马蓝靛蓝铝色淀的制备及其在琼脂中的应用OA

Indigo aluminum lake was a food colorant with a bright blue-violet color and strong coloring power.However,the current food industry primarily used chemically synthesized indigo as raw material for producing indigo aluminum lakes.To expand the source of natural indigo as a food colorant,natural indigo extracts from Baphicacanthus cusia(Nees)Bremek.were used as raw materials,and a natural indigo aluminum lake(NIAL)was prepared by sulfonation-coordination precipitation process.The chemical structure and optical properties of synthetic indigo aluminum lake(SIAL)and NIAL were compared by means of comparative analysis of components,Fourier-transform infrared spectroscopy,and ultraviolet-visible spectrophotometry.The coloring performance and color stability of NIAL were also investigated.The results showed that the indigo aluminum lake(NIAL-1)prepared from a B.cusia extract with an indigo purity of 48.24%was safe,compliant and of good quality.The characteristic absorption peaks at 1 640 and 1 477 cm-1 of NIAL and SIAL were the same,and the core functional group structures were the same.The NIAL-1 was added to agar at a dosage of 0.01%-0.05%,to form a uniform blue-violet color,and the blue color was deeper with the increase of addition amount.The NIAL-1 had better color stability when it was applied to agar,but it was weaker than the indigo aluminum lake(SAIL-1)prepared from chemical synthetic indigo with a purity of 50%.The coloring intensity of agar containing NIAL-1 decreased by 8.3%after UV irradiation for one hour,while the agar containing SIAL-1 decreased by 5.3%.The NIAL-1 should be stored for less than5 days at room temperature(25℃)and relatively high temperature(40℃),and it exhibits stability under neutral to weakly alkaline conditions.