Extraction, encapsulation of natural colorant fucoxanthin obtained from microalgae with different methods and its storage stability and use in model foods

Microalgae with the increasing importance in the recent years, are emerging as a sustainable resource for the production of natural coloring materials with the features of being produced by biotechnological methods, showing rapid inrease in biomass due to multiplication and obtaining a higher amount of pigment compared to plants by this method. Fucoxanthin, one of the natural colorants, is a very important for commercial reasons due to its brown color. In accordance with the legislation of the countries, the use of synthetic colorants is decreasing day by day and consumers' preferences are towards to natural colorants. In this thesis, fucoxanthin production (extraction and purification) from Phaeodactylum tricornutum with brown color, the enhancement of its stability against environmental conditions with the encapsulation technology and the use of fucoxanthin in model food samples were aimed. Firstly, the effect of 3 different forms of dry, frozen, wet and most suitable solvent type acetone, diethyl ether and ethanol-water solution and their ratios (95:5, 90:10, 80:20 v/v) were analyzed, considering the possible fields of application, and the most convenient pretreatment method was investigated. Frozen form and 80:20 ethanol-water solution yielding the highest amount of fucoxanthin (17.43±1.02 mg/g) were selected and optimization studies were performed according to the CCRD experimental design, targeting the maximum fucoxanthin in the process variables (biomass/solvent ratio, time, vibration, speed, power) specific to classical, ultrasonic and microwave extraction methods. Extraction was carried out by the classical extraction method giving the highest amount of fucoxanthin and the densest brown-green color. The fucoxanthin extracted at the optimum condition by the classical extraction method was subjected to the purification process. Different purification methods and parameters were tested to determine the most economical and desirable dense brown-green color. This condition was obtained by evaporating the extracted fucoxanthin and freeze drying the remaining part of the solvent. Then, it is aimed to increase the stability of the purified food grade fucoxanthin by encapsulation with spray drying and coacervation methods. The optimization study was performed according to the combined D-Optimal design experimental patterns to determine the mixing ratios of the combination of coating materials which are suitable for each encapsulation method and the process parameters specific to the encapsulation method. The encapsulation efficiency was chosen as the response in the optimization study performed by spray drying and coacervation methods. Optimum spray dryer conditions were determined by using the Design-Expert, the mixing ratio of the coating material is 39.2% maltodextrin, 60.8% whey protein isolate and the air inlet temperature is 150°C. Another microencapsulation method, the coacervation process, optimum mixture ratios of coating materials and temperature of solution determined by Design-Expert were 50.0% gum arabic, 50.0% gelatin and solution temperature of 31.31°C. Additionally, microencapsulation yield, total phenolic content, antioxidant activity (DPPH), 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 for microencapsulated fucoxanthin samples. The last step of the study, the stability of purified and encapsulated fucoxanthin at different temperatures, relative humidity, pH and light/dark conditions was determined. The additions of additives in all samples were performed in the most stable pH, temperature and light environment and the stability of the products was enhanced with the additives as a conclusion. In the all experimental conditions, the degredation kinetics and half life of fucoxanthin were determined. As noncapsulated fucoxanthin, fucoxanthin encapsulated by two different methods and synthetic caramel colorant (E150a) were tested in model foods like whipped cream, jelly and pastry for the storage stability of the color. The coloring properties of the microencapsulated products added to the model food according to the process (hot or cold process) showed different behaviour. With the effect of high heat treatment during baking of pastries, it was also observed that a loss of color in samples containing fucoxanthin but it was observed to be more preferred by the panelists.