Effect of high-temperatures and aqueous ethanol treatment on the formation process and properties of V-type Granular Starch (VGS)

Effect of ethanol addition on the physicochemical, structural and in vitro digestive properties of Tartary buckwheat starch-quercetin/rutin complexes

The effects of ethanol on the physicochemical, structural and in vitro digestive properties of Tartary buckwheat starch-quercetin/rutin complexes (e-TBSQ and e-TBSR) were investigated. Ethanol restricted the gelatinization of Tartary buckwheat starch (TBS), which resulted an increase in ∆H, G' and G" as well as a decrease in apparent viscosity of e-TBSQ and e-TBSR. The particle size, scanning electron microscopy and X-ray diffraction results showed that ethanol influenced the morphological structure of TBS granules and the starch crystalline structure in e-TBSQ and e-TBSR changed from B-type to V-type when the ethanol concentration was 25%. Saturation transfer difference-nuclear magnetic resonance results revealed that ethanol weakened the binding ability of quercetin/rutin to TBS in e-TBSQ and e-TBSR, leading to a change in the binding site on the quercetin structural unit. The residual ungelatinized TBS granules in e-TBSQ and e-TBSR induced a high slowly digestible starch content, and thus displayed a "resistant-to-digestion".

V-type granular starches prepared by maize starches with different amylose contents: An investigation in structure, physicochemical properties and digestibility

V-type granular starches (VGSs) were prepared via an ethanol-alkaline (EA) method using maize starch with different amylose contents, specifically, high amylose (HAM), normal maize starch (MS), and waxy maize starch (WS). The X-ray diffraction pattern of the native starch was completely transformed into a V-type pattern after the EA treatment, indicating a structural change in the starch granules. The VGSs prepared by HAM had highest relative crystallinity (31.8°), while the VGSs prepared by WS showed amorphous diffraction pattern. Excessive NaOH, however, would disrupt the formation of V-type structures and cause granular shape rupture. The quantity of double-helical structures, particularly those formed by amylopectin at the starch granules' periphery, significantly decreased. Conversely, single-helical structures formed by amylose increased. A notable rise in the relative crystallinity of V crystals. Four VGS samples, characterized by granular integrity, were chosen for the next investigation of physicochemical and digestive properties. VGS prepared from HAM exhibited higher granular integrity, lower cold-water swelling extent (59.0 and 161.0 cP), improved thermal stability (the value of breakdown as lower as 57.67 and 186.67 cP), and higher resistance to digestion (RS content was up to 10.38 % and 9.00 % higher than 5.86 % and 5.66 % of VGS prepared from WS and MS). The results confirmed that amylose content has a substantial impact on the microstructural and physicochemical properties of VGSs.

Effects of frying on the surface oil absorption of wheat, potato, and pea starches

The effects of structural changes on surface oil absorption characteristics of wheat starch, pea starch and potato starch during frying under different water content (20%, 30%, 40%, 50%) were studied. Fried potato starch with a 40% water content exhibited the highest surface oil content. When the initial moisture content reached 30%, the scattering intensity of the crystal layer structure decreased for wheat and pea starches, while the scattering peak for potato starch completely disappeared. At 40% moisture content, the amorphous phase ratio values for fried potato, wheat and pea starches were 13.50%, 11.78% and 11.24%, respectively, and the nitrogen adsorption capacity of fried starch decreased in turn. These findings that the structure of potato starch was more susceptible to degradation compared to pea starch and wheat starch, resulting in higher surface oil absorbed by potato starch during frying process.

Effects of explosion puffing on the native structural organization and oil adsorption properties of starch

The effects of explosion puffing (EP) on the native structural organization (i.e., thermal properties, crystalline structure, short-range order, granule morphology and powder properties) and oil adsorption properties of puffed starch (PS) were investigated. The results showed that EP treatment could decrease the melting enthalpy of starch double helices and increase the V-type crystallinity. The highest V-type crystallinity (24.7 %) was obtained when the puffing pressure was 0.4 MPa and the starch:ethanol:water ratio was 1:2:1 (w/w). By controlling the puffing conditions, EP treatment can alter the morphology, and increase the particle size, flowability and specific surface area of PS. The high amorphous proportion and porous sheet structure of PS resulted in the highest oil adsorption capacity when the starch:ethanol:water ratio was 1:1:1 (w/w). Pearson correlation analysis showed that oil adsorption capacity was significantly and positively correlated with the 1022/995 cm-1 value and V-type crystallinity, but negatively correlated with bulk density and angle of repose. Furthermore, oil retention capacity was strongly dependent on V-type crystallinity. These findings demonstrated that EP is an innovative technology with the potential to enhance the V-type crystallinity and adsorption performance of starch.

Complexing curcumin and resveratrol in the starch crystalline network alters in vitro starch digestion: Towards developing healthy food materials

Starch is an abundant and common food ingredient capable of complexing with various bioactive compounds (BCs), including polyphenols. However, little information is available about using native starch network arrangement for the starch-BCs inclusion. Herein, two BCs, curcumin, and resveratrol, were undertaken to delineate the role of different starch crystalline types on their encapsulation efficiency. Four starches with different crystalline types, botanical sources, and amylose content were examined. The results suggest that B-type hexagonal packing is necessary to encapsulate curcumin and resveratrol successfully. The increase in XRD crystallinity while maintaining the FTIR band at 1048/1016 cm^-1 suggests that BCs are likely entrapped inside the starch granule than attaching to the granule surface. A significant change in starch digestion is seen only for the B-starch complexes. Embedding BCs in the starch network and controlling starch digestion could be a cost-effective and valuable approach to designing and developing novel starch-based functional food ingredients.

Fabrication of Charged Self-Assembling Patchy Particles Templated with Partially Gelatinized Starch

Starch, as a staple carbohydrate, is frequently used as a thickener to enhance food texture. As such, there is an increasing interest in studying starch modification to improve its thickening ability. Instead of the conventional mechanism of swelling-based thickening, the present work presents an alternative using starch-based patchy particles as a texturizer prepared through a bottom-up method by physically grafting small amaranth starch granules (∼1 μm) onto corn starch granules (>10 μm). After thermal treatment in aqueous ethanol, starches were partially gelatinized, and the particle stiffness was reduced. The corn starch and amaranth starch were modified to carry a negative charge and a positive charge, respectively. The hydrated swollen starch granules were centrifuged and dehydrated, which stitched particles together, forming a corona-shaped patchy structure with a negatively charged core and positively charged patches. The electrostatic interaction allowed particles to associate, and the pockets created in the flocs were able to trap more water. The enhanced water-holding capacity consequently contributed to a significantly higher storage modulus, loss modulus, and viscosity compared to the native starch and the mixed charged starch with the same blending ratio between amaranth and corn starch. The enhanced viscoelasticity was not affected by cooking and mechanical stress, which could be used as a shear-reversible thickener to modify texture with less raw ingredients, thus helping to reduce the amount of energy-dense starch in diets. This is the first time that the concept of patchy particles has been extended to food-grade ingredients with a facile and scalable method.

Structural transformation and oil absorption of starches with different crystal types during frying

The changes in the structure and oil absorption characteristics of three different crystalline starches under different initial moisture levels (20-50%) during frying were investigated. The granule morphology of potato starch was more severely disrupted during frying, especially under 40% moisture or higher. At 50% moisture, the crystallinity of potato starch decreased by 29.7% and the R₁ value decreased by 0.17. The effect of frying treatment on the structural properties of wheat starch and pea bean starch was less than that of potato starch. At 30% moisture, the ΔH values for wheat starch, potato starch, and pea bean starch were 7.8, 5.5, and 8.1 J/g respectively. The above results showed that B-type potato starch was more susceptible to the effects during frying than A-type wheat and C-type pea bean starch, which led to more oil absorption of B-type potato starch than A-type wheat or C-type pea bean starch.

Improving the cold water swelling properties of oat starch by subcritical ethanol-water treatment

The granular cold water swelling oat starch was prepared by subcritical ethanol-water, and the changes of properties and structure on oat starch were investigated. The oat starch was modified at the temperature of 95 °C and ethanol concentration of 48% and showed a higher cold water swelling ability of 22.58 g/g, whereas native oat starch was 6.73 g/g. Modified oat starch granule was kept intact, and it was swollen when dispersing in the water. The gelatinization enthalpy declined to 0 J/g. The surface of modified oat starch granules was honeycomb and porous observed by scanning electron microscope. The X-ray diffraction showed the A-type crystal decreased and the V-type crystal increased, and the result was quantitatively confirmed by solid-state ¹³C NMR spectroscopy. The ratio of 1047 cm^-1/1022 cm^-1 (determined by Fourier transform infrared spectroscopy) of modified oat starch was decreased. The molecular weight distribution of modified oat starch was slightly reduced, and the amylose content increased from 26.18% to 31.68%, and only a small amount of carbohydrates leached during the modification. Subcritical ethanol-water modification improved the cold water swelling ability of oat starch. The starch crystals changed from A-type to V-type provide a potential mechanism of subcritical ethanol-water modified oat starch.

Preparation of V-type cold water-swelling starch by ethanolic extrusion

Ethanolic extrusion was used to prepare V-type cold water-swelling starch (VCWSS). Effects of extrusion temperature, ratio of starch to ethanol, and ratio of starch to water on the properties of VCWSS were investigated. It was found that when the extrusion temperature was 100 °C, the ratio of starch to ethanol was 1:0.30, and the ratio of starch to water was 1:0.60, the resulting VCWSS could quickly swell into paste in cold water with the highest V-type relative crystallinity (12.90%) and cold paste viscosity (3058 cP). Then the formation mechanism of cold paste viscosity of VCWSS was evaluated. The cold paste viscosity of VCWSS was positively related to its V-type relative crystallinity. Extrusion destroyed the granular morphology of native starch, and VCWSS particles exhibited rock-like morphology that is much larger than the granules of native starch. Formation of the V-amylose-ethanol complex during extrusion was the direct cause of rapid hydration of VCWSS.