Research And Application Of Strengthened Compound Colorant Based On The Mechanism Of The Photosensitivity And Thermal Sensitivity Of Natural Pigments

To investigate the photosensitivity and thermal sensitivity of four kinds of natural pigments using spectrophotometry,the temperature and light stability of natural pigments were determined and sorted by measuring the changes of absorbance and preserving rate under the changing conditions of temperature and light factors.Based on the characteristic analysis of Fourier infrared spectrum and Excitation-Emission-Matrix Spectra,the changes of several natural pigments were preliminarily discussed.According to the results of stability experiment,three kinds of edible natural pigments commonly used in meat products were selected for compounding.The response surface optimization method was adopted to analyze the composite pigments with better light and heat resistance by taking minced pork as the medium.Theresults were as follows:(1)The change of temperature and light in the environment would affect the color of the natural pigments added in the product,causing fading or discoloration,and affecting the color sense of the product.The thermo tolerance of the FNRPs was in this sequence:CRPs>SRPs>MRPs>BRPs.Consequently,the nature pigments,in storage,were instable in relatively high centigrade circumstance for heating sensitivity.The illumination retention rate was arrayed in sequence as SRPs>CRPs>BRPs?MRPs.Hence,the order of different light sources affecting the stability of pigment was B>G>R,explained that the shorter wavelength of monochromatic light emitting relative high energy and resulting in the pigment varied more unfavorable under the same conditions.(2)The infrared spectrum of cochineal red pigments were not obvious.Cochineal red pigment solution had two fluorescences at(225,350)nm and(275,365)nm.After the heating and illuminating treatment,the position of the fluorescence changed,at(315,440)nm,and the fluorescence intensity was greater.The results showed that temperature and light had an effect on carmine red pigment.The reason for the discoloration of sorghum red pigments may be that heat destroyed CH and C=O on aromatic rings and light destroyed C-OH and C=O,and the fluorescence spectrums of the pigments also changed significantly under different treatments.The main discoloration reason of monascus red pigments may be that heating destroyed C=H and C=O on the benzene ring,while illumination destroyed-CH2,C-O and C=O.According to the fluorescence spectrum,the monascus red pigments had an obvious fluorescence at(475,525)nm,which was destroyed by temperature and light.After lighting treatment,a weak fluorescence was formed at(225,340)nm.The main reasons for the discoloration of beet red pigments may be the destruction of the chromophoric group(1,7-diazo heptyl base)vibrates C=O,causing the degradation of betaine into betalamic acid(BA)and cyclodopa-5-o-glucoside(ODG).But,there were no obvious fluorescence indicating that the pigments were not suitable for fluorescence spectral analysis.(3)According to the test results of the first three chapters,three natural pigments commonly used in meat products,namely,cochineal red pigments?sorghum red pigments and monascus red pigments were selected for compounding.Quadratic multinomial regression equation was obtained ?a*value(Y)=3.46+0.62A-0.33B-0.42C+0.19AB+0.20AC-0.057BC-0.12A2+0.094B2+0.40C2.Optim ized by design-expert 8.0 software,the optimal ratio of composite pigments were monascus red pigments:sorghum red pigments:cochineal red pigments=0.0856:0.1353:0.2788.Under this condition,the predictive ?a*value was 2.27808.Validated experiments,the actual ?a*value was 2.27,below the predicted value and other actual values.So the experimental model was effective and reliable,and choosed the proportion as the best formula of the composite pigments.After scanning,the maximum absorption wavelength of the compound pigments was 494.5nm.The influence of pH value and metal ions on the complex pigment was found that weak acid and weak base conditions had little influence on the complex pigments.Especially pH less than5 or pH more than 11,the retention rate of complex pigments decreased significantly.Na+,K+,Ca2+,and Mg2+ had little effect on the compound pigments,while Fe3+,Cu2+,and Zn2+all produced precipitation,and Fe3+had the most obvious effect.