Characterization Of Melanoidins From Hydrothermal Treatment Of Food Waste And Their Effects On Acidogenic Fermentation

In this passage,melanoidins formed during hydrothermal treatment?HT?of food waste?FW?were studied.Some problems related to melanoidins need to be solved,including the difficulty of characterization of melanoidins,the ambiguous effects of melanoidins on the acidogenic fermentation of FW,and inadequate focus on melanoidins formation when the HT was optimized.Therefore,the goals of this study were:firstly,to develop a method to characterize and semi-quantify melanoidinss created by HT of FW.Then,to identify the effects of melanoidins on volatile fatty acid?VFA?accumulation during acidogenic fermentation.At last,to optimize the HT process and VFA production,the influence of solubilization of organic matters and the formation of melanoidins was further investigated.This article mainly draws the following conclusion:?1?The 3DEEM method combined with fluorescence regional integration?FRI?and parallel factor analyses?PARAFAC?were able to differentiate clearly between melanoidins and other dissolved organic compounds.The volume of fluorescence?from FRI and maximum fluorescence intensity F_max from PARAFAC were found to be suitable semi-quantitative parameters for determination of melanoidins under different hydrothermal conditions.The minimum melanoidins was validated to obtained at temperature below 130?and pH 5.0.?2?It can be found that the accumulation of VFA during acidogenic fermentation was inhibited in high melanoidins-dosed reactors,while the VFA accumulation was unaffected by the low doses of melanoidins.The presence of melanoidins displayed an unremarkable effect on degradation of carbohydrates but inhibited the degradation of proteins.The acidogenic disparity could not be prominent because carbohydrates contribute major part of VFA.Besides,specific substrate utilization results showed the existence of melanoidins remarkably inhibited bovine serum albumin degradation,while melanoidins had no significant effect on glucose degradation.Further exploration revealed that melanoidins formation mainly caused the substrate consuming and thereby resulted in the reduction of VFA production.?3?The melanoidins/biodegradable organic matters in hydrothermal FW systems could be characterized by F_max?C₂?/F_max?C₁?value,and a polynomial equation of the relationship between the response and the model term was obtained.Analysis results from ANOVA showed that the separate and interactive effects of temperature,pH and reaction time on the F_max?C₂?/F_max?C₁?were significant,and the influence of C/N and water content can be ignored.The optimaized conditions for HT were finally fitted:temperature 132?;reaction time 27 min;pH 5.6.Under this condition,the predicted F_max?C₂?/F_max?C₁?value?0.011?was far below the initial value?0.05?.Results demonstrated that the VFA production under optimized HT conditions was accelerated 18%compared to untreated conditions,and optimal C/N condition was obtained?C/N=40?.