# Quality Assessment of Honey Powders Obtained by High- and Low-Temperature Spray Drying
## 3 Results and Discussion
### Antioxidant Activity
The method used to determine phenols is sensitive to their composition (and the possible presence of other reducing compounds reacting under the conditions of the assay) [27]; hence, the structural changes in the components of phenol mixture (not necessarily associated with their breakdown to other compounds) may have resulted in determining their lower content using the Folin-Ciocalteu method. In the case of rapeseed honey dried by the traditional method, a significantly greater proportion of the carrier in the reducing potential of the powder (22%) was also noted than in the case of drying by the dehumidified air spray drying with (9%). The beneficial effect of the use of dehumidified air on the reducing potential of rapeseed honey during spray drying using various carriers, including Nutriose(r), was also observed in our previous studies [13]. The activity of extracted antioxidants against DPPH radical expressed in Trolox equivalents was lower than their reduction capacity (Table 2). The antiradical activity of each of the powders (expressed per 100 g of powder solids) was also clearly lower than the raw material honey used for their production. The activity of powder is a result of raw material activity, the impact of the process and the presence of the carrier that has a very low activity (0.2 mg Trolox/100 g). Powders produced with the spray drying method at low temperatures were again a source of compounds with better activity against DPPH\(\bullet\). The activity of both honeydew honey (HH) powders was higher than rapeseed honey (RH) powders. The negative impact of spray drying temperature on antioxidant activity against DPPH radicals was also observed by [PERSON] and [PERSON], 2016 on the example of beet juice [28]. Without taking into account the activity, the source of which was the carrier used in the research, antiradical activities were obtained, whose source was the dried material itself. In this experiment, the activity of both kinds of honey dried by the new spray drying method was higher than the activity of raw materials. This was probably the result of a very low loss of phenolic compounds (9-20%) as a consequence of spray drying at a lower temperature with dehumidified air (DASD), as well as favorable transformations of these compounds under proposed conditions, which has already been observed in the reducing potential tests. The proportion of the carrier activity in the whole activity of powders was low (below 3%), except RH-SD of the lowest activity (carrier share in the activity was almost 7%). Antioxidant activity against DPPH radicals was positively correlated with the content of phenolic compounds (r = 0.83; \(p<\)0.05). Such a correlation is known and confirmed in many studies [25; 26]. The fact that the correlation obtained in this paper was quite weak may confirm the concept of beneficial structural changes in some phenolic compounds in the process of honey spray drying. In the case of such changes, the activity would not be strongly related to the total content, taking into account the raw material and the samples processed in a different way. In contrast, no correlation between the reduction capacity measured by CUPRAC with phenolic compound content or antiradical activity against DPPH\(\bullet\)was noted. The action of bioactive compounds leading to deactivate the DPPH radicals is based on both basic mechanisms of antioxidant activity, single electron transfer (i.e., through the reducing potential of the molecule), and hydrogen atom transfer, although the mechanism is believed to be much more complex [29]. The lack of correlation in both experiments of antioxidant activity testing indicates the importance of this second mechanism for the action of antioxidants contained in honey against DPPH radicals.