Gopika Talwari and B.S. Ghuman JAE : 51 (2) Journal of Agricultural Engineering Vol. 51 (2): April-June, 2014 Optimization of Microwave Assisted Process for Extraction of Celery Seed Essential Oil Gopika Talwari1 and B.S. Ghuman2 Manuscript received: March, 2013 Revised manuscript accepted: April, 2014 ABSTRACT Microwave assisted extraction (MAE) method was developed for extraction of essential oil from celery seeds. A domestic microwave oven was modified and Clevenger apparatus attached to it to make it an extraction unit. Effect of various parameters such as soaking time, temperature and power density during MAE was studied. A multivariate study based on a Box-Behnken design was used to evaluate the influence of three major variables (soaking time, temperature and power density) affecting the performance of MAE on celery seed. Oil yield, time of extraction and energy consumption (MJ.kg-1 oil) by MAE were determined and compared with those obtained by the traditional hydro-distillation (HD). It was found that microwave assisted process gave approximately same oil yield (1.90%) in less time ( 93.5 min) and with low energy consumption (58191.78 MJ.kg-1 oil). Results revealed that the selected parameters had significant effect on the responses. Key words: Celery seed, essential oil, microwave assisted extraction, hydro distillation Essential oils are the volatile oils distilled from aromatic an average contains 2.5% volatile oil containing 60-70% plant material. Essential oils are contained in the glands, d-limonene and 1-20% beta selinene and 15%–17% fixed sacs and veins concentrated in different parts of the plant. oil. Celery seed is mainly cultivated in Amritsar district in All spices and herbs contain essential oils (spice oil), Punjab, Panipat district in Haryana and Saharanpur district which provide characteristic flavour and taste to it. The in Uttar Pradesh (Bhatia, 2001). Indian celery seed and oil Indian essential oil industry manufactures rose oil, kewda is exported from Bombay and Amritsar market to various oil, lemon grass oil, peppermint oil, champa oil, citrus oil, countries like America, Britain, France, Italy, Canada, palmarosa, mentha and celery oils. The major Indian cities Australia, Netherland, Spain, Jawa, Germany, etc. which have essential oil plants are Mumbai, Mysore and Chennai. In the last decade, there has been considerable rise The main methods to obtain essential oils from the plant in production of essential oils. In 1990-91, the export was materials are hydro-distillation (HD), steam distillation, 892 Mt worth Rs.31.99 crores, which increased to 4,400 Mt steam and water distillation, maceration, empyreumatic (or worth Rs.386.48 crores in 2000-01(Singhal, 2003). destructive) distillation, and expression. Steam distillation, hydro-distillation and simultaneous distillation– extraction Celery seed is the dried fruit of Apium graveleons L. methods are known to be the most common methods for the belonging to the Umbelliferae family. Celery is used in extraction of essential oils. It is known that conventional various forms such as fresh herb, seeds, oil and oleoresin methods used for the extraction of essential oils from plant for flavouring foods. It is valued as a spice and imparts a materials have some disadvantages, mainly concerned warm and pleasing flavour to foods such as canned soups, with the quality of the final product like losses of some sauces, pickles, tomato products and meats. Celery is volatile compounds, low extraction efficiency, degradation extensively cultivated for their seeds in India, France and of unsaturated or ester compounds through thermal or United States of America. Celery seed oil lends a floral hydrolytic effects and toxic solvent residue in the extract like odour to oriental perfumes to which it imparts warm (Ferhat et al., 2006; Kaufmann and Christen, 2002). and clinging notes (Farooqi and Sreeramu, 2001). The ground seed is mixed with table salt to give “celery salt’’ Some recently published studies have successfully utilized which is used in flavouring fish, salads, and eggs. Celery a microwave oven for the extraction of active components oil is extensively used in meat seasonings, and to flavour from medicinal plants/herbs (Lucchesi et al., 2004; Wang soups, gravy, salad dressings, confections and non-alcoholic et al., 2006; Lucchesi et al., 2007). Solvent free microwave beverages (Agrawal et al., 2001; Anon, 2002).The seed on extraction has been used to obtain essential oils from three 1Assistant Professor ,College of Dairy Science & Technology, GADVASU, Ludhiana, Punjab, India; corresponding author email: engg_gopika@ yahoo.co.in ; 2Senior Research Engineer (retd.), Department of Processing and Food Engineering, PAU, Ludhiana,Punjab. 9 April-June, 2014 Optimization of Microwave Assisted Process for Extraction of Celery Seed Essential Oil different spices as ajowan, cumin, pumpkins seeds and star used for the experiment was found to be 7.3% (wet basis). anise (Lucchesi et al., 2004; Jiao et al., 2014), three different aromatic herbs as basil, garden mint, and thyme (Lucchesi et Modification of Domestic Microwave al., 2004), and cardamom seed (Lucchesi et al., 2007). Presti A domestic microwave oven (T37, MagiCook, National, et al. (2005) compared the traditional hydro-distillation India, 800W; 2.45GHz) was modified for MAE operation (HD), supercritical fluid extraction (SFE), organic solvent with the addition of a water condenser, temperature extraction (SE), and microwave assisted hydro-distillation measurement device-K type thermocouple (−200 °C to (MAHD) techniques and evaluated their effectiveness in +1350 °C, with sensitivity of approximately 41 µV.°C-1), the isolation of rosemary essential oil. Acidic pH based time controlling device i.e. PID controller (TZ4ST series, microwave assisted extraction has been tried on yellow Autonics, USA) and voltage regulator (Fig. 1). The horn by Qu et al. (2014). dimensions of the cavity of microwave oven were 22.5cm x 37.5cm x 38.6cm. The microwave oven was modified Microwave-assisted hydro-distillation (MAHD) has been by drilling a hole at the top. Round bottom flask having a developed and used for the extraction of essential oils capacity of 1000 ml was placed in the oven and connected from Xylopiaaromatica (Lamarck) and Lippiaalba (Mill.) to Clevenger apparatus through the hole. The flask was setup (Stashenko et al., 2004). MAHD was also reported for the within the microwave oven cavity, and a condenser was extraction of essential oils from Cuminumcyminum L. used on the top (outside the oven) to collect the extracted and Zanthoxylum bungeanum Maxim (Wang et al., 2006). essential oils (Fig. 1). The hole made in the ceiling was However, no work has been published on the microwave sealed with metal wool and Polytetrafluoroethylene (PTFE)/ assisted extraction (MAE) of essential oil from celery species. Teflon material so that no microwave radiations could pass Therefore, the objectives of this study were to develop a out of the cavity (Bayramoglu et al., 2008). modified process using microwave for rapid extraction of essential oils from celery seed (ApiumgraveleonsL.) and optimize the process taking extraction time, oil yield and Oil Extraction energy consumption as responses. For extraction, 100 g of celery seed sample was taken. Celery seed sample was soaked in 1000 ml of water for MATERIALS AND METHODS stipulated time period (4, 8 and 12 h). After soaking of seeds for stipulated time period, excess water was drained off. This Plant Material soaked sample was then put in flask of Clevenger apparatus Celery seeds grown in Punjab was used in the present study. and the microwave was run at particular temperature and Celery seed was purchased from Suran Singh Ram Singh power density as per the selected design. Power density is Pvt., Ltd., Vala Road, Amritsar. Moisture content of seeds expressed as power of microwave per unit mass of material. was measured in triplicate according to AACC (1983) The extracted oil got settled on top of aqueous phase (Fig.1) method, using a laboratory oven at 105oC until constant in Clevenger apparatus. The oil was manually drained by weight was achieved. The moisture content of celery seed operating a valve. Fig. 1: Experimental set up for microwave assisted extraction process 10 Gopika Talwari and B.S. Ghuman JAE : 51 (2) The oil thus obtained was checked for quality parameters Based on the above relationship, the independent extraction such as specific gravity and refractive index as also solubility parameters and their levels in the form of coded variables of the essential oil in alcohol. The effects of soaking time, are given in Table 1. temperature and power density on extraction time, oil yield and energy consumption were also examined. The results Yield were compared with those obtained with hydro-distillation Essential oil yield was expressed in terms of the weight method used as control. of the oil collected in mg per 100 g of dry plant material. Experimental Design Physical properties of essential oil For carrying out the study on optimization of MAE, an Specific gravity, refractive index and solubility (in 85% experimental plan was chosen from the family of three- ethanol v/v) of the essential oils extracted by hydro- level designs available in response surface methodology distillation and MAE at different variable levels were (Cox and Cochran, 1964). Three variables taken were measured. soaking time, temperature and power density; and three levels were chosen based on preliminary trials conducted Specific gravity prior to final experimentation (Table 1). A Box–Behnken design of three variables and three levels, each with three Specific gravity was calculated by dividing the weight of centre point combinations, was used (Box and Behnken, 1 ml essential oil by that of 1 ml distilled water. Weights 1960). This design was taken as it fulfilled most of the were measured using a balance with an accuracy of 0.001g requirements needed for optimization of the microwave (CY220, Citizen Scale, India). assisted extraction process.