Study On The Changes Of Red Pigment In Fermented Pepper And Its Stability Control Technology During Storag

Fermented pepper is made from fresh red pepper by seasoning and fermentation,and it is an important fermented condiment in southwest China.However,there is a lack of systematic and effective prevention and control techniques for the common problem of fermented peppers fading during fermentation and storage.Therefore,by examining the difference of carotenoid content in different pepper varieties,analyzing the correlation between different pigment monomer and pepper color difference value,the fermentation stability of the main pigment monomers in chili peppers has been elucidated.Subsequently,the influence of fermentation temperature,fermentation bacteria,different excipients and color fixative,sterilization time,sterilization temperature on the quality and color of fermented peppers are analyzed,so as to obtain the best color protection formula and the best color preservation conditions.Then explore the influence of storage conditions such as light,air and packaging materials on the color of fermented peppers.Finally,the molecular mechanism of Capsanthin fading and color protection was investigated by influencing the main factors of Capsanthin stability on the molecular structure of Capsanthin.The experimental results are as follows:（1）Through the Meiren pepper,Zhoupi pepper,Hongerjing pepper main raw material varieties of carotenoid content analysis found that the variety of pepper samples identified Violaxanthin,Capsanthin,Xanthophyll,Zeaxanthin,β-Cryptoxanthin,α-Carotene,β-Carotene and different varieties of pepper carotenoid content differences.Capsanthin content is the highest among them,the content of Capsanthin in Zhoupi pepper is higher than that of the other two peppers,the second is Zeaxanthin.β-Carotene,β-Cryptoxanthin.The Capsanthin is significantly positively correlated with the L*value and a*value of pepper fruit.But there was no significant correlation with b*value and h value.This means that the peppers with high Capsanthin content are more red and brighter.By studying the stability of Capsanthin,Zeaxanthin andβ-Carotene pigment monomer under different excipients,fermentation temperature,pasteurization and p H conditions,it was found that the stability ofβ-Carotene and Capsanthin adding liquor was the worst,whileβ-Carotene had good thermal stability.However,the thermal stability of Capsanthin is poor,andβ-Carotene is easy to be decomposed by p H value.The adverse effects of excipients,temperature,p H and other products should be noted in the production and processing of fermented peppers.（2）By studying the influence of different fermentation temperature,fermentation strains and concentration on the quality of fermented peppers,it was found that the intensive inoculation fermentation of 4%Lactobacillus acidophilus could improve the color of fermented peppers products.The three factors of salt,liquor and ginger,garlic were analyzed by Topsis method.Taking the content of Capsanthin,p H value,total acid content and comprehensive evaluation results as the indicators.The results showed that 6%salt,3%liquor and 15%ginger and garlic had the best color protection effect.Low-salt formula can not only play a color protection effect,but also will not reduce the acid production capacity of the product.Uniform design was adopted to screen and optimize the storage conditions,and the regression equation was established by secondary polynomial step by step regression.The results showed that the optimal combination of storage conditions for fermented peppers was 0.11%lactic acid,0.31%chitosan,the sterilization temperature was 65℃,and the sterilization time was 14 min.Among them,the addition of lactic acid and chitosan could improve the color of the product,and the color protection effect could be strengthened after fermentation.By setting three light conditions of natural light,indoor light and light avoidance and three different air conditions,it is proved that light and air will affect the color and sense of fermented peppers,and the surface of the inflatable packaging group will form white bacterial membrane,resulting in the increase of L*value.By studying three kinds of packaging materials:glass bottle,aluminum foil bag and self-sealing bag,it is clear that the sealing and light transmittance of packaging materials will affect the color of fermented peppers.Materials with good sealing and light avoidance should be selected when choosing packaging materials.（3）Dynamic analysis method was used to explore the variation rule of Capsanthin’s chroma difference parameters at different heating temperatures.The results showed that the h value of Capsanthin monomer followed the zero-order and first-order reaction kinetics models with high degree of fitting,indicating that Capsanthin faded at 50℃and 100℃.The results of UV-Vis spectra showed that the absorption value at the maximum absorption wavelength decreased with the increase of temperature,and the zero order and first order kinetic equation k values fitted with the absorption value were negative,which proved that Capsanthin degradation occurred.Raman spectrum results showed that Capsanthin C-H₃,C-C and C=C structures were degraded to different degrees,which indicated that Capsanthin molecular chromophoric group was destroyed at 50℃and 100℃,making it fade.The research on the color protection effect of lactic acid at different temperatures showed that 50℃and 100℃destroyed the conjugated double bond and carbonyl group of Capsanthin,and lactic acid had certain color protection effect on Capsanthin at 50℃and 100℃.The change of capsanthin under different lighting conditions was investigated.The kinetic fitting results of the parameters of Capsanthin color difference showed that h value had a high fitting degree in the zero-order and first-order reaction kinetics models,indicating that Capsanthin molecules would fade under ultraviolet-visible light irradiation,and the fading under ultraviolet light was the most serious.The results of UV-Vis spectrum showed that the absorption value of each group decreased with the shortening of the light wavelength.Meanwhile,the absorption value at the maximum absorption wavelength followed the zero-order and first-order reaction kinetics model,and the k values of equation were all negative,indicating that Capsanthin degraded.Raman spectra showed that the carbonyl structure and conjugated double bond of Capsanthin degraded to different degrees.The FTIR spectra of color protection effect of lactic acid showed that the absorption intensity of structural characteristic peaks of-OH,-CH₂-,C=C and C=O changed under ultraviolet-visible light irradiation.At the same time,lactic acid had a certain color protection effect on Capsanthin under visible wavelength range,but it would accelerate the fading under ultraviolet light.By comparing the effects of light and heat on capsanthin,it is clear that the stability of Capsanthin in red light is the best,and the influence of temperature at 50℃is second only to that of red light.The stability of Capsanthin at 100℃is lower than that of each visible light treatment group,and the stability of ultraviolet light group is the worst.