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There are few studies applying pulsed electric field (PEF) on solid foods in databases. Egg white protein (EWP) was subjected to PEF for elucidating mechanism of changes in molecular structure of enzymes and protein components for solid foods. Determination of free and total sulfhydryl groups, ultraviolet (UV) spectroscopy, infrared (IR) spectroscopy, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to compare EWP before and after PEF treatment. The results showed that the amount of free sulfhydryl increased while that of total sulfhydryl decreased after PEF exertion. PEF did not change the SDS-PAGE patterns visibly and no shift in maximum absorption wavelength but intensity could be observed in UV spectra of EWP. IR spectra of EWP were subjected to Gaussian multi-component peak modeling for molecular secondary structure analyses. Either the voltage of the PEF ( P < 0.01) or the residence time of the sample ( P < 0.05) significantly decreased the relative portion of α-helices while increased that of β-sheets in EWP, and impact could also be seen in respect of contents of β-turns and random coils in amide I region of EWP and its fractions. The results are of reference values to potential applications of PEF on solid foods. [ABSTRACT FROM AUTHOR]

Barley is a cereal to seek for higher value added. Its β-glucan has been paid much attention as a soluble dietary fiber. Barley polysaccharide (BP) of a cultivar for brewing was extracted by ultrasonic assistance and derived by using a relatively lower toxic esterifying agent-sulfamic acid to obtain sulfated barley polysaccharides (SBPs) with various degrees of substitution (DS). Comparisons were made amongst SBPs and BP in antioxidant abilities in vitro with total reducing power, scavenging effect on DPPH , hydroxyl radicals, superoxide anion radicals and lipid antioxidation and inhibition against α-glucosidase. The results showed that antioxidant activity of BP was significantly enhanced by sulfation modification. The activities increased with the concentration and DS. Kinetic analyses revealed that the inhibitory effects of SBPs and BP on α-glucosidase were reversible and SBPs exhibited a mixed type of inhibition while BP was a noncompetitively inhibitory process. The present work reflected that BP could be a potential raw material for the development of antiglycemic pharmaceuticals. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) was applied to moisture-preconditioned canola seeds to evaluate the effect on oil yield. The effect of PEF on functional and structural properties of canola protein left over after oil extraction were also examined in albumin and globulin fractions obtained at optimal conditions for oil yield. Generally, PEF pretreatment significantly improved (P < 0.01) the following functional properties of canola protein and its fractions: solubility, water-holding capacity, emulsibility, emulsion stability, oil-holding capacity, foamability, and foam stability. Infrared spectrometry revealed that the secondary structure of the protein changed upon PEF, as shown by changes in the proportions of α-helices, β-sheets, and β-turns in the amide I region. An increased amount of free sulfhydryl groups and surface hydrophobicity suggested alterations in tertiary structure as well. PEF caused the formation of new protein aggregates with low molecular mass, demonstrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and changes in the number of total sulfhydryl groups. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) is promising in food industry in modifying properties of materials. The influences of PEF pretreatment on hydrolysis, texture, multi-scale and semi-crystalline lamellar structure, thermal properties, and flavor of rice were investigated with two special treatments for high and low contents of slowly digestible starch and resistant starch, using enzymatic hydrolysis, scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry, small angle X-ray scattering, attenuated total-reflection Fourier-transform infrared spectrometry, texture profile analysis, and gas chromatography-mass spectrometry (MS)-MS. Upon PEF pretreatment, the starch hydrolysis degree and glycemic index of cooked rice increased slightly; the hardness, springiness, cohesiveness and chewiness of cooked rice increased significantly (P < 0.05). PEF reduced the integrity of cell structure, altered the gelatinization enthalpy, relative crystallinity degree, semi-crystalline layered structure of rice lightly, without obviously changing the diffractive pattern type of rice grains. PEF pretreatment caused decrease of phenols and ketones and increase of acids and aldehydes in cooked rice. • Pulsed electric field (PEF) significantly affected texture of cooked rice. • PEF significantly enhanced starch hydrolysis and increased glycemic index of cooked rice. • PEF significantly changed composition of volatile compounds of rice. [ABSTRACT FROM AUTHOR]

Critical melting pretreatment for granular swelling and soluble starch release was performed before freeze-thawing (FT) to enhance the effect of FT treatment on structure modification of potato starch. The critical melting temperature applied was based on the onset melting temperature (T o) of the native potato starch. After pretreatment, the effect of multiple FT cycles on the morphology, structure, and functionality was investigated. The pretreatment effectively induced granular swelling and partial disruption of the crystalline structure by increasing the volume of water molecules inside the granules. The pasting pattern changed obviously after treatments with the significantly increased final viscosity (up to 5000 from 2900 mPa s) and decreased breakdown (1/5th of native starch). Soluble starch released due to the both critical melting and FT treatments had a strong tendency to reassociate outside the granules, which effectively raised the thermal stability of starch granules. Moreover, increased water (∼109–∼164%) and oil (∼56–∼64%) absorption of starch at room temperature were observed. The synergistic effect of the combination of critical melting pretreatment and mechanical force of ice crystals effectively modified the properties of potato starch, suggesting a useful clean-label method for starch modification. [Display omitted] • Pretreatment enhanced modification effect of freeze-thawing on potato starch (PS). • Critical melting pretreatment applied is based on onset melting temperature of PS. • The combined treatment changed the morphology, structure, and functionality of PS. • Thermal stability of PS granules raised significantly after the combined treatment. • Partial disruption of chain arrangement and soluble starch release plays a key role. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) was efficient in inactivating lipase in wheat grains. To understand the modification in wheat components, the functional, rheological, and structural properties of vital wheat gluten (VWG) were evaluated after PEF treatment. The results showed that the PEF parameters, electric field intensity (EFI), pulse frequency, pulse width, and material residence time significantly (P < 0.01) affected the solubility, water-holding capacity, oil-holding capacity, foaming capacity, foam stability, and emulsion stability to different extents. The transition temperature and denaturation enthalpy of gluten protein decreased significantly (P < 0.01). The elastic modulus, viscous modulus, tanδ of the wet gluten protein, and the apparent viscosity of VWG changed slightly; however, they changed significantly (P < 0.05) with the increase in EFI. Larger EFIs resulted in a more homogeneously condensed and evenly distributed wet gluten pore. The proportion of α-helices and β-sheets had decreased and increased with the increase in EFI, respectively, while the proportion of random coils changed insignificantly (P > 0.05). The amount of free and total sulfhydryl increased and decreased significantly (P < 0.01) with an increase in EFI, respectively. Surface hydrophobicity was significantly reduced (P < 0.01). • Pulsed electric field (PEF) was applied to dry wheat gluten powder. • Functional, rheological and structural properties were investigated. • PEF showed significant actions on gluten protein properties to different extent. [ABSTRACT FROM AUTHOR]

Rice accounts for more than half the global population as staple food with starch predominating the major component. The effect of pulsed electric field (PEF) on thermal, paste and digestible properties, morphology, and hierarchical structure of rice starch in solid state was investigated. Upon PEF treatment, the gelatinization enthalpy (Δ Η) of starch decreased, the retrogradation value of starch paste decreased slightly; and the rapid digestible starch (RDS) increased, the slowly digestible starch (SDS) decreased and the resistant starch (RS) changed slightly. PEF might act on the outer structure of starch granules, slightly changed the molecular structure of rice starch by rearranging the short-range structure and damaging the amorphous and crystalline structure. Pearson correlation analysis suggested that molecular weight of amylopectin, Δ Η and digestibility were strongly dependent on the electric field strength; the changes in multi-scale structure was closely related to those in properties of PEF. The improvement of digestibility of rice starch might be attributed to the disruption of starch granule surface as evidenced by SEM observation and the rearrangement of multi-scale structures of rice starch induced by PEF. • PEF can modulate the properties and multi-scale structures of rice starch. • M w of amylopectin, ΔΗ and digestibility changes depending on the EFI input. • The digestibility improvement attributes to rearrangement of starch structures. [ABSTRACT FROM AUTHOR]