Phenolic profile, chromatic parameters and fluorescence of different woods used in Balkan cooperage

The aim of this research was to study phenolic compounds of diverse botanical species of wood commonly used in cooperage in Balkan countries. Several botanical species have been considered including mulberry (Morus alba L.), myrobalan plum (Prunus cerasifera Ehrh.), black locust (Robinia pseudoacacia L.), wild cherry (Prunus avium (L.) L.), and oak (Q. petraea (Matt.) Liebl., Q. robur L., and Q. cerris L.). A total of 37 compounds were quantified, demonstrating the presence of phenolic acids, flavonols, flavones, flavanones, flavanonol taxifolin, stilbenoids, and coumarins. Taxifolin was the most abundant in wild cherry (8455.70 mg kg−1), while ellagic acid predominated in oak wood (8872.05–10099.32 mg kg−1 in sessile oaks, and up to 15,958.80 mg kg−1 in pedunculate oak from Slavonia). The highest content of protocatechuic acid (533.39 mg kg−1) was found in myrobalan plum. Also, isoflavones were characteristic of wild cherry, while mulberry was abundant in stilbenoids. Total phenolic content, as well as antioxidant, chromatic, and fluorescence properties were studied. The spectral shapes and maxima of fluorescence emission spectra of bare wood samples were compared with those of the corresponding wood extracts. The Principal Component Analysis (PCA) was applied in order to find patterns in emission spectra for differentiation among wood samples.