Comparative Study of the Yield and Chemical Profile of Rose Oils and Hydrosols Obtained by Industrial Plantations of Oil-Bearing Roses in Bulgaria

Bulgaria is famous for its oil-bearing rose. R. damascena Mill. and R. alba L. are mainly cultivated in the country, but a recent survey of industrial plantations in 2020 revealed that R. centifolia L. and hybrids of R. damascena Mill. X R. gallica L. are also common in the rose valley. Although their essential oil cannot be compared in quality with the classic, these species are preferred by farmers with high yields of flowers and resistance to diseases and pests. All these roses are also used to produce rose water and extracts. The aim of this investigation was to compare the yield and chromatographic fingerprints of seven rose oils and hydrosols produced in Bulgaria. The quantitative composition of the main components of the oils was compared with the norms of the world standards. Our study showed that the yield of essential oil from these roses was in the range of 0.015-0.048%. The main group in the chemical composition is terpene alcohols, which vary in range: geraniol (15.85-34.02%), citronellol (6.70-28.72%), and nerol (5.80-11.90%) but with a different ratio. Hydrocarbons are represented by saturated aliphatic homologs with an odd number of carbon atoms, the main ones being nonadecane (8.10-22.67%), heneicosane (4.37-10.21%), heptadecane (1.07-2.98%), and triclosan (0.81-5.90%). In contrast, the chemical profile of the hydrosols was performed using phenylethyl alcohol (27.45-69.88%), geraniol (13.72-28.67%), and citronelol+nerol (4.56-17.37%). The results show that the presence of plantations with a genotype different from that of R. damascena implies differences in the quality of rose oils and hydrosols. This determines their properties of use.