Microencapsulation of enzymatically extracted Zn-chlorophyll derivatives from nettle by electrical methods

The demand for the use of natural coloring materials as coloring agents in food products is increasing steadily. The use of chlorophylls, which give a natural green color that is specific to plants, is not very common for this purpose. Because chlorophyll is extracted from the cell and the green color they have is transformed into unwanted brown after oxidative and enzymatic reactions. Stinging nettle is used as a raw material in order to eliminate this situation and to provide natural green colorant production. The microencapsulation of the chlorophyll by molecular stabilization, extraction after enzymatic pretreatment and ionic gelation of the obtained extract have been studied in this thesis. In the first step, the metal-chlorophyll complex formation method has been chosen for stabilizing the chlorophyll molecule, which has very low stability in natural form. The stabilized chlorophyll molecules were then extracted with high efficiency using enzymatic extraction method. Four different microcapsules were produced by different applications on the method in order for the ionic gelation method to give better results. Group 1 (control group) (K) was produced by classical ionic gelation method (1% sodium alginate, 20% Zn-chlorophyll extract, 2% calcium chloride) while on microcapsules produced by the classical method, coated with chitosan (0,4%) in group 2 (KK). Iontophoresis method (I) (1% sodium alginate, 20% Zn-chlorophyll extract, 2% calcium chloride, electric current applied to calcium chloride solution, 20 V, 0,05 A) was used as an electrical method in group 3 microcapsules. Group 4 microcapsules were obtained by coating with microcapsules produced by electrical iontophoresis with chitosan (0,4%) (IK). The change in total chlorophyll content, color (L *, a *, b *) and pH values over 8 weeks storage period was determined to determine the effect of storage on 4 different microcapsule groups. Apart from these repeated analysis for fresh raw materials were also examined SEM images, total dry matter, zinc, release test, model food experiments to characterization of microcapsules. When the results obtained were examined, it was determined that color and pH values were decreased in all experimental groups throughout the storage period (p <0,05). The decrease in total chlorophyll content in the microcapsule groups according to the initial amount was found to be 17.32% in the group 1 (control), 44.97% in the group 2, 4,18% in the group 3 and 26.52% in the group 4. The microcapsules obtained using the electrical method provided higher protection of chlorophyll during storage than other groups. Chitosan application as a second layer to microcapsules resulted in an increase in chlorophyll decay in both control and iontophoresis methods (p <0,05). It has been determined that the application of chitosan in chlorophyll microencapsulation is not appropriate.