## 4 Conclusions  
Analytical results confirmed significant differences in the biopolymer composition of oyster mushroom basidiocarps. In the vibrational spectra of basidiocarp samples, characteristic bands of proteins and polysaccharides were found that make it possible to evaluate individual strains by their biopolymer composition, and therefore can be used to assess the quality of mushrooms as culinary ingredients and also as the source for preparation of food supplements. The combination of vibrational spectroscopy and chemometrics proved to be successful in discriminating basidiocarp samples based on protein contribution and, to a lesser extent, total glucans. The results obtained can be considered as an example of screening of individual oyster mushroom strains, the criterion of which is the choice of forms for the purpose of their selective cultivation and further use. Obviously, high protein content is preferable for culinary purposes, while the presence of \(\beta\)-d-glucans can have dietary and even medicinal significance. A combination of the above methods has also been proposed to predict the biopolymer contents of basidiocarps. Again, the models for predicting proteins were found to be more precise and accurate than the corresponding models for total glucan. Thus, despite the high content of polysaccharides in basidiocarps compared to proteins, multivariate analysis of vibrational spectra was more effective in relation to proteins than total glucans. The difficulties associated with spectroscopic assessment and quantification of the total amount of glucans in basidiocarp can be explained by the wide structural diversity of these polysaccharides in oyster mushrooms. In addition, the spectral contribution of other polysaccharides, namely mannogalactan and chitin, may be responsible for the poorer results for total glucans. Further research is required to better evaluate and distinguish the basidiocarps of different strains in terms of their polysaccharide composition. Despite these difficulties, the result of this study shows that the combination of vibration spectroscopy with multivariate statistical methods can serve as a powerful potential tool for assessing  
Figure 5: Using the Raman band of the Phe ring breathing vibration at 1004 cm\({}^{-1}\) for determination of proteins in _P. ostreatus_ basidiocarps: (**a**) measuring of the height; (**b**) correlation between this height and protein content (% _w/w_). the content of not only proteins, but also polysaccharides in oyster mushrooms, which have culinary and medicinal value. Quantification of proteins and glucans is especially important for the characterization of fungi, as it allows determination of the efficiency of cultivation and the most appropriate time for harvesting. In addition, it is known that different parts of the basidiocarp (stems, caps and spores) can differ significantly in biopolymer composition. The universal character of vibration spectroscopy allows these methods to be applied in the analysis of other types of edible mushrooms, of course, taking into account the peculiarities of their composition. Nevertheless, this approach can be proposed as an alternative to the widely used expensive and time-consuming analytical methods. Conceptualization, A.S. and P.K. ; methodology, E.B. and R.B. ; software, M.S. and I.S. ; validation, M.S. and I.S. ; formal analysis, E.B., R.B. and L.S. ; investigation, E.B., R.B. and A.S.; resources, I.J. ; data curation, E.B. and L.S. ; writing--original draft preparation, E.B. and R.B. ; writing--review and editing, E.B., R.B. and A.S.; supervision, A.S. and J.C.; project administration, J.C. and A.S.; funding acquisition, P.K., I.J. and A.S. All authors have read and agreed to the published version of the manuscript. This research was funded by the Ministry of Agriculture of the Czech Republic, project number QK1910209, and by Specific University Research of UCT Prague, project number 21-SVV/2020. The authors are grateful to Ing.