Journal of the Science of Food and Agriculture J Sci Food Agric 85:1999–2004 (2005) DOI: 10.1002/jsfa.2169 Process optimisation of encapsulated pandan (Pandanus amaryllifolius) powder using spray-drying method Seng Kean Loh, Yaakob B Che Man, ∗ Chin Ping Tan, Azizah Osman and Nazimah Sheik A Hamid Department of Food Technology, Faculty of Food Science and Biotechnology, Universiti Putra Malaysia, 43300 UPM Serdang, Selangor DE, Malaysia Abstract: A study on the production of spray-dried pandan (Pandanus amaryllifolius) powder was conducted and optimised using response surface methodology (RSM). Parameters investigated include inlet temperature (170–200 ◦ C) and feed rate (6–12 rpm), with a preset outlet temperature of 90 ◦ C. The estimated regression coefficients (R 2 ) for the physicochemical characteristic and sensory responses of pandan powder were ≥0.800, except for overall acceptability. Some mathematical models could be developed with confidence based on the results from all responses. An optimum drying process for spray drying represents conditions that would yield acceptably high colour index (such as L value, a value and b value), low moisture content, low water activity (a w ), high solubility and high colour, flavour, odour and overall acceptability for sensory responses. Optimum conditions of 170 ◦ C inlet temperature and 6 rpm feed rate, with a constant outlet temperature of 90 ◦ C, were established for producing spray-dried pandan powder as an edible colouring and flavouring powder.  2005 Society of Chemical Industry Keywords: optimisation; Pandanus amaryllifolius; RSM; spray drying; powder INTRODUCTION Spray drying is a unit operation widely used in the food industry. The most important commodity in this respect is spray-dried skim milk, but the spray drying of many other liquid foods such as fruit juices and vegetable extracts, coffee and tea extracts and other dairy products such as whey is also of economic importance. 1 Spray drying is one of the most practical methods by which a solution of solids in water can be dehydrated to yield a solid final product. Other methods for the removal of water from such solutions, eg freeze-drying, are usually much more expensive, whereas a method such as liquid–liquid extraction requires the use of solvents, which is often undesirable. 1 Optimisation of the dehydration process is per- formed to ensure rapid processing conditions yielding an acceptable-quality product and a high-throughput capacity. 2 Rapid food-engineering operations such as dehydration reduce the overall cost of the pro- cess; however, adverse reactions occur in biological products being dried, 2,3 namely loss of vitamins, development of undesirable colour, development of off-flavours, volatilisation of flavour compounds, solubility changes and loss of essential amino acids. When many factors and interactions affect desired responses, response surface methodology (RSM) is an effective tool for optimising the process. 4,5 The basic aim of RSM is to improve product properties via regression equations that describe relationships between input parameters and these properties. 6 In Malaysia, many fruits, plants, spices and herbs contain natural flavouring and colouring compounds. The leaves of pandan (Pandanus amaryllifolius) have a strong aroma and are widely used in South East Asia as flavourings for various foods such as bakery products, sweets and even home cooking. 7 Today, various drying methods such as spray and drum drying are applied to produce encapsulated flavouring and colouring powders. 8,9 These powdered products have been widely used in ice cream, yogurt, soup, cake, tea, ‘nasi lemak’, a type of Malaysian traditional pandan-flavoured rice, and even Malaysian traditional coconut jam, ‘seri kaya’. 8 Drying is an ancient process used to preserve foods. It is the most common food preservation process. Hundreds of variants are actually used in the drying of particulate solids, pastes, continuous ∗ Correspondence to: Yaakob B Che Man, Department of Food Technology, Faculty of Food Science and Biotechnology, Universiti Putra Malaysia, 43300 UPM Serdang, Selangor DE, Malaysia E-mail: yaakub@fsb.upm.edu.my Contract/grant sponsor: Ministry of Science, Technology and Environment (MOSTE); contract/grant number: IRPA 03-02-0168-EA001 (Received 22 October 2003; revised version received 28 October 2004; accepted 4 January 2005) Published online 4 May 2005  2005 Society of Chemical Industry. J Sci Food Agric 0022–5142/2005/$30.00 1999