RESUMO
Immobilization of enzymes has many advantages for their application in biotechnological processes. In particular, the cross-linked enzyme aggregates (CLEAs) allow the production of solid biocatalysts with a high enzymatic loading and the advantage of obtaining derivatives with high stability at low cost. The purpose of this study was to produce cross-linked enzymatic aggregates (CLEAs) of LipMatCCR11, a 43 kDa recombinant solvent-tolerant thermoalkaliphilic lipase from Geobacillus thermoleovorans CCR11. LipMatCCR11-CLEAs were prepared using (NH4)2SO4 (40% w/v) as precipitant agent and glutaraldehyde (40 mM) as cross-linker, at pH 9, 20 °C. A U10(56) uniform design was used to optimize CLEA production, varying protein concentration, ammonium sulfate %, pH, glutaraldehyde concentration, temperature, and incubation time. The synthesized CLEAs were also analyzed using scanning electron microscopy (SEM) that showed individual particles of <1 µm grouped to form a superstructure. The cross-linked aggregates showed a maximum mass activity of 7750 U/g at 40 °C and pH 8 and retained more than 20% activity at 100 °C. Greater thermostability, resistance to alkaline conditions and the presence of organic solvents, and better durability during storage were observed for LipMatCCR11-CLEAs in comparison with the soluble enzyme. LipMatCCR11-CLEAs presented good reusability by conserving 40% of their initial activity after 9 cycles of reuse.
Assuntos
Proteínas de Bactérias/química , Geobacillus/enzimologia , Lipase/química , Agregados Proteicos , Proteínas de Bactérias/genética , Reagentes de Ligações Cruzadas/química , Estabilidade Enzimática , Geobacillus/genética , Lipase/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genéticaRESUMO
The aim of this research was to evaluate the effect of ultraviolet-C light on physicochemical, bioactive, microbial, and sensory characteristics of carrot beverages. Beverages were formulated with different concentrations of carrot juice (60, 80, and 100% [v/v]) and treated with ultraviolet-C light at different flow rates (0, 0.5, 3.9, and 7.9 mL s(-1)) and times (5, 10, 15, 20, and 30 min), equivalent to ultraviolet-C dosages of 13.2, 26.4, 39.6, 52.8, and 79.2 J cm(-2) Total soluble solids, pH, and titratable acidity were not affected by the ultraviolet-C light treatment. Ultraviolet-C light significantly affected (p < 0.05) color parameters of pure juice; however, at low concentration of juice, total color change was slightly affected (ΔE = 2.0 ± 0.7). Phenolic compounds (4.1 ± 0.1, 5.2 ± 0.2, and 8.6 ± 0.3 mg of GAE 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) and antioxidant capacity (6.1 ± 0.4, 8.5 ± 0.4, and 9.4 ± 0.3 mg of Trolox 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) of carrot beverages were not affected by ultraviolet-C light treatment. Microbial kinetics showed that mesophiles were mostly reduced at high flow rates in carrot beverages with 60% of juice. Maximum logarithmic reductions for mesophiles and total coliforms were 3.2 ± 0.1 and 2.6 ± 0.1, respectively, after 30 min of ultraviolet-C light processing. Beverages were well accepted (6-7) by judges who did not perceive the difference between untreated and Ultraviolet-C light treated beverages.
Assuntos
Bebidas/análise , Daucus carota , Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Raios Ultravioleta , Antioxidantes/análise , Bebidas/microbiologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos/métodos , Concentração de Íons de Hidrogênio , Fenóis/análise , Pigmentos Biológicos/análiseRESUMO
The medium optimization for the production of the Geobacillus thermoleovorans CCR11 thermoalkalophilic lipase was carried out in shake flask cultures using safflower high oleic oil. In the first step of optimization, a two level fractional factorial design allowed the identification of the concentration of nutrient broth and temperature as the main variables significantly affecting lipase production (P<0.05). In a second step, a D-optimal design was applied to determine the variables optimal values, defined as those yielding maximal lipase production in shaken flasks, thus demonstrating that the optimal concentration of nutrient broth was 3.8 g/l and the optimal culture temperature was 39.5°C. The model was experimentally validated, yielding a lipase production of 2283.70 ± 118.36 U/mL which represents a 6.7-fold increase in comparison to the non-optimized medium.