The peaks and shoulder peak observed in the UV-Vis spectrum of beta-cyclodextrin hydrate are due to the electronic transitions of the molecule. Beta-cyclodextrin is a cyclic oligosaccharide composed of seven glucose units. When beta-cyclodextrin forms a hydrate, it can interact with water molecules, leading to changes in its electronic structure and, consequently, its UV-Vis spectrum. The peaks at 225 nm and 272 nm are likely related to specific electronic transitions in the beta-cyclodextrin hydrate molecule. The shoulder peak is typically a less intense peak that appears on the high-energy side of a more prominent peak. It indicates the presence of another electronic transition that occurs at a slightly higher energy level. The shoulder peak may result from different conformations or interactions of the beta-cyclodextrin hydrate with water molecules or other species present in the sample.

In the pdf, there is no absolute reason mentioned about the peaks.