Investigation of the mechanism of gelatin to enhance 3D printing accuracy of corn starch gel: From perspective of phase morphological changes.

The study examined the impact of phase morphological transformations within the corn starch/gelatin system, induced by varying gelatin content, on its rheological properties and 3D printing performance. Gelatin addition inhibited the gelatinization and retrogradation of starch, which leaded to the transformation of continuous phase structure. The transition process from starch continuous phase to gelatin continuous phase promoted a thinner wall structure of the gel and loosed its dense network, resulting in reduced flow stress (τf) and storage modulus (G'). These changes improved the extrusion and "extrusion swelling" of gel ink materials, which made the print size of printed product closer to the set model. The formation of a gelatin continuous phase in the gel was helpful in increasing τf and G', resulting in enhanced support capacity of the printed product. This study presented meaningful information for the application of 3D printing to starch-gelatin complex foods.

Enzymatic Modification of Starch Using Recombinant Genes from Sorghum in Escherichia coli: Insights and Potential Applications.

SBEIIb (Sobic.004G163700), SSSIIa (Sobic.010G093400), and GBSSI (Sobic.010G022600) genes that regulate starch synthesis in sorghum endosperm were transferred into Escherichia coli by transgenic technology. SBEIIb, SSSIIa, and GBSSI enzymes were separated and purified through a Ni column and analyzed by electrophoresis with molecular weights and activities of 91.57 84.57, and 66.89 kDa and 551 and 700 and 587 U/µL, respectively. Furthermore, they were applied to starch modification, yielding interesting findings: the A chain content increased from 25.79 to 89.55% for SBEIIb-treated waxy starch, while SSSIIa extended the A chain to form DPs of the B chain, with A chain content decreasing from 89.55 to 37.01%, whereas GBSSI was explicitly involved in the synthesis of B1 chain, with its content increasing from 9.59 to 48.45%. Modified starch was obtained, which could be accurately applied in various industries. For instance, we prepared a sample (containing 89.6% A chain content) with excellent antiaging and antidigestion properties through SBEIIb modification. Moreover, higher RS3 (34.25%) and SDS contents (15.75%) of starch were obtained through the joint modification of SBEIIb and SSSIIa. These findings provide valuable insights for developing sorghum starch synthesis-related enzymes and offer opportunities for improving starch properties through enzymatic approaches.

Digestibility, structural and physicochemical properties of microcrystalline butyrylated pea starch with different degree of substitution.

In this study, microcrystalline butyrylated pea starch (MBPS) with higher contents of resistant starch (RS) was synthesized via esterification with butyric anhydride (BA) using microcrystalline pea starch (MPS) as the raw material. With the addition of BA, the new characteristic peaks appeared at 1739 cm-1 and 0.85 ppm obtained from FTIR and 1H NMR, respectively, and increased with the higher degree of BA substitution. Moreover, an irregular shape of MBPS, such as condensed particles and more cracks or fragments, had been observed by SEM. Further, the relative crystallinity of MPS increased then native pea starch and decreased with the reaction of esterification. MBPS had higher decomposition onset temperature (To) and temperature of maximum decomposition (Tmax) with increasing DS values. Simultaneously, an increasing trend RS content from 63.04 % to 94.11 % and a decreasing trends in rapidly digestible starch (RDS) and slowly digestible starch (SDS) contents of MBPS were recorded with increasing DS values. MBPS samples showed higher production capacity of butyric acid ranging from 553.82 µmol/L to 892.64 µmol/L during the fermentation process. Compared with MPS, the functional properties of MBPS were significantly improved.

Structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm: A review.

This review focuses on the structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm. Sorghum is an important cereal crop that is well suited to grow in regions with high temperatures and limited water resources due to its C4 metabolism. The endosperm of sorghum kernels is a rich source of starch, which is composed of two main components: amylose and amylopectin. The synthesis of starch in sorghum endosperm involves multiple enzymatic reactions, which are regulated by complex genetic and environmental factors. Recent research has identified several genes involved in the regulation of starch synthesis in sorghum endosperm. In addition, the structure and properties of sorghum starch can also be influenced by environmental factors such as temperature, water availability, and soil nutrients. A better understanding of the structure and genetic regulation of starch formation in sorghum endosperm can have important implications for the development of sorghum-based products with improved quality and nutritional value. This review provides a comprehensive summary of the current knowledge on the structure and genetic regulation of starch formation in sorghum endosperm and highlights the potential for future research to further improve our understanding of this important process.

Characterization of starch structures isolated from the grains of waxy, sweet, and hybrid sorghum (Sorghum bicolor L. Moench).

In this study, starches were isolated from inbred (sweet and waxy) and hybrid (sweet and waxy) sorghum grains. Structural and property differences between (inbred and hybrid) sweet and waxy sorghum starches were evaluated and discussed. The intermediate fraction and amylose content present in hybrid sweet starch were lower than those in inbred sweet starch, while the opposite trend occurred with waxy starch. Furthermore, there was a higher A chain (30.93-35.73% waxy, 13.73-31.81% sweet) and lower B2 + B3 chain (18.04-16.56% waxy, 24.07-17.43% sweet) of amylopectin in hybrid sorghum starch. X-ray diffraction (XRD) and Fourier transform infrared reflection measurements affirm the relative crystalline and ordered structures of both varieties as follows: inbred waxy > hybrid waxy > hybrid sweet > inbred sweet. Small angle X-ray scattering and 13C CP/MAS nuclear magnetic resonance proved that the amylopectin content of waxy starch was positively correlated with lamellar ordering. In contrast, an opposite trend was observed in sweet sorghum starch due to its long B2 + B3 chain content. Furthermore, the relationship between starch granule structure and function was also concluded. These findings could provide a basic theory for the accurate application of existing sorghum varieties precisely.

Antimicrobial Activity, Microstructure, Mechanical, and Barrier Properties of Cassava Starch Composite Films Supplemented With Geranium Essential Oil.

In this study, we prepared cassava starch-based films by the casting method. Afterwards, the effects of geranium essential oil (GEO) on the prepared films' physicochemical, morphology, and antibacterial properties were revealed. We found that the thickness and elongation at the break of cassava starch films increased with increasing GEO concentration (from 0.5, 1, and 2%). However, increasing GEO concentration decreased the water content, water vapor permeability, and tensile strength of the prepared films'. Further, the addition of GEO increased the surface roughness, opacity, and antibacterial properties of the prepared films. With the increase of GEO concentration, L * and a * of cassava starch film decreased, while b * and Δ E increased. This study provides a theory for cassava starch-based films as a biological packaging material.

The formation of starch-lipid complexes by microwave heating.

This study investigated the impact of microwave treatment on the formation of starch-lipid complexes, and physicochemical properties of wheat starch (WS) fortified with lipids, such as lauric acid (LA), glycerol monolaurate (GML), and stearic acid (SA). Specimens were prepared using a conventional water bath and microwave heating and evaluated using macrostructural and microstructural analyses. Iodine staining and scanning electron microscopy revealed interplay between WS and LA. Diffraction peaks around 7.5°, 13°, and 20° and the absence of the absorption band in the 2850 cm-1 were observed in microwave treated WS-lipid samples than conventional water bath samples. Further, more type I complexes were formed in WS-LA microwave-assisted samples, as demonstrated by differential scanning calorimetry. Additionally, more resistant starch was formed in specimens treated by microwave than water bath treated counterparts, the finding that was proved by in vitro enzymatic hydrolysis. In short, the current study may suggest the applications of microwave treatment in foods for hypoglycemia.

The impact of gliadin and glutenin on the formation and structure of starch-lipid complexes.

This study evaluated the influence of the main gluten fractions (gliadin and glutenin) on the physicochemical properties of binary wheat starch-Lauric acid (WS-LA) complexes during heat processing to explore the complex structure and digestion of WS-LA in the presence of gluten. Ternary WS-LA-glutenin complexes were prepared at different pH (5.2 and 7), whereas WS-LA-gliadin was prepared using ethanol, and their physicochemical properties were analyzed. We found that the addition of glutenin displayed a sharper and higher diffraction peak than samples without protein, which increased short-range order structure (low full width at half-maximum (FWHM) of the band at 480 cm-1) and good thermal stability (melting peak appeared at a higher temperature); the opposite was shown for gliadin. Even though glutenin increased the resistant starch (RS) content than WS-LA, all samples prepared in 65% ethanol showed higher RS content than WS-LA-glutenin samples. These findings might improve our understanding of the relationship between gliadin/glutenin and binary complexes and provide a theoretical basis for preparing starch-based foods with a low glycemic index.

Effects of different moisture contents on the structure and properties of corn starch during extrusion.

Herein, corn starch samples with different moisture contents (native corn starch, 30, 35, 40, 45, and 50%) were prepared by twin-screw extrusion, and the structural and physical properties were analyzed and correlated. Scanning electron microscopy observed the morphology, attenuated total reflection-Fourier transform infrared spectroscopy investigated the double helix structure, X-ray diffraction analyzed the crystal region, ion chromatography observed the chain length distribution, and rapid viscosity analyzer measured the viscosity of corn starch samples. We found that the corn starch crystallinity, degree of order, and double helix degree decreased with increasing moisture content. The moisture content has a crucial role in the peak viscosity, breakdown, final viscosity, and setback in pasting property experiments. With the increase in moisture content, the longer chain was transformed into a shorter chain, and the dispersion of molecular weight distribution continuously increased. This study provides a theoretical basis for the production of extruded corn starch.

Preparation and evaluation of starch-based extrusion-blown nanocomposite films incorporated with nano-ZnO and nano-SiO2.

The effects of nano-ZnO and nano-SiO2 nanoparticles on the properties of starch-based films prepared by extrusion blowing were investigated in this study. New hydrogen bonds between hydroxypropyl starch (HS) and nanoparticles during the extrusion process were formed as shown by Fourier transform infrared spectroscopy (FTIR). The diffraction patterns of nanocomposite films reinforced with nano-ZnO were similar to those of nano-ZnO, except that the peak intensity decreased, whereas, the addition of SiO2 nanoparticles decreased the intensity of the main characteristic peaks, regardless of the HS and nano-ZnO reinforced films. The thermal stability, tensile strength, moisture barrier property, and surface hydrophobicity of nanocomposite films were improved with the incorporation of nano-ZnO and nano-SiO2, the finding that could be attributed to a strong interplay between nano-ZnO, nano-SiO2, and the starch matrix during the extrusion film blowing process. Similarly, the nano-ZnO/nano-SiO2 composite-reinforced films showed smooth, flat, and uniform appearances by scanning electron microscopy (SEM) and atomic force microscope (AFM) tests. In sum, Nano-ZnO and nano-SiO2 nanoparticles can be used as composite reinforcing agents for preparation of starch-based films through extrusion blowing.

Antibacterial activity, optical, and functional properties of corn starch-based films impregnated with bamboo leaf volatile oil.

In this study, the optical, morphological, antibacterial, and physical properties of corn starch-based films prepared by a solution casting method were investigated after adding various levels of bamboo leaf volatile oil (BVO, 0.5, 1, and 2%). Further, the roughness was measured by atomic force microscopy and the antibacterial activities were tested by agar diffusion method. We found that the thickness (TC) and elongation at break (EAB) of the corn starch-based films increased significantly (Duncan's range test, P < 0.05) with the addition of BVO (TC from 0.121 to 0.207 mm; EAB from 2.48 to 10.40%). However, with the addition of BVO, the moisture content (MC) and water-solubility decreased (MC: from 13.12 to 11.41%; water solubility: from 30.58 to 26.95%), and the water vapor permeability (WVP) and tensile strength (TS) decreased significantly (WVP: from 3.91 to 3.05 g m m-2 s-1 Pa-1; TS: from 20.64 to 10.68 MPa, Duncan's range test, P < 0.05). Furthermore, supplementation of BVO to corn starch-based films increased the surface roughness and the antibacterial effects. The addition of BVO also increases the opacity of the films, which is helpful to protect food from ultraviolet damage. In sum, this study provides a theoretical basis for using corn starch-based films as alternative packing biomaterial.

Effects of proteins on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid complexes under various cooking methods.

Herein, we investigated the effects of gluten proteins (Pr) on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid (WS-LA) complexes under various cooking methods (steaming, boiling, and baking). There was no ternary complex formation between WS, LA, and Pr in the samples after different cooking methods. Scanning electron microscopy (SEM) and fluorescence microscopy showed variation in size, structure and distribution of WS-LA of WS-LA-Pr samples after cooking. An increase in the intensity of V-type diffraction peak and thermal stability was observed in steamed and baked samples, however, opposite trend was noticed in boiled sample. Additionally, a higher 1022/995 cm-1 absorbance ratio was noted in WS-LA-Pr sample treated with boiling than other cooking methods. Further, in vitro resistance to enzymatic hydrolysis was improved in samples treated with steaming and baking compared with boiled treated samples. In sum, this study may offer a thorough understanding on how these interactions take place during food processing, to optimize the production and development of new food products with desired microstructure and functionality features.

Effect of moist and dry-heat treatment processes on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid complexes.

Herein, we investigated the impact of moist (steaming and boiling) and dry (baking and microwaving)-heat treatment processes on the structure and physicochemical properties of wheat starch (WS) supplemented with lauric acid (LA). Elemental composition analysis revealed the interplay between WS and LA. Scanning electron microscopy (SEM) and iodine staining revealed that lamellar crystalline structure of WS-LA complexes was improved after moist-heat treatment (relative to samples without any heat treatments); the finding which is at variance to dry-heat treatment process. Additionally, high resistance to thermal decomposition and a lower 1022/995 cm-1 absorbance ratio were observed in moist-heat treated WS-LA compared with dry-heat samples. Moreover, the V-type diffraction peak intensity and resistance to in vitro enzymatic hydrolysis of samples treated with moist-heat were increased to a greater extent than the dry-heat treated counterparts. In sum, this study would facilitate the application of functional starch-lipid complexes in food necessitated heat treatments.

The formation and in vitro enzymatic digestibility of starch-lipid complexes in steamed bread free from and supplemented with different fatty acids: Effect on textural and retrogradation properties during storage.

Herein, the formation of starch-lipid complexes in steamed bread (SBr) free from and supplemented with fatty acids of varying chain lengths, including lauric acid (LA), glycerol monolaurate (GML), stearic acid (SA), and glycerol monostearate (GMS) and their effects on in vitro enzymatic digestibility were investigated. The enthalpy value of SBr samples (1.86-3.46 J/g) was significantly decreased (P < 0.05) compared to wheat starch samples (5.64-7.17 J/g) fortified with fatty acids. The relative crystallinity (16.5%-32.8%) of SBr corresponds to the content of starch-lipid complexes. SBr supplemented with fatty acids exhibited softer texture than lipid-free SBr stored at 4 °C for 0, 1, 4, and 7 days. Higher enzyme resistance was observed in SBr samples supplemented with fatty acids and the content of resistant starch (RS) was increased from 7.54% to 23.13% in SBr supplemented with LA. As demonstrated by microscopic computed tomography (mCT), the crystalline structure of SBr samples supplemented with LA and GML have a higher density than SBr fortified with SA and GMS; the findings which are in line with thermal properties and X-ray diffraction analysis. In sum, the formation of starch-lipid complexes could be considered as a new way to improve the SBr textural features during storage.

Effects of pullulanase debranching on the properties of potato starch-lauric acid complex and potato starch-based film.

The effects of different debranching time on the properties of potato starch and its films were evaluated. Potato starch granules were debranched with pullulanase for 0, 0.5, 1.0, 1.5 or 2.0 h. The effects of pullulanase debranching treatment on the chain-length distributions of amylopectin were analysed by high performance anion exchange chromatography (HPAEC), which proved that the shorter debranching treatment generated more linear chains with favourable lengths to facilitate the formation of potato starch-lauric acid complexes. The debranched starch-lipid complexes showed higher lauric acid content than that of the untreated sample. X-ray diffraction showed that the diffraction intensity of the debranched sample was stronger than that of the undebranched sample, and when the debranching time was >1.5 h, the diffraction intensity and relative crystallinity of the complexes decreased. The sample exhibited a high melting enthalpy (ΔH) under the pullulanase debranching treatment for 1.5 h. Scanning electron microscope data indicated that the surface of the composite film was flatter after the debranching treatment and that the films exhibited the lowest water vapour permeability and highest tensile strength after the treatment time for 1.5 h.

Effects of amylose content and enzymatic debranching on the properties of maize starch-glycerol monolaurate complexes.

The effects of pullulanase debranching on the properties of maize starch (waxy, normal and high amylose)-glycerol monolaurate (GML) complexes were studied. Pullulanase pretreatment produced more starch chains with favourable lengths (DP ≥ 25) to encourage inclusion complex formation. The debranched starch showed higher amylose content (from 11.2 to 58.6%) than the native starch (from 0.68 to 53.4%). The V-type characteristic diffraction peaks (7.5°, 13.1° and 20.2° 2θ) became more obvious after the starch received the debranching treatment. Thermal properties indicated that the melting enthalpy of the debranched starch-GML complexes (from 6.45 to 10.13 J/g) was higher than those of the untreated complexes (from 0 to 8.91 J/g). The swelling power values and degree of hydrolysis of the starches decreased with the increase in amylose content. In vitro digestibility analysis suggested that the hydrolysis of the starch-GML samples was further restricted by applying the debranching treatment to the starch.

Effects of different treatment methods on properties of potato starch-lauric acid complex and potato starch-based films.

The effects of different treatment methods on the physicochemical properties of potato starch (PS) and PS-based films were studied. The complexing indices of PS-lauric acid (LA) complexes followed the order: pullulanase debranching (PD) > ultrasound treatment (UT) > dimethyl sulfoxide heating (DSH) > Control. Light microscopy showed that PS-LA complexes exhibited irregularly shaped fragments. X-ray diffraction indicated that the diffraction intensity of the PD sample was stronger than that of the other samples. The melting enthalpies (△H) of the DSH, UT and PD samples were higher than that of the Control. PD sample had the lowest enzymatic-hydrolysis rate among all of the tested samples. PS-LA composite films showed higher tensile strength, lower elongation at break, and lower moisture permeability than native starch-based film, and the films prepared by PD method had the highest tensile strength and lowest water vapour permeability among all of the tested films.

Effects of ultrasonic treatment on amylose-lipid complex formation and properties of sweet potato starch-based films.

To investigate the effect of ultrasonic treatment on the properties of sweet potato starch and sweet potato starch-based films, the complexing index, thermograms and diffractograms of the sweet potato starch-lauric acid composite were tested, and light transmission, microstructure, and mechanical and moisture barrier properties of the films were measured. The results indicated that the low power density ultrasound was beneficial to the formation of an inclusion complex. In thermograms, the gelatinization enthalpies of the ultrasonically treated starches were lower than those of the untreated sample. With the ultrasonic amplitude increased from 40% to 70%, the melting enthalpy (ΔH) of the inclusion complex gradually decreased. X-ray diffraction revealed that the diffraction intensity of the untreated samples was weaker than that of the ultrasonically treated samples. When the ultrasonic amplitude was above 40%, the diffraction intensity and relative crystallinity of inclusion complex gradually decreased. The scanning electronic microscope showed that the surface of the composite films became smooth after being treated by ultrasonication. Ultrasonication led to a reduction in film surface roughness under atomic force microscopy analysis. The films with ultrasonic treatment exhibited higher light transmission, lower elongation at break, higher tensile strength and better moisture barrier property than those without ultrasonic treatment.