Starch hydrogels: The influence of the amylose content and gelatinization method

Xia

J Food Process Engineering

et al. 2019

The effect of extrusion treatments on oat gelatinization, microstructure, and macroproperties were important during twin‐screw extrusion. In this work, single factor and orthogonal experiments were conducted to evaluate gelatinization degree, expansion ratio, water solubility index, and water absorption index of oat powder before and after extrusion. Results indicated that the optimum gelatinization degree was 96.92% under the conditions of 18% moisture content, 155°C barrel temperature, and 150 rpm screw rotating speed. According to appearance by scanning electron micrograph, the extruded oat changed from the original tightly wrapped texture to spongy and porous form with lower gelatinization temperature (88.00°C) than those without extrusion (91.35°C). Rapid viscosity analysis showed that extruded oat became more stable and easier to gelatinization, which was consistent to the in vitro digestion experiment, suggesting extruded oat could be applied as ready‐to‐eat food in the further application. Practical applications The purpose of this research was aimed to optimize the extrusion and ripening process of oat powder, to explore the effect of curing method on the characteristics of oat powder, and to compare the physical and chemical properties of oat powder before and after extrusion. Eventually, the optimized process of oat powder using twin‐screw extrusion technology improved the structural characteristics of oat powder and enhanced the digestibility of the product.

Section: Methodsmentioning

confidence: 99%

“…The gelatinization degree was determined by a colorimetric method with iodine according to Brich and others (Biduski et al, 2018;Birch & Priestly, 1973).…”

Section: Gelatinization Degree。mentioning

confidence: 99%

Effect of twin‐screw extrusion on gelatinization characteristics of oat powder

Xia

J Food Process Engineering

et al. 2019

“…Hydrogels represent a group of materials, composed of three-dimensional crosslinked networks of hydrophilic/hydrophobic polymers, capable to absorb and retain a significant amount of water [1].…”

Section: Introductionmentioning

confidence: 99%

Potato Starch Hydrogels Produced by High Hydrostatic Pressure (HHP): A First Approach

2019

Starch-based hydrogels have received considerable interest due to their safe nature, biodegradability and biocompatibility. The aim of this study was to verify the possibility of producing natural hydrogels based on potato starch by high hydrostatic pressure (HHP), identifying suitable processing conditions allowing to obtain stable hydrogels, as well as to characterize structural and mechanical properties of these products. Sieved (small size granules and medium size granules) and unsieved potato starch samples were used to prepare aqueous suspensions of different concentrations (10–30% w/w) which were processed at 600 MPa for 15 min at different temperatures (25, 40 and 50 °C). Products obtained were characterized by different techniques (light and polarized microscopy, Fourier transform infrared spectroscopy (FTIR), rheology and differential scanning calorimetry (DSC)). Results obtained so far demonstrated that potato starch suspensions (20% starch–water concentration (w/w)) with granules mean size smaller than 25 µm treated at 600 MPa for 15 min and 50 °C showed a complete gelatinization and gel-like appearance. Potato HHP hydrogels were characterized by high viscosity, shear-thinning behavior and a highly structured profile (G’ >> G’’). Moreover, their FTIR spectra, similarly to FTIR profiles of thermal gels, presented three absorption bands in the characteristic starch-gel region (950–1200 cm−1), whose intensity increased with decreasing the particle size and increasing the processing temperature. In conclusion, potato starch hydrogels produced by HHP in well-defined processing conditions exhibited excellent mechanical properties, which can be tailored according to the requirements of the different applications envisaged.

“…Sucrose could reduce the water availability and act as an anti‐plasticizing agent requiring higher energy to gelatinization thus retarding this process . In addition, the starches with high amylose content, like those used in this research (28.9 ± 1.58% and 31.7 ± 2.09%, for CPS and APS, respectively, classified as “high amylose content”; Student‐ t test showed no significant differences between them [ t ( 4 ) = −1.79, P > 0.05]), had higher PT and FV than starches with low amylose content, probably due to greater hydrogen bonding interactions …”

Section: Resultsmentioning

confidence: 77%

Textural, Pasting, and Rheological Behavior of Starch‐Pectin‐Sucrose Gels: Relation with Sensory Perception

et al. 2019

The aims of this research are: (1) to analyze textural, pasting, and rheological characteristics of gels made with Andean potato starch (APS) compared with commercial potato starch (CPS); (2) to assess the sensory texture features; and (3) to relate instrumental behavior to human perception. Ten starch‐pectin‐sucrose systems are elaborated: five with CPS and five with APS (at 2.5–3.5–4.5–5.5–6.5% starch concentrations), and characterized by textural profile analysis (TPA), back extrusion test (BET), rapid‐visco analyzer (RVA), oscillatory tests, and sensory analysis. The systems have a weak gel behavior. The samples having the lowest concentrations of both starches are associated with springiness, while those with the highest concentrations are associated with sensory firmness, gumminess, chewiness, consistency, PV, and G′. From 5.5%, effect of starch type is more important on gels behavior. Spreadability is the variable mostly affected by starch type and concentration.