A research on producing alternative herbal tea with natural herbal extracts

Thesis Type: Doctorate

Institution Of The Thesis: Bursa Uludağ University, ZİRAAT FAKÜLTESİ, GIDA MÜHENDİSLİĞİ, Turkey

Approval Date: 2014

Thesis Language: Turkish


Supervisor: Ömer Utku Çopur


In this research, melissa (Lippia citriodora), linden (Tilia argentea), coneflower (Echinacea purpurea), sage (Salvia triloba) rosemary (Rosmarinus officinalis), heather (Erica arborea), green tea (Camellia sinensis), mate (Ilex paraguarensis) herbs and a herbal mix (rosemary, heather, green tea, mate, linden) were used as raw material for herbal tea beverage production. For this aim, two different production methods [sucrose added beverage (1) and energy reduced beverage (2)] were applied. Beyond these two methods, three more subproducts were manufactured which were named as herbal tea beverage (A), carbonated herbal tea beverage (B) and natural mineral water added herbal tea beverage (C). Analysis of moisture, ascorbic acid, color (L, a, b), minerals (Fe, Ca, Mg, K, Na), total antioxidant capacity (DPPH, FRAP, CUPRAC), total phenolic compounds and bioavailability (total antioxidant activity and total phenolic compounds) were carried out for raw material of herbal tea beverages. In addition, volatile oils were extracted from raw material and subjected to volatile compound analysis with GC-MS. Water soluble dry matter content of the beverages were changed between 4,80-5,93 and 7,43-8,40 g/100g for energy reduced and sucrose added beverages respectively. Minimum and maximum values of beverage results were given as follows; total acidity 0,11 and 0,22 g/100mL (sitric acid), pH 2,93 and 3,93, total ascorbic acid content 15,17 and 31,46 mg/100mL, L values 11,47 and 22,00, a values -11,30 and -0,23, b values 0,40 and 8,93, turbidity 0,40 and 9,60 NTU, Fe 0,01 and 2,04 mg/L, Ca 37,26 and 161,35 mg/L, Mg 15,20 and 67,40 mg/L, K 14,40 and 222,28 mg/L, Na 6,35 and 107,56 mg/L. Besides, total antioxidant capacity with chemical and physiological extracts (bioavailability) were determined as in DPPH method 12,67-27,81 and 6,53-16,83 µmol troloks/mL, in FRAP method 13,56-51,12 and 2,78-22,45 µmol troloks/mL and in CUPRAC method 17,72-123,11 and 0,02-13,97 µmol troloks/mL respectively. Total phenolic compounds of chemical and physiological extracts were ranged between 172,57-587,32 and 90,78-2255,70 mg gallic acid equivalent/100mL. Beverages were also analyzed for color, odor, appearance and taste criteria with ranking test and hedonic test for sensory evaluation. It has been shown that, selected herbs were available for herbal tea beverage production.