ARIANA DE SOUZA SOARES EFEITO DA TECNOLOGIA DE ULTRASSOM NA ATIVIDADE DE ENZIMAS COMERCIAIS VIÇOSA -MINAS GERAIS

SOARES, Ariana de Souza Soares, D.Sc., Universidade Federal de Viçosa, May, 2020, Effect of ultrasound technology on trade enzyme activity. Advisor: Afonso Mota Ramos. Co-advisors: Bruno Ricardo de Castro Leite Júnior and Pedro Esteves Duarte Augusto. The use of enzymes in several segments is growing, such as textiles, medical, pharmaceutical, food. Enzymatic reactions have high efficiency, specificity, are nontoxic, and therefore have great industrial importance. However, the use of enzymes, on a large scale, is limited due to high cost and low stability. The ultrasound technology has been proposed to modify the enzymatic performance, and, therefore, it can be an alternative to minimize these limitations. In this context, this study aimed to evaluate the effect of ultrasound on the activity of commercial enzymes, in order to improve the performance of these enzymes. For the study, an ultrasonic bath was used, operating at 25 kHz (invertase and lipase) and 40 kHz (amyloglucosidase), with volumetric power of 22.0W/L (invertase and lipase) and 9.5 W/L (amyloglucosidase). At first, the effect of ultrasonic processing, as a pre-treatment of amyloglucosidase, on the enzymatic activity and stability was evaluated. The activity was evaluated under optimal and not optimal conditions of temperature and pH and its stability was evaluated during storage at 8 ° C. For invertase, the effect was evaluated in three situations: the reaction (invertase acting on the substrate under ultrasound processing), the isolated substrate (sucrose) and the isolated enzyme (invertase). Ultrasonic processing was carried out under different pH and temperature conditions. Finally, the effect of ultrasound was studied on the performance of lipase in the hydrolysis of fat from goat's milk. The processing was carried out under different temperature conditions, evaluating the effect in three approaches: lipase, goat cream and reaction. Ultrasound was able to increase, reduce or not change the enzymatic activity of amyloglycosity, depending on the conditions applied. Under different ultrasound conditions, mainly at 35 and 65 ° C, the enzyme activity did not change. The increase in activity (up to 15%) occurred under non-ideal conditions of pH and temperature (pH 3.5 or 5.5 / 80 ° C). The ultrasound-assisted reaction promoted by invertase was accelerated in relation to conventional processing. This process increased the rate of sucrose hydrolysis by 33% at 40 ° C and 30% at 30 ° C. Ultrasound as a pretreatment method did not promote sucrose hydrolysis, but slightly reduced invertase activity, regardless of pH and the temperature. As a pre-treatment, ultrasound did not induce hydrolysis of the goat's cream, but slightly increased the lipase activity (up to 12%), depending on the temperature and processing time. Ultrasound-assisted fat hydrolysis showed a higher conversion rate (12 28%) when compared to conventional processing at different temperatures. Therefore, ultrasound technology appears as an interesting alternative to improve the performance of these enzymes and accelerate enzymatic reactions.