Impact of Process Parameters on the Acid Modification of Potato Starch

Abstract

The acid‐modification of a regular potato starch (PS) using the slurry process is systematically investigated. The hydrolysis parameters temperature (30, 40, and 50 °C), acid concentration (0.3, 0.6, and 0.9 M HCl), and reaction time (4, 10, and 20 h) are graded, and characteristics regarding the modification process as well as the resulting acid‐thinned samples are analyzed based on size exclusion chromatography‐multi angle laser light scattering‐differential refractive index detection (SEC‐MALS‐DRI) experiments. The data are examined statistically. Significant impacts on the amount and the molecular composition of solubilized starch polymers are identified. Increasing parameter values increased the carbohydrate solubilization and concurrently decreased the weight average molar mass (Mw) of the dissolved starch. Moreover, the Mw of the resulting acid‐thinned starch samples as well as the corresponding amylose fraction (AM) decreased incrementally with enhanced temperature, acid concentration, and hydrolysis time, respectively. The results indicated the simultaneous molecular degradation of both AM and amylopectin (AP) during the acid modification in slurry. The potential for preparing almost identical acid‐thinned samples by applying combinations of different parameter specificities is shown.

Functional Properties of Acid‐Thinned Potato Starch: Impact of Modification, Molecular Starch Characteristics, and Solution Preparation

“…Anyway, according to the ANOVA (Table ), all investigated factors (hydrolysis process parameters and paste preparation temperature) were identified to be statistically significant to the hot paste viscosity determined at low (0.95 s −1 ) medium (4.265 s −1 ) and high (85.88 s −1 ) shear rates. Hence, the paste viscosity depends mainly on the molecular composition of the starch sample, which was proven to be controllable by both the modification process and the paste preparation procedure.…”

“…The acid modification was performed in an aqueous suspension (40% w/w) under continuous stirring (400 min −1 ) according to the description elsewhere using HCl as acid. The reaction was stopped by addition of NaOH.…”

“…The molecular properties ( M w starch and M w AM fraction; analysis by means of SEC‐MALS‐DRI) and the dry matter contents (DM) of the starch samples (acid hydrolyzed and native) were determined in a previous study by Ulbrich and Flöter and are summarized in Table . The M w of the native potato starch and the corresponding AM fraction were 25.8 × 10 6 and 5.7 × 10 5 g mol −1 , respectively.…”

“…Since the hydrolysis occurs within the amorphous regions of the semicrystalline granule structure, the acid‐induced cleavage of the starch polymers can be basically considered as effectively specific with the predominantly molecular degradation of the amylopectin (AP). However, a recent study proved the basically collaborative degradation of both starch polysaccharide fractions, the largely unbranched amylose (AM) and the highly branched AP . Anyway, quasi‐specifically modified AT starches (e.g., with the desired degree of degradation; specific M w range) may possess excellent technofunctional properties making them suitable and interesting for industrial application.…”

“…For the purpose of investigating the modification process – molecular starch structure relationship, corresponding potato starch based AT samples were prepared in slurry by triple gradation of the hydrolysis temperature, the acid concentration, and the hydrolysis time and comprehensively molecularly characterized ( M w starch and M w AM fraction; size exclusion chromatography‐multi angle laser light scattering‐differential refractive index detection (SEC‐MALS‐DRI) experiments) as reported in a previous study . The present study is focused on particularly examining the relationship between the molecular properties of the AT starches, the solution state or the disintegration conditions, respectively, and several technofunctional properties like hot solution viscosity, mechanical gel strength and T of the system.…”