by retaining and increasing the beta carotene (2.97mg/100g), calcium (26;37mg/100g), potassium (1522.7mg/l 00g), sodium (90.25mg/100g), selenium (0.54mg/100g) and phenol (1.71%) content ofthe turmeric samples while sun-drying method retained and increased the vitamin C (9.67mg/100g), flavonoid (2.57%) and tannin (0.37%) contents. No significant difference existed (P>0.05) between the alkaloid and saponin contents of oven-dried and sun-dried turmeric samples. The sun-drying technique exhibited more antioxidant DPPH scavenging (50.77% and 56.96%) and FRAP reducing (43.51% and 41.49%) activities in ginger and turmeric samples respectively. The results in. this study could help the consumer in the selection ofthe suitable option for drying ginger and turmeric regarding antioxidant, phytochemical and micronutrient purposes