Evaluation of Phytochemical, Nutritional and Antioxidant Properties of a Functional Tea Prepared from Blends of Local Spices Utazi (Gongronema latifolium), Nchanwu (Ocimum gratissium) and Tumeric (Curcuma longa)

Abstract

The study assessed the phytochemical, nutritional and antioxidant properties of a functional tea made from mixture of Utazi leaf Gongronema latifolium), Nchanwu leaf (Ocimum gratissimum) and Turmeric rhizome (Curcuma longa). The three spices were individually processed by drying and mincing before combining them at different ratios that resulted to 16 samples. The samples were generated through D-optimal mixture design using statistical software (Design Expert version 12). The samples were evaluated for phytochemical, nutritional and antioxidant properties. The fresh raw materials were destalked (for the leaves), sorted, washed, withered, oxidized for 24 h, oven dried at 60oC for 30 min, cooled and milled, and packaged. Fresh turmeric rhizome were sorted, washed blanched at 90oC for 2 min, cooled, peeled, sliced, oven dried at 60oC for 30 min, cooled, milled and packaged in teabags and high density polyethylene. The alkaloids, saponin, phenol, cardiac glycoside, flavonoid, tannin, steroid and anthocyanin content ranged from 12.00-22.00, 0.42-1.15, 11.67-15.63, 0.06-0.67, 12.67-22.00, 0.56-0.89, 1.00-1.67, 46.00-54.00 mg/100g respectively. The vitamin C and E content ranged from 3.03-4.13, 0.31-0.64 mg/100g respectively. The minerals iron and zinc content of the tea samples ranged from 3.53-4.70, 0.06-0.78 ppm respectively. The sensory evaluation score of the tea infusion of the sample AB and DA were ‘liked very much’ with the rating of 8.60 and 8.20 respectively, these samples were more acceptable to the panelist. The antioxidant scavenging activity ranged from 42.00-47.00% with sample EC exhibiting the highest level of activity, and the proportion was 70g, 24.62g, 5.38g of Utazi leave, Nchanwu leave, and Turmeric rhizome.