Microencapsulation of kaff maryam (Anastatica hierochuntica) extract and diffusion characterization

Microencapsulation stabilizes active ingredients that are sensitive to external factors by encapsulating them in micro-sized suitable wall materials. Microcapsules increase the stability of active ingredients by preventing their degradation and loss due to external environmental factors such as moisture, heat, light, oxygen and ultraviolet rays. It extends the shelf life of the targeted product. Microencapsulation is considered one of the most successful methods in terms of protecting flavorings, masking unwanted odors, increasing thermal and oxidative stability, limiting high volatility, controlling rapid release, increasing bioavailability and use in food systems. In this way, flavoring agents can be retained in the food content for longer periods of time, unwanted interactions between food and flavoring agent can be prevented and the compound can be protected from light-interactive reactions. The volume of extract of the Kaff Maryam (KM) used as core material is determined as 10% (w/v). For the first KM extraction process, the decoction (brewing in the ultrasonic bath) method was determined and applied at 50° C for 5 minutes within the preliminary trial studies. KM extract with a final moisture content of 90.8% was obtained by using a rotary evaporator (800 rpm rotary speed, 75° C water tank temperature, 12.3° C cooler temperature, 0.8 mbar vacuum pressure for 500 mL KM extract, 40 minutes). In microcapsule production, 20% of KM extract (with 9.2% of dry matter) as core material and 2% sodium alginate as wall material were applied for the construction of microcapsules. Sodium alginate wall material, KM extract and distilled water mixture was transferred throught the isotonic and 2% (w/v) calcium chloride (CaCl₂) donor solution (mechanical stirrer used at 250 rpm rotary speed) as microencapsulation process was performed by ionic gelation method by using syringe pump (2 mL/min) at room conditions (25 °C). Half of the wet microcapsules were dried at room conditions (25 °C) for 24 hours. The other half was first frozen in a deep freezer (-25 °C) for 12 hours. Then, they were freeze-dried in a lyophilizer (-51 °C, 1.0x10⁻³ mbar vacuum pressure) for 50 hours. The similarities and differences between room condition dried and freeze-dried microcapsules were determined and compared based on total antioxidant content, total phenolic content, microcapsule size and membrane thickness, microcapsule yield and controlled release at 90 °C studies. In addition, the presence of core and wall materials was determined by FT-IR analysis. The lyophilized microcapsules were found to have higher antioxidant capacity than the microcapsules dried at room temperature (334.67 ± 2.64 mg TE/g) with a dry weight range of 318.23 ± 0.825 mg TE/g. The diameter length of the KM microcapsules dried at room conditions was 0.6865 ± 0.009 mm and the diameter of the freeze dried ones was 0.9881 ± 0.015 mm. It was determined that there was a difference between both drying methods and the diameter length of the microcapsules dried by lyophilization was 1.44 times larger than those dried under room conditions (p<0.05). When the membrane thicknesses of the microcapsules were examined, it was found that there was no difference between them (p>0.05). The b* value representing the yellow color intensity of the lyophilized and dried KM microcapsules was higher than the microcapsules dried under room conditions. During the controlled release, it is noteworthy that the release reaction of the lyophilized KM microcapsules took place 2 minutes earlier on average than the microcapsules dried under room conditions. In the study, KM concentrate was made more effective in both room-dried and freeze-dried microcapsules and was applied to the industrial form of tea bags.