Synthesis of vanillyl-maltoside using glucosidases by response surface methodology

Amyloglucosidase from Rhizopus mold and β-
glucosidase from sweet almond, catalysed synthesis of
vanillyl-maltoside was optimized using response surface
methodology. A central composite rotatable design involving
32 experiments of five variables at five levels was employed.
Among the variables employed, glucosidases (10–
50% w/w of maltose), vanillin (0.5–2.5 mmol), incubation
period (24–120 h), buffer volume 0.4–2.0 ml (0.04–0.2 mM)
and pH (4.0–8.0); enzyme, buffer concentration and buffer
pH were found to be significant with both the enzymes. Surface
plots generated clearly brought out the maltosylation
behaviour of the two glucosidases in this reaction with both
the enzymes exhibiting yields in the range 5–60%. Saddleshaped
surface plots observed with both the enzymes exhibited
total reversal of the maltosylation behaviour at certain
critical crossover points like 30% (w/w maltose) enzyme
concentration, buffer pH 6.0 and a buffer concentration of
1.25 ml (0.125 mM), implying that a critical enzyme to
buffer concentration and pH dictate the extent of vanillin
maltosylation. Validation experiments conducted at certain
random selected conditions as well as those conducted at optimum
conditions obtained from the reduced model showed
good correspondence between predicted and experimental yields