Headspace Solid Phase Microextraction and Gas Chromatography−Olfactometry Dilution Analysis of Young and Aged Chinese “Yanghe Daqu” Liquors

Abstract

The aroma compounds of young and aged Chinese "Yanghe Daqu" liquor samples were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography (GC)-olfactometry dilution analysis. The original liquor samples were diluted with deionized water to give a final alcohol content of 14% (v/v). The samples were stepwise diluted (1:1) with 14% (by volume) ethanol-water solution and then extracted by headspace SPME. The samples were preequilibrated at 50 degrees C for 15 min and extracted with stirring at the same temperature for 30 min prior to injection into GC. The aroma compounds were identified by both GC-MS and GC-olfactometry using DB-Wax and DB-5 columns. The results suggested that esters were the major contributors to Yanghe Daqu liquor aroma. Ethyl hexanoate, ethyl butanoate, and ethyl pentanoate had very high flavor dilution values in both young and aged liquors (FD > 8192). Methyl hexanoate, ethyl heptanoate, ethyl benzoate, and butyl hexanoate could also be very important because of their high flavor dilution values (FD > or = 256). Moreover, two acetals, 1,1-diethoxyethane and 1,1-diethoxy-3-methylbutane, also were shown high flavor dilution values in Yanghe Daqu liquors (FD > or = 256). Other aroma compounds having moderate flavor dilution values included acetaldehyde, 3-methylbutanol, and 2-pentanol (FD > or = 32). Comparing young and aged liquors, the aroma profiles were similar, but the aroma compounds in the aged sample had higher flavor dilution values than in the young ones.

Profile of Volatile Compounds in 12 Chinese Soy Sauces Produced by a High-Salt-Diluted State Fermentation

“…In the current analytical method, a HS-SPME with a 50/30 μm DVB/CAR/PDMS (2 cm) was applied to study the volatiles in Chinese soy sauces on the basis of a wide range of odorants that can be extracted. Baek and Kim 1 reported that the SPME extraction from a DVB/CAR/PDMS fibre was similar to the original odour of samples, which was in agreement with the observations from other reports 6,29 .…”

“…Before extraction, adding salt to maximize extraction is a common practice and the addition of salts has been previously shown to improve the adsorption of analytes for SPME analyses 6 . The dissociated ions disrupt the sample matrix by decreasing the solubility of the aroma molecules, which then partition more readily into the headspace 6 .…”

“…The dissociated ions disrupt the sample matrix by decreasing the solubility of the aroma molecules, which then partition more readily into the headspace 6 . For this study, addition of 10% (w/v) sodium chloride was adequate for the preparation of all samples with saturated salt, as soy sauce resulting from an HSDSF process contains about 20% salt in its product form.…”

“…However, a number of other esters and aldehydes were less in this condition, especially benzaldehyde, ethyl β-phenylacetate and β-phenylethyl acetate, which were not detected. It has been reported that the concentration of esters resulting from short-chain fatty acids have a tendency to decrease along with extension of extraction time, while the longchain fatty acid esters show the opposite performance 6,25 . Based on peak areas and numbers of peaks, the analysis condition chosen was 40°C for 50 min.…”

Changes in Volatile Compounds of Chinese Rice Wine Wheat Qu During Fermentation and Storage

“…SPME is a solventfree extraction technique and has been used to extract a wide range of volatile and semi-volatile aroma compounds in solid food samples such as mushroom 11 , beef 20 , breakfast cereal 15 , olive oil 16 and alcoholic beverages 7,29,31 . The volatiles were analyzed and the concentration changes in the volatile compounds during fermentation and storage were documented.…”