Studies On Determination Of Aroma Components Of Zhenjiang Fragrant Vinegar Parched Rice And Its Antioxidant Activity

In 2002 China State Bureau of Quality and Technical Supervision had issued Zhenjiang Fragrant vinegar standard (GB18623-2002) to specify classification, requirement, labeling, packaging, storage, transport and inspecting of Zhenjiang Fragrant vinegar. For increased color and aroma of Zhenjiang Fragrant vinegar, parched rice must be added into Zhenjiang Fragrant vinegar, which is one of Zhenjiang Fragrant vinegar characteristics technology compare with other famous china vinegar. Parched rice made from rice which was stir-frying and solved in water. The following methods were used in this paper: gas chromatography-mass spectrometry (GC-MS) method combined with headspace-solid phase microextraction (HS-SPME) was used to optimize aroma components analysis conditions of Zhenjiang Fragrant vinegar parched rice. The characteristic aroma components of Zhenjiang Fragrant vinegar parched rice were determined using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and Osme method combined with HS-SPME. In order to study the antioxidant activity of Zhenjiang Fragrant vinegar parched rice and its melanoidin in vitro, reducing power, chelating ability and radical scavenging ability were experimented. The aim of the study is to provide a theory basis in improving technology and ensuring quality of Zhenjiang Fragrant vinegar. The results were summarized as follows:1. Compared with conventional liquid-liquid extraction, HS-SPME with 50/30μm DVB/CAR/PDMS fiber is the better sampling method for the analysis of Zhenjiang Fragrant vinegar parched rice volatile compnents. HS-SPME conditions were listed as follow: extraction temperature was 40℃, extraction time was 30 min, Zhenjiang Fragrant vinegar parched rice extraction volume was 5ml and NaCl content was 2g, rotational speed is 100rpm.2. The volatile components of Zhenjiang Fragrant vinegar parched rice were analyzed by GC-MS-O and HS-SPME; twenty-nine compounds were identified, including a variety of odor properties such as caramel, fruity, roasted peanut, herbaceous and woody et al. On the basis of the Osme values (Osme values≥3), furfural, 2,3-dimethyl-pyrazine, 2-ethyl-3-methyl-pyrazine, 2,2'-methylene difuran, acetic acid 2-methylpropyl ester, 3-methyl-1-butanol acetate, 2-methyl-1-butanol acetate, 2-isopropyl pyrazine, 2-ethyl-6-methyl-pyrazine, 3-ethyl-2,5-dimethyl-pyrazine and phenylethyl alcohol can be considered as the most powerful odorants of Zhenjiang Fragrant vinegar parched rice.3. According to absorbance at 470nm of the melanoidin solutions extracted from Zhenjiang Fragrant vinegar parched rice by water containing different concentration of ethanol, the results indicate that absorbance of an exponential increase significantly with the lower alcohol concentration, when using pure water as solvent extraction up Max, the use of water as a solvent extraction more appropriate.4. This study was designed to evaluate in vitro antioxidant capacity of Zhenjiang Fragrant vinegar parched rice and the melanoidin fractions separated from Zhenjiang Fragrant vinegar parched rice using different antioxidant tests, including reducing power, radical scavenging and chelating activities, the results showed that both Zhenjiang Fragrant vinegar parched rice and its melanoidin have strong activity of antioxidation. The reducing power and radical scavenging of Zhenjiang Fragrant vinegar parched rice and its melanoidin were inferior to Vc, but their chelating activities were prior to EDTA.