High Value Utilization Of Tomato Peels Based On Enzymatic Hydrolysis

In this study,tomato peels,a by-product of tomato processing,were the raw materials and enzymatic modification was used to improve the extraction yield of lycopene and soluble dietary fiber(SDF).Then,the structure characters,gelling properties,physicochemical properties and functional property of enzymatic-SDF(E-SDF)and original-SDF(O-SDF)were analysed.After that,the application of enzymatic tomato peels in tomato paste was explored.All the results provided theoretical basis and practical reference for the application of tomato peels.The main research contents were as follows:Firstly,Viscozyme L was chosen to hydrolyze tomato peels and lycopene content was chosen to evaluate enzymolysis conditions.The influence of enzyme addition,p H value,temperature and reaction time on the extraction content of lycopene were determined.The optimal enzymatic conditions were obtained:5%(v/w)Viscozyme L solution addition,p H 6.0,temperature as 45?and reaction time as 35 min.The extraction yield of lycopene and SDF were increased by 23.8%and 72.3%respectively in the optimal enzymatic conditions.Then,the structure characters of O-SDF and E-SDF were analysed.The molecular weight(Mw)and?-potential of E-SDF were 7.09×10⁴ Da and-37.6 m V,which were lower than O-SDF.Compared to O-SDF,the monosaccharide composition results showed that the content of rhamnose,arabinose and glucose in E-SDF were decreased,but the content of fucose,fructose and galacturonic acid were increased.FT-IR results revealed that some characteristic peaks disappeared in E-SDF.Additionally,the results of scanning electron microscopy and atomic force microscopy showed that the structure of O-SDF was tighter while E-SDF was looser.Finally,the rheological,physicochemical and functional properties of O-SDF and E-SDF were explored.The results of steady-state rheology showed that SDF solutions were characterised as Newtonian fluid at low concentrations and exhibited shear thinning at high concentrations.The dynamic rheology showed E-SDF possessed a stronger gelling ability than O-SDF in the presence of Ca²⁺.Meanwhile,enzymatic hydrolysis could improve the hydration and thermal properties of dietary fiber,and the glucose absorption capacity of E-SDF was improved with the increase of Ca²⁺concentration.Preliminary explored the application of enzymatic tomato peels in tomato paste and 4%(w/w)was the optimal additions.These studies had high practical value which provided theoretical supports and guidance for the high value utilization of tomato peels,and provided some references for solving the problems of low economic value-added and environmental pollution of tomato peels.