8 research outputs found
Decolorization of Solophenyl Red 3BL Polyazo Dye by Laccase-Mediator System: Optimization through Response Surface Methodology
Clarification of pomegranate juice by ultrafiltration: study of juice quality and of the fouling mechanism
Introduction. Ultrafiltration (UF) is a single-unit
operation for the clarification and fining of fruit juices. The
purpose of the UF is to remove suspended solids as well as haze-inducing
and turbidity-causing substances to obtain a clear juice during
storage. Specifically, the polymerization of phenolic compounds
and their interaction with other components (e.g.,
proteins) could cause a haze complex and turbidity in fruit juices,
which can foul the ultrafiltration membrane. Materials and methods.
Fresh pomegranate juice was clarified by the ultrafiltration process
on a laboratory scale. In experimental tests performed according to
the total recycle and the batch concentration mode, the effects
of transmembrane pressure (TMP) and enzyme pre-treatment on permeation
flux and quality of juice were studied. Results. With the total
recycle mode, the effect of TMP on the color and clarity of clarified
pomegranate juice was significant. The initial color of the raw
pomegranate juice was reduced from 74% to 33% and the clarity decreased
from 77% to 42% by UF when the TMP increased from (1 to 3.6)Â bar.
Total phenolic rejection decreased from 45% to 21% when the TMP
rose from (1 to 2)Â bar and remained constant above this value. With
the batch concentration mode at TMP = 2 bar and velocity 1 m·s–1,
the enzymatic treatment (5 U·mL–1, 300 min, T = 20 °C)
of pomegranate juice provided the highest permeate flux, a decrease
in total phenolics of 50% and an increased clarity of 30%. Fouling
of the UF membrane during pomegranate juice processing is mainly due
to the retention of polyphenols and/or proteins; thus, several blocking mechanisms
were studied, using a recently developed membrane-fouling model.
Analysis revealed that the membrane separation process was controlled
by the gel layer mechanism of raw pomegranate juice and complete pore
blocking mechanism with enzymatic pre-treatment
Application of Asymetrical and Hoke Designs for Optimization of Laccase Production by the White-Rot Fungus Fomes fomentarius in Solid-State Fermentation
Statistical approaches were employed for the optimization of different cultural parameters for the production of laccase by the white rot fungus Fomes fomentarius MUCL 35117 in wheat bran-based solid medium. first, screening of production parameters was performed using an asymmetrical design 2533//16, and the variables with statistically significant effects on laccase production were identified. Second, inoculum size, CaCl2 concentration, CuSO4 concentration, and incubation time were selected for further optimization studies using a Hoke design. The application of the response surface methodology allows us to determine a set of optimal conditions (CaCl2, 5.5 mg/gs, CuSO4, 2.5 mg/gs, inoculum size, 3 fungal discs (6 mm Ø), and 13 days of static cultivation). Experiments carried out under these conditions led to a laccase production yield of 150 U/g dry substrate