The Research On Ultraviolet Spectral Characteristics Of Liquid Fermented Food And The Establishment Of The Technology System Of Authenticity Identification

Liquid fermented food such as vinegar, soy sauce and liquor had thousands of years of history in China. Because of the inadequate science and technology investment in the field of liquid fermented food, many traditional processing methods and technology still in use today, the above reasons led to the low development level, the unstable product quality, the disorder market, the particularly serious phenomenon of counterfeit and shoddy of the liquid fermented food industry, these seriously restrict the development of the liquid fermented food industry and threaten human’s health. Studying the rapid detection technology of vinegar, soy sauce, liquor and improving the scientific level of detection technology have important significance for cracking down on fake commodities, standardizing the production and sale market of liquid fermented food and promoting the industry development healthily and quickly.The research based on the practical situations of production, consumption and the market of the liquid fermented food in China. 89 vinegars, 34 soy sauces and 35 liquors were used as the research objects. The pretreatment process conditions of samples and the basic methods of ultraviolet spectral acquisition were determined. Then the spectral features of vinegar, soy sauce and liquor were studied, the fingerprint characteristics of the ultraviolet spectrum of liquid fermented food such as vinegar and soy sauce were revealed. The identification effect of ultraviolet spectrum and near infrared spectroscopy to vinegar, soy sauce and different brands of liquors was studied. The identification methods of vinegar, soy sauce and different brands of liquors were established through ultraviolet spectrum combined with the ultraviolet spectral similarity of samples. The main results were as follows:(1) The ultraviolet spectral acquisition method of vinegar was: The vinegar sample was diluted with distilled water at the dilution rate vinegar : water = 1 : 6(v/v), the diluted vinegar was distilled with rotary evaporation under the temperature 45℃and vacuum 0.0925 M pa, then collected the vinegar distillate. Used distilled water as reference solution, the ultraviolet spectrum of vinegar distillate with obvious and clear feature could be obtained? under instrumental resolution 1 nm and wavelength range of 245～330 nm. (2) The distillation treatment could eliminate interference to the ultraviolet spectrum of vinegar distillate from pigments and other involatile constituents in vinegar. The ultraviolet spectral characteristics of vinegar distillate presented as: The ultraviolet spectra of the same vinegar had very good repeatability and stability, The ultraviolet spectra of different vinegars had significant difference and strong specificity; the above shown that the ultraviolet spectrum of vinegar had typically fingerprint feature.(3) The fingerprint feature of ultraviolet spectrum of vinegar? combined with the similarity of the ultraviolet spectrum be used to distinguish different vinegars, the identification correct rate of different vinegars was 99.31%. With the fingerprint feature, ultraviolet spectrum can be used to establish the technology system of vinegar identification.(4) The GC-MS results of vinegar distillate shown that, there were ten kind of main material compositions which contributed to the ultraviolet spectrum at 245～330 nm of Qishan sorghum vinegar. They were furfural, tetramethyl pyrazine, 3-hydroxy -2-butanone, 2,3-butanedione, acetic acid, trimethyl pyrazine, phenylethyl alcohol, furfuryl alcohol, acetone, trimethyl oxazole. Through the methods of spectral simulation, furfural, tetramethyl pyrazine and 3-hydroxy-2-butanone were determined as the compositions which had most influence on the ultraviolet spectrum of Qishan sorghum vinegar. The contribution rate of furfural, tetramethyl pyrazine and 3-hydroxy-2-butanone were 82.31%, 13.78% and 2.23% respectively.Through the research on the feature of vinegar’s ultraviolet spectrum and the analysis on the material compositions of vinegar, furfural, tetramethyl pyrazine and 3-hydroxy-2- butanone were preliminarily determined as the main material compositions which affected the ultraviolet spectrum at 245～330 nm of vinegar.(5) The way of the ultraviolet spectral acquisition of soy sauce was similar with vinegar’s. The soy sauce sample was diluted with distilled water at the dilution rate soy sauce : water = 1 : 6(v/v), the diluted soy sauce was distilled with rotary evaporation under the conditions of temperature 45℃and vacuum 0.0925 M pa, then collected the soy sauce distillate. Used distilled water as reference solution, the ultraviolet spectrum of soy sauce distillate was collected under instrumental resolution 1 nm and wavelength range of 190～330 nm.Through the research on the difference, repeatability and stability of the ultraviolet spectra of soy sauce distillate found that, the ultraviolet spectrum of soy sauce also had fingerprint feature. Different soy sauces were distinguished through the usage of fingerprint feature combined with the similarity of ultraviolet spectrum of soy sauce, the identification correct rate of different soy sauces was 99.21%. Ultraviolet spectrum combined with the similarity could be an effect way of identification of soy sauce.(6) The ultraviolet spectral acquisition method of liquor was: The spectrum of liquor could be collected directly without pretreatment. Used distilled water as reference solution, the ultraviolet spectrum of liquor was collected under instrumental resolution 1 nm and wavelength range of 220～330 nm.The ultraviolet spectra of different brands of liquors had significant difference, good repeatability and strong stability, the above shown that the ultraviolet spectra of different brands of liquors had fingerprint feature. The usage of the fingerprint feature of ultraviolet spectrum of different brands liquors combined with the similarity can be an effect way of identification of different brands of liquors.Organic acids, esters and furfural were preliminarily considered as the main compositions which generated the ultraviolet spectrm of liquor at 230 nm, furfural and other aldehydes and ketones were the main compositions which generated the ultraviolet spectrum of liquor at 280 nm.(7) The method of similarity identification of ultraviolet spectrum been proved as the best identification method through the comparison with Euclidean distance longest distance method, Mahalanobis distance longest distance method and 12 kind of cluster analysis methods of near infrared spectroscopy.(8) This paper put forward the basic conception of establishing the vinegar ultraviolet spectral database, made clear the basic requirements to the database and constructed the basic frame of the vinegar ultraviolet spectral database.