Study On Aromatic Compounds In Camellia Oil Based On SPME/GC

With the improvement of people's life quality, the need for high quality edible oil keep increasing. Sensory characteristic is the important index of oil quality, and aroma is one important factor composing the flavor of oils. Different oils all have their characteristic odor, we can easily distinguish them by their odor. Camellia oil is only maked from our country, it is famous for nutritional value and claimed health-care functions. However, there are few research reports about oil aroma in our country, and systematic research report about the aroma of camellia oil has not been found indeed. Thus, researching volatile profiles and understanding relation between volatile profiles and quality of camellia oil have important significance for improving value of camellia oil and protecting health of consumers.Camellia oils from different areas and different extracting method were as materials, the aroma of camellia oil was researched by Head Space Solid Phase Micro-extraction(HS-SPME) contecting with GC/MS. The conditions of HS-SPME extracting the volatile profiles of camellia were optimized, and the analysis effect of GC was verified. Then, the aroma of different camellia oils was analyzed by sensory analysis and instrument analysis. In addition, the change of routine quality indexes of camellia oil and volatile profiles was probed during refining, and their relation was studied. The main results were shown as follow:The oil sample containing three different total standards amount (29.62μg/g,59.23μg/g,118.46μg/g) was applied for the test, the total peak area and average peak area of standards were as evaluation indexes, the performance of SPME fibers with four different coatings was studied, we found that the fiber was coated by 50/30μmDVB/CAR/PDMS was applicable to analyze the volatile profiles of camellia oil.Total peak area, ratio of total peak area to number of peaks, peak number and peak area of main volatiles were as evaluation indexes. The effect of extraction temperature, sample mass, stirring rapidity, extraction time, desorption temperature and time for extracting volatile profiles was studied. Extraction conditions were found that:1.00 g oil sample in 15 mL vessel,exposure for 25 min at 40℃, stirring at 100r/min, and desorption for 3 min at 260℃in GC. Calibration curves of 13 standards showed good linearity, with coefficients of determination(R2) ranging from 0.9841 to 0.9999 and limits of detection(LOD) from 0.04μg/g to 0.44μg/g. The recoveries and coefficient of variation in standards determination ranged from 91.83% to 105.11% and from 2.51% to 8.00%.The aroma of different camellia oils was described by sensory evaluation using scoring test, simple description method and triangular test, characteristic aroma of camellia oil was described generally. The aroma of camellia oils from different areas and different extracting method was studied by HS-SPME contecting with GC/MS,48 volatile compounds were identified, the number of aldehydes, alcohols and alkanes accounted for 70% of all compounds number. It was found, that volatile compounds of camellia oils from different areas had some different part, but some compounds were same, which occurted in the aroma of camellia oils different extracting method. Combining sensory evaluation, nonanal,α-pinene, ethyl acetate, pentanol, benzaldehyde, octanol, a-muurolene, nonanol, octanal, hexanal, styrene were ascertained as the main volatile compounds of characteristic aroma of camellia oil.In this study for the effect of bleaching for oil quality indexes and volatile profiles, we found that acid value increased, UV absorbance at 232 and 270 nm went up gradually in accordance with the amount of active clay and bleaching time, While peroxide value decreased continuously. The decreasing of peroxide value indicated decomposing of hydroperoxides, then produced a number of volatile compounds, which accord with the increasing of total peak area of volatile compounds. myrcene, 1,5-heptadiene-3,4-diol,ε-caprolactone, terpinolene,2-amino octanoic acid, (E,Z)-2,4-decadienal which were not found in the oil without adding active clay and less active clay. This finding indicated that bleaching could produce some new volatile compounds. The amount of a great part of volatiles increased clearly with the mount of active clay and bleaching time. Conjugated diene compounds liked as (E,Z)-2,4-decadienal, (E,E)-2,4-decadienal, 2,6-Dimethyl-5,7-octadien-2-ol increased also, which accorded to the change of K232. It showed that the amount and constitute of volatile profiles of camellia oil was effected heavily by bleaching technics.It indicated that volatile profiles of camellia oil could be analyzed well by HS-SPME coupled with GC/MS. The characteristic aroma of camellia oil was made up of many main volatile compounds. Bleaching could produce some new volatile compounds, and volatile profiles had many affiliations with oil quality.