Preparation And Stability Of Starch-Based Lycopene Complexes

As a natural functional pigment,lycopene has poor stability and is easily affected by light,oxygen,heat,acid and other factors to cause degradation and loss.In order to improve the stability of lycopene,Amylose-Lycopene Complexes(ALCs)were prepared by utilizing the rejuvenation characteristics of starch.On the basis of structural characterization,molecular dynamics simulation is used to explore the formation process and interaction mechanism between ALCs,and a shelf-life prediction model is constructed on the basis of their stability changes to reveal their stability changes.The main studies are as follows:(1)Preparation of ALCs using solvent method,the composite index of ALCs was 15.53±1.01%,and the composite rate could reach 83.97±0.16%;The results of scanning electron microscopy,polarizing microscope and particle size determination showed that ALCs were spherical,the polarized "cross" weakened,the relative crystallinity was 65.32±0.22%,and the particle size was significantly larger than that of amylose.The results of fourier infrared,raman spectroscopy and differential scanning calorimeter showed that amylose and lycopene combined to form V-type subcrystalline structure,with type Ⅱ crystal thermal characteristics.Solid-state nuclear magnetic resonance(13C CP/MAS NMR)and X-ray diffraction showed that amylose coated with lycopene formed V-type single helix and double helix structures.(2)Study the interaction mechanism between ALCs components through molecular dynamics simulation.The simulated conformation and interatomic distance results of ALCs showed that lycopene was isomerized,and the central part of amylose was combined with lycopene to form a V6Ⅲ-complex with a helical structure.The results of principal component analysis,rms deviation,rotation radius and rms fluctuation showed that the ALCs components were closely related and structurally stable,and the presence of lycopene had a stabilizing effect on the structure of amylose.The results of solution-accessible surface area and radial distribution function showed that hydrophilic interaction was the main driving force promoting the recombination of amylose and lycopene,and van der Waals maintained the stability of ALCs structure.(3)Amylose and lycopene entangled to form an enveloped complex with good color stability,antioxidant activity stability,lycopene content stability and configuration stability;The higher the temperature,the greater the effect on the color,antioxidant activity,lycopene content and configuration of the sample.The proportion of lycopene cis in the prepared complexes increased significantly from 11.82±0.04%to 13.76±0.13%,among which the lycopene isomers were:5-Z>All-E>9-Z>13-Z.(4)The content of lycopene in the complexes was significantly related to its color,antioxidant activity and configuration;The degradation kinetic results showed that ALCs conformed to the zero-level degradation kinetic model at 5℃-25℃ and the first-level degradation kinetic model at 35℃～45℃.The degradation degree of lycopene was negatively correlated with temperature,and its half-life and tenth-life were 32.37 d and 6.48 d(5℃),respectively,which were significantly higher than those of 10.78 d and 1.63 d(45℃).The activation energy required for ALCs reaction is as high as 106.29 kJ/mol,which is more stable;The shelf life prediction models for further construction of ALCs are:(?)(5℃~25℃)and(?)(35℃~45℃).