ORIGINAL PAPER Multi-Objective Optimization of Osmotic–Ultrasonic Pretreatments and Hot-Air Drying of Quince Using Response Surface Methodology Mohammad Noshad & Mohebbat Mohebbi & Fakhri Shahidi & Seyed Ali Mortazavi Received: 26 August 2010 / Accepted: 4 April 2011 / Published online: 23 June 2011 # Springer Science+Business Media, LLC 2011 Abstract In this study, application of a multi-objective optimization technique based on response surface methodology has been presented. Quince slices were dehydrated using osmotic dehydration with sucrose solutions at different concentration (40 and 60 Brix), processing time (1, 1.5, and 2 h), and ultrasonication time (0, 15, and 30 min) were the factors investigated with respect to water loss, solid gain, and weight reduction. Response surface methodology was used to determine the optimum processing conditions that yield maximum water loss and weight reduction and minimum solid gain during osmotic dehydration of quinces. Dehydrated quince slices at optimized osmo-ultrasound condition were then subjected to air-drying at 60 and 80 °C. Rehydration ratio, shrinkage, and moisture content of dried samples were regarded as responses to the non-thermal and air-drying conditions. Multi-objective optimization led to obtaining the best condition for production of dried quince slices with lowest moisture content, and shrinkage. Keywords Air-drying . Optimization . Quince . Response surface methodology . Ultrasonic–osmotic dehydration Introduction Quince (Cydonia oblonga Mill) is a member of pomes fruit family; 83.8% water and 15.3% carbohydrates (wet basis) are the main constituents of quince. Minor ingredients of quince are proteins (0.4%, wet basis) and fats (0.1%, wet basis). It is presumed to be a good source of fiber, potassium, and vitamin C. The mean of the last 10 years’ (1998–2008) world production of quince is estimated to be 510,000 t (FAO 2010). Fruit drying is a well-known process mostly used for preservation of fruits. Dried quince can also be used as ingredient of traditional Iranian food such as quince Khoresh and chowder. The traditional way, which is often used in Iran for quince drying, is to spread it into the direct sunlight. In such traditional drying methods, serious decreases of nutritive and sensorial values are possible, damaging mainly the flavor, color, and nutrients of the product (Lenart 1996; Lin et al. 1998). Therefore, it is essential to find better ways for drying quince. Since air-drying is a simultaneous heat and mass transfer process, which results in phase change, it is an energy intensive and consequently expensive process (Barbanti et al. 1994). To reduce initial water content or to modify the fruit tissue structure and decreasing drying time, different pre- treatment have been applied by researchers. Osmotic dehydration is the most reported pretreatment used prior to air-drying (Antonio et al. 2008; Pani et al. 2008; Lombard et al. 2008; Fernandes et al. 2008; Azoubel et al. 2009; Bchir et al. 2011; Sosa et al. 2011). Among emergent new technologies, ultrasonication is an encourag- ing process, which is commonly regarded as a non-thermal process; such process is favorable because of reduction in food degradation. No liquid phase change will occur in this process for water removal (Povey and Mason 1998; Fernandes et al. 2008). The ultrasonic pretreatment includes the immersion of the fruit in water or in a hypertonic aqueous solution to which ultrasound is applied. Ultrasonic waves in frequency range of 20–100 kHz can cause rapid series of alternative compressions and expansions in a similar way to a sponge M. Noshad (*) : M. Mohebbi : F. Shahidi : S. Ali Mortazavi Department of Food Science and Technology, Ferdowsi University of Mashhad, Mashhad, Iran e-mail: mo.noshad@gmail.com Food Bioprocess Technol (2012) 5:2098–2110 DOI 10.1007/s11947-011-0577-8