## 1 Introduction  
Non-centrifugal sugar (NCS) is a typical unrefined sugar produced by dehydating sugarcane juice without centrifugation. As many of the micronutrients and bioactive components, such as phenolics, minerals, proteins, amino acids, and long chain lipids (policosanol, steroids, terpenoids etc. ), are not removed during the manufacturing process of NCS, its nutritional and biological properties have been widely investigated [1; 2; 3]. Today, NCS is used as an alternative for table sugar since refined/purified sugar has been linked to several health problems like obesity, dental caries, and cardiovascular disease [4; 5]. Apart from the nutritional and bio-functional attributes, the unique aroma properties of NCS have extended its scope of applications to confectionery, bakery, and beverage products [6; 7; 8]. In general, NCS is produced from clarified sugarcane juice, through evaporation to a water content to 88-94% (dehydration process), followed by crystallization and drying [1]. The presence of the aroma in NCS has been linked to two main sources, sugarcane plant and the volatile components developed during the manufacturing and storage processes [9; 10]. The main sources of volatile compounds in the NCS manufacturing process are attributed to the thermal degradation of carbohydrates via caramelization reactions and/or the Maillard reaction. The Maillard reaction involves a complex reaction between amino acids and reducing sugars and has been identified as the major contributor to the aroma development process [11]. In addition to Maillard reaction products (MRPs), other volatiles, including acids, alcohols, phenolics, esters, sulfur compounds etc., also contribute to the overall aroma quality and characteristic. To understand the formation of aroma profiles of NCS and determine formulations of NCS-based food and beverage products, many studies have been conducted to identify the aroma components in sugarcane juice [12; 13; 14], commercial NCS products [7; 15; 16; 17], and NCS beverages at different brakes [8], and the impacts of the storage process on the NCS aroma properties [6]. Among the various steps in the NCS manufacturing process, the dehydration process is the key step where aroma products are developed, contributing significantly to the overall aroma quality of the final product. Currently, the dehydration process under atmospheric condition is adopted worldwide, including the open pan (OP), the horizonal thin film (HTF), and the vertical thin film (VTF) drying processes. [PERSON] and co-authors (2016) [10] systematically studied the impacts of the three drying-solidification processes on the physical and the antioxidant properties of NCS products and the fractions of the volatiles present in them. It was shown that NCS derived from HTF and VTF processes (132-135 \({}^{\circ}\)C) contains a greater proportion of aroma components than that from the OP (128-132 \({}^{\circ}\)C) process. This was attributed to the larger upper surface area of the OP process which enhanced the release of aroma components to the environment. The higher temperature in both HTF and VTF enhance the formation of the MRPs and the cylindrical shape of the evaporator tubes prevents aroma compounds from vaporization and allows entrapment of these compounds in the solidified sugar products. In addition to temperature, the production of MRPs is also depend on pH, water activity, type of substrate species, and substrate concentration [6; 18]. Clarification is a process that removes the non-sugars impurities, such as proteins and polysaccharides etc., that affect aroma formation in the subsequent concentration/dehydration process [9]. The membrane filtration process has been demonstrated as a superior clarification process to the traditional chemical processes for NCS production (M-NCS), as a higher proportion of nutritional and antioxidation components were found with the M-NCS [1]. A preliminary analysis of the volatile flavor components in M-NCS has been carried out [1].