Search

The effect of an interchain entanglement on the enhancement of starch and hydrocolloid synergism and their changes in structural and functional properties was investigated. Potato starch (PS) and xanthan gum (XG) were taken as research materials, and critical melting at the onset melting temperature of starch combined with freeze-thawing (CMFT) was used to promote interchain entanglement of PS/XG. The work suggested that CMFT effectively stabilized the aqueous mixture system of PS/XG, showing no phase separation in the water phase system, even after 12 h of storage. The PS/XG composite prepared by CMFT had significantly improved stability against acid, salt, and shear stress during the thermal process DSC demonstrated that CMFT raised the T o of composite to ∼67 from 62.79 °C for native PS. RVA suggested that when pasted in distilled water, acid, and salt solution media, the breakdown viscosity of PS/XG composite declined to ∼380, 660, and 240 from 3615, 1541, and 1114 mPa s for native PS, respectively. CMFT significantly affected the apparent dropping properties of the starch paste, displaying a shorter and more cohesive paste drop against gravity. CMFT effectively improved the gelling properties of starch, with significant improvement in apparent surface adhesion properties and texture of gels, as well as freeze-thawing stability. [Display omitted] •Critical melting and freeze-thawing (CMFT) enhanced potato starch/xanthan gum (PS/XG) synergism. •Release of soluble starches by CMFT effectively promotes interchain entanglement with XG. •Partial melting of the ordered crystalline structure is beneficial to promoting PS/XG interaction. •CMFT significantly improved the pasting and gelling properties of starch. •CMFT effectively raised the thermal, acid, salt, and shear stability of starch paste. [ABSTRACT FROM AUTHOR]

Porous starch is one of the widely used multifunctional materials in food and pharmaceutical industries. This work was carried out to prepare porous starch by a novel clean-label method of critical melting (CM) and freeze-thawing (FT) treatment. Porous starch prepared by CMFT showed observable grooves and holes on the surface, channels and cavities inside the granule. Repeated FT after CM promoted the formation of porous structures, in which freezing rates showed different effects on the pore-forming properties of starch granules. Compared to the native counterpart, porous starch prepared by CMFT showed significantly increased thermal stability as shown by water solubility, swelling power, DSC, and RVA. CMFT treatment significantly increased water and oil absorption of porous starch from 85 to 75% (native) up to about 160 and 100%, respectively. Moreover, CMFT prepared porous starch showed the appearance of a visible diffraction peak at 20°, indicating a more ordered double-helical structure in starch granules. The synergistic effect of CM combined with FT could be used to prepare porous starch with "clean-label". [Display omitted] • Critical melting with freeze-thawing could be used for porous starch preparation. • The prepared porous starch has an increased thermostability. • Treatment significantly increased the water and oil absorption of porous starch. • Melting energy and ice crystals recrystallization are critical for porous structure formation. • Reassociation of leached soluble starches during treatment raised thermostability of starch. [ABSTRACT FROM AUTHOR]

An aqueous suspension of native potato starch (PS)/xanthan gum (XG) mixture was subjected to physical treatments, including critical melting (mild heating, MH; partial gelatinization, PG) and freeze-thawing (FT) treatments. The Physical treatments significantly changed the morphology, pasting, and structural characteristics of potato starch compared with the simple aqueous blending of PS and XG. Microscopy revealed that the starch granules partially melted and some of the melted granules aggregated into a cluster after critical melting and FT treatment. The overall intensity of X-ray diffraction peaks and relative crystallinity also decreased obviously after treatment, indicating partial disruption of the starch inner structure. Both XG addition and physical treatment decreased the solubility index, swelling power, and water holding capacity of starch after physical treatments. Moreover, the final viscosity (from 2988 to about 5000 mPa s) and shear stability (from 3542 to about 200 mPa s) of starch paste were substantially increased by the physical treatments. The critical melting caused the leaching of soluble starch, which induced the formation of starch/XG aggregate matrix attached to the surface of starch granules during FT treatment, contributing to the starch property modification. While the formation of these matrices might also be the reason for the increased thickness of the starch semi-crystalline lamellar structure. [Display omitted] • Critical melting and freeze-thawing treatments with xanthan gum (XG) effectively modified potato starch. • Treatments significantly changed the morphology, pasting and structural characteristics of starch. • Formation of soluble starch/XG matrix during treatments stabilized the starch granules against heating. • Treatments raised the final viscosity and shear stability of starch pastes. • Intensity of X-ray diffraction peaks and relative crystallinity decreased obviously after treatments. [ABSTRACT FROM AUTHOR]