## 1 Introduction
One of these heritage varieties is the _Ilzer Rose_ apple, which is a variety that was described for the first time more than 120 years ago with its origin in the village Ilz. _Ilzer Rose_ apples are rather small, red-cheeked, white-fleshed apples with a pronounced rose-like flavour which makes them particularly attractive for the production of apple wine [14]. The _Ilzer Rose_ volatileome was recently investigated. Interestingly, in addition to the well-known apple volatiles, many terpenoids were identified, especially in the skin of this apple variety [17]. In several grape varieties such as Muscat grapes, approximately 90% of the terpenes are glycosylated bound [18]. Thus, it is common practice to add enzymes with \(\beta\)-glucosidase activity to release higher amounts of terpenes upon enzymatic cleavage from the glycone and, as a consequence, to impact the flavour of the resulting wine due to an increase in the amount of free terpenes. In a recent study of our group, the treatment of the _Ilze Rose_ marsh with an oenological enzyme possessing pronounced \(\beta\)-glucosidase activity led to a concentration increase in terpenoids such as linalool, however, the overall linalool concentration was too low to impact the flavour of _Ilzer Rose_ apple wine [19]. In this study on the flavour of _Ilzer Rose_ apple wine, some common oenological practices (i.e., application of different enzymes that are commonly used in wine technology, maceration, mash fermentation) were transferred from oenology to the production of _Ilzer Rose_ apple wine in order to gain (i) deeper understanding of the flavour and volatile compounds of the products and to (ii) investigate the impact of technological/oenological practices on the development of _Ilzer Rose_ apple wine flavour. On the global wine market, a new type of wine was introduced approximately a decade ago [20; 21]. Wines of this type are known as 'orange wines' or 'natural wines' and they are produced in a manner similar to that used in the ancient Georgian traditional Qvevri wine-making method [22]. Even though the classification of the term 'orange wine' does not seem to be completely clear [23], 'orange wines' have recently gained popularity among wine consumers. In contrast to modern oenological practice, in which white grapes are pressed immediately after the harvest followed by immediate fermentation of the grape juice, to produce 'orange wines' the white grapes are macerated and fermented in direct contact with the mash which results in wines with completely different properties [21; 24]. In this study, we transferred this concept to _Ilzer Rose_ apple wine production and investigated the final product after apple mash fermentation. With the knowledge that volatiles such as terpenoids are enriched in the apple skin, apple wines with interesting properties were expected. In order to gain a deep understanding of these _Ilzer Rose_ apple wines on a molecular and a sensory basis, we applied analytical techniques that are common in flavour chemistry (i.e., headspace solid phase micro extraction coupled to gas chromatography mass spectrometry, HS-SPME GC-MS) together with techniques from modern sensory science (i.e., check all that apply, CATA). We hypothesize that the application of the described oenological measures will significantly impact the flavour of _Ilzer Rose_ apple wine. The results will not only help to deepen the knowledge of the product, but also to assist fashioning apple wine flavour and to make these products even more attractive to consumers.