| Wild Vitis quinquangulanis Rehd. lees are important by-products of wine-makingindustry, and are produced during the fermentation of wild Vitis quinquangulanis Rehd. wine.The main chemical constituents of wild Vitis quinquangulanis Rehd. lees includes:polyphenolic compounds, saccharides, organic acids and inorganic salt ions. Lees, as waste inwineries, have a huge market potential. L(+)-tartaric acid and L(+)-lactic acid are the mostabundant organic acids present in wild Vitis quinquangulanis Rehd. lees; meanwhile, they arealso widely used as food additives in food industry. Currently, chemical synthesis andbiological fermentation methods are widely used in our country to produce L(+)-tartaric acidand L(+)-lactic acid, but the reports on extraction process of these two organic acids fromwild Vitis quinquangulanis Rehd. lees are scarce. Therefore, the study on the extractionprocess of L(+)-tartaric acid and L(+)-lactic acid from wild Vitis quinquangulanis Rehd. leesis essential in reducing the production cost of these two organic acids and in raising theadded-value of wild Vitis quinquangulanis Rehd. products.In this paper, wild Vitis quinquangulanis Rehd. lees have been taken as the experimentalmaterial. The recovery of L(+)-tartaric acid from distilled vinification lees coming from thewild Vitis quinquangulanis Rehd. winemaking technology was optimized using responsesurface methodology and the process parameters models were built according to theexperimental results. The most suitable organic solvent was chosen in this study to extractL(+)-lactic acid from lees and the effects of different factors on the L(+)-lactic acid extractionprocess were also discussed. Finally, the optimum extraction conditions were determined. Themain test results are as follows:1. With the results of one-factor tests, response surface analysis was applied to optimizethe acid maceration process of L(+)-tartaric acid from wild Vitis quinquangulanis Rehd. lees.The results showed that the optimum maceration conditions were determined as follows:maceration temperature82℃,37%HCl volume8mL, maceration time7min. Under theseconditions, the maximum maceration yield of L(+)-tartaric acid from wild Vitisquinquangulanis Rehd. lees in theory will be reached to42.55g/L, and the actually maximummaceration yield of L(+)-tartaric acid from wild Vitis quinquangulanis Rehd. lees will be reached to41.63g/L.2. With the results of one-factor tests, response surface analysis was successfullyapplied to optimize the precipitation process of L(+)-tartaric acid from wild Vitisquinquangulanis Rehd. lees. The results showed that the optimized precipitation conditionswere CaCl2mass concentration50g/L, pH value6.64, reaction time2.4h. Under theseconditions, the maximum recovery rate of L(+)-tartaric acid from wild Vitis quinquangulanisRehd. lees in theory will be reached to88.34%, and the actual recovery rate of L(+)-tartaricacid from wild Vitis quinquangulanis Rehd. lees will be reached to87.64%.3. The product of L(+)-tartaric acid was white crystalline powder. The quality tests ofL(+)-tartaric acid were studied and the main indicators were as follows: ignition residue0.079%, heavy metals (as Pb)0.00068%, heating loss7.42%, melting range169℃～179℃,oxidative substances qualified. The results showed that all these indications met the standardsof national norm.4. Extraction of L(+)-lactic acid from wild Vitis quinquangulanis Rehd. lees by meansof organic solvent extraction was studied. L(+)-lactic acid was extracted with trioctylamine(TOA) as extractant, dodecane as diluent and decanol as modifier, and the most suitablecomposition of this organic solvent was30%trioctylamine-20%decanol-50%dodecane.Meanwhile, the effects of different factors on the L(+)-lactic acid extraction process were alsodiscussed. The optimum extraction conditions were as follows: extraction temperature25℃,pH value4, O/A=1:1, oscillation time15min. Under these conditions, the recovery rate ofL(+)-lactic acid will be reached to99.4%. With5-time RP-extraction of organic solvent bydeionized water, the total recovery rate of L(+)-lactic acid will be reached to91%.5. The product of L(+)-lactic acid was light yellow sticky liquid. The quality tests ofL(+)-lactic acid were studied and the main indicators were as follows: chroma49.7, readilycarbonizable substances qualified, ignition residue0.058%, heavy metals (as Pb)4mg/kg,arsenic(as As)0.64mg/kg. The results showed that all these indications met the standards ofnational norm. |
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