Effect of processing methods on nutritional, phytochemical and sensory properties of powdered herbal tea from bushbuck leaf (Gongronema latifolium)

Abstract

Powdered herbal bushbuck leaf tea is a functional powdered beverage produced using modified technological methods of green, white and oolong tea of countries such as Japan and China, among others. The leaves were processed into green, white and oolong tea powders which were evaluated for proximate, selected micronutrients, phytochemical and sensory properties. Conventional commercial Camellia sinensis powdered tea products served as reference powdered tea samples. Proximate composition (%) of the bushbuck leaf powdered samples indicated that moisture content varied from 11.56-12.51, ash: 10.41-12.31, fat: 2.92-4.36, protein: 10.41-13.73, fibre: 9.67-11.00 and carbohydrate: 48.28-41.45. Calcium, sodium and potassium contents ranged from 0.60-0.80, 1.01-1.40 and 2.32-3.10 mg/l, respectively. The provitamin A contents ranged from 2.52-4.50 IU and vitamin C; 30.20-35.00 mg/100g. Alkaloid contents ranged from 3.15-3.61%, while flavonoid composition varied from 6.36 and 7.11%. Sensory attribute scores for the tea infusion showed that oolong tea infusion was more acceptable by the panellists than others. Hence, functional herbal tea powdered samples could be processed from bushbuck leaves which might be a leeway to commercial production of tea samples that can assist in the maintenance of healthy lifestyle on regular consumption.

Keywords: Bushbuck leaf, drying, plate mill, powered herbal tea, withering