# Disaccharides: Influence on Volatiles and Phenolics of Sour Cherry Juice
## 3 Discussion  
The effect of sugar addition on the volatile compounds in different fruit products was investigated through several studies. A positive effect of trehalose on volatiles was observed for different samples depending on the properties of the volatile compounds, but also on the sample composition and conditions during processing and storage [13; 14; 15; 16; 17; 18; 19]. Also, there have been studies showing similar results on the protection of phenolics, flavonoids and anthocyanins by trehalose addition under different conditions during processing and storage [19; 20; 21; 22; 23]. In contrast to these results, in the study of [PERSON] et al. [24] it was demonstrated that maltose also had a protective effect on anthocyanins in sour cherry puree, but those samples were prepared by freeze-drying. In this study, juice was investigated as the food matrix, which in the highest percentage contains water. It is well known that water has a very specific and important role as a solvent and a reactant in many chemical reactions in foods. When water activity is high, reactions limited by diffusion are enhanced. Those reactions together with enzymatic activity, oxidation, and molecular mobility, which are all consequence of more available water, are causes of the degradation of sensitive compounds [25]. Anthocyanins are pigments soluble in water, thus water plays a major part in their degradation. The degradation of anthocyanins starts with the hydrolysis of the glycosidic bond in its structure and the formation of unstable anthocyanins, followed by the opening of the pyrilium ring and the formation of chalcones and brown end products [26; 27]. Also, in the presence of oxygen, water can increase the oxidation rate of anthocyanins. The investigated sugars (sucrose, maltose and trehalose) are chemical isomers, but as it is evident from the results on phenolics as well as volatiles, their behavior in a complex matrix can be different. Even if they are chemical isomers, they show different behavior in a much simpler system like water. Sugar molecules change water dynamics resulting in the effect of sugars on volatile and phenolic compounds. Trehalose binds to a larger number of water molecules than maltose and sucrose, leading to higher effect on water structure. Also, trehalose is able to form larger clusters than sucrose, but smaller than maltose. [PERSON] et al. [28] suggested that trehalose-water mixtures are more homogeneous than sucrose or maltose water solutions based on the hydration number, the radius of gyration, the glycosidic dihedral angles and cluster formation. Steric hindrance developed by the disaccharide, which can protect or slow down the nucleophilic attacks of water that could cause the degradation of anthocyanins, were probably more pronounced in samples with trehalose addition because of the higher stability of trehalose, since trehalose structure is very stable regarding hydrolysis in comparison with sucrose [29]. Except for slowing down water dynamics, it is possible that some weak interactions occurred between trehalose and some of the compounds. The formation of stable intramolecular complexes between trehalose and unsaturated compounds that possess the _cis_-type olefinic double bond or with other structurally similar compounds [like benzene and p-cresol] is also a possible explanation of trehalose's positive effect on phenolics and some volatiles [30; 31; 32]. These complexes can be formed with trehalose, but not with other disaccharides, due to the unique nature of trehalose, since the aromatic ring of compounds can approach the dehydrated, hydrophobic pocket of trehalose leading to the formation of the complex [32]. Volatiles are characterized by their diffusion. Sugars have different diffusion coefficients in water, but they also change the diffusion coefficient of water [33], thus, they are probably responsible for the