| Kushui rose(R.setate×R.rugosa)is a famous variety of oil rose in China and the essential oil produced by this rose has bright color and pure fragrance.In the food industry,rose essential oil is often used to produce food additives to increase food flavor and prolong food storage period.At present,it has been found that the salt process which the petals immersed in the sodium chloride solution in the process of the distillation can effectively enhance the yield of essential oil,but it is unknown whether the quality of the essential oil changes after such treatment.In the meanwhile,the expensive and unstable property of rose essential oil have greatly limited its application.Therefore,this article takes Kushi rose as the research object and comprehensively studies the effect of salt treatment on the composition,aroma profile and antioxidant activity of essential oils and hydrosols.Finally,a portable and common rose essential oil product,Kushui rose essential oil microcapsule,was prepared.The results can provide theoretical guidance for the application of rose essential oil in food industry and the development of deep-processing products.The main research contents and results are as follows:1.Influence of salt treatment on the essential oil and hydrosols composition of Kushui rose(1)Influence of salt treatment on the essential oil composition of Kushui rose GC-MS was used to identify the composition of fresh rose essential oil(FREO)and salt rose essential oil(SREO).Total 193 and 190 compounds were detected in FREO and SREO,respectively.Among these,a total of 55 compounds were detected in the two essential oils,and the contents of each compound in the two essential oils were significantly different.After salt treatment,there were 15 compounds whose content more than doubled,such as heptaldehyde,calamene,spathulenol,geranyl acetate,etc.,while the content of the remaining 40 compounds also varied by 10-50%.In addition,138 compounds were only detected in FREO,and 135 compounds were only detected in SREO.The compositions of FREO and SREO were detected completely by using GC-MS and GC×GC-TOF/MS technology,and it was verified that the significant effect of salt treatment on the rose essential oil composition.(2)Influence of salt treatment on the hydrosol volatile composition of Kushui rose SPME-GCMS was used to identify the composition of fresh rose hydrosol(FRH)and salt rose hydrosol(SRH).Total 57 volatile compounds were detected in FRH,while 61 volatile compounds were identified in SRH.Among these,there are 33 kinds of volatile compounds in the two hydrosols,but the content of the common substance changes greatly after salt treatment.There were 17 compounds whose content more than doubled after salt treatment,such as 2-nonanone,linalool,terpineol,eugenol,rose oxide,etc.,while the content of the remaining 16 volatile compounds varied by 5%-50%.In addition,24 volatile compounds were only detected in FRH,and 28 volatile compounds were only detected in SRH,which indicates that the salt treatment has a remarkable effect on the volatile composition of Kushui rose hydrosols.2、Effects of salt treatment on the aroma and antioxidant activity of essential oils,hydrosols(1)Aroma analyze for FREO and SREO,23 and 25 kind of characteristic aroma components were obtained in FREO and SREO,respectively,which were prominent with the aroma series of fragrant(grass),floral and sweet.The aroma anlysis showd that salt treatment did not have a great influence on the aroma profiles of the essential oils as can be draw from the similar aroma profiles between two essential oils.However,the total OAV of SREO was significantly higher than FREO,indicating that the aroma of SREO is stronger than that of FREO.(2)21 kind of aroma compounds were obtained from the FRH,while a total of 20 characteristic volatiles were detected in SRH.The aroma of the two kinds of hydrosol was different in the types of fatty,fruity and woody,which demonstrates that the salt treatment has a significant effect on the aroma profile of the hydrosols.(3)In terms of functional characteristics,the maximum value of total antioxidant capacity of FREO and SREO were 0.128 mg Vc/m L and 0.138 mg Vc/m L,respectively.The rates of scavenging DPPH free radical were 53.92% and 43.20% and IC50 value of scavenging DPPH free radical were 8.34 mg/m L and 4.46 mg/m L.The maximum value of total antioxidant capacity of FRH and SRH was 0.022 mg Vc/m L and 0.027 mg Vc/m L,respectively.The rates of scavenging DPPH free radical were 3.67% and 5.65%,respectively.The results showed that the antioxidant capabilities of the SREO was superior to the FREO and the difference of the antioxidant capabilities between the two kinds of hydrosol was not significant,indicating that the salt treatment has a greatly impact on the functional characteristics of essential oils,but has an indistinctively impact on hydrosols.3、Preparation and performance evaluation of essential oil microcapsule of Kushui rose(1)Essential oil microcapsule was prepared by a saturated aqueous solution method,and the optimum preparation conditions were as follows: the ratio of ethanol to essential oil was 1:25(m L: m L),the stirring time was 3h,the stirring temperature was 60℃,and the stirring speed was 800 r.The embedding rate of essential oil microcapsules reached 46.19%.(2)Observation of the microcapsules with an electron microscope showed a spherical shape and a smooth surface.and the appearance.The volatile components of Kushui rose essential oil and oil microcapsules were detected by SPME-GC-MS technology.The total content of volatile components in Kushui rose essential oil was 19709.42mg/kg,and the total content of volatile components in microcapsules was 287.37mg/kg.Embedding rate of essential oil volatile components reaches 98%,indicating that the microcapsules had a good embedding effect.(3)The results of microcapsule sustained-release evaluation showed that the retention rate of essential oils stored at 35℃ for 24 h was 3.63%,while the essential oil retention rate of essential oil microcapsules was 69.75% under the same conditions,indicating that essential oil microcapsules can effectively maintain the essential oil composition.The stability of the essential oil microcapsules at 35℃(69.75%)compared to the essential oil microcapsules at 75℃(59.86%),indicating the essential oil microcapsules are more conducive to storage and use under low temperature conditions. |
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