VOL. 3, NO. 5, OCTOBER 2008 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2008 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com EFFECTS OF PRE-TREATMENT CONDITION ON THE YIELD AND QUALITY OF NEEM OIL OBTAINED BY MECHANICAL PRESSING Felycia Edi Soetaredjo, G. M. Budijanto, R. I. Prasetyo, and N. Indraswati Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan, Surabaya, Indonesia E-Mail: felyciae@yahoo.com ABSTRACT Neem (Azadirachta indica A. Juss) is one of the very few trees known in the Indian subcontinent. Neem seed is a part of Neem tree which has high concentration of oil. Neem oil extraction using mechanical pressing is the cheapest method, and some pretreatment such as heating influenced its yield and physical and chemical characteristics. The quality of Neem oil extracted by mechanical pressing was changed during storage. The results of this experiment showed that the optimum pressure for mechanical pressing of Neem seed was 5000 psi. The pretreatment heating on the Neem seed particles and storage caused the oil quality reduced, therefore room temperature was found to be the recommended temperature for the Neem oil extraction using mechanical process. Keywords: neem, oil, yield, quality, extraction, pressing. INTRODUCTION Neem tree (Azadirachta indica) belongs to the mahogany family, Meliaceae. Neem tree is a tropical plant with a good environmental adaptability [1,2]. In Indonesia, neem tree can be found in several regions, such as East Nusa Tenggara, Bali, West Nusa Tenggara, East Java, Central Java, and West Java. All parts of the tree have many beneficial uses for natural insecticide, cosmetics ingredient, health treatment, soap and toothpaste ingredient, etc [1-4]. Even though the Neem tree has many potential applications; the utilization of this tree in Indonesia for industrial purposes still limited, as a canopy tree. Part of Neem tree which is commonly used is the seed. Neem seed has the largest oil fraction (approximately 40-58.9% weight) compared to the other parts of the tree [1,5]. The kernels yield a greenish to brown-colored oil with strong odor resembling garlic. The refined and purified Neem oil has the following characteristics: specific gravity 0.9087; refractive index 1.4612; iodine value (Wij's) 66.4; saponification value 290.9; and unsaponifiable matter 0.8% [5]. Neem oil has been used in many different industries, especially cosmetics and pharmaceutical industries (as supporting ingredient for medicines) [1-3]. Extraction of oil from Neem seeds can be performed using three different methods: mechanical extraction, solvent extraction, and supercritical fluid extraction. Mechanical extraction is the common method used to extract the Neem oil from the seed [1,6] , since this method is effective for seed contain 30-70% oil [7]. The mechanical extraction has several advantages compared to the other methods, such as simple equipment and low investment, low operating cost, and the oil does not undergo solvent separation process, etc. [6]. Usually the quality and quantity of the oil obtained by mechanical extraction process are affected by various operating conditions such as pretreatment of the Neem seeds, extraction pressure, and storage condition. Effect of extraction condition on quality of oil has been investigated in several studies for wide variations of material, including conophor nut [6], olive [8], jojoba [9], and groundnut [10], and peanut kernel oil [11]. The changes of oil quality during storage also has been investigated for numerous materials, such as soybean [12], peanut kernel [11], sunflower [13], olive [8, 14], and fish oil [15]. The aim of this research was to investigate the effect of heat pretreatment on the yield and physical- chemical characteristics (saponification value, iodine value, acid number and refractive index) of Neem oil during storage. MATERIALS AND METHODS Preparation and mechanical extraction Neem seeds (Azadirachta indica) from Bali were used in this experiment. Neem seeds were peeled and washed using water to remove dirt then dried in the open air. Dried kernels were ground into powder using seed grinder PHILIPS HR1701 for 15 seconds, to obtain fine particles without significant loss on seed's oil. Samples were taken for measurement of initial moisture content using moisture determination balance OHAUS MB200, and the result was 7.8%. Seed particles were preheated using oven MEMMERT UM400 at 40, 50, 60, 70, and 80°C until the moisture content constant. Mechanical extraction of Neem seeds was performed using hydraulic pressing equipment ENERPAC RC-256 and P-39. Untreated seed particles were pressed with various pressures to determine the optimum pressure. Pressure was started at 2000 psi as the oil started to flow out of the seedbed, and stopped at 6000 psi since the oil yield relatively constant at the pressure above 6000 psi. Mechanical extraction was performed for 25 minutes when the oil has stopped flowing out. Oil yield measurement was conducted using mass balance PRECISA 3000D. Oil analyses Filtered Neem oil was stored at room temperature (30°C) in dark glass bottles for 14 days. During storage, 45