| Vinegar aroma is an important criterion that reflects its aroma quality. Analysis and fingerprint of Vinegar aroma components are vital to its quality control and appraisal. At present, few papers were on the aroma components of Zhenjiang Fragrance vinegar and its key brewing process, no reports were on their aroma fingerprint. The following methods were used in this paper: gas chromatography(GC) method combined with solid phase microextraction (SPME) was used to optimize the vinegar aroma components analysis conditions of Zhenjiang Fragrance Vinegar. SPME was used to extract the aroma components of Zhenjiang Fragrance vinegar produced in different years, The extraction methods including SPME, simultaneous distillation extraction (SDE) and direct solvent extraction (DSE) were respectively applied to extract the aroma compounds of Zhenjiang Fragrance vinegar during the brewing, the extracted aroma compounds were analyzed by gas chromatography mass spectrometry (GC-MS), and their main aroma formation mechanism was studied. According to the high contents and low odor threshold of aroma components, the characteristic aroma components of Zhenjiang Fragrance vinegar and its key brewing process were determined using GC-MS method combined with solid-phase microextraction, at the same time, the fingerprint of aroma components of Zhenjiang Fragrance vinegar and its key brewing process were established. The aim of the study is to provide a theory basis in improving the processing technology and ensuring quality of Zhenjiang Fragrance vinegar. The results were summarized as follows:1．The optimum conditions for temperature programming of GC: held at 35℃for 3 min, then ramped at 5℃/min to 120℃and held for 5 min. Then raised to 240℃at 10℃/min and held for 5 min. The PDMS fibre (Polydimethylsiloxane, 100um) was used in this study. SPME conditions were listed as follow:the extraction temperature was 40℃, the extraction time was 25 min, the vinegar extraction volume was 5ml and NaCl content was 1．5g.2．52 aroma components of four Zhenjiang Fragrance vinegars produced in different years were identified, which mainly were acids, esters, alcohols, ketones and herterocylic components.Among them, the relative contents of acetic acid, ethyl acetate, furfural and tetramethyl parazine reached above 50% in all, which possibly affected the aromatic quality of Zhenjiang Fragrance vinegar. The research showed that the aroma components of Zhenjiang Fragrance vinegars decreased during aging.3．The aroma compounds of Zhenjiang Fragrance vinegar during the brewing mainly were alcohols, acids, esters, aldehydes, ketones, herterocylics, alkanes, ethers and phenolic compounds. 72 and 77 aroma compounds were respectively detected in cooking rice and the color of rice, which formed many herterocylic compounds, for example furans. The contents of alcohols were 78．38% in alcohol fermentation, ethanol reached 51．45%. Acids mainly formed during the acetic fermentation. Acetic acid reached above 20% in all. Acids and acetic acid were as high as 32．38% and 29．16% in decocting vinegar. Ketones contents reached above 10% during the fermentation. Before and after decocting vinegar, ketones were 17．96% and 25．49%. Esters mainly formed during the alcohol fermentation and the acetic fermentation. The aroma compounds decreased to 15 during decocting vinegar. Esters contents reduced 30% to 9．71%. Decocting vinegar attenuated aroma of Zhenjiang Fragrance vinegar.4．SPME method provided better extraction for low boiling compounds, such as acetic acid, ethanol, 2-methyl propanal. But SDE and DSE methods were esay to extract high boiling point compounds, for example dolicho-chain acids and esters. Bulk alkanes and all ethers were detected only in the extraction of SDE and DSE methods. Three methods of extraction can complement each other.5．Aroma components of Zhenjiang Fragrance vinegar during the brewing and aging mainly derived from aroma components transfer, microorganism metabolism, Maillard reaction, Strecker degradation, oxidation-reduction, composition and decomposition, and so on. For example transfer of alcohols, acids, aldehydes, ketones and herterocylic components in rice, adjunct raw material, the color of rice and alcohol fermentation. Ethanol was mainly produced from Glucose via the yeast metabolism. Phenylethanol was produced by the reduction of Phenylacetaldehyde formed in Strecker degradation of phenylalanine. Acetic acid was produced from ethanol via the role of Acetic acid bacteria. 3-methyl butanoic acid was formed by microorganism degradation of Leucine. 2,3-butanedione was produced by the oxidation of 2,3-butanediol. Ethyl acetate was generated from esterification reaction of ethanol and acetic acid. Tetramethyl pyrazine was formed by Maillard reaction.6．The characteristic aroma components of Zhenjiang Fragrance vinegar were phenethanol, 3-methyl butanoic acid, phenylacetic acid, 3-methyl butanal, 2-methyl butanal, furfural, 2,3-butanedione, 3-hydroxy-2-butanone, acetic ether, 2,3-butanedio-diacetate, trimethyloxazole, trimethylpyrazine, tetramethylpyrazine, dihydro-5-ethyl-2(3H)-furanone, 2-methoxy-4-vinylphenol. The characteristic aroma components in cooking rice were 2-ethyl-1-hexanol, furfural, benzaldehyde, 4-hydroxy-3-methyl acetophenone, 2-furanyl methanol, 1-(2-furanyl)-ethanone. The characteristic aroma components in alcohol fermentation were 3-methyl-1-butanol, phenylethanol, hexanal, ethyl acetate, ethyl decanoate, 2-furyl methanol. The characteristic aroma components in vinegar solid of completing exposding underlayer were Phenylethanol, 3-methyl butanoic acid, decanal, 2,3-butanedione, 3-hydroxy-2-butanone, ethyl acetate, ethyl hexanoate, tetramethyl-pyrazine, dihydro-5-pentyl-2 (3H)-furanone. The characteristic aroma components in ripe vinegar solid were Phenylethanol, 3-methyl butanoic acid, 2,3-butanedione, 3-hydroxy-2-butanone, ethyl acetate, 3-methyl-1-butanol acetate, acetic acid-2-phenylethyl ester, tetramethyl-pyrazine, dihydro-5-pentyl-2(3H)-furanone. The characteristic aroma components in vinegar solid of completing fermentation were Phenylethanol, 3-methyl butanoic acid, 2-ethyl hexanal, 2,3-butanedione, 3-hydroxy-2-butanone, ethyl acetate, 3-methyl-1-butanol acetate, acetic acid-2-phenylethyl ester, tetramethyl-pyrazine, dihydro-5-pentyl-2(3H)-furanone. The characteristic aroma components in showering vinegar were Phenylethanol, 2-methyl butanoic acid, hexanoic acid, decanal, 2,3-butanedione, 3-hydroxy-2-butanone, ethyl acetate, 2-methyl-2-propenoic acid Propyl ester, acetic acid-2-phenylethyl ester, trimethyl-oxazole,trimethyl-pyrazine,tetramethyl-pyrazine,dihydro-5-pentyl-2-(3H)-furanone, 2-methoxy-4-methyl phenol. The characteristic aroma components in decocting vinegar were Phenylethanol, 2-methyl butanoic acid, hexanoic acid, benzene acetaldehyde, 2,3-butanedione, 3-hydroxy-2-butanone, ethyl acetate, 2-hydroxy propanoic acid ethyl ester, 2-pentanolacetate, trimethyl-pyrazine, tetramethyl-pyrazine, dihydro-5-hexyl-2(3H)-furanone,2-methoxy-4-methyl phenol. Fingerprint of aroma components of Zhenjiang Fragrance vinegar and its key brewing process were established by their characteristic aroma components and their contents.
|
PDF Full Text Request