Research On Change Of Phenolic Compounds In Sugarcane Juice And Influence During Sugar-making Sulphitation Process

The phenolic compounds of sugarcane exist as the colored compound or pigment predecessor. Phenols colorant is one of the main factors that deepen the color value in juice which are formed by enzymatic and chemical reaction. This paper mainly studies on the change of phenolic compounds in sugarcane juice and influence during sugar-making sulphitation process. The main research contents and results are reported as follows:1. Establishing method of the best colorimetric conditions of the Folin-Ciocalteu determination for mensurating total content of phenolic compounds in the sugarcane juice. The results showed that Folin-Ciocalteu determination has a good linear relationship, good stability and precision. The recoveries ranged from99.98%to107.18%. Which is an easy, fast, accurate and secure method for mensurating total content of phenolic compounds in that juice which exclude or less contain reducing impurities.2. Gallic acid, gatechin, caffeic acid, epicatechin, ferulic acid, rutin and naringin were chosen as study objects, establishing reverse-phase column- highperformance liquid chromatography-UV detector (RP-HPLC-UV) method of determining seven mono-phenols simultaneously and accurately. The results showed that this determination’s linear correlation coefficient was more than0.99, low detection limit, the relative standard deviation(RSD)<5%, The sample solution is stable within48hours and the recoveries ranged from81.6%to93.7%.3. Total phenolic content, content of flavanols, condensed tannin content and seven mono-phenols content were chosen as study objects, evaluating the effect of unit operation of sulphitation process on phenolic compounds and their relationship with color values, which results showed that:(1) The two steps of phosphorus-preliming then lst-heating, sulphitation-neutralization play a significant role on lower the color values of juice, decolori-zation rate was37.3%before and after phosphorus-preliming then1st-heating operation; decolorization rate was56.2%before and after sulphitation-neutraliza tion operation.(2) Sulphitation-neutralization operation play a significant role on reducing total phenols content of juice. Total phenols removal rate was18.7%before and after this operation, it had obvious correlation between total phenolic content change and colour value change, and the linear correlation coefficient was0.9008.(3) Two steps of sulphitation-neutralization and settlement after2nd-heating played a significant role on reducing the contents of flavanols in the juice. The operation of sulphitation-neutralization can remove17.8%of the flavanols, settlement after2nd-heating can remove41.6%. The change of flavanols had obvious correlation with color value change, and the logarithmic equation correlation coefficient was0.7799.(4) Two steps of sulphitation-neutralization and settlement after2nd-heating played a significant role on reducing the contents condensed tannin in the juice. The operation of sulphitation-neutralization can remove44.0%of condensed tannin, settlement after2nd-heating can remove36.5%. The change of condensed tannin content had obvious correlation with color value change, and the logarithmic equation correlation coefficient was0.8838.(5) It was proved that caffeic acid had a significant change before and after phosphorus-preliming, the juice after preliming could not be detected its content. Chlorogenic acid had a significant change in before and after phosphorus-preliming and sulphitation-neutralization, The operation of phosphorus-prelim ing can remove chlorogenic acid29.3%, the operation of sulphitation-neutralization can remove100%. Epicatechin had a significant change before and after sulphitation-neutralization can remove100%. Gallic acid and ferulic acid had a significant change at settlement after2nd-heating, can remove38.7%and11.0%separately. The content of rutin and naringin weren’t affected in the process.4. Changing the parameters of sulfitation process to study the impact of various parameters on the decolorization rate and total phenols removal rate, and research the correlation of total phenols removal rate and decolorization rate. Single-factor experiments showed that, the total phenols removal rate and decolorization rate had positive correlation while total content of P2O5was in the range of200-400mg/L in juice, also had a certain positive correlation while first heating temperature was in the range of55～65℃; so as the intensity of sulfitation is in the range of14-20mL. There is no significantn correlation in the range of selected preliming pH and neutralization pH. The best scheme of removal of phenol and color removal was:total content of P2O5was450mg/L, preliming pH6.8, sulfitation intensity16mL, and neutralization pH7.0.5. Based on the sugar-making sulphitation process, adding CTA-CTS at sulphitation-neutralization unit, combination of single factors and orthogonal experiments, obtained the optimum conditions of sulfitation clarification process aided with quaternized chitosan:preliming pH6.8, intensity of sulfitation16mL the dosage of CTA-CTS600mg/L. Carried out verification experiment based on the optimal level of orthogonal test, the results showed that, total phenols content and color value of juice was decreased14.75%and28.39%separately than sulfitation clarification process, but the purity of juice was decreased0.04percentage points. We can reach the goal of removal total phenol and decolorize with using quaternized chitosan in sugar cane juice.