TITLE Ohmic Heated Hydrodistillation of ‘Serai Wangi’. 1. 0 INTRODUCTION 1. 1 General Overview Hydrodistillation is a method to extract essential oil from various plant materials and was used to separate essential oil from Cymbopogon flexuosus (lemongrass). Mostly used by small scale producers of essential oils. In hydrodistillation the plant material is almost entirely covered with water as suspension in the still which is placed on a furnace. Water is made to boil and essential oil is carried over to the condenser along with the steam.
The yield is dependent on various parameters like weight of raw material, volume of water, size of raw material and nature of raw material. (Parikh J. K. , 2011) Lemongrass commonly known as “East Indian Lemongrass” is a perennial and multicut aromatic grass. The prefix ‘lemon’ owes to its typical lemon like odour, which is mainly due to the presence of citral, a cyclic monoterpene. Lemongrass is the source of Lemongrass oil, a good source of natural citral, which is used as a basic raw material for synthesis of ? ionone used for synthesis of a number of useful aromatic compounds and Vitamin-A. Citral itself is used in perfumery for various grades of soaps detergents, cosmetics and flavour agent for soft drinks. Consumption of Lemongrass in Ayurvedic preparation like Balm is also increasing. In ohmic heating processes, foods are made part of an electrical circuit through which alternating current (AC) flow causing heat to be generated within the food due to the electrical resistance of the foods. AC voltage is applied to the electrodes at both ends of the product such as both ends of vessel.
The rate of heating is directly proportional to the square of the electric field strength and electrical conductivity. The most important factor that effectuates the rate of heating is electrical conductivity and its temperature dependence. (Ruan et. al, 2001) The advantages of ohmic heating technology have been claimed in previous research. The heating food materials by internal heat generation without the limitation of conventional heat transfer and some of the non-uniformity commonly associated with microwave heating due to limited dielectric penetration.
Ohmic heating take place volumetrically and the product does not experience a large temperature gradient within itself as it heats. Besides, the higher temperature in particulates than liquid can be achieved, which is impossible for conventional heating. Other, it also has high energy efficiency because 90% of electrical energy is converted into heat. (Ruan et. al, 2001) 1. 2 Problem Statement Nowadays, hydrodistillation is commonly used to extract essential oil from plant materials. The mixture of the plant and water is heated by means of electrical element or by flame heating.
The low thermal conductivity of plant material compared to water effectuates the heat transfer from water to plant material and from plant material to oil bearing cells. Thus, this principle takes a long time to yield the oil. In ohmic heating processes, the electrical current is used for heating food material by internal heat generation. Therefore, in a liquid-particulate food mixture, if the electrical conductivity of the two phases are comparable, heat could be generated at the same or comparable rate in both phases in ohmic heating.
In other conditions, heat can also be generated faster in the particulate than in the liquid. Ohmic methods thus offer a way to extract the essential oil with faster processing rate. The focus of this study is to validate of using ohmic heated hydrodistillation in producing essential oil of ‘Serai Wangi’. 1. 3 Background of the Project Nowadays, the increasing demand of essential oil product effectuates the developing method of extraction. One of new extraction method that has been developed is microwave extraction method.
This study is focus to investigate the applicability of microwave irradiation for essential oil extraction. Forest Research Institute Malaysia (FRIM) is a one research institute that has been done it research on the extraction of essential oils from the lemongrass, patchouli, Melaleuca cajuputi, Eurycoma apiculata and Zingiber. The essential oils were extracted by using hydrodistillation and solvent extraction method. (Extracted from Azlina, 2005) Figure 1: The steam distillation and water-distillation unit used at FRIM. Extracted from Azlina, 2005) Furthermore, Malaysian Agricultural Research and Development Institute (MARDI) also has done research on the extraction of the tea tree oil. The tea tree oil is extracted by hydro-distillation at atmospheric pressure. Both equipments consist of a still proper, condenser and a separator. All the equipment parts are made of stainless steel. (Extracted from Azlina, 2005) Figure 2: The hydro-distillation unit at MARDI (Extracted from Azlina, 2005) 1. 4 Objective The objectives of this study are: To measure essential oil concentration during distillation at various power level after the onset of boiling. * To measure essential oil content in aqueous phase prior to the onset of boiling. * To measure essential content in aqueous phase for solutions maintained for a prolong period below the boiling temperature. 1. 5 Process Flow Diagram Figure 3: Process Flow Diagram in Producing Essential Oil of ‘Serai Wangi’ Figure 2 shows the flow process in producing essential oil of ‘Serai Wangi’. Firstly, the raw material which is ‘Serai Wangi’ will be divided into two parts.
The first part will be cutting and another part will be grinding. After that, the cutting part will be soaking in certain volume and place in water bath of ohmic heated hydrodistillation unit. Figure 4 shows the ohmic heated hydrodistillation unit to use as pre-treatment to enhance extraction of oil from ‘Serai Wangi’. The electric current passes through a mixture of plant material and water in hydrodistiller, where the greatest heat resistance of plant material will produce more heat rather than low resistant of plant material.
The temperature will be control until the boiling temperature is reached and the oil will diffuse out of plant matrix. The extraction of essential oil from ‘Serai Wangi’ occurred. Then, the oil will be carried away by the generated steam which is lastly condensed in the condenser. The sample than will be collected and the experiment will repeated for grinding sample. (Hishamuddin, 2011) Figure 4: Unikl Ohmic Heated Hydrodistillation (Extracted from Hishamuddin, 2011) REFERENCES Arnoldi A. , Richardson P. (ed. (2001) Thermal Processing and Food Quality, Thermal Technologies in Food Processing, England: Woodhead Publishing Limited. Hishamuddin J. (2011) Ohmic Heated Hydrodistillation, Universiti Kuala Lumpur Malaysia Institute of Chemical and Bioengineering Technology, Malaysia. Nurul Azlina M. (2005) Study on Important Parameters Affecting the Hydrodistillation for Ginger Oil Production, Master Thesis, Universiti Teknologi Malaysia, Malaysia. Ruan R. , Ye X. , Chen, Doona C. J. , Richardson P. (ed. ) (2001) Ohmic Heating, Thermal Technologies in Food Processing, England: Woodhead Publishing Limited.