Characterizations of encapsulated bioactive compounds extracted from orthosiphon stamineus /
Pang Sook Fun
- Kuantan, Pahang : UMP, 2017
- xvi, 201 p. : ill. (some col.) ; 30 cm. + 1 CD-ROM
Faculty of Chemical and Natural Resources Engineering
Thesis (Doctor of Philosophy in Bioprocess Engineering) -- Universiti Malaysia Pahang – 2017
Bibliography : p. 171-195
Orthosiphon stamineus contains many medically useful bioactive components known as polyphenols. Recovery of polyphenols from O. stamineus using microwave assisted extraction (MAE) is not available in the literature and hence this is one of the aims of this work. Extraction using ultrasonic (UAE) and maceration (ME) is also studied for comparison. Bioactive compounds are known to suffer from a degradation process when exposed to high temperature over a long period, which is often the case during the extraction and spray drying. Degradation can be minimised by microencapsulation technique, however the encapsulation mechanism and controlled release of O. stamineus polyphenols from the microcapsule is not yet understood and hence was studied in this work. The mechanism and kinetics of O. stamineus polyphenols degradation is not yet understood hence this is one of the objectives in this work. Mechanism of polyphenol degradation was elucidated with the aid of mass spectroscopy analysis. Qualification and quantification of the polyphenols was performed using ultra-performance liquid chromatography-tunable UV-quadrupole time of flight mass spectroscopy (UPLC-UV-QTOF). Upon investigation by principle component analysis, the MAE extracts was found have a different chemical profile compared to that obtained from UAE and ME. The yield of danshensu, protocatechuic aldehyde, caffeic acid, salvianolic acid A, ethyl caffeate, tetramethyl-o-scutellarin and salvianolic acid S were found to be significant higher in extract by MAE, whereas the extract by UAE and ME is rich in salvinolic acid B and chicoric acid. Compound such as salvianolic acid A, protocatechuic aldehyde, ethyl caffeate and salvinolic acid S uncovered in this work is never reported before for O. stamineus extract. Microencapsulation of polyphenols from O. stamineus by spray drying using encapsulant consisting of whey protein isolate (WPI), gum arabic (GA) and maltodextrin (MD) resulted in a high retention of polyphenol content. The most effective formulation of 1:9 WPI:GA produced high retention of rosmarinic acid (89.41%), sinensetin (89.14%) and eupatorin (86.66%) compared to other wall material. Analysis of the microcapsule via transmission electron microscopy-energy dispersive x-ray (TEM-EDS) shows a type of encapsulation mechanism known as irregular shaped hollow sphere homogeneous mixture. The polyphenol in the microcapsule was found to be stable and well preserved within 30 months. Release of polyphenols from the microcapsule was observed to be much better in the intestinal fluid compared to gastric fluid. The effect of thermal treatment on salvionolic acid B, chicoric acid, eupatorin and rosmarinic acid derived from O. stamineus leaves were investigated at temperature ranging from 90 to 150 °C up to 90 min. The result shows that salvianolic acid B at first undergoes ester bone breakage to produce lithospermic acid and danshensu. Subsequently, the lithospermic acid undergo decarboxylation to produce salvianolic acid A, followed by dehydrogenation of salvianolic acid A to produce salvianolic acid C. Danshensu and caffeic acid were produced by thermal induced ester bone breakage of rosmarinic acid. Chicoric acid breaks to form caffeic acid and tartaric acid via hydrolysis process. The results showed salvianolic acid B, chicoric acid, eupatorin and rosmarinic acid degradation followed the first-order kinetics model. The salvionolic acid B showed the highest degradation rate constant, followed by chicoric acid rosmarinic acid and eupatorin for all studied temperature, indicating a most thermolabile compound. Findings from this work may serve as a useful guideline to produce a high quality functional food from O. stamineus.
THE0007913(Local)
Faculty of Chemical & Natural Resources Engineering--Dissertations