The combination of branching enzyme (BE) and amylomaltase (AM) were
selected to modify cassava starch. AM were used to elongate the glucan chains in order to
enhance BE activity to create branching linkages. Cassava starch were gelatinized and
incubated with BE or AMBE or BEAMBE or simultaneous AM and BE. The
molecular analysis of the products including amylopectin chain length distribution,
content of α-1,6 glucosidic linkages, absolute molecular weight distribution and
digestibility were examined. Only BE catalysis showed 7.8% of branching linkages. The
sequential AMBE-treated starch showed 9.9%-10.0% branching linkages, while the
sequential BEAMBE-treated starch gained 10.9%-13.1% of branching linkages.
Moreover, the sequential AMBE and BEAMBE-treated starch retarded the
digestion rate of α-amylase and glucoamylase. Overall, sequential BEAMBE
catalysis resulted in more extensive branching as compared to all other enzyme treatment
combinations and the products also exhibited the lowest digestion rate constant (1.4x10-3
min-1) than that of glycogen (1.7x10-3 min-1).
The effect of amylose content on BE and combinatorial BEAMBE chain
transfer were studied in order to produce slowly digestible and resistant maltodextrin
structures. Well-defined ratios of amylose only-barley starch (AO) and waxy maize
starch (WX) with non-granular AO content varied from 0 to 100% were used as a
substrate. For only BE catalysis, an increase rate of α-1,6 linkage formation for the 0%
AO sample treated with BE was 1.5-fold while the 100% AO sample showed a 34.0-fold
as compared to the original substrates. An increase in α-1,6 linkages for the 100% WX
treated sequentially with BEAMBE was 1.8-fold as compared to the WX substrate
used while the 100% AO showed a 39.0-fold. All BE and BEAMBE treated starches
showed a decrease in w and dispersity compared to the non-modified WX and AO.
The α- and β-limit dextrin content from both BE and BEAMBE catalysis were
decreasing when increasing AO proportion. Glucose released from all modified starches
after hydrolysis by human pancreatic α-amylase and further hydrolysis by rat intestinal α-
glucosidase was decreased with increasing AO ratios. The 100% AO sample treated with
BE and BEAMBE showed lower glucose released compared to 0% AO sample. In
addition, the BE treated sample treated showed higher glucose released compared to
BEAMBE treated sample. The combination of BEAMBE produced more
resistant α-glucan products as compared to BE alone. The high amylose starch showed
potential to apply as a raw material for enzymatic modification to produce slowly- and
indigested dextrin.
Slowly and resistant maltodextrin conferring isomaltooligosaccharides (IMO)
production was prepared by using simultaneous α-amylase and BE followed by α-
transglucosidase (ABT) and simultaneous α-amylase and BE followed by simultaneous
β-amylase and α-transglucosidase (ABbT) with 30% and 50% (w/v) cassava starch
substrate concentration. ABT catalysis showed branching linkages content ranging from
51.2% and 67.8%, and TDF content was 16.6 and 17.4% when using 30% and 50%
substrate, respectively. ABbT catalysis showed branching linkages content of 82.9% and
85.5%, and TDF content was 24.8 and 25.6% when using 30% and 50% (w/v) substrate,
respectively. Prebiotics index of ABbT samples was higher than ABT samples and not
significant difference from FOS but lower than commercial IMOs. The acetate content
M was the highest short chains fatty acids produced from ABbT samples. Overall, all α-
glucan products had stimulated probiotics activity as compared to native starch.