Effect Of Grinding Degree On The Stability Of Paprika Red In Paprika Powder

Paprika red is a kind of natural red pigment, which is bright in color, high color value, better tinting strength, non-toxic, healthy and therefore has broad application prospects. The stability of natural pigments are generally poor and limit their application. However, it is worthy of attention that the stability of natural pigments within the cell is better than been extracted. In this paper, the light and thermal stabilities of paprika red in paprika powder of different particle size were compared, and the integrity and protection mechanisms of plant cells were further explored.The results showed that the grinding degree can increase the rate of extraction of the pigment, but on the other hand, grinding degree has a greater impact on the stability of the paprika red in paprika. With the increase of light intensity, the stability of paprika red in paprika powder of different particle size decreased. With the exposure of4000lux light intensity, when the grinding degree was100mesh and150mesh, paprika red preservation rate was reduced to39.9%and20.8%after light irradiated for6d; when the grinding degree was more than200mesh, the stability of paprika red in paprika powder declined rapidly, and after6d the preservation rate was0%; the preservation rate of paprika red dissolved in n-hexane was4.5%. As for thermal stability, paprika red was stable in low temperature (20°C-40°C), the preservation rate was still remained above80%after6d, but when the temperature reached100°C, the stability of paprika red in paprika powder of different particle size rapid declined, and after10h the preservation rate dropped to60%. These results suggest that when the integrated structure of paprika cell was completely destroyed, cell lost its protective effect on paprika red. Therefore, considering the extraction rate and stability of paprika red in paprika cell, the optimal grinding degree was about100mesh.Fresh paprika cells were observed by microscope and found that paprika red was in the chromoplast of paprika cell cytoplasm. In order to further determined the states of paprika red in paprika cell, the chromoplast of cell was collected and the protein content was assayed to be5.73%+1.35%and the soluble protein content was2.58%+0.12%. It indicated that paprika red in chromoplast may be existed as capsanthin-protein complexes.