## 1 Introduction  
Fresh-cut processing induces a catena of physiological responses [1; 2] finally resulting in the loss of quality and aroma and pronouncedly shortens the storage life of fresh-cut produce [3]. In current practice, fresh-cut fruit for fruit salads are often stored in sugar syrup (ca. 20%), especially for use by bulk purchasers [4]. This storage method may extend product shelf life by preventing enzymatic and oxidative browning and transpiration, slows down respiration, ethylene metabolism and other physiological processes [5; 6; 7]. In this context, however, microbial spoilage is the main factor limiting shelf life [7]. It is therefore very important to remove the microorganisms adherent to the fruit skin [8] before processing.  
In practice, e.g., apple slices are dipped in a mixture of citric and ascorbic acid solutions for sanitation purposes. To prevent the consumption of these chemicals especially in organic production, gentle physical sanitation methods are demanded.  
As such, hot-water treatments (HWT) in the temperature range of 40-80 \({}^{\circ}\)C were shown to effectively reduce microbial contamination, and are relatively inexpensive and easy to use [9]. In addition, HWT maintains storage quality of fruits [10; 11; 12]. Since they are chemical-free, particularly short-term (15-60 s) hot-water treatments (sHWT) are suitable for organic production [13; 14]. Besides earlier studies on the impacts of HWT on structure and function of fruit epidermal tissue [15; 16], only recently, the effects of sHWT on surface tissue, heat transfer dynamics and suitability for pre-processing of intact apples for fresh-cut salads were investigated in detail [12; 17]. Furthermore, the implications of sHWT on important quality parameters such as tissue browning, tissue strength and on microbial loads of apple slices immersed in sugar syrup have been studied under semi-practical conditions [18]. On the effects of sugar syrup storage on fresh-cut fruit quality attributes only very few studies are available [7; 19].  
In contrast to analyses of sHWT impacts on visual and internal quality attributes of fresh-cut fruit [12; 17; 18], studies on potential variations in fruit aroma, a very important aspect of fruit quality sensation [2; 20], are completely lacking. Aroma is generated by a great variety of permanent or secondary VOCs [21], synthesized via numerous biosynthetic pathways, which, in turn, are regulated by a great variety of enzymes and substrates [2; 22; 23]. Moreover, both respiration and ethylene biosynthesis are also involved in VOCs evolution [24]. In addition, microbial growth may, directly or indirectly, negatively affect product aroma [25; 26]. Short-term-HWT and sugar syrup immersions may influence all of these processes. Knowledge on the impact of both sugar solution and sHWT on aroma development and physiological properties of immersed fresh-cuts is lacking.  
Thus, the present study focused on the evaluation of the potential effects of sHWT (30 s, at 55 \({}^{\circ}\)C or 65 \({}^{\circ}\)C) on the aroma-related quality of 'Braeburn' apple slices stored in sugar syrup under strictly simulated practical condition. Some parts of the samples were also pre-treated with a commercial ascorbic/citric acid solution to test the potential synergistic effects of this treatment on aroma. During a 13 days-storage at 4 \({}^{\circ}\)C, respiration, ethylene emission and, for the first time, the processing-induced direct and indirect changes in VOC profiles were measured at defined intervals. This will enable comprehension of the respective quality-related physiological processes, to effectively select the optimal process conditions and to verify whether sHWT can safely replace the use of chemicals in processing of ecologically produced fresh-cut fruit salads.