Amylose step in the food industries to acquire

and amylopectin are established highly branched molecules of starch with anhydroglucose
units joined by glucosidic bonds and is potentially degradable by the
amylolytic enzymes (Guan et al., 2013). Liquefaction
of starch by ?-amylase is primarily an
important process step in the food industries to acquire different syrups that
are further used as additives with obvious functional properties in many
processed food products (Li eta al., 2016). The
hydrolysis/liquefaction percentages of cornstarch in the present study by the Bacillus amyloliquefaciens KU-20 ?-amylase both at 800C
and 900C with added 5 mM of Ca2+ at pH 5.5 are shown Fig. 4 and 5.
The conditions of direct gelatinization/liquefaction were chosen based on the
results of observed viscosity measurements. whereby the readings were stable
and showed no undesirable fluctuations in the viscosity curves. The cornstarch liquefaction
at stipulated concentrations was carried out and the results show that the % of
hydrolysis increased as the incubation time progresses. As shown, the enzyme liquefied
cornstarch with various percentages of hydrolysis, depending on the temperature,
starch concentration and incubation time. At 10% cornstarch slurry, the highest
% of hydrolysis was 55% both at 800C and 900C after 30min
of incubation. A comparable effect was observed for 20% (Fig. ), whereas at 30%
initial corn starch concentration and at 900C, the % of hydrolysis
reduced to (50% ?). Likely, this might be a result of uncompleted
gelatinization of starch generated by less water mobility inside the phases (Shariffa et al., 2009; Li et al., 2015), which probably
led to lower hydrolysis of the starch gel-enzyme complex or invariably,
decreased enzyme stability and activity at this high temperature. In contrast,
such decrease in activity was not observed at 800C, independent of
the initial corn starch concentrations and, in this case, the final %
hydrolysis remained constant at 55% in all runs, indicating that the enzyme was
active and stable at this temperature. This confirms the viscosity curve
results obtained at 800C (Fig. 1,2 and 3) which showed similar
tendency with final viscosity values < 0.01 Pa S-1, independent of initial starch concentration.