Abstract
AbstractA matrix of 27 acid‐thinned (AT) potato starch (PS) samples is prepared in a laboratory scale in slurry by gradation of the process parameters temperature (30, 40, and 50 °C), acid concentration (0.3, 0.6, and 0.9 m HCl) and time (4, 10, and 20 h), and is investigated in terms of functional properties (range of molar mass [Mw] between 17.7 × 106 and 1.95 × 104 g mol−1). The solubility (S) increased basically with a higher degree of molecular degradation and disintegration temperature, and the viscosity decreased systematically with decreasing Mw and increasing disintegration temperature. The existence of a specific Mw range of the starch to achieve highest gel strength is proved. However, an impact of the molecular properties on the light transmittance (Tgel) can be excluded, since all starch gels are opaque. A correlation between the strength and the specific non‐freezable bound water content (wnf) of the gels is found. High gel strength is accompanied by comparatively low wnf. In particular, the viscosity (processing) and the gel strength (final product characteristic), which are important technofunctional properties for the industrial application of AT starches, are found to be directly correlated to the Mw of the starch product. Moreover, the latter is controllable by the hydrolysis process parameters.
Highlights
(reaction rate), molar acid concentration, and acid type, respectively, and the laboratory scale in slurry by gradation of the process parameters temperature duration of the hydrolysis can con
The water binding of the starch gels (7.5% w/w, storage for 24 h at 5.5 ± 1.5 °C) was determined based on differential scanning calorimetry (DSC; DSC 204 F1 Phoenix fitted with an intracooler, Netzsch, Selb, Germany) freezing experiments according to the description elsewhere[25] with modifications
The acid hydrolysis of the starch polymers to the desired degree is controllable without steps by varying both acid concentration and hydrolysis time within the investigated parameter field according to the relationship apparent from Figures 7A,B, which is limited by the experimental design
Summary
Commercial native PS (Superior, Emsland-Stärke, Emlichheim, Germany) was used as the basis for the modification. 27 AT samples were produced by systematic gradation of the process parameters hydrolysis temperature (30, 40, and 50 °C), acid concentration in the aqueous phase (0.3, 0.6, and 0.9 m HCl) and hydrolysis time (4, 10, and 20 h). The denotation of the modified sample (AT) is systematically applied, according to the hydrolysis temperature (e.g., 30 °C), the adjusted acid concentration (e.g., 0.3 m) and the reaction time (e.g., 4 h) in the form of, for example, AT-30-0.3-4. The Mw of the native potato starch and the corresponding AM fraction were 25.8 × 106 and 5.7 × 105 g mol−1, respectively
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