Modification of corn starch via innovative contactless thermal effect from induced electric field

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".

Effects of plasma-activated water combined with ultrasonic treatment of corn starch on structural, thermal, physicochemical, functional, and pasting properties

In this study, corn starch was used as the raw material, and modified starch was prepared using a method combining plasma-activated water and ultrasound treatment (PUL). This method was compared with treatments using plasma-activated water (PAW) and ultrasound (UL) alone. The structure, thermal, physicochemical, pasting, and functional properties of the native and treated starches were evaluated. The results indicated that PAW and UL treatments did not alter the shape of the starch granules but caused some surface damage. The PUL treatment increased the starch gelatinization temperature and enthalpy (from 11.22 J/g to 13.13 J/g), as well as its relative crystallinity (increased by 0.51 %), gel hardness (increased by 16.19 %) compared to untreated starch, without inducing a crystalline transition. The PUL treatment resulted in a whitening of the samples. The dual treatment enhanced the thermal stability of the starch paste, which can be attributed to the synergistic effect between PAW and ultrasound (PAW can modify the starch structure at a molecular level, while ultrasound can further disrupt the granule weak crystalline structures, leading to improved thermal properties). Furthermore, FTIR results suggested significant changes in the functional groups related to the water-binding capacity of starch, and the order of the double-helical structure was disrupted. The findings of this study suggest that PUL treatment is a promising new green modification technique for improving the starch structure and enhancing starch properties. However, further research is needed to tailor the approach based on the specific properties of the raw material.

Enhancement of the carboxymethylation of corn starch via induced electric field

This study aimed to enhance the synthesis of carboxymethyl starch (CMS) by induced electric field (IEF). Corn starch was alkalized, pumped into IEF system, and then reacted with monochloroacetic acid at excitation voltages of 0-400 V. IEF enhanced the carboxymethylation by accelerating the rate of OH- and ClCH2COO- attacking starch particles and slightly intensifying the thermal effect by ~7.1 °C (30 min). Compared with the control (0 V), IEF increased the degree of substitution and reaction efficiency by 0.056-0.148 and 9.37-24.56 %, caused more destruction in starch granular and crystal structure, and thus increased its water solubility, swelling power, and paste transparency. Furthermore, some new crystals were formed during IEF treatment, which enhanced the thermostability of CMS, showing an increase of the maximum decomposition temperature by 16-26 °C. Overall, the results classified that IEF could improve the carboxymethylation and enhance the thermostability of products, which provided guides for the applications of electro-techniques in starch modification involving charged species.

The effects of pulsed electric fields treatment on the structure and physicochemical properties of dialdehyde starch

The structural and physicochemical properties changes of corn starch oxidized by sodium periodate under the assistance of pulsed electric fields (PEF) were studied. It was found that dialdehyde starch (DAS) particles produced by PEF-assisted oxidation exhibited shrinkage and pits, and had a larger particle size when compared to the control without PEF. The solubility of the DAS (12 kV/cm PEF- assisted oxidation) improved by 70.2% when compared to the native starch. Increment in the strength of the PEF, led to a decrease in the viscosity of the DAS. In addition, the aldehyde group content of the DAS produced by PEF-assisted oxidation exhibited shrinkage and pits, and had a larger particle size when compared to the control increased by 11.6% when compared with the traditional oxidation method. PEF is an effective method to promote oxidation reaction of starch.

Pulsed electric field-assisted esterification improves the freeze-thaw stability of corn starch gel by changing its molecular structure

The influence of pulsed electric field (PEF) combined with octenyl succinic anhydride (OSA) on the freeze-thaw stability of corn starch gel was investigated. After five freeze-thaw cycles, the syneresis value of OSA starch treated with PEF-assisted esterification for 15 min was lower by 29.5 %, while that of OSA starch without PEF treatment was lower by 10.17 %, compared to that of native starch. Low-field nuclear magnetic resonance data showed that the introduction of OSA groups greatly increased the water-holding capacity of starch. Results from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) showed that the PEF-assisted esterification markedly hindered the re-formation of the helical structure of starch during freeze-thaw cycles. Moreover, PEF-assisted esterification improved the viscoelastic properties of the starch gel. It is found that the freeze-thaw stability of the PEF-modified starch depends not only on the degree of substitution but also on the starch molecular fine structure. PEF-assisted OSA starch with a high degree of substitution, a low content of amylose, and a high content of short amylopectin chains were found to have high freeze-thaw stability. This study shows that PEF-assisted esterification is a promising technique that should be used for preserving the quality of frozen foods.

The physiochemical and photodynamic inactivation properties of corn starch/erythrosine B composite film and its application on pork preservation

This study explored the effect of erythrosine B (EB) as a photosensitizer in corn starch (CS) film and its physicochemical properties and photodynamic bacteriostatic ability against Staphylococcus aureus, Escherichia coli, and Salmonella both in vitro and inoculated on pork under the irradiation of D65 light-emitting diode (LED) (400-800 nm). The study revealed that the physiochemical properties of CS films: moisture content, water solubility, and water vapor transmission were improved with the addition of EB. In addition, the elasticity and the thermal stability of the film were enhanced. The results showed that the CS-EB films stimulated a maximum of 26.36 μg/mL hydrogen peroxide and 74.5 μg/g hydroxyl radical under irradiation. The CS composite films with a 5 % concentration of EB inhibited the bacterial growth by 4.7 Log CFU/mL in vitro after 30 min of illumination, and 2.4 Log CFU/mL on the pork samples under the same experimental condition. Moreover, the antibacterial ability was enhanced with the increase in EB concentration. Overall, the CS-EB composite films can inhibit the growth of bacteria through photodynamic inactivation and has the potential to become a new type of environmentally friendly packaging material.

Application of multistage induced electric field for acid hydrolysis of starch in a continuous-flow reactor

Herein, a multistage induced electric field (IEF) combined with a continuous-flow reactor was utilized to assist the acid hydrolysis of corn, potato, and waxy corn starch for avoiding plate corrosion and heavy metal leakage. It was found that adding IEF stages was beneficial to improve the hydrolysis efficiency. Treating potato, corn, and waxy corn starch via continuous-flow IEF increased the reducing sugar contents up to 78.76 %, 57.86 %, and 66.18 %, respectively. The electrical conductivity of starch grew with the reaction stages, while starch yield demonstrated the opposite trend. Treated starch had higher solubility and gelatinization peak temperature than native starch, with the gelatinization enthalpy showing fluctuations. Meanwhile, the swelling power decreased as the number of IEF stages was increased. Observations of Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy indicated that the treated starch became more ordered, and crystalline regions were destroyed to various degrees with pores forming on particle surfaces. These variations could be attributed to acid hydrolysis and IEF.

Effect of annealing using plasma-activated water on the structure and properties of wheat flour

In this study, wheat flour (WF) was modified by annealing (ANN) using plasma-activated water (PAW) for the first time. Compared with WF and DW-WF, the results of scanning electron microscopy (SEM) and particle-size analysis showed that the granule structure of wheat starch in PAW-WF was slightly damaged, and the particle size of PAW-WF was significantly reduced. The results of X-ray diffraction and Fourier transforming infrared spectroscopy indicated that PAW-ANN could reduce the long-range and short-range order degrees of wheat starch and change the secondary structure of the protein in WF, in which the content of random coils and α-helices was significantly increased. In addition, the analysis of solubility, viscosity, and dynamic rheological properties showed that PAW-ANN improved the solubility and gel properties of WF and decreased its viscosity properties and short-term regeneration. PAW-ANN, as a green modification technology, has the potential for further application in WF modification, as well as in the production of flour products.

Influence of ultrasound and microwave treatments on the structural and thermal properties of normal maize starch and potato starch: A comparative study

The effects of ultrasound and microwave on the physicochemical properties of normal maize and potato starches were compared. The cavitation effect of ultrasound loosened the internal space and destroyed the structure of starch granules, increased the damaged starch content, which was consistent with the decrease in relative crystallinity and the number and brightness of Maltese crosses, and the increase in D(0.5) and D(4,3) values. Microwave vibrated the molecules inside the granules and generated heat to destroy the structure of starch. The content of damaged starch was significantly lower in microwave-treated starch compared with ultrasound-treated starch. Microwave treatment promoted the formation of amylose-lipid complex, with the larger peak area at 20°(2θ) than that of the ultrasound-treated starch. The type of starch and the treatment sequence showed a significant effect. The results might help understand the mechanism of ultrasound and microwave treatments influencing the structural properties of starches.