| Rose (Rosa rugosa Thunb.), a deciduous shrub, is native to North China, Japan and Korea, and now widely cultivated around the world. Some species in Rosa(Rosa. L), from whose flowers essential oils and other spices can be extracted, have been also broadly and collectively called oil rose at home and abroad, and extensively used in cosmetics, food, chemical and other industries. The plant materials of oil rose involved in this paper were Rosa rugosa'Purple branch', now successfully introduced in Chongming, Shanghai.Currently, studies on production and processing of rose natural products focus on the extraction, purification, yield, composition changes, aroma characteristics and other aspects of essential oils. However, the changes in both compositions and contents of aroma in the natural state and flower water with same high value, as well as differences between processing methods extracting flower water, were rarely reported. Herein, Rosa rugosa'Purple branch'planted in Eco-Village Rose Planting Demonstration Base in Xiaodong Village, Jianshe Town, Chongming Island, was discussed from the following perspectives including compositions and contents of aroma and flower water, two different extraction processes of flower water. From May to July 2010, vivo aroma of Rosa rugosa'Purple branch'was collected using Tenax TA sampling tubes combined with thermal desorption and gas chromatography-mass spectrometry (GC-MS) to analyze the compositions and content changes. Meanwhile, rose water was obtained using steam distillation and sub-vacuum cold air processing units, followed by analyses by means of macroporous resin adsorption and gas chromatography mass spectrometry (GC-MS) for differences of volatile aromatic components. In addition, the quality of rose water obtained by different methods of extraction and processing were compared and evaluated.The results showed that: alcohols were the most important aroma constituents in both half open and full open flowers of'Purple branch', followed by terpenes and esters. Geraniol and nerol are concentrated in May, with their corresponding esters decreasing by months. The number and content of terpenes and alcohols decreased month by month while those of acid increased. The relative content of citronellol and its corresponding ester in full open flowers were higher than those in half open flowers. Terpenes and aldehydes were higher in half open flowers than those in full open flowers, when alcohols, esters and phenols were the opposite, leading to fragrance changing in the process of opening. Therefore, the best time for smelling natural aroma of'Purple branch'was May, mainly based on full open flowers. Compared with other species,'Purple branch'in Chongming had low citronellol, high phenylethanol, especially highα-pinene far more than them. Citronellyl acetate and limonene were similar with other species. Compared with essential oil of'Purple branch'at the same period, natural aroma had high phenylethanol, low phenols, as well as more terpenes both in types and quantities.The front part of flower water extracted from Rosa rugosa'Purple branch'had sweeter and richer fragrance than the back part. It was mainly caused by the differences between alcohols, phenols and terpenes. So the front part had higher quality and value. In terms of monthly changes, alcohols representing the iconic fragrance were highest in May. Terpenes made the most outstanding contribution in June. Flower water in May was less affected in the negative sense of phenols, ketones and acids than the other two months. Therefore, flower water in May was the best in quality, followed by June and July. Compared with essential oil and vivo aroma of'Purple branch'at the same period, flower water had similar types and numbers of alcohols and terpenes with vivo aroma and similar contents of terpenes with essential oil. However, the quality defects of'Purple branch'flower water were low esters in types and contents and high phenols in contents. Flower water of'Purple branch'in Chongming had the same main characteristics of volatile components with roses from other species and areas, but differed in relative contents of certain compounds.Processing time had no significant effect on types and contents of volatile components in'Purple branch'cell liquid when sub-vacuum and cold air circulation device was used. The front part of cell liquid was better than the back one in quality due to the higher relative contents of geraniol and nerol. Compared with flower water extracted by traditional steam distillation, cell liquid had simple volatile components, including more than 70% phenylethanol, lower main aroma components of geraniol, citronellol and nerol, lower phenols, higher terpenes and similar esters, reasulting in different volatile components extracted by two processes above. Cell liquid smelled light and thin, and showing a fresh and terpene flavor. Compared with essential oil and vivo aroma of'Purple branch'at the same period, cell liquid had high phenylethanol as a single advanced component, while main alcohols and their corresponding esters were low or even could not be detected. Compared with rose cell liquid in other areas,'Purple branch'in Chongming had higher phenylethanol, lower eugenol and methyl eugenol, and higher terpenes. All cell liquids above showed delicate fragrances. |
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