| Wine as a fermented beverage with ethanol at a lower level is rich in nutrition. Itis renowned for being good for one’s health, containing many sorts of polyphenols,amino acids and vitamins. It does offer some health benefits, such as to prevents andcontrols cardiovascular disease or reduce the risk of coronary heart disease deathwhen consumed in moderation. Protein haze in bottled wines presents quite easily.Instability of proteins in white wines is one of the most common non-microbialdefects of commercial wines. Coagulation of proteins in white wines may result fromunfavorable storage conditions, leading to their aggregation. The denatured proteincan subsequently precipitate to form an amorphous sediment or deposit or flocculateand produce a suspended and haze in the bottled wine that reduces its commercialvalue, making it unacceptable for sale. So it is obviously important to control theprocess conditions for clarity and stability in the actual production, only wines whichpassed the clarity and stability exam can lead into circulation phase. The traditionaluse of bentonite is the only effective method to stabilize wine. Drawbacks of thismethod are that some products are lost leading to weakness of wine, and solidresidues with a high environmental impact are also generated. Chitosan is a natureexisted alkaline polysaccharide. With a lot of aminos and hydroxyls on its chains,chitosan is easy to get chemical modification to become particularly functional carrier.Recently the application of chitosan in food is getting more and more widely; Themechanism responsible for protein haze formation in wines remains essentially to beelucidated which would also be involved in this paper.Through the preparation of4different kinds of chitosan resins, They wereapplied in white wine clarification and stabilization and helped in discovering themain influence factors causing the wine turbidity. The aim was to provide a newalternative clarifying agent and offer kind of support to the illumination of themechanism of wine instability. The main research results are as follows: (1)The4different kinds of resins were made from chitosan, by oppositecrosslinking method in this paper. Resins were first selected by testing their stabilityproperties. All resins were stable at the environmental temperature of0-60℃, pH of2.0-8.0, ethanol content of5.0-60.0%(all performed well comparatively exceptresin2).Resin1,2,3performed well in ethanol-water aqua. Resins, were applied inwine clarification and stabilization. Right resins (resin1and resin3) were selected,because they could enhance the charity and the stability of wine. As for the winepost-processing with resin, resin1,3are in rules of the round shape, particle sizeuniform. The average particle size of resin3was about460-660μm, and resin1520-720μm. The results of DSC showed that the cross linking reaction may tookplace.(2)Selected resins(resin1and resin3) were applied in wine to study the effects ofclarification and the protein stability of wine after heat-stability test, so resin3wasdefined as the candidate to clarify wine White wine was considered stable when1.00g resin3was added to100.0ml wine, with interval stirring for36h at15℃. Resin3could also enhance the stability of protein in wine after being reused for3times andregenerated. The total proteins and the total polyphenols content in white winestreated with CBR decreased by around34%and30%, respectively, meanwhile, nosignificant effect on the content of total sugar, reducing sugar, alcoholic degree andpH of wine was detected. Under room temperature, wines treating with resin3behaved no significantly differences as bentonite. Experiments proved theoreticalfoundation and basic technology instruction for Resin3in the application of whitewines.(3) This part is to study white wine protein stabilization in a continuous processwith resin1and resin3packed in a column and to evaluate how the treatment affectsthe protein profile and the final stability of the wine. The total protein of wine alldecreased and then stayed stable by resins. Wine could be considered to be stablewhen the total protein adsorption is higher throughout the same treatment. But thecontent of the total protein was not able to decide whether the wine stable or not. With the help of HPLC, the protein fractions were divided into4parts: above70KDa,50-70KDa,20-30KDa,15KDa. Their behaviors were quite different from each other.And the correlations with wine stability are also different. Protein fraction that has amolecular weight above70KDa seems to have the greatest effect on whether the whitewine is thermally stable or not. However, it cannot be assumed that the50-70KDafraction and20-30KDa plays an important role in the stabilization as the fractionabove70KDa. They performed a similar adsorption behavior possibly because of thesame carrier-chitosan. The concentration levels of the protein fractions of20-30KDaand50-70KDa depended on the sort of the adsorbent. The protein fractioncorresponding to15KDa seems not to affect the difference in turbidity, because in allthe tests it remained practically constant, although the protein stability varied. In allcases, the reduction was only around20%of initial value. Analysis of SO42-with IonChromatograph showed that SO42-could supposedly be one of the X-factors in wine.Low concentration of wine can lead to protein-stable wine. So it was inferred thatSO42-itself could not affect the stability of wine. But the instability of wine can beinduced by SO42-participating in some protein degeneration.It was speculated thatsome protein component had close relationship with SO42-. |
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