Effects of removal of surface proteins on physicochemical and structural properties of A- and B-starch isolated from normal and waxy wheat.

The effects of protein removal on the physicochemical and structural properties of normal and waxy wheat and their A- and B-type granule fractions were investigated. No evident changes were observed in the morphological, birefringence pattern and X-ray diffraction pattern after treatment, but there was evidence showing that the relative crystallinity, swelling power and percentage syneresis of all samples were significant increased. Protein removal treatment increased the peak, setback, final viscosity, breakdown viscosity of normal and waxy native wheat starch, and their A- and B-type starch granule fractions, whereas it decreased the pasting temperature, peak time and trough viscosity. Meanwhile, the thermal transition temperatures (To, Tp, Tc) and gelatinization temperature range (ΔTr) of normal and waxy wheat and their isolated A- and B-type granules were increased, but the enthalpy decrease slightly. The different genetic factors and amylose content in normal and waxy wheat starch and their A- and B-type wheat starch granules fractions were related to the different physicochemical and structural characteristics of those starches.

An ultrasensitive electrochemical sensor based on NiFe-LDH-MXene and ruthenium nanoparticles composite for detection of nitrofurantoin in food samples.

The excessive use of nitrofurantoin (NFT) represents a threat to ecosystems and food safety, making it necessary to develop efficient and accurate detection methods. Herein, the Ru/NiFe-LDH-MXene/SPCE electrode was successfully synthesized by one-step electrodeposition and employed to the NFT electrochemical sensing. Combining 2D MXenes with multifunctional 2D layered double hydroxides (LDHs) creates synergistic interactions within the MXene-LDH heterostructures, modifying the electrochemical performance. Furthermore, the incorporation of noble metal nanoparticles and nanoclusters can significantly enhance electrochemical performance by promoting favorable interactions at the metal-carrier interface and optimizing the rearrangement of electronic structure. Based on this, the developed Ru/NiFe-LDH-MXene/SPCE sensor demonstrates remarkable sensitivity (152.44 µA µM-1 cm-2) and an ultralow detection limit (2.2 nM). Notably, the sensor was employed for NFT detection in food samples with satisfactory recoveries, making it a promising electrochemical sensor for the detection of NFT.

Effects of Wheat Tempering with Slightly Acidic Electrolyzed Water on the Microbiota and Flour Characteristics.

Slightly acidic electrolyzed water (SAEW) was prepared and used as wheat tempering water. This study explored the impacts of tempering with SAEW on microbial load and diversity and quality properties of wheat flour. As SAEW volume ratio increased, the residual level of total plate counts (TPC) and mould/yeast counts (MYC) decreased dramatically (p < 0.05). Based on genomics analysis, bacterial 16S rRNA gene and fungal ITS1 gene region were performed to characterize the changes in microbial communities' composition and diversity in response to SAEW treatment. SAEW optimal volume ratio (6.5:10, v/v) of SAEW with distilled water influenced wheat microbiome composition, with a higher microbial diversity and abundance discovered on the control grains. Bacteroidetes of predominant bacterial phylum and Ascomycota of the most abundant fungal phylum were reduced after SAEW optimal volume ratio tempering. The flour yield is higher and ash content is lower than the control samples. Falling number and "b*" in terms of colour markedly increased. DSC (Differential Scanning Calorimetry) test showed that To (onset temperature), Tp (peak temperature), and Tc (conclusion temperature) were significantly decreased in thermal characteristics of flour. Gluten content, protein content, ΔH and pasting properties tests showed no significant change. It can be concluded that SAEW should be applied on wheat tempering for producing clean wheat flour. ANOVA and Tukey's honestly significant difference (HSD) test were used for the analysis of variance and differences between the experimental and control groups, with p < 0.05.

Effect of radio frequency treatment on functional, structural and thermal behaviors of protein isolates in rice bran.

To investigate the influence of radio frequency (RF) stabilization treatment on rice bran protein isolate (RBPI) properties, functional, structural and thermal behaviors of RBPI obtained from RF treated RB were evaluated under various temperatures between 80 and 120 °C holding for 5 min. The results showed that RF heating had negative impact on the yield, purity, foaming properties and solubility of RBPI when the treatment temperature was higher than 100 °C, while the absorption and emulsifying properties were improved. No significant changes were observed in primary structure of RF treated samples, but the second structure changed with an increase in random coil and a decrease in ß-sheet, α-helix and ß-turn. The decreased tryptophan fluorescence and increased surface hydrophobicity suggested alterations in tertiary structure. RF treatment also caused noticeable decrease in denaturation temperature and enthalpy of RBPI. The results would provide basic information for food applications of proteins isolated from RF stabilized RB.

Repeated heat-moisture treatment exhibits superiorities in modification of structural, physicochemical and digestibility properties of red adzuki bean starch compared to continuous heat-moisture way.

The effects of repeated heat-moisture treatment (RHMT) and continuous heat-moisture treatment (CHMT) on structural, physicochemical and digestibility properties of red adzuki bean starch have been investigated and compared. The results showed that the starch granules had many rupture and scallops and some of the polarization cross disappeared after CHMT and RHMT. The crystal type of CHMT and RHMT starches changed from C-type to A-type. The pasting temperatures and gelatinization transition temperatures of CHMT and RHMT starches increased, while the pasting viscosities (peak, trough, breakdown, final and setback viscosity), solubility and swelling power of CHMT and RHMT starches decreased compare to native starch. The RDS and SDS contents of starch samples were higher than native starch, which indicate that the digestibility was improved by CHMT and RHMT. On the whole, the RHMT measures have more advantages in the changes of starch structural, physicochemical and digestibility properties compared to CHMT ones.

Recrystallization characteristics of high hydrostatic pressure gelatinized normal and waxy corn starch.

High hydrostatic pressure (HHP) can lead to starch gelatinization at room temperature, while the retrogradation mechanism of HHP gelatinized starch is not well known. HHP gelatinized normal and waxy corn starches were stored at room temperature for 192 h in order to investigate the retrogradation characteristics. The scanning electron microscopy (SEM), polarised light microscopy and differential scanning calorimetric (DSC) analysis showed that the pressurization of normal and waxy corn starch suspensions with concentration of 30% (w/v) at 600 MPa for 15 min resulted in a complete gelatinization. In addition, the pressure-gelatinized normal and waxy corn starch gels were stored and subjected to X-ray diffraction (XRD) analysis, resistant starch content determination, swelling power and pasting behavior. The retrograded normal maize and waxy maize starch showed a substantial loss of A-type crystallinity. Both pressure-gelatinized normal and waxy corn starches showed an increase in resistant starch content and relative crystallinity degree with the increase of storage time. In addition, restricted starch swelling power and lower pasting viscosities were observed for these two retrograded starches. The amylose molecule within starch granules has been regarded as the main factor to affect the structural and physicochemical properties during the retrogradation process of HHP-gelatinized starch granules.

Physicochemical characteristics of high pressure gelatinized mung bean starch during recrystallization.

The changes in physicochemical and structural properties of Ultra high pressure (UHP) gelatinized mung bean starch were investigated during 0 to 196h retrogradation process by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). XRD analysis showed that the UHP-gelatinizated granules regenerated its original C-type crystallinity structures after retrogradation. The swelling power and solubility of native starch were increased with the increase in the assay temperatures from 50 to 90°C, while the changing trend of the retrogradated granules was more gradual over entire assay temperatures. In addition, retrogradated granules showed a progressive decrease in the light transmittance and an increase in the amount of resistant starch as the ageing time increased from 0 to 192h. DSC analysis suggested a slight increase in the transition temperatures (To, Tp and Tc) and the retrogradation enthalpy as the storage time increased. In contrast no endothermic transition peak could be observed using DSC after storage of heat-gelatinized mung bean starch gel.

Effect of nitrogen and sulfur fertilization on accumulation characteristics and physicochemical properties of A- and B-wheat starch.

The effects of nitrogen (N) fertilization at the rates of 0 and 230 kg hm(-2) combined with selected sulfur (S) fertilization rates of 0, 46, 56, 77, and 115 kg hm(-2) on A- and B-wheat starch granule accumulation, composition, and thermal and pasting properties were investigated. Scanning electron micrographs revealed that A- and B-starch granules accumulation during grain filling can be influenced significantly by N and S fertilization, and B-granules tend to be more sensitive to S fertilization than A-starch granules. The doses of nitrogen and sulfur fertilization on starch properties were not positively correlated; higher concentration of fertilizers failed to cause a higher effects. N230S46 and N230S56 treatment resulted in the higher peak viscosity, trough viscosity, breakdown viscosity, final and setback viscosity, and gelatinization temperature (To, Tp, Tc) according to differential scanning calorimeter (DSC) and rapid visco analyzer (RVA), respectively.

Physicochemical properties of A- and B-starch granules isolated from hard red and soft red winter wheat.

Large A- and small B-starch granules separated from hard red and soft red winter wheat grains were investigated for their morphological, structural, and physicochemical properties. A-granules displayed a disk or lenticular shape, and B-granules showed a spherical or polygonal shape according to SEM. XRD analysis showed that both A- and B-granules had A-type crystallinity. A-granules contained a higher amount of amylose and a lower protein content and amylopectin/amylose ratio than B-granules. A-type granules exhibited a higher hydrolysis extent and swelling power and a lower iodine affinity than did B-granules. A-granules showed a higher peak, trough, breakdown and final viscosity, and gelatinization enthalpy than did B-granules, while B-granules exhibited a higher gelatinization temperature. The study demonstrated that the A- and B-granules separated from both hard red and soft red winter wheat grains exhibited a similar structure and very different physicochemical properties.

Studies on the amino acid and mineral content of buckwheat protein fractions.

Protein fractions were extracted by successive extraction and analysis method in four buckwheat varieties including Japanese spring buckwheat, Japanese summer buckwheat, Yuqiao No. 1 and Yuqiao 6-21. The amino acid and the mineral content of each protein fraction were also analyzed in this paper. The basis for the data on the experiment was the relationship between protein fractions and amino acids, and the mineral contents of protein fractions. The distribution and proportion of amino acids and the minerals in each protein fraction in the buckwheat kernel as well as the nutritional value of buckwheat kernel were discussed. The results showed that there is a high amount of soluble protein and very low amount of prolamin in the buckwheat kernel. Leucine is the first limited amino acid in buckwheat, and buckwheat protein is only a seminutritional protein. The buckwheat kernel is rich in K, Zn in the albumin, Ca, Mg and Mn in the globulin, Na in the prolamin and glutelin.