Sirih (Piper Betle L.): extraction and drying technology of its bioactive components

Piper betle L., more commonly known as betel or local name of Sirih, belongs to the family Piperaceae. Previous re¬search has shown that the leaves of P. betle possess tremendous beneficial effects including antimicrobial, antioxidant, anti-diabetic, wound healing and gastro-protective properties. The presence of these beneficial properties indicates that leaf extract of betel has great potential for development into a wide range of health food supplements. However, there is a lack of research on the processing aspects to produce its bioactive component. This book aims to provide information and experimental studies on a few key processes including post-harvest betle leaves drying, solid-liquid extraction, spray drying and freeze drying of extracts which are involved in processing of bioactive extract from betel leaves. Different experiments were designed and carried out to look into the effects of various operating parameters on the qualitative and quantitative aspects of betel leaves extract. Hydroxychavicol (HC) and eugenol (EU) were selected as the quality indicators of the product because these two compounds were reported to play an important role in the bioactivities of betel leaves including antioxidant, anti-inflammatory, and anticarcino¬genic and antibacterial

Extraction of eugenol from betel leaves (Piper betle L.) using hydrodistillation and supercritical carbon dioxide technique

Betel (Piper betle L.) is one of the precious herb plants originated from Malaysia. The leaves of betel have been used traditionally for various medicinal purposes. Scientific research on the leaf of this plant claims that it possesses many beneficial bioactivities. Extract from betel leaves has a great potential to be used in developing commercial products. However, there is lack of research on the processing aspects to produce its bioactive extract. Many extraction methods are widely used in extracting bioactive compounds. However, each method is different since it has advantages and disadvantages. This study focuses on two processes involved in producing bioactive extract of betel leaves namely hydrodistillation and supercritical fluid extraction. Different experiments were designed and carried out to look into the effects of various operating parameters. The first part of this study investigated the effect of type of leaves and extraction time on yield and composition of eugenol by using conventional hydrodistillation method. Results of the study showed that fresh betel leaves were more preferable over dried betel leaves. Six hours was compatible for extraction of fresh betel leaves. The second part of this study is to examine effect of pressure and temperature on yield and concentration of eugenol by using supercritical fluid extraction. Response surface methodology (RSM) was applied to obtain the optimum process parameter. Optimized pressure and temperature which were suggested by RSM are 190 bar and temperature 50 °C. The predicted properties of extract are 0.5% yield and 21.57 mg/ml concentration of eugenol. The kinetic model was used to describe the mass transfer phenomena. The highest value of mass transfer coefficient was found to be 0.208 min-1 at pressure 160 bar and temperature 50 °C. Del Valle-Aguilera model showed the best fit with experimental data with lowest average absolute relative deviation (AARD). This equation is recommended for betel oil solubility in supercritical fluid extraction.Comparison of supercritical carbon dioxide technique and hydrodistillation was studied. Supercritical carbon dioxide technique offers many important advantages over hydrodistillation. Therefore, this technique can be considered as a distinguished technology for the extraction of betel leaves,not only due to proclaimed advantages over the conventional techniques but also due to the high target compound concentration and yield with short extraction time (1 hour)

Radical Polymerization in Aqueous Heterogeneous Systems under Compressed Gases

Miniemulsion polymerization has received significant attention because polymer particles are generated directly from monomer droplets. However, the problem with current methods of synthesizing miniemulsions is the requirement for high energy mixing approaches. The ability to synthesize miniemulsions using low energy methods would be of very significant academic and practical importance. In the present thesis, radical polymerization in heterogeneous systems under compressed gases has been investigated with a view to the development of low energy miniemulsion polymerization.The mechanistic aspects of radical polymerization of styrene in aqueous emulsions pressurized by CO2 have been investigated. It has been demonstrated that CO2 pressurization to the so-called transparency pressure (PT) of an emulsion comprising styrene/hexadecane/Dowfax 8390/water leads to a decrease in droplet size as well as an increase in emulsion stability. However, the radical polymerization under CO2 pressure reveals that these polymerizations do not proceed as true miniemulsion polymerization systems (i.e., via exclusive monomer droplet nucleation) but are also characterized by a significant contribution of particle formation via secondary nucleation as in an ab initio emulsion polymerization.Photopolymerization of miniemulsions under compressed CO2 has been performed under UV and visible-light irradiation. For the UV-light system, the rate of polymerization of a transparent miniemulsion under compressed CO2 was found not to be affected by the transparency. However, the transparency affected the polymerization rate under visible-light irradiation. This is due to the transparency of refractive index matched miniemulsions favours less light scattering than turbid miniemulsions at the at the appropriate wavelength (transparency is associated with high visible light transmission).Pressurization of an emulsion comprising styrene/hexadecane/Dowfax 8390/water to PT has been performed under compressed ethane. Under the same condition, the value of PT for emulsions under compressed ethane is lower than that of the compressed CO2 due to the solubility difference between ethane and CO2 in water. Polymerization of the emulsion under compressed ethane has been conducted with the initiator VA-044. The polymerization has been found to proceed via conventional emulsion polymerization mechanism as revealed by the mechanistic investigation