Encapsulation of sour cherry juice concentrate with spray drying and increasing encapsulation yield by using various proteins

According to the literature, sour cherry contains high levels of antioxidants and phenolic substances similar to other red fruits. For this reason, in this study, sour cherry concentrate was chosen as the extract to be encapsulated because of its nutritional value. Some studies have been performed in recent years on encapsulation for the protection and improvement of bioactive components. There are many techniques used for encapsulation in previous studies. These are spray drying; spray cooling and freezing, extrusion coating, fluid bed coating, coating with liposome, coacervation and rotational suspension separation etc. Spray drying is one of the extensively used techniques in food industry to obtain powders under optimal processing conditions. Fruit juice powders have several benefits such as reducing weight and packaging, making transportation easier, and increasing shelf life. The major advantages of spray drying are being a simple, economical, easy, fast and convenient technique. The aim of this thesis is to investigate spray drying ability of sour cherry concentrate with different wall materials. The sour cherry concentrate was dissolved in water to adjust to 11% brix and drying was carried out in the spray dryer. Due to the sticky structure of cherry, maltodextrin was used as a coating material at different concentrations (5%, 10%, 15%), and dextrose equivalent (6-12-18DE) at inlet temperatures of 110°C, 135°C and 160°C. First, optimization of maltodextrin type and concentration was performed to reach the most efficient powder production. Optimum conditions for spray drying of sour cherry concentrate were determined by response surface methodology (RSM). Response surface methodology parameters were inlet temperature, maltodextrin concentration and maltodextrin dextrose equivalent (DE). 15 trials were performed and then 8 trials were done again since the first application did not include some parameters. Secondly, the selected conditions were kept constant (110°C and DE12) and 15% MD concentration was mixed with two different proteins (whey and egg white) with concentrations of %1 and %0.5. At this stage, it was investigated whether the protein increases the yield. After proving that protein was effective at increasing the yield of the powder, the maltodextrin concentration (5-10%) was gradually reduced and mixed with the whey protein or egg white to feed the spray dryer samples. When only maltodextrin was used, the yield of the spray dried powder was only 7.8%, whereas the yield powder with protein changed from 6.6% to 14.8%. The use of 1% protein provided more efficient powder than 0.5%. 15% maltodextrin concentration was the most efficient and the whey protein was more efficient than egg white. In addition, it was observed that whey protein increased powder yield than egg white except 10% MD concentration. When the efficiency of proteins and maltodextrin is compared in spray drying, combination of maltodextrin and protein (whey or egg white) is more effective than maltodextrin only. For this reason, it can be said that inlet temperature, maltodextrin type and concentration factors influence of the powder. However, if other factors were held constant, high temperature meant to increase powder yield. In addition, as the concentration increased according to the protein concentration, the whey and egg white gradually increased. After spray drying, moisture content, the total phenolic content, the antioxidant capacity, the total monomeric anthocyanin content, the color properties of the cherry powders were analyzed. The moisture content of the powder was calculated to be between 2.3% and 4.1%. The total phenolic content of the powder ranged from 2.10 to 7.29 mg (GAE)/ g dry weight. Total antioxidant capacity was determined by two methods; DPPH, CUPRAC analyses. When using only maltodextrin, DPPH values ranged from 0.8 to 12.2 mg trolox equivalent (TEAC)/g dry weight, while DPPH results were found between 9.2 and 13.2 mg TE/g dry weight with mixing protein and maltodextrin. As the concentration decreased, the DPPH values increased. 5% concentration of MD was determined as the highest antioxidant capacity within powders produced with whey protein. The CUPRAC results were calculated 17.1-36.2 mg TEAC/g dry matter. The 5% MD had the highest antioxidant capacity compared to other maltodextrin concentrations. The total anthocyanin content of powders changed from 29 to 49.5 mg/g by using pH differential method. In addition, powder color, colloidal stability and glass transition temperature (DSC) analysis were performed. For color analysis L*, a*, b* values were measured and these values decreased when the concentration of maltodextrin was reduced. Moreover, by increasing the protein concentration of both whey and egg white, the L* value increased but a* and b* values did not change significantly. L* results were determined between 27.7 and 56.4; a* results were determined to be ranging from 6.7 to 14.2; b* results were determined between 3.9 and 6.8. As maltodextrin concentration decreases, L*, a* and b* values decreases. Glass transition temperature (Tg) was determined by using differential scanning calorimeter (DSC). An equilibrium temperature of -10°C to 120°C was used for cherry powder samples and for maltodextrin, egg white and whey protein the temperature changed between 0°C and 180°C. The Tg was found to be between 24.8 and 56.4 °C for sour cherry dried powders. The Tg of maltodextrin was 87-105.6 °C and for whey Tg was 142-143.8 °C. For egg white Tg was found to be ranging from 91.4 to 106.9°C.