TY - JOUR
T1 - Stabilization of semi-solid-state starch by branching enzyme-assisted chain-transfer catalysis at extreme substrate concentration
AU - Jensen, Susanne Langgård
AU - Larsen, Flemming Hofmann
AU - Bandsholm, Ole
AU - Blennow, Andreas
PY - 2013/3/5
Y1 - 2013/3/5
N2 - In this study a branching enzyme (BE, α-1,4→α-1,6 glycosyltransferase) was used to modify starch granules of different structures at high temperature and at extreme starch dry matter content (30-40%, w/v) to restrict temperature-induced swelling. As opposed to diluted systems, such conditions led to stabilization of the granular structure for low-phosphate starch types at the highest BE activity. Bright field/polarized light and scanning electron microscopy confirmed maintenance of granular structure. The product compared to the control had significantly increased degree of branching as identified by shorter branch-length of the α-1,4 chains assessed by chromatography and larger proportion of α-1,6 links to α-1,4 links as assessed by 1H nuclear magnetic resonance spectroscopy. Size exclusion chromatography demonstrated the presence of uniform molecules with smaller size. Further the polysaccharide product was 40% more soluble at 25°C than the corresponding heat treated control. Both of these observations were supported by 13C solid-state MAS NMR. Hence, significant chain transfer took place in the semi-solid state starch permitting conservation of the main granular organization in the final product. A hypothetic model is presented to account for the observed phenomenon.
AB - In this study a branching enzyme (BE, α-1,4→α-1,6 glycosyltransferase) was used to modify starch granules of different structures at high temperature and at extreme starch dry matter content (30-40%, w/v) to restrict temperature-induced swelling. As opposed to diluted systems, such conditions led to stabilization of the granular structure for low-phosphate starch types at the highest BE activity. Bright field/polarized light and scanning electron microscopy confirmed maintenance of granular structure. The product compared to the control had significantly increased degree of branching as identified by shorter branch-length of the α-1,4 chains assessed by chromatography and larger proportion of α-1,6 links to α-1,4 links as assessed by 1H nuclear magnetic resonance spectroscopy. Size exclusion chromatography demonstrated the presence of uniform molecules with smaller size. Further the polysaccharide product was 40% more soluble at 25°C than the corresponding heat treated control. Both of these observations were supported by 13C solid-state MAS NMR. Hence, significant chain transfer took place in the semi-solid state starch permitting conservation of the main granular organization in the final product. A hypothetic model is presented to account for the observed phenomenon.
U2 - 10.1016/j.bej.2012.12.013
DO - 10.1016/j.bej.2012.12.013
M3 - Journal article
SN - 1369-703X
VL - 72
SP - 1
EP - 10
JO - Biochemical Engineering Journal
JF - Biochemical Engineering Journal
ER -