The Research Of Characteristic Components Of Citrus Honey Samples

Solid-phase microextraction(SPME)is a sample pretreatment and enrichment technology,which integrates sampling,extraction,condensation and sample injection into one step.SPME is used widely to analyze trace compounds from complex matrix by combining with gas chromatography-mass spectrography(GC-MS).The research of volatile components of citrus honey samples can discriminate adulterated citrus honey and label different floral honey.In this paper,the research about volitale compounds of citrus honey samples includes two aspects:the analytical method and trial about storage time.1.GC-MS with head-space SPME sampler was applied to qualitative and quantitative analysis of Chinese citrus honey samples for their volatile components.The fibre head of DVB/CAR/PDMS was used as microextractor in SPME.The honey sample(4.00 g)and water(1.00 g)were mixed in the head-space flask and after capping tightly;it was equilibrated at 50? for 10 min,and treated by SPME for 50 min.The microextractor was removed out and desorbed(at 250? for 3.5 min)at the injection port of GC.TG-5MS capillary column was used for chromatographic separation.Mode of EI was adopted in MS.Thirteen citrus honey samples were analyzed by the proposed method,105 volatile components were identified,mainly including alcohols,hydrocarbons,aldehydes and esters,among which limonene,trans-and cis-linalool oxide,/3-linalool and citral were acknowledged as characteristic compositions(or markers),their content were found in the range of 0.10-47.18,13.62-3854.85,3854.85-1136.15,0.10-131.69,131.69-22.67 ?g·100g-1.In analyzing all honey samples by the present method,values of RSD's(n=5)of absolute peak area of the markers were between 2.9%and 19.7%.2.The determination of volatile compounds of eight citrus honey samples was in progress.SPME combined with GC-MS was applied to extract,separate and detect all citrus honey samples during different storage time(1,30,60,90,150 days),which were kept the storage temperature at 25? and protected from light.All citrus honey samples contained ethanol,o-cymene,limonene,citral,trans-and cis-linalool oxide,1-(1,1-dimethy lethy l)-2-methyl-1,3-propane-diy 1-2-methyl propanoate,?-linalool,hotrienol and a-terpineol during the whole storage.Possible marker compounds could also be found for citrus honey samples were as follows:1,1,5-trimethyl-1,2-dihydronaphthalene(kumquat honey samples);lilac alcohol isomer I,?-terpinene,isophorone,safranal,etc(gaza sugar orange honey samples);1,7,7-trimethyl bicyclo[2.2.1]hept-2-ene and(E)-nerolidiol(ponkan honey samples);3-methyl-1-butanol,acetate and ethyl hexanoate(tangerine honey samples);methyl salicylate(navel orange honey samples).Different varieties of citrus honey samples were classified by principal component analysis in the process of storage,variance of first principal component was 47.7%,and variance of second principal component was 24.8%.The longer the storage time,the more volatile components types,mainly including esters and alcohols;relative content of linalool and its derivatives were reduced,which led to lower flavor.