The Study Of Characteristic Aroma Compounds In Mandarin (Citrus Reticulata Blanco) Juices

In this study, four main experimental parameters were optimized, such as coating material of fiber, extraction temperature, extraction time and salt addition of headspace solid-phase micro-extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for analysis of mandarin juice samples. As a result, the best extraction conditions were 50/30 ?m divinybenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS)fiber, 45 °C and 40 min of SPME, the amount of sodium chloride addition was 1.5 g in 8 g mandarin juice. Under the optimized conditions the limits of detection (LOD) and limits of quantification (LOQ) of SPME were ranged from 0.015 to 0.534 ?g/kg and 0.050 to 1.779?g/kg. The linear regression value (R2) of the standard curve was higher than 0.972.Meanwhile the repeatability and reproducibility values of this method were all below 20%.And the relative recoveries of analytical compounds were in a range of 60.23%-121.08%. All these results indicated that this method could be successfully applied in the extraction of mandarin juices aromas.Volatile compounds of eight varieties mandarin (Citrus reticulata Blanco) juices were investigated by use of the optimized SPME, GC-MS and GC-O. A total of 57 compounds including esters, alcohols, aldehydes, ketones, monoterpenes and others, were identified by GC-MS analysis. In addition, 42 volatile compounds were detected after GC-O analysis,among them 4 compounds were unknown. According to the quantitative results, 36 aroma compounds were at concentrations higher than their corresponding odor thresholds which indicated their odor activity values (OAV)>1. Partial least squares regression (PLSR) was used to analyze the relationship between mean scores from sensory evaluation by the panelists and aroma-active volatile compounds (OAV>1). The results indicated that a-Pinene was positive related to woody. (E)-2-Hexenal, 1-Octen-3-ol and 1-Penten-3-ol were related to peely. Ethyl acetate, Ethyl propionate, Methyl butyrate, ?-Terpinene,p-Cymol and Terpinolene were related to fruity and floral. Among them, Ethyl propionate, y-Terpinene,p-Cymol and Terpinolene were had significant positive relationship with fruity. In addition,sweet note was significant positively correlated with y-Terpinene and Terpinolene. However,?-Myrcene, p-Cymol and Terpinolene were significant negatively related to green.Furthermore, PCA and AHC analysis could well distinguished the eight mandarin juices. On the basis of GC-O results (Intensity?1) and odor activity values (OAV>1) of these volatile compounds, 22 aroma-active compounds were mixed to simulate the overall aroma of PG mandarin juice. Furthermore, omission experiments confirmed that Nonanal, Hexanal,Linalool and D-limonene were the key odorants for the overall aroma of PG juice sample and?-Ionone, Decanal, ?-Terpinene and Methyl butyrate were also important aroma-active compounds.