# Cellulose as a Delivery System of Raspberry Juice Volatiles and Their Stability
## 3 Discussion
Polar (hydrophilic) compounds are more soluble in water and can diffuse more easily through the matrix, which can explain the lower retention of polar volatile compounds [52]. Terpenes that were generally better retained throughout storage on the complexes with higher amount of cellulose, have higher molecular weight in combination with high values of hydrophobicity. Release ratio of watermelon flavor from \(\gamma\)-cyclodextrintrin inclusion complexes decreased with the increaseof hydrophobicity, implying the different affinities of hydrophobic flavor guests to \(\gamma\)-cyclodextrinrin [46]. This could slow down diffusion of volatiles during the storage period. Structure of carbohydrate is very important, and usually it is not sufficient for the polymer to be able to bind volatiles, but some other properties may also be required. Investigation on the binding of different volatiles to \(\beta\)-cyclodextrinrin and \(\alpha\)-cyclodextrinrin revealed the importance of carrier structure. Investigated volatiles had higher affinity for \(\beta\)-cyclodextrinrin due to the different size of cyclodextrin cavity. Additionally, the hydrophobicity of volatiles was also important, proving that the driving force for complex formation was hydrophobic/hydrophilic interactions [53]. Oxidized corn starch and oxidized amaranth starch were used for encapsulation of vanillin as a possible replacement of gum arabica. It was observed that oxidized starch forms can be used for encapsulation of this compound with similar efficiency as gum arabica and additional advantages, such as freedom from hygroscopicity [54]. Application of cellulose nanocrystals in preparation of starch-based film structures caused change in permeability of \(\beta\)-limonene [55]. Encapsulating agents such as maltodext, modified starch, gum arabica, xanthan gum and \(\beta\)-cyclodextrinrin were used for encapsulation of synthetic strawberry flavor by different drying techniques. The results revealed that the blend of maltodext/modified starch/\(\beta\)-cyclodextrinrin exhibited the best capability for encapsulating the flavor, followed by maltodext/gum arabica/\(\beta\)-cyclodextrinrin and maltodext/xanthan gum/\(\beta\)-cyclodextrinrin [56; 57]. [PERSON] and [PERSON] [25] studied the retention of organic volatiles in freeze-dried solutions containing various carbohydrates. Based on the experiments and studies on freeze-dried samples, a mechanism for the retention and loss of volatiles during drying was postulated. The mechanism involves formation of micro-regions in the dry cake in which volatiles are entrapped. The bulk structure of the dry cake indicates that these micro-regions are held together in some type of matrix, most likely made up of bridges of H-bonded carbohydrates. These micro-regions become impermeable to organic compounds when the water content decreases below a critical level. Their experiments have shown that slow freezing and decreasing sample thickness promoted retention of volatiles. An increase in polysaccharide concentration leads to decrease in the release of flavor compounds due to complexation and viscosity effect of the polysaccharide themselves. [PERSON] et al. [15] studied the release of limonene and menthol from different xanthan solutions. They found out that with higher xanthan concentration, the release of limonene decreased which was explained by the higher hydrophobic character of xanthan in comparison to other hydrocolloids. Xanthan consists of a cellulose backbone with ionized trisaccharide branches. The ordered molecule is stabilized through hydrogen bonds by non-covalent side chain-main chain interactions involving hydrogen bonding. In this way, xanthan may create a hydrophobic interior in the carbohydrate molecule, which can include volatile compounds. The hydrophobic character of cellulose, properties of volatiles and interactions between them during complexation as well as the formation of micro-regions during freeze-drying could be the combination that makes cellulose an acceptable carrier of raspberry volatiles.