# Quality Assessment of Honey Powders Obtained by High- and Low-Temperature Spray Drying
## 3 Results and Discussion
### FTIR Spectroscopy  
The first series of clearly visible bands are present in all samples, at 3650-3000 cm\({}^{-1}\), and are consistent with the findings of [PERSON] et al., 2015, [PERSON] et al., 2020, and [PERSON] et al., 2015 [37; 38; 39]. This region is characteristic of -OH stretching, which may originate from carbohydrates, organic acids, or water. Moreover, the NH\({}_{3}\) stretching band of free amino acids may also be present in this range. The region of 3000-2800 cm\({}^{-1}\) is dominated by a series of bands that may be assigned to stretching vibrations of sugar C-H skeleton. The band, with its maximum at -3332 cm\({}^{-1}\), represents carboxylic acids, whose irregular absorption enhances the stretching vibrations of C-H groups. Additionally, the strong hydrogen bonding of carboxylic acid dimers broadens the \(\
u\) (-OH) vibrations band [37]. The fingerprint region starts with a moderate intensity band with the maximum at -1715 cm\({}^{-1}\), which most likely originates from the stretching of carbonyl C=O functionalities present in fructose (ketone) and glucose (aldehyde) [39; 40].  
Another characteristic series of bands occurs at lower wavenumbers, namely in the range of 1480-700 cm\({}^{-1}\). This part of the fingerprint region is characteristic of C-O, C-C, and C-H stretching vibrations, as well as the bending vibrations of C-H present in the chemical structure of carbohydrates [35]. In some cases, these bands may also originate from organic acids and carotenes. The most prominent bands in this region are present at 1453, 1412, and 1338-1264 cm\({}^{-1}\). These signals most likely originate from the deformative vibrations of O-CH and C-C-H groups in carbohydrate, as well as from bending of -OH groups of the C-OH structure. Other significant bands within the range from 1245 to 940 cm\({}^{-1}\) are assigned to the stretching vibrations of C-H groups or (C-O) in carbohydrates. The vibrations of C-O groups in C-O-C are represented by the bands at 1145 and 1030 cm\({}^{-1}\), while the C-OH group or C-C stretching in the carbohydrate structure generate bands between 1030-940 cm\({}^{-1}\) and below 900 cm\({}^{-1}\)[38; 40; 41; 42; 43].  
Finally, the region of 900-700 cm\({}^{-1}\) reflects the vibrations of the anomeric region in carbohydrates or C-H and C-C deformation [42; 44]. Changes in this range often evidence relatively strong modifications of sugar fraction bonds. It is also noteworthy that the considerable differences between bands observed at 1200-940 cm\({}^{-1}\) point towards differences between powders obtained using traditional methods and those obtained with the use of dehumidified air. This in turn suggests a strong impact of the modifications on the vibrations of the carbohydrate structure and bonds existing between said groups in the sugar skeleton. Further differences between samples in the analyzed context are evidenced in the spectral range of 3600-3000 cm\({}^{-1}\) (Figure 1). To recap this part of FTIR studies, it should be underlined that primary differences in terms of the obtained spectral bands are observed in the regions of approx.: 3600-3000, 1440-1250, and 1140-980 cm\({}^{-1}\) (Figure 1). The regions primarily reflect the content of polyphenols and antioxidative components. Differences in terms of water content may also be a factor, but these are mainly related to the method of sample preparation.  
Figure 1: ATR-FTIR absorption spectra of the analyzed samples RH-SD, RH-DASD, HH-SD, HH-DASD in the spectra range 730–3750 cm\({}^{-1}\).