## 3 Results and Discussion
### Characterization of Encapsulated Pumpkin Oil in Carbohydrate Shells
#### 3.3.3 Oxidative Stability of Encapsulated Pumpkin Oil  
Pumpkin oil powders were characterized by high oxidation stability (from 9.5 h for wall material with trehalose to 15.1 h for wall material with wheat starch). It is worth pointing out that the oxidative stability of cold pressed pumpkin oil is in the range of 6.8-9.4 h [48; 49; 50]. High OSI of powders can be explained by the possibility of carbohydrate wall materials to form a glassy shell that blocks the surface pores and creates a barrier, which can limit oxygen diffusion toward the core material [44]. The lowest OSI powder with trehalose can be explained by the hygroscopic nature of trehalose, which increases the tendency to absorb water from the environment, resulting in possibility of crystallization. [PERSON] et al. [51] reported, that in the glassy state trehalose decreases lipid oxidation. Additionally, powder with lactose compared to powder with wheat starch had low OSI (12.4 h). According to [PERSON] et al. [52] lactose is very hygroscopic, and under varying storage conditions, the amorphous lactose undergoes an irreversible transition to stable crystalline forms. This crystallization leads to a coating of crystals on the surface of the spray dried powder particles which decreases the shelf life of the powders. Distribution of Unsaponifiable Lipophilic Compounds in Surface and Core Oils of Encapsulated Pumpkin Oil  
Used in current study pumpkin oil contained 320, 260 and 50.8 mg/100 g of sterols, squalene and tocopherols, respectively (Table 4). Among tocopherols two compounds were determined: \(\alpha\)-tocopherol (16.7%) and \(\gamma\)-tocopherol (83.3% of total). This content and composition of pumpkin oil is similar to those found previously by [PERSON] et al. [49] and [PERSON] et al. [50]. In the case of sterols, shares of spinasterol + \(\beta\)-sitosterol, \(\Delta\)7,22,25-stigmastatrienol, \(\Delta\)7-stigmasterol and \(\Delta\)7,25-stigmastadienol were 52.8, 21.3, 4.4 and 21.6%, respectively. Presented sterol composition is similar to that reported by [PERSON] et al. [50] and [PERSON] et al. [53], who showed that \(\Delta\)7-sterols are predominating in pumpkin oil. Such unique composition of pumpkin sterols was recently confirmed by the study conducted in Italy, which showed the ca. 95% of total sterols of Berretina pumpkin seed oil are composed of \(\Delta\)7-sterols [54]. Usually, these sterols groups account for at least 91% of pumpkin oil, so their lower level can indicate pumpkin oil adulteration [49; 55]. In general, sterols, tocopherols, and squalene content and composition are relatively constant between pumpkin seed oils produced from plants cultivated in various world regions [56]. Encapsulation efficiency of each identified compound in sterols and tocopherols groups and of squalene was determined only for three carbohydrates with the highest encapsulation efficiency of pumpkin oil, which were maltodextrin, wheat starch and steel. The results of the experiments were summarized in Table 4. \begin{table}
\begin{tabular}{c c} \hline \hline
**Compound** & **Content (mg/100 g)** \\ \hline \(\alpha\)-tocopherol & 8.48 (1.36) \\ g-tocopherol & 42.3 (3.19) \\ Total topcherols & 50.8 (5.76) \\ Squalene & 260 (7.83) \\ Spinasterl + \(\beta\)-sitosterol & 169 (4.26) \\ \(\Delta\)7,22,25-stigmastatrienol & 68 (2.30) \\ \(\Delta\)7-stigmasterol & 13.9 (0.47) \\ \(\Delta\)7,25-stigmastadienol & 69 (1.90) \\ Total sterols & 320 (8.68) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Bioactive unsaponifiable compounds in native pumpkin oil. Figure 4: SEM images of encapsulated pumpkin oil in carbohydrate shells: maltodextrin (M), wheat starch (WS), rice starch (RS), maize starch (MS), lactose (L) and trehalose (T). lactose (Table 2). Among used carbohydrates the best properties to entrap all lipophilic pump-unsaponifiable compounds were found for maltodextrin (encapsulation efficiency in range 67.5-75.3%) (Table 5).