Extraction and encapsulation of natural colorant phycocyanin obtained from cyanobacteria with different methods and its storage stability and use in model foods

Color is one of the major features that attract customers and makes the foods more desirable. Due to varying demand of customer and food legislations, use of synthetic colorants is being decreased day by day. Phycocyanin is a commercially important colorant due to its blue color. For sustainable and innovative production of natural colorants, Spirulina platensis was used for the production (extraction, purification) of blue colored phycocyanin and encapsulation of pigments for improved stability against environmental conditions and usage of these natural colorants in model food samples are also aimed in this study. In the first stage of the study the effect of 3 different forms of biomass which are dry, frozen, wet forms and most suitable solvent type among distilled water, Na-Phosphate pH7 suspension and 1.5 % CaCl2-water solution was analyzed, due to possible field of application, and the most convenient pretreatment method was investigated. According to the results, the highest total phycocyanin content (55.33 mg/g) was extracted from frozen biomass and 1.5 % CaCl2-water solution as a solvent. After determining the most suitable pretreatment and solvent type for phycocyanin, the process variables of classic homogenizing, ultrasonic and microwave extraction methods (solvent/biomass ratio, time, vibration, speed, power) was optimized considering the CCRD experimental design to enrich maximum phycocyanin concentration and attractive blue color. Ammonium sulphate precipitation (%30-70) and dialysis method were used for purification of total phycocyanin which was extracted via classic homogenization method at optimum condition. Improvement of stabilization of purified food grade phycocyanin against environmental conditions is achieved by encapsulation using spray drying and coacervation methods. For determining the suitable coating material combination ratios and specific process parameters of encapsulation method, optimization will be done according to combined D-Optimal design trial patterns for each encapsulation method. Microencapsulation efficiency is chosen as the response in the optimization. Optimum spray drying condition was determined using the Design-Expert package program; The coating material combination ratios is 34.4% maltodextrin, 65.6% whey protein isolation and the air inlet temperature is 167.6 ° C. In the coacervation process, which is another microencapsulation method, optimum coating material combination ratios and inlet temperature determined by Design-Expert package program was 26.67% gum arabic, 73.33% gelatin and inlet temperature of 45.68 ° C. Microencapsulation yield, total phenolic content, Hunter L *, a * and b * color values, moisture content, water activity, solubility, particle diameter, span, uniformity, particle morphology, and FT-IR characteristics were also examined which are not used in the optimization study but are very important for microencapsulated phycocyanin samples. The last stage of the study was defining the stability of the purified and encapsulated phycocyanin in various temperatures, pH, illumination conditions and food additives. After determining the optimum stable temperature, pH, illumination conditions, stability analyses for food additives are performed. Accordingly, it was observed that all food additives contributed to maintain the stability of the products. Total phycocyanin content at different conditions was determined by degradation kinetics. The colorant is used in model foods like whipped cream, ice cream, crème, acidic and fizzy drinks, jelly and cake for testing the storage stability of the color. It has been observed that the samples of encapsulated and non-encapsulated phycocyanin have no effect on the appearance, texture and taste criteria of the model foods. It has also been determined that a loss of color in samples containing phycocyanin is present due to the effect of high heat treatment during baking of cakes.