STUDY ON RESIDUAL OIL RECOVERY FROM EMPTY FRUIT BUNCH BY COMBINATION OF WATER AND STEAM PROCESS JAVIER CHAVARRO GOMEZ 1 , MOHD NORIZNAN MOKHTAR 1,4 , ALAWI SULAIMAN 2 , RABITAH ZAKARIA 1 , AZHARI SAMSU BAHARUDDIN 1 and ZAINURI BUSU 3 1 Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Selangor 43400 UPM, Malaysia 2 Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia 3 Felda Global Ventures Plantation Malaysia Trolak Region, Sungkai, Perak, Malaysia 4 Corresponding author. TEL: +603-89466367; FAX: +603-8946 4440; EMAIL: noriznan@upm.edu.my Received for Publication July 10, 2014 Accepted for Publication October 23, 2014 doi:10.1111/jfpe.12169 ABSTRACT In this study, the recovery of residual oil from the spikelet of oil palm empty fruit bunches (OPEFB) was conducted. Residual oil was present in the OPEFB due to mechanical processes such as the loading of fruit into the sterilizer cage, steriliza- tion and threshing, in which a certain portion of the oil from the fruitlet was impregnated mainly on the surface of the spikelet rather than on the stalk of OPEFB. The highest residual oil content was found mainly in the small OPEFB (28.49 ± 5.20% dry basis). The oil extraction process was introduced as hydro solvent-assisted steam extraction, which comprises of four main steps, i.e., flood- ing, injection, soaking and draining. The overall process resulted in above 83% residual oil removal from the spikelet. The proposed method can be an option to be implemented in the palm oil mill because it is a chemical-free, environment- friendly and novel process. PRACTICAL APPLICATIONS The implementation of aqueous extraction for the recovery of residual oil from oil palm biomass is a viable process because water and steam are readily available in palm oil mills. The high content of residual oil in OPEFB contributes to oil losses and a recovery process is needed to increase the oil extraction rate. The aqueous extraction process is safe and environment friendly compared to other chemical extraction processes (e.g., n-hexane extraction). INTRODUCTION The world’s crude palm oil (CPO) production is being led by Malaysia, Indonesia and some countries from Latin America and Africa. Malaysia produced around 19 million tons of CPO in 2012 (MPOB 2013a), establishing it as the second world CPO producer, behind Indonesia (31 million tons) (Oosterveer 2014). The world’s demand for CPO has shown an increase in the last years with a continuous growth. In Malaysia, the export of CPO was estimated at 15.41 and 17.58 million tons in 2008 and 2012, respectively (MPOB 2013b). With this increasing demand and the limi- tation to explore any new forest land that was imposed by the Malaysian government (Basiron 2007), the CPO indus- try has diverted its efforts to increasing oil production by optimizing the process rather than focusing on agricultural expansion. The oil extraction rate (OER) has been used as a control- ling and management instrument to evaluate the efficiency of the mill and plantation by comparing the ratio of palm oil produced per day with the total fresh fruit bunches pro- cessed per day (Husain et al. 2003). The OER depends on many factors such as the gender and the age of oil palm tree, the weight of oil palm fresh fruit bunches (OPFFB) and the total number of fruits (Haniff and Noor 2002). According to the Palm Oil National Key Economic Area (Pemandu 2014), the expectation is for Malaysia to increase its OER up to 23% by 2020 under the Entry Point Project 4. However, according to the Economic and Development Division of MPOB (2013c), 20.35% OER was obtained in 2012, indicat- ing that current technologies in the mill have a low effi- ciency compared to the proposed goal. Among strategies on increasing the OER, one of them is recovering the remaining CPO from oil palm wastes. The Journal of Food Process Engineering ISSN 1745-4530 385 Journal of Food Process Engineering 38 (2015) 385–394 © 2014 Wiley Periodicals, Inc.