Effect of Sodium Chloride on Glassy and Crystalline Melting Transitions of Wheat Starch Treated with High Hydrostatic Pressure: Prediction of Solute‐induced Barostability from Nonmonotonic Solute‐induced Thermostability

Abstract

Wheat starch was high hydrostatic pressure (HHP)-treated in aqueous solutions with various sodium chloride (NaCl) concentrations (0 to near-saturation), in order to explore the effects of salt on glassy and crystalline transitions of starch during the treatment, using differential scanning calorimetry (DSC). For wheat starch at atmospheric pressure, glass and crystalline melting transitions of amylopectin (reported as gelatinization peak temperature) increased up to 2 M NaCl, and then decreased with further increase in NaCl concentration, but the gelatinization peak temperature was higher in all NaCl solutions than in water alone. In contrast, the melting transition for the amylose-lipid complex (reported as peak temperature) increased continuously with increasing NaCl concentration. When 50% (w/w) starch slurries were HHP-treated in water and various NaCl concentrations (0.1, 2 and 5 M) for 15 min at 257C, the presence of salt significantly protected glass and crystalline transitions of starch during the HHP treatment. Although the baroprotective effect was maximal near the lyotropic 2 M NaCl concentration [1-5], all NaCl concentrations were more baroprotective than was water alone for HHP-treated wheat starch. As reported previously [6] for corn starches in a lyotropic concentration of NaCl (ionic solvent) or a non-equilibrium concentration of sucrose (glass-forming solvent) [7], solute-induced thermostabilization of the wheat starch gelatinization transition predicted solute-induced barostabilization.

Influence of salts on starch degradation: Part I – sodium chloride

“…Gelatinisation peak temperatures were then 83.1, 79.8 and 73.6°C for wx maize, cassava and potato starches, respectively. Such an increase in the gelatinisation temperature of starches due to the presence of NaCl, within the concentration studied, was already reported by several authors 19–23. Samples prepared from native starches that had been heated at 230°C for 45 min without NaCl showed no gelatinisation peaks between 70 and 85°C.…”

Retrogradation kinetics and glass transition temperatures of Pueraria lobata starch, and its mixtures with sugars and salt

“…Table shows that NaCl also promotes retrogradation of the starch at −22°C. Ionization of NaCl into Na + and Cl − in the maximally freeze‐concentrated solution result in water losing the ability to develop a tetrahedral structure, leading to the binding forces between water and starch molecules decreasing . Thus, water molecules between starch molecules are easily excluded to accelerate mutual combination between starch molecules promoting retrogradation of P. lobata starch at −22°C.…”

Differential Scanning Calorimetry Analysis of the Effects of Heat and Pressure on Protein Denaturation in Soy Flour Mixed with Various Types of Plasticizers

“…An empty pan was used as a reference. DSC calibration and other aspects of DSC methodology, for example as applied to other legume proteins (Slade and Levine ), were as previously reported (Kweon and others ,b). DSC analysis for each sample was done at least in duplicate.…”

“…As in our previously published studies using HHP (Kweon and others ,b), a Multivessel Apparatus Unipress 111 (Poland) was used for the HHP treatment. Soy flour and either water or another solution were mixed, in a weight ratio of 1:1, by hand to form a homogeneous paste.…”