| Abstract [eng] |
Various technological factors applied during the gel production process can change their texture and quality. It is known that the increasing mixing time used in the production of hydrogels can significantly increase the values of the texture parameters of the hydrogels, while increasing mixing speed can significantly reduce them. Increasing intensity of the ultrasound or the duration of its application can also significantly change the texture of the test hydrogels. The aim of the final project is to study the influence of technological factors on the quality of gels with chitosan and essential oil. The test hydrogels are produced by the mass-volume method using magnetic and digital stirrers with different stirring speeds (500, 1000, 1500 rpm) and stirring times (15, 30 and 45 minutes) and ultrasonic baths with different ultrasonic intensities (50 , 75, 100 percent) and duration of application (15, 30, and 45 minutes). The quality of the produced hydrogels is investigated by texture analysis, pH determination, microscopic and stability studies by differential centrifugation, physical and accelerated stability methods. The influence of turmeric essential oil, glycerol and technological factors applied during the production of gels with glycerol on their texture parameters is also evaluated. The obtained results showed that 4 and 5 percent hydrogels remain stable by inserting <0.327 percent turmeric essential oil into them. Depending on the oil concentration, the values of gel hardness, consistency, cohesiveness and viscosity index change significantly. It was found that up to a certain limit (1000 rpm) the increasing mixing speed reduced the values of the texture parameters of the produced hydrogels (except for the viscosity index). Prolonged mixing time significantly increases these values. Increasing the intensity of the ultrasound and prolonging the application time of the ultrasound (from 15 to 30 minutes), as well as the mixing speed, significantly reduces the values of the texture parameters. Hydrogels prepared at 500 rpm and mixed for 45 minutes were found to have the highest values for texture parameters. Of the hydrogels produced by the ultrasonic method, gels with the ultrasonic intensity of 50 percent and an ultrasonic duration of 15 minutes have the highest values. Ultrasonic hydrogels in all cases reveal poorer texture parameters. Glycerol was found to significantly increase the hardness values of the test hydrogels but decreased their cohesiveness. In the production of gels with glycerol, only using the mixing method yields hydrogels with higher values of texture parameters (except viscosity index). Based on the results of pH determination, microscopic examination, evaluation of physical stability and differential centrifugation test, it was found that the test gels, which are produced using ultrasound, acidify faster over time. Furthermore, cavitation bubbles are observed in these gels after production. Of the hydrogels produced by the mixing method, instability after 3 months was observed in a gel produced at a mixing speed of 1500 rpm. Also, instability was observed in 5 percent hydrogel after 2 months with 100 percent ultrasonic intensity in production, and after 3 months, physical instability was observed in all hydrogels, which was produced using ultrasound. The test hydrogels remain stable for up to 2 months under the conditions of the accelerated stability test. The results showed that the mixing speed, mixing time, ultrasonic intensity and ultrasonic application time determines the final texture properties of chitosan hydrogels and affects their quality, so in order to achieve optimal product texture parameters and ensure good gel quality, it is necessary to control the technological factors used in their production. |
