TY - JOUR
T1 - Mechanisms controlling wheat starch gelatinization and pasting behaviour in presence of sugars and sugar replacers
T2 - Role of hydrogen bonding and plasticizer molar volume
AU - Renzetti, Stefano
AU - van den Hoek, Irene A.F.
AU - van der Sman, Ruud G.M.
PY - 2021
Y1 - 2021
N2 - The effect of sugars and sugar replacers (i.e. plasticizers) on the gelatinization and pasting behaviour of wheat starch was studied. The intrinsic properties of the plasticizers, i.e. the molar volume density of effective hydroxyl groups NOH,s/vs, and the volumetric density of hydrogen bonds in the sugar solutions treated as a single solvent, i.e. Φw,eff, were proposed as factors controlling swelling (i.e. pasting) and gelatinization behaviour. Different classes of plasticizers were used including sugars, polyols, amino acids, soluble fibres such as oligofructoses, and mixtures thereof. The onset, peak and end temperature of starch gelatinization obtained by differential scanning calorimetry could be well described by Φw,eff for all solutions, following predictions from an adapted Flory-Huggins model for polymer melting. The multiple transitions involved in starch gelatinization could be well related to different ranges of Φw,eff following a side chain liquid crystalline model for starch. Deviations from the model predictions were observed mainly for Tonset in conditions of intermediate and excess solvent with high sugar concentrations (50% w/w). In such conditions phase separation likely occurs, increasing the effective starch concentration and consequently gelatinization temperatures. Pasting behaviour related to swelling, i.e. peak viscosity, was found to be a sigmoidal Fermi function of NOH,s/vs of the plasticizers. Plasticizers with high NOH,s/vs enhanced swelling compared to water while those with low NOH,s/vs had an inhibition effect. Overall, a comprehensive mechanism of starch plasticization, swelling and melting is proposed. Swelling associated with solvent ingress and helix-helix dissociation is affected by kinetic factors related to size and viscosity of the plasticizers (both described by NOH,s/vs) and by thermodynamic factors related to sugar partitioning and H-bonding ability (both related to Φw,eff). Melting of crystalline domains associated to helix-coil transition is controlled by thermodynamics, based on solvent H-bonding ability Φw,eff.
AB - The effect of sugars and sugar replacers (i.e. plasticizers) on the gelatinization and pasting behaviour of wheat starch was studied. The intrinsic properties of the plasticizers, i.e. the molar volume density of effective hydroxyl groups NOH,s/vs, and the volumetric density of hydrogen bonds in the sugar solutions treated as a single solvent, i.e. Φw,eff, were proposed as factors controlling swelling (i.e. pasting) and gelatinization behaviour. Different classes of plasticizers were used including sugars, polyols, amino acids, soluble fibres such as oligofructoses, and mixtures thereof. The onset, peak and end temperature of starch gelatinization obtained by differential scanning calorimetry could be well described by Φw,eff for all solutions, following predictions from an adapted Flory-Huggins model for polymer melting. The multiple transitions involved in starch gelatinization could be well related to different ranges of Φw,eff following a side chain liquid crystalline model for starch. Deviations from the model predictions were observed mainly for Tonset in conditions of intermediate and excess solvent with high sugar concentrations (50% w/w). In such conditions phase separation likely occurs, increasing the effective starch concentration and consequently gelatinization temperatures. Pasting behaviour related to swelling, i.e. peak viscosity, was found to be a sigmoidal Fermi function of NOH,s/vs of the plasticizers. Plasticizers with high NOH,s/vs enhanced swelling compared to water while those with low NOH,s/vs had an inhibition effect. Overall, a comprehensive mechanism of starch plasticization, swelling and melting is proposed. Swelling associated with solvent ingress and helix-helix dissociation is affected by kinetic factors related to size and viscosity of the plasticizers (both described by NOH,s/vs) and by thermodynamic factors related to sugar partitioning and H-bonding ability (both related to Φw,eff). Melting of crystalline domains associated to helix-coil transition is controlled by thermodynamics, based on solvent H-bonding ability Φw,eff.
KW - Fibres
KW - Gelatinization
KW - Hydrogen bonding
KW - Starch
KW - Sugars
KW - Swelling
U2 - 10.1016/j.foodhyd.2021.106880
DO - 10.1016/j.foodhyd.2021.106880
M3 - Article
AN - SCOPUS:85105553163
SN - 0268-005X
VL - 119
JO - Food Hydrocolloids
JF - Food Hydrocolloids
M1 - 106880
ER -