TY - JOUR
T1 - Effect of molecular mass and degree of substitution of carboxymethyl cellulose on the formation electrostatic complexes with lentil protein isolate
AU - Wang, Yingxin
AU - Pillai, Prasanth K.S.
AU - Nickerson, Michael T.
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/12
Y1 - 2019/12
N2 - The electrostatic interaction between lentil protein isolate (LPI) and carboxymethyl cellulose (CMC) of different molar mass (MM; 90 and 250 kDa) and degree of substitution (DS; 0.7, 0.9 and 1.2%) was examined during a turbidimetric pH acid-titration over a pH (8.0–1.5) and mixing ratio (LPI: CMC; 1:1–10:1) rang. For LPI-CMC (0.7% DS, 250 kDa) at a 1:1 ratio, pHs linked soluble (pHc) and insoluble complexes (pHϕ1) being formed, maximum coacervation (pHopt) and the dissolution of complexes (pHϕ2) occurred at pHs of 6.8, 2.6, 2.1 and 1.7, respectively. As the mixing ratio increased, pHc and pHϕ2 remained unchanged; however, pHϕ1 and pHopt shifted to higher pHs until plateauing at a 4:1 mixing ratio. Molecular mass and DS had no significant effect on critical pHs but did have an impact on the size and number of complexes formed. The maximum optical density at pHopt was found to decrease from 0.495 to 0.406 as the DS increased from 0.7% to 1.2% on the CMC (constant at 250 kDa), suggesting that complexes were likely smaller as they scattered less light. As the MM of CMC decreased from 250 to 90 kDa (at 0.7% DS), maximum optical density increased from 0.495 to 0.527, respectively. Confocal laser scanning microscopy preformed at pHopt showed an increasing number of aggregates as the DS or MM of CMC decreased. From isothermal titration calorimetry (ITC), larger enthalpy values in LPI-CMC with increased DS and MM were observed.
AB - The electrostatic interaction between lentil protein isolate (LPI) and carboxymethyl cellulose (CMC) of different molar mass (MM; 90 and 250 kDa) and degree of substitution (DS; 0.7, 0.9 and 1.2%) was examined during a turbidimetric pH acid-titration over a pH (8.0–1.5) and mixing ratio (LPI: CMC; 1:1–10:1) rang. For LPI-CMC (0.7% DS, 250 kDa) at a 1:1 ratio, pHs linked soluble (pHc) and insoluble complexes (pHϕ1) being formed, maximum coacervation (pHopt) and the dissolution of complexes (pHϕ2) occurred at pHs of 6.8, 2.6, 2.1 and 1.7, respectively. As the mixing ratio increased, pHc and pHϕ2 remained unchanged; however, pHϕ1 and pHopt shifted to higher pHs until plateauing at a 4:1 mixing ratio. Molecular mass and DS had no significant effect on critical pHs but did have an impact on the size and number of complexes formed. The maximum optical density at pHopt was found to decrease from 0.495 to 0.406 as the DS increased from 0.7% to 1.2% on the CMC (constant at 250 kDa), suggesting that complexes were likely smaller as they scattered less light. As the MM of CMC decreased from 250 to 90 kDa (at 0.7% DS), maximum optical density increased from 0.495 to 0.527, respectively. Confocal laser scanning microscopy preformed at pHopt showed an increasing number of aggregates as the DS or MM of CMC decreased. From isothermal titration calorimetry (ITC), larger enthalpy values in LPI-CMC with increased DS and MM were observed.
KW - Carboxymethyl cellulose
KW - Coacervation
KW - Degree of substitution
KW - Lentil protein isolate
KW - Molar mass
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U2 - 10.1016/j.foodres.2019.108652
DO - 10.1016/j.foodres.2019.108652
M3 - Article
C2 - 31732081
AN - SCOPUS:85071942021
SN - 0963-9969
VL - 126
JO - Food Research International
JF - Food Research International
M1 - 108652
ER -