Thesis (M.Sc.)--Chulalongkorn University, 2008

This research aimed to develop sterilized mixed herbal drink product formula and processes from Imperata cylindrical (L.) P. Beauv. [IM], Murdannia loriformia (Hassk.) Rolla Rao et Kammathy [ML], Hedyotis corymbosa Lamk. [HC], and Orthosiphon aristatus Miq [OA]. The chemical composition and potassium content of the herbs were analyzed. The appropriate extraction condition using herb: water ratio of 1: 49, and extracting at 70 ℃ , 80℃ and 90 ℃ for 30, 45 and 60 minutes were investigated. The formula of mixed herbal drink was developed to determine the proportion of each herbal infusion and sugar level. The most acceptable formula of mixed herbal drink was then sterilized at 130℃, 135 ℃ and 140 ℃ to obtain F[subscript 0] of 3, 4 and 5 minutes and filled in PET bottle then all samples were investigated. The sterilized mixed herbal drink was kept at 30℃ for 4 months and at 45 ℃ and 55℃ for 2 months. Changes in the physical, chemical, microbiological properties and panelists’ preference of the samples were determined every week during storage. From the study, all herbs had high amount of fiber (24.11-60.45%) and low amount of protein (1.16-10.96%) and fat (0.46-10.12%). ML and OA had the high amount of potassium (2.01% and 1.35%). Increasing extraction temperature and time caused darker product, reduction in antioxidant activity and ascorbic acid but increasing in total phenolic compounds and potassium. From response surface methodology, the most appropriate extraction condition was 74.6 ℃ for 41 minutes. The most acceptable formula contains 14% IC infusion, 35% ML infusion, 27% HC infusion, 17% OA, and 7% sugar. Increase F[subscript 0] in sterilization step resulted in darker product and reduction in antioxidant activity and total phenolic compounds, but did not affect pH, total soluble solid, and potassium. Moreover, no microorganism was detected in all samples. The most appropriate sterilization process was 135.4℃ with F[subscript 0] = 3 minutes. Increasing storage time and temperature caused a decrease in antioxidant activity and total phenolic compounds and increase in panelists’ preference. Total phenolic compoundswere predicted to deplete absolutely in the week 27[superscript th]at 30 ℃