Development of Herbal Tea Incorporated with Gammalu (Pterocarpus marsupium L.) and Evaluation of its Quality Parameters

Abstract

Blended tea products, which are incorporated with various parts of medicinal plants and black tea or green tea, are becoming popular among a health conscious population in the world. Gammalu (Pterocarpus marsupium L.) is a common medicinal plant in Sri Lanka that is reported to have many health benefits including reduction of blood sugar levels and serum cholesterol levels in humans. Therefore, the objective of the present research was to develop herbal tea bag mixing together Gammalu and black tea. A triangle sensory test was carried out to find out the maximum percentage of Gammalu that can be added without adversely changing the sensory properties of black tea and to find out the best blend of Gammalu and black tea as a herbal tea product. The physicochemical (moisture content and ash content), microbiological as well as sensory properties of the product were determined. The 16% blend of Gammalu with black tea was selected as the best blend for herbal tea and was further tested for Total Plate Count, Coliforms and E. coli. A sensory panel of 30 untrained panelists was used to carry out the sensory tests in order to compare the sensory properties of the Gammalu tea with those of other commercially available herbal tea products in the market. Furthermore, a clinical test with 10 human volunteers was carried out to determine the effect of the product on the blood sugar levels of human volunteers after a standard meal. The moisture content and total ash content of the final product were 9.6% and 6.9%, respectively. The Total Plate Count/Aerobic Plate Count of the developed product was 2.1 x 103 CFU/g and it had a coliform count of 10 CFU/g. Further, Gammalu herbal tea did not contain E. coli. Sensory test showed significantly higher (P<0.05) sensory properties in the Gammalu herbal tea compared to other commercial herbal tea products. The consumption of Gammalu herbal tea after a standard meal appeared to reduce the blood sugar level in the blood stream in human volunteers. Hence, Gammalu herbal tea may be recommended for diabetic patients as an alternative medicine.