•An induced-electric-field assisted extraction system was developed.•Efficient extraction of polysaccharides from mulberry leave was achieved.•The yield improved as the series number and excitation voltage increased.•A wider range of effects can be achieved by various arrangements of the reactors.A multi-series fluidic system based on the transformer concept was designed and built for the induced-electric-field-assisted extraction (IEFAE) of mulberry leaves polysaccharides (MLPs). Extraction was accelerated by exposing a secondary coil, made from a flowing mixture of sample grains and extractant, to a 20–80 kHz induced alternating electric field. The results indicate that this method benefits the release of polysaccharides without significantly affecting the quality of the products as evidenced by carbohydrate, protein, uronic acid, sulfuric radical and total polyphenol contents as well as average molecular weights and FT-IR. The polysaccharide yield improved as the excitation voltage increased, but the voltage frequency had a negative impact on the yield. At a solid-liquid ratio of 1:20 (g/mL), pH of 2.5, 60 °C temperature, 1000 V excitation voltage, and 20 kHz frequency, the 16-series system is performed optimally with a yield increased by 225.95% compared to the control (0 V). The relatively low environmental pH is conducive to extraction under the electric field, making the proposed system efficient for the extraction of valuable compounds without using metal electrode.

The properties and functionalities of chitosan are closely related to its degree of deacetylation (DD). This study aimed to determine the DD of chitosans, which were of identical molecular weight, by a proposed electro-analytical system based on inductive methodology. Statistically significant differences in electrical parameters, including terminal voltage (U′S) and λ (the ratio of primary voltage to U′S) were observed among chitosans with different DDs. Both U′S and λ were linearly correlated with the DD value, regardless of frequency, suggesting that these electrical parameters can be used to determine the DD of chitosan. More chitosan's coils contributed to higher measurement accuracy, but the change in measurement position showed no improvement. The highest linear coefficient of determination (0.9941) between DD and U′S was obtained by the experimental transformer with 100-turn chitosan's coils at a primary voltage of 10 V and a frequency of 400 Hz. This study explored the potential of an innovative electro-analytical system to determine the DD of chitosan.

•The electro-assisted acid hydrolysis of potato starch includes three steps.•IEF-HCl first attacks the external crystalline shell.•Next, the internal crystalline and amorphous regions are hydrolyzed simultaneously.•The remaining crystalline part is further fragmented into pieces.Compared to traditional heating methods by static immersion or stirring, induced electric field (IEF) treatment can significantly increase hydrolysis rate of potato starch. The aim of this study was to examine the characterization of acid hydrolysis of granular potato starch under IEF. Potato starch was hydrolyzed using 0.15 mol/L HCl combined with IEF (IEF-HCl) at an excitation voltage of 75 V from 4 h to 120 h. The changes in granular, crystal, and molecular structure of starch granules during IEF-HCl hydrolysis were investigated. Scanning electron microscope analysis showed the outer surface of potato starch was firstly attacked by free ions and then the inner structures was completely disrupted and broken into pieces. X-ray diffraction studies indicated that the crystallinity decreased from 38.92% to 34.9% after 4-h hydrolysis, and then gradually increased to 41.88% as hydrolysis time increased to 96 h, but decreased thereafter. The weight-average molecular weight dramatically decreased from 104.7 × 106 Da to 9.291 × 106 Da in the first 24 h and then decreased gradually. These results suggested that there were three steps in the catalytic process of IEF-HCl hydrolysis. Initially, hydrogen ions destroyed the external crystalline shell of granules. Next, hydrogen ions attacked the loose amorphous region and dense crystalline part within starch granules simultaneously. Finally, the remaining crystalline region was hydrolyzed slowly.Download high-res image (170KB)Download full-size image

•Freezing resulted in dissociation of amylose-lipids and proteins leaching for B-granules.•Freezing increased the gelatinization temperatures, enthalpy, and paste viscosities.•Bread made with frozen B-granules had a smaller specific volume and firmer crumb texture.•B-granules were more sensitive to the freezing/thawing treatment than A-granules were.The impact of freezing on the wheat starches with different particle size was studied using a range of characterization methods including X-ray diffraction, differential scanning calorimetry, the Rapid Visco Analyser and a reconstitution dough system. Wheat starches were fractionated into A- and B-type granules, and then subjected to freezing/thawing treatment for 3 cycles. The freezing treatment did not cause apparent damage on A-type granular surface but induced cracked structure on B-type granules. It facilitated materials such as amylose, proteins, and lipids leaching from starch granule and an increase in gelatinization temperatures, melting enthalpy, and pasting viscosities. A smaller bread specific volume was obtained from freezing-treated B-granules while the crumb firmness significantly increased (p > 0.05). No marked differences were observed in the counterparts of A-granules after freezing treatment. It seemed that the B-type granules were more sensitive to the freezing/thawing treatment, thus facilitating structural transformations from dough to bread. Results indicated that the deterioration in frozen bread quality derived from starch could be minimized by increasing the A-granules content.

•Lower depolymerization degree was detected in glutenin macropolymer enriched dough.•Frozen dough bread quality loss was alleviated with additional glutenin macropolymer.•Dough elasticity and gas retention capability were raised by glutenin macropolymer.•Glutenin macropolymer depolymerization played pivotal role in frozen dough quality.Depolymerization of glutenin macropolymers (GMP) widely exists in the frozen dough with little effort in elucidating its effects on steamed bread quality. To clarify this, GMP was fractionated from wheat flour and reconstituted to yeast and chemical leavened dough (YLD/CLD). Results showed that with supplementary GMP fraction, depolymerization degree was alleviated in frozen dough. The bread quality loss from freezing was partially counteracted along with better preserved GMP content. Both of dough elasticity and gas retention capability were enhanced in GMP-enriched frozen dough. Gassing power in frozen YLD decreased while remained constant in CLD. Addition of GMP did not affect the gassing power, which allowed interpreting the improved bread qualities from the enhanced dough elasticity and gas retention capability. Based on the improved facts of frozen steamed bread dough quality with additional GMP fractions, this study revealed the pivotal role of GMP depolymerization on the frozen steamed bread dough quality.

•Sodium dodecyl sulfate (SDS) removed the surface components from starch granules.•Freezing treatment after SDS washing was applied to claim the role of water absorption.•SDS + freezing starch featured rough surfaces and hollow structure with amylose leaching.•SDS + freezing treatment increased gelatinization parameters and pasting viscosities.•Bread made with SDS + freezing starch had lower specific volume and firmer crumb texture.The effect of freezing on functionality of native and sodium dodecyl sulfate (SDS)-treated wheat starches was investigated, with the aim of understanding the role of water absorption during freezing process. SDS is one of most efficient detergents to remove non-starch components (such as proteins and lipids) for starches but does not cause any apparent damage on granular structure. Slow swelling could be converted to rapid swelling by SDS washing, indicating higher water absorption. Freezing process induced slight roughness on starch granules but the non-starch components content was little affected. Combined SDS + freezing treatment significantly decreased both amylose and proteins non-starch components contents, which was accompanied with high gelatinization temperatures, melting enthalpy, and pasting viscosities. A smaller bread specific volume was obtained from SDS + freezing-treated starches while the crumb firmness significantly increased (p < 0.05). SDS mainly extracted the surface components from starch granules, leading to high water absorption and making granules sensitive to the freezing treatment.

•Potato starch was subjected to induced electric field treatment.•Changes of crystal structure, gelatinization and pasting properties were studied.•Structural change of modified starch significantly affected its properties.•Combination of induced electric field with heating could enhance these changes.The effects of induced electric field (IEF) on the crystal structure and physicochemical properties of potato starch were investigated by subjecting identically treated control and electrically-modified samples to the same temperature history. Additionally, a method of combining IEF with heating for efficient modification of native polymer was also proposed. Results showed that the application of IEF at an electric voltage of 75 V has a statistically significant effect on starch gelatinization and pasting properties, especially when combined with heating at 50 °C. After treatment by the combination method for 96 h, the gelatinization temperatures increased, which can be explained by the slight increase in the ratio of 1044/1015 cm−1 and relative crystallinity. Furthermore, IEF reduced granular swelling and therefore contributed to decreasing the peak, breakdown, and setback viscosity of potato starch. This study explores the potential of IEF as innovative technology for starch modification.

Using the mutual conversion between electric energy and magnetic energy, we designed and built an experimental device based on the o-core transformer structure for extraction of garlic polysaccharides. That is, an acidic solvent acted as the secondary coil conductor under the action of alternating magnetic flux and then induced an electric field in the biochemical medium (the sample and extractant) at 20–60 kHz. The polysaccharide yield improved, in comparison to the conventional heating method, when the excitation voltage applied on the primary coil was increased. Low pH helps to improve the polysaccharide yield due to the enhancement of the ionic conduction resulting from the induced electric field. However, the polysaccharide yield decreases with the increase of partial frequency due to the resulting decrease in the input power of the system. The orthogonal experiments showed that the excitation voltage, frequency, pH, and temperature all significantly affected the polysaccharide yield. The garlic polysaccharide extracted by using the induced electric field method had a DPPH radical scavenging ability and a ferric-reducing power. This novel system is a potential alternative for the extraction of garlic polysaccharides without the use of powered electrodes inserted into solutions, unlike other electric-field-assisted techniques.

•Gelatin hydrolysates were effective in protecting protein oxidation and in preventing lipid oxidation.•Gelatin hydrolysate inhibited the displacement of water molecules between the different compartments.•Gelatin hydrolysate could act as both antioxidant and cryoprotectant in unwashed fish mince.•Gelatin hydrolysate could serve as the functional ingredients to maintain the quality of seafood.Antioxidant and cryoprotective effects of Amur sturgeon skin gelatin hydrolysates prepared using different commercial proteases in unwashed fish mince were investigated. Gelatin hydrolysates prepared using either Alcalase or Flavourzyme, were effective in preventing lipid oxidation as evidenced by the lower thiobarbituric acid-reactive substances formation. Gelatin hydrolysates were able to retard protein oxidation as indicated by the retarded protein carbonyl formation and lower loss in sulfhydryl content. In the presence of gelatin hydrolysates, unwashed mince had higher transition temperature of myosin and higher enthalpy of myosin and actin as determined by differential scanning calorimetry. Based on low field proton nuclear magnetic resonance analysis, gelatin hydrolysates prevented the displacement of water molecules between the different compartments, thus stabilizing the water associated with myofibrils in unwashed mince induced by repeated freeze–thawing. Oligopeptides in gelatin hydrolysates more likely contributed to the cryoprotective effect. Thus, gelatin hydrolysate could act as both antioxidant and cryoprotectant in unwashed fish mince.

•The foaming volumes of gliadin solution decreased upon frozen storage.•The α-helix structure increased at the cost of β-sheet and unordered structure.•The surface hydrophobicity of gliadin solution decreased upon aging.•γ-Gliadin was the main contributor to weakened foaming properties.In this study, the effect of frozen storage on the foaming properties of wheat gliadin was investigated and further elucidated by evaluating its physicochemical changes. The foaming volumes of gliadin solution decreased while the foaming stability increased during the frozen storage. This was directly attributed to decreased gliadin content and increased foam density and protein concentration involved in the foams. A more rigid conformation was observed when the frozen storage time increased: the α-helix structure increased at the cost of β-sheet and unordered structure with the decreased surface hydrophobicity and increased surface tension of gliadin aqueous solutions. The percentage of γ-gliadin within gliadin foams gradually decreased, indicating that γ-gliadin was the most sensitive to freezing and the main contributor to the weakened foaming properties during the frozen storage. This study extended the knowledge of gliadin deterioration upon frozen storage and might contribute to the better understanding of frozen dough quality loss.

•Cycloamylose (CA) was prepared by combined treatment of isoamylase and TA 4αGTase.•The maximum yield of CA increased from 24.6% to 45.6% after debranching of amylomaize.•The minimum DP of CA produced by TA 4αGTase was 5 despite reaction conditions.•The larger CA molecules (DP > 22) were main constitutes after 24 h of reaction.Amylomaize (AMM) was utilized as the substrate for cycloamylose (CA) production in this study. After debranching, AMM was incubated with 10 U/g of Thermus aquaticus 4-α-glucanotransferase (TA 4αGTase) for various reaction times in water or in DMSO reaction system. The maximum conversion yield of CA was greatly improved from 24.55% to 45.58% and from 27.40% to 47.25% after debranching in the water and DMSO reaction systems, respectively. Compared with the method that produced CA from commercial potato amylose, this method produced CA from a natural amylopectin containing starch with enhanced conversion yield after debranching. Meanwhile, we found that the minimum degree of polymerization (DP) of CA from TA 4αGTase treatment was 5, regardless of the reaction conditions. These results were different from those reported in the literature that stated the minimum DP of CA produced with a TA 4αGTase treatment was 22 regardless of the reaction conditions.

•Peptide Pro–Ala–Gly–Tyr (PAGT) with molecular weight of 405.99 Da was isolated from Amur sturgeon skin gelatin hydrolysate.•Free radical quenching was the antioxidant mechanism of PAGT.•PAGT showed antioxidative and cryoprotective effects in minced fish model system.•PAGT could potentially be useful as a functional food ingredient.The peptide Pro–Ala–Gly–Tyr (PAGT) was isolated from Amur sturgeon skin gelatin and its antioxidant activity and cryoprotective effect in Japanese sea bass (Lateolabrax japonicus) mince was investigated. PAGT showed scavenging activity against DPPH, ABTS and hydroxyl radicals with no metal chelating activity. At a level of 25 ppm, PAGT prevented lipid oxidation in minced fish, but at higher levels it was ineffective. Low-field nuclear magnetic resonance (LF 1H NMR) detected three water pools in mince in the range of 1–10, 10–100 and 100–300 microsecond (ms), respectively. PAGT influenced water distribution in the mince. Mince with PAGT (25 ppm) had the highest T21 population, corresponding to a lower amount of water in T22 population after 6 freeze/thaw cycles (P < 0.05). Myosin and actin denaturation decreased in the presence of PAGT. Lipid oxidation in mince was impeded when PAGT was incorporated at 25 ppm as evidenced by the lower hydroperoxides from Fourier transform infrared (FTIR) spectra.

This study was performed to investigate the angiotensin I-converting enzyme (ACE) inhibitory activity of peptides derived from fertilized eggs and elucidate the inhibition mechanism of these peptides. During incubation, ACE inhibitory activity of the peptides remained stable before day 12 and then increased markedly on day 15. Two ACE inhibitory peptides, VGVIKAVDKKAGGAGKVT and HLFGPPGKKDPV, were purified from peptides on day 15 by consecutive chromatography. Because HLFGPPGKKDPV possessed a higher ACE inhibitory activity (IC50 = 125 μM), an antihypertensive effect of this peptide was further evaluated in vivo. The result showed that this peptide had an antihypertensive effect in spontaneously hypertensive rats (SHRs) at a dosage of 10 mg/kg. Furthermore, Lineweaver–Burk plots suggested that HLFGPPGKKDPV played as a non-competitive inhibitor against ACE, as supported by docking simulation. These data indicated that a fertilized egg has potential as antihypertensive components in functional foods and nutraceuticals.

β-Cyclodextrin–phenylethanoid glycosides inclusion complex was prepared and its releasing characteristic was investigated in this study. The results, obtained from Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, indicated that phenylethanoid glycosides (PG) were able to form an inclusion complex with β-cyclodextrin (β-CD). This complex exhibited different spectroscopic features, thermal stability and crystalline structure from PG. Molecular simulation results showed the benzene rings of PG incorporating into the hydrophobic cavity of β-CD during the complex formation. Furthermore, the releasing rate of the included PG in the inclusion complex was positively correlated with temperature and it was slightly higher in 0.5 % HCl solution than in water. These results suggested that the complexation technique using β-CD was a promising strategy for increasing the applications of PG in food and healthcare industries.

Food grade biopolymers, such as dextrin, have been suggested as a technological solution for the controlled delivery of health promoting substances. The main focus of this work is to improve the stability of poly-unsaturated fatty acids (PUFAs) and controlled release by encapsulating with helical spring dextrin (SD). The encapsulation was formed between SD with a DP¯ of 62 and α-linolenic acid (ALA) or linoleic acid (LA) at 60 °C and characterized by WXRD, DSC, TGA and SEM. Under conditions which simulated the human environment of the gastrointestinal system, 21.7% and 18.5% of SD–ALA and SD–LA were released, respectively. A molecular dynamics simulation indicated that the space of helix cavity for ALA–SD complex was larger than that for LA–SD complex. This research work supports the idea that these complexes not only can improve the stability of ALA and LA, but also can achieve the targeted delivery of functional lipids or other bioactive components to the small intestine.Highlights► Spring dextrin encapsulation complexes can improve the stability and controlled release of α-linolenic acid (or linoleic acid). ► Enzymatic digestion release is related to the degree of unsaturation of the fatty acid. ► Less linear polyunsaturated fatty acid requires a wider helix cavity. ► Van der Waals attraction is the primary driving force toward complexation.

Fertilized hen egg is traditionally considered as a dietary supplement in many Asian countries. This work aimed to obtain information on the effect of fertilization on total nutritional composition of egg contents and protein conformation. Chemical analysis showed that the lipid level in fertilized egg began to decrease after day 9. Fertilized egg before day 9 was higher in essential free amino acids (EFAA) and monounsaturated fatty acids (MUFA) contents but lower in cholesterol and polyunsaturated fatty acids (PUFA) than unfertilized counterparts. Fertilized egg proteins were characterized by an increase in hydrophobicity and a decrease in electrostatic interaction. Circular dichroism analysis showed that β-sheet decreased with increasing incubation time, whereas unordered structure increased. The findings observed in this work provide a crucial basis for understanding nutritional composition and protein conformation of fertilized egg, with the potential of being utilized as an EFAA/MUFA-rich, low-cholesterol dietary supplement.

In this study, spring dextrin (SD) has been noncovalently wrapped onto single-wall carbon nanotubes (SWNTs) to explain the number of glucose residues per turn larger than eight. Differential scanning calorimetry (DSC), FR-IR and Raman spectroscopy demonstrated that SD formed supramolecular complex with SWNTs. Furthermore, Atomic force microscope (AFM) micrograph indicated that SD wrap around SWNTs into helical superstructures. Finally, molecular dynamic simulation suggested that the space of helix cavity changed with different diameter of SWNTs, and SD wrapped around SWNTs (1 nm, 1.5 nm and 2 nm) were 11, 14 and 17 glucose units per turn, respectively.Graphical abstractHighlights► DSC, FR-IR and Raman spectroscopy demonstrating spring dextrin complexing with SWNTs. ► The number of glucose residues per turn (spring dextrin) larger than eight. ► Spring dextrin wrapped around SWNTs (1 nm, 1.5 nm and 2 nm) were 11, 14 and 17 glucose units per turn.

The effects of spring dextrin on amylose recrystallization were investigated by wide-angle X-ray diffraction (WXRD) and differential scanning calorimetry (DSC). Recrystallinity of amylose was reduced in terms of adding SD7, SD9, or SD11. Alternatively, SD3 or SD5 accelerated the degree of crystallinity. DSC data were analyzed using the Avrami equation and confirmed the results of WXRD. Finally, molecular dynamic simulation was adapted to predict the behavior of polymers in water, and the results showed that the small spring dextrins disturbed amylose retrogradation by inhibiting or altering amylose–amylose interaction.

In this study, the impact of the addition of β-cyclodextrin (β-CD) on bread staling was investigated by texture profile analysis (TPA), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). Results showed that the retardation effect of β-CD on bread staling was found to be significant as less changes of hardness, cohesiveness and springiness were observed during the storage. The addition of β-CD also significantly decreased recrystallization rate k, and increased Avrami exponent n, indicating that the nucleation type was transformed. Investigated by X-ray diffraction, changes of crystalline patterns occurring in crust and crumb were retarded by the development of A + V and B + V intermediate patterns for stored crust and stored crumb, respectively. This retardation was attributed to the amylose–lipid–β-CD complex formation observed and analyzed by DSC technique, resulting in nucleation type transformation and lowering the rate of bread staling.

Interaction forces that caused the formation of amylose recrystallite and led to the enthalpy change of the recrystallite were studied. Results obtained from differential scanning calorimetry (DSC) in combination with molecular simulation showed that the amylose recrystallite was formed and the volume of amylose fractions decreased as the short-term retrogradation occurred. This volume decrease indicated that a disordered conformation of amylose fractions was transformed to an ordered one. It was further confirmed that the formation of ordered configuration and the enthalpy change that occurred in DSC measurement for amylose recrystallite were related to a decrease in bonded interaction energy and an increase in Van der Waals attraction and hydrogen bonds formed.

•Effect of germination on physicochemical properties of brown rice flour was studied.•Effect of germination on physicochemical properties of isolated starch was studied.•Physicochemical properties of rice flour changed significantly during germination.•Only small changes of these properties could be found in isolated starch.•The mechanisms of changes and reasons for these different effects have been discussed.The present work was designed to obtain information on the effect of germination time on the selected physicochemical properties of brown rice flour and starch prepared from three different rice cultivars. Changes in total starch, amylose and amylopectin contents of flour, amylopectin/amylose ratio and molecular weight of starch, gelatinization, pasting, rheological, and morphological properties of flour and starch during 5 days of germination were investigated. Significant changes of pasting and rheological properties of brown rice flour were found during germination, but only small changes of these properties could be found in isolated starch. Scanning electron micrographs of flour showed that the continuous matrix structure of flour was highly destroyed after germination and scanning electron micrographs of isolated starch showed that after three days of germination, pits and holes were discovered on the surface of some starch granules. Germination had little effect on the average molecular weight of starch, but the polydispersity value in germinated brown rice (2–5 days germination) was higher than that in non-germinated brown rice. The changes observed in physicochemical properties of brown rice flour and starch after germination provided a crucial basis for understanding flour and starch modification mechanisms with potential applications for an industrial scale.

•An induced-electric-field assisted extraction system was developed.•Efficient and green aqueous extraction of seed oil from yellow horn the was achieved.•The oil yield was improved as the increase of series number and excitation voltage.•Widely extraction effect can be achieved by various connection mode.A novel and environmentally-friendly technique for the aqueous extraction of natural substances from sustainable resources is the use of induced electric fields. Based on this concept, a fluidic system was developed for the rapid extraction of seed oil from yellow horn under mild conditions (55 °C). The flowing sample solution at pH 4.5 acted as the secondary coil was exposed to the field at 20 kHz to accelerate the extraction. Results revealed that this method was beneficial to the release of oil without affecting oil quality. Positive factors affecting oil yield include the number of reactors connected in both series and parallel, as well as the excitation voltage. Increasing the number of reactors improved in the rate of extraction. Various series and parallel connection modes of the system significantly affected yield even when the input power was held constant. Maximum yield was observed only for the series mode. It has been concluded that the induced electric field-assisted extraction (IEFAE) developed in this study is an ideal technique for the extraction of seed oil because of its high efficiency, avoidance of metal electrode usage.Download high-res image (197KB)Download full-size image

Physicochemical properties of Acipenser schrenckii skin gelatin were determined as a function of acid pretreatment. Yield and gel strength of gelatin were decreased as the acid concentration and pretreatment time increased (P<0.05). FTIR spectra of all gelatins showed a significant loss of the triple-helix (Amide III/Amide 1450 wavenumber ratio less than 1) which indicated the conversion of collagen to soluble gelatin. Amide I absorption peak of gelatin obtained with higher acid concentration for longer soaking time appeared at higher wavenumber, compared to those obtained with lower acid concentration and time. All gelatins contained α-chains and β-chains as the predominant components. The hydroxyproline content, gelling and melting temperatures of gelatin were 6.1 g/100 g, 14 and 22 °C, respectively. The gelling and melting temperatures were intermediate between those of cold-water and warm-water fish gelatins, partly due to the differences in culture water temperature. The suitable acid concentration and pretreatment time were obtained as 0.05 M and 3 h, providing the good yield and gel strength.

•An efficient extraction system using varying magnetic flux was proposed.•The yield was improved by rotary magnet field combined with pipe fluid.•High Reynolds number is conducive to the increase of polysaccharide yield.•The yield increased and then declined with the increase of rotational frequency.Pumpkin polysaccharides are considered as functional materials with bioactivities. However, the conventional aqueous extraction method for pumpkin polysaccharides is limited by long time consumption, low efficiency and potential damage to their bioactivities. To improve the efficiency of pumpkin polysaccharides extraction, we designed a new experimental system combining a rotary magnetic field and flowing conductive solution. Polysaccharide extractions by 1) acidic sample solution with agitation, 2) flowing acidic sample solution, 3) static magnetic field combined with flowing acidic sample solution, and 4) rotary magnetic field combined with flowing acidic sample solution were conducted at pH level of 2–4, temperature of 30–50 °C, and treatment time of 0–180 min. The extraction by use of rotary magnetic field combined with flowing acidic sample solution resulted in the highest polysaccharide yield. Then, the effects of rotational frequency, Reynolds number, pH, and temperature on extraction yield were investigated. The yield increased at first and then decreased with an increase in rotational frequency. The high polysaccharide yield was achieved at large Reynolds number, high temperature, and low pH. From the ultraviolet, Fourier transform-infrared spectrum and chromatographic analysis, the extracts proved to be polysaccharides with an average molecular weight of 1.435 × 105 Da. The extracted pumpkin polysaccharides exhibited a dose-dependent radical-scavenging capacity within 0.1 to 5 mg/mL in the order of hydroxyl radical > DPPH radical > superoxide radical.Industrial relevanceRare report on the application of the combined magnetic field and pipe-fluid technique in extraction functional components from food materials. In this study, a novel experimental apparatus combining rotary magnetic field and spiral-pipe flow was designed to accelerate the extraction of pumpkin polysaccharides. In comparison with 1) agitation, 2) flowing acidic sample solution, and 3) static magnetic field combined with flowing acidic sample solution, the method combining rotating magnetic field and flowing acidic sample solution 4) significantly increased the polysaccharide yield. The increments were 40.18%, 32.14%, and 23.32%, respectively, after 180-min extraction. The pumpkin polysaccharides extracted by this novel method possessed a molecular weight of 1.435 × 105 Da and showed desirable antioxidant activities in vitro. Therefore, the combined magnetic field and pipe-fluid technique it is a potential method for efficient extraction of valuable compounds from food materials.

•A detecting system based on transformer method has been established.•Terminal voltage on the secondary circuit in which eggs act as coils could be measured sensitively.•Egg terminal voltage was positively correlated with conductivity, irrespectively of frequency.•Mathematical correlations between terminal voltage, λ-value and quality indices were observed.This study was aimed to establish a detecting system based on transformer method to evaluate moisture content and conductivity of egg albumen and yolks during storage. Results showed that the decrease in impedance of albumen and yolk resulted in the increase in the secondary terminal voltage during the eggs’ storage. Terminal voltage positively correlated with electric conductivity, regardless of frequency. The highest linear coefficient of determination (0.9955) between moisture content of yolk and terminal voltage at 50 Hz was observed. Exponential correlations emerged between the eggs’ conductivity and terminal voltage, with highest coefficient of determination (R2 = 0.8311 for albumen, R2 = 0.9772 for yolk) at 200 Hz and 400 Hz, respectively. The correlations obtained in frequencies ranging from 50 to 400 Hz at 10 V laid the foundation for a method of evaluating moisture content and conductivity in albumen and yolks. Results facilitate an alternative application of the technique for rapid evaluation of the quality indices of liquid food products.

•An impregnation system based on the electric transformer concept was built.•Electric fields induced by magnetic energy avoided the need of powered electrodes.•The higher the voltage frequency the smaller the Ca2+ content became in apple samples.•High overall operating costs resulted from the low power factor of this system.•The electric transformer concept inspired a novel process system.An experimental impregnation system based on the inductive methodology was established and used to investigate the effect of electric fields on the calcium content of fresh-cut apples. An induced electric field was generated when the Ca2+ solution acted as the secondary coil of the transformer system under the action of an alternating magnetic flux. The calcium content in fresh-cut apples was found to increase with the enhancement of the excitation voltage. Additionally, samples immersed in a CaCl2 solution exhibited a calcium content higher than those suspended in the calcium lactate solution. The latter presented a higher load power factor, the impedance in the CaCl2 solution being lower. Frequency at 20–60 kHz had a negative impact on the calcium content of fresh-cut apples due to the weakening of the electropermeabilization effect. This method utilized the conversion of electric energy into magnetic energy, and the electric field induced needing no insertion of powered electrodes into the solution under treatment. This might provide a reference for rapid impregnation of agricultural materials.

•Coixol and GABA contents of adlay flour significantly increased after germination.•Germination led to the protein hydrolysis and starch degradation.•Germination led to changes in pasting and thermal characteristics of adlay flour.•Changes in micrographs and FTIR peaks were observed during germination process.Adlay has garnered a great deal of research attentions in recent years as a highly nutritious food material and herbal medicine. This study characterized the changes of nutritional and physicochemical properties of adlay seeds during a 60-h germination. The results showed that the 60-h germination brought about a 3.4-fold increase in γ-aminobutyric acid (GABA) and 3.6-fold increase in coixol compared to ungerminated adlay seeds, while the triolein content slightly decreased. Some high molecular proteins were hydrolyzed into smaller proteins, peptides and amino acids after germination. Scanning electron micrographs (SEM) showed that the germination process destroyed the continuous matrix structure of adlay flour and created pits and holes on the surface of some starch granules. Germination resulted to changes in the pasting and gelatinization properties of adlay flour. The results of present study suggest that germination efficiently enhances the nutritional compounds while altering the physicochemical characteristics of adlay seeds.

•IEF accelerates the acid hydrolysis of potato starch.•Elevated electric conductivity in the sample improves IEF system efficiency.•IEF-HCl hydrolysis destructs the semi-crystal and granular structure of starch.•IEF-HCl hydrolysis decreases the swelling power and pasting viscosity of starch.The induced electric field assisted hydrochloric acid (IEF-HCl) hydrolysis of potato starch was investigated in a fluidic system. The impact of various reaction parameters on the hydrolysis rate, including reactor number (1–4), salt type (KCl, MgCl2, FeCl3), salt concentration (3–12%), temperature (40–55 °C), and hydrolysis time (0–60 h), were comprehensively assessed. Under optimal conditions, the maximum reducing sugar content in the hydrolysates was 10.59 g/L. X-ray diffraction suggested that the crystallinity of IEF-HCl-modified starches increased with the intensification of hydrolysis but was lower than that of native starch. Scanning electron microscopy indicated that the surface and interior regions of starch granules were disrupted by the hydrolysis. The solubility of IEF-HCl-modified starches increased compared to native starch while their swelling power decreased, contributing to a decline in paste viscosity. These results suggest that IEF is a notable potential electrotechnology to conventional hydrolysis under mild conditions without any electrode touching the subject.

•Dough under frozen storage and freeze/thaw showed different degradation kinetics.•Dough weight loss contributed most to reduced bread loaf volume under frozen storage.•GMP depolymerization dominated in degraded bread loaf volume under freeze/thaw.Successive freeze/thaw (FT) cycle was a widely used empirical approach to shorten the experimental period since it could accelerate frozen dough deterioration compared with frozen storage (FS). In order to compare the effect of FS and FT cycle on deterioration procedure of chemical-leavened steamed bread dough, kinetic studies of bread quality indices were performed and the relationships between bread quality and dough components were further established. Results showed that degradation of steamed bread loaf volume and firmness followed first-order kinetics during FS and zero-order kinetics during FT, respectively. Glutenin macropolymers (GMP) depolymerization and dough weight loss occurred steadily throughout FS and FT. Significant enhancement of damaged starch and crystallinity were observed at the later FS period and FT cycle. Multiple regression study led to the conclusion that dough weight loss contributed the most to the reduced bread loaf volume under FS whereas GMP depolymerization dominated under FT condition.

•Chemical leavened dough showed higher freeze stability in steamed bread quality.•Gassing power of frozen yeast leavened dough decreased due to yeast viability loss.•Frozen chemical leavened dough showed stable gassing power and faster release rate.•Gluten depolymerization and secondary structure conversion indicated its degradation.•Chemical leavener was conducive to the more freeze-tolerant gluten network.The present study comparatively evaluated the evolution of yeast and chemical leavened steamed bread dough (YLD/CLD) quality during freeze/thaw (FT) cycles. The steamed bread quality of CLD was more freeze-stable than that of the YLD after 3 FT cycles. Decreased yeast viability contributed to the loss of gassing power in YLD while no significant differences were observed for CLD during FT cycles. However, faster gas release rate in frozen CLD indicated gas retention loss due to the distortion of gluten network. Glutenin macropolymers (GMP) depolymerization via breakage of inter-chain disulfide (SS) bonds and conversions of α-helix and β-turn to β-sheet structures were the main indicators of gluten deterioration. Gluten network was more vulnerable in frozen YLD, resulting in detectable loss of viscoelasticity. The results suggested that supplement of chemical leavener contributed to a more freeze-tolerant gluten network besides its stable gassing power.