# Quality Assessment of Honey Powders Obtained by High- and Low-Temperature Spray Drying
## 3 Results and Discussion
### Antioxidant Activity  
The reducing potential (CUPRAC) of powders obtained in the current work was in the range from 13.2 \(\pm\) 0.2 to 65.7 \(\pm\) 2.1 mg Trolox/100g powder solids (Table 2). Lower values (from 13.2 \(\pm\) 0.2 to 31.8 \(\pm\) 0.9 mg Trolox/100g powder solids) were found in powders obtained for rapeseed honey (RH), which as a raw material was also a lower source of compounds with a reducing effect (38.7 \(\pm\) 0.8 mg Trolox/100 g honey solids). The RH powder obtained by the new spray drying method (DASD) showed twice the reduction power compared to that obtained by the conventional process (RH-SD). In contrast, drying of honeydew (HH-274.6 \(\pm\) 9.7 mg Trolox/100 g honey solids), which was very rich in compounds with reducing effects, resulted in obtaining powders with similar antioxidant effects for both drying methods. The activity shown by the carrier was presented, expressed per 100 g powder solids. It was small (2.9 mg Trolox/100 g), and its variability resulting from values of raw material dry matter differed only on the 3 rd decimal place. However, due to the unequal activities of the powders, the proportion of carrier in the total powder activity was different. The presence of the carrier had a small impact (below 5%) on the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **RH** & **HH** & **RH-DASD** & **HH-DASD** & **RH-SD** & **HH-SD** \\ \hline \multicolumn{7}{c}{**TPC**} \\ mg GAE/100 g powder solids & \(-\) & \(-\) & \(32.5\pm 3.0\) ab & \(53.3\pm 3.3\) c & \(16.5\pm 3.7\) a & \(34.1\pm 4.6\) b \\ mg GAE/100 g honey solids & \(86.1\pm 6.4\) d & \(122.7\pm 14.8\) e & \(68.9\pm 6.4\) ab & \(112.2\pm 7.0\) c & \(35.0\pm 7.8\) a & \(71.8\pm 9.8\) b \\  & & & (80\%) & \(91\%) & (41\%) & (59\%) \\ \hline \multicolumn{7}{c}{**CURRAC**} \\ mg Trx/100 g powder solids & \(-\) & \(-\) & \(31.8\pm 0.9\) ab & \(61.5\pm 1.5\) c & \(13.2\pm 0.2\) a & \(65.7\pm 2.1\) c \\ mg Trx/100 g honey solids & \(38.7\pm 0.8\) a & \(274.6\pm 9.7\) d & \(67.4\pm 1.9\) b & \(129.5\pm 3.3\) c & \(28.0\pm 0.4\) a & \(138.2\pm 4.5\) c \\ AC mg Trx/100 g powder solids & \(-\) & \(-\) & \(2.9\pm 0.1\) a & \(2.9\pm 0.1\) a & \(2.9\pm 0.1\) a & \(2.9\pm 0.1\) a \\ \hline \multicolumn{7}{c}{**DPPH**} \\ mg Trx/100 g powder solids & \(-\) & \(-\) & \(8.3\pm 0.3\) b & \(21.1\pm 0.4\) d & \(2.9\pm 0.1\) a & \(14.3\pm 0.5\) c \\ mg Trx/100 g honey solids & \(12.1\pm 0.2\) b & \(37.7\pm 0.4\) e & \(17.6\pm 0.7\) c & \(44.5\pm 1.0\) f & \(6.1\pm 0.2\) a & \(30.2\pm 1.0\) d \\ AC mg Trx/100 g powder solids & \(-\) & \(-\) & \(0.2\pm 0.0\) a & \(0.2\pm 0.0\) a & \(0.2\pm 0.0\) a & \(0.2\pm 0.0\) a \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Total phenolic content (TPC) and antioxidant activity (CUPRAC, DPPH) of rapeseed honey (RH) and honey (HH) powders obtained by traditional spray drying (SD) and dehumidified air spray drying (DASD); AC–activity introduced into the powders by the carrier; in brackets–relative retention in comparison to raw honey. a–f: differences between mean values followed by different letters in rows were statistically significant (P<0.05). activity of the HH powders, on the contrary to the RH, in which this impact was 9 and 22%, after SD and DASD, respectively. The activity of the honey itself (without taking into account the carrier) in both HH powders was equal and accounted for about half of the strong activity of the raw material honey. In the case of weaker performing (38.7 \(\pm\) 0.8 mg Trolox/100 g honey solids) rapeseed honey (RH), the proposed new spray drying method (DASD) showed a significant increase in activity (67.4 \(\pm\) 1.9 mg Trolox/100 g honey solids). This was probably due to beneficial changes in antioxidants, including some phenolic compounds.