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 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.

Super Anti-Wetting Colorimetric Starch-Based Film Modified with Poly(dimethylsiloxane) and Micro-/Nano-Starch for Aquatic-Product Freshness Monitoring.

Colorimetric starch film containing anthocyanins is extensively used in eco-friendly intelligent food packaging, but its high water wettability limits its practical application in the food industry. Herein, a super anti-wetting colorimetric starch film was prepared by surface modification with a nano-starch/poly(dimethylsiloxane) (PDMS) composite coating. The water sensitivity, optical properties, mechanical properties, surface morphology, and surface chemical composition of this film were systemically investigated by multiple methods. The obtained film exhibited an extremely high water contact angle (152.46°) and low sliding angle (8.15°) owing to the hierarchical micro-/nanostructure formed by nano-starch aggregates combined with the low-surface-energy PDMS covering. The anti-wettability, optical barrier, and mechanical properties of this film were also significantly improved. The self-cleaning and liquid-food-repelling abilities of this film were comprehensively confirmed. Moreover, this super anti-wetting colorimetric starch film can be applied to monitor the freshness of aquatic products without being disabled by water.

Type III Resistant Starch Prepared from Debranched Starch: Structural Changes under Simulated Saliva, Gastric, and Intestinal Conditions and the Impact on Short-Chain Fatty Acid Production.

Type III resistant starch (RS3) has high resistance to enzymatic digestibility and benefits colonic bacteria by producing short-chain fatty acids (SCFAs) via fermentation. Studies have delineated RS preparation and the description of RS fractions with different types of starch, but the digestion process has received little attention. The molecular and crystalline structure changes, thermal properties, and SCFA content of RS3 obtained from debranched starch were investigated in simulated salivary, gastric, and intestinal digestion systems. The average degree of polymerization and the melting enthalpy change of the digested RS3 residues increased; a high molecular order was reflected by the higher relative crystallinity. Fine structural changes suggested that enzyme-resistant starch might form during digestion by the rearrangement of short amylose chains into enzyme-resistant structures with higher relative crystallinity. After fermentation of human feces, RS3 increased the SCFA content, especially of butyric acid, indicating that this recrystallized RS3 could be a new prebiotic product.

Interactions between debranched starch and emulsifiers, polyphenols, and fatty acids.

Debranching modifications of waxy corn starch with pullulanase can generate short-chain amylose or debranched starch (DBS), which is easy to recrystallize. Herein, we firstly investigated the regulation of recrystallization behaviors of DBS by studying the interactions between DBS and emulsifiers, polyphenols, and fatty acids. Sodium dodecyl sulfate at the 3.0% level had strong interactions with DBS. When the concentration of epigallocatechin gallate was 15%, the enthalpy change (ΔH) of DBS was close to 0 J/g and the relative crystallinity of DBS was 0, clearly indicating the strong interactions between epigallocatechin gallate and DBS. When the concentration of caproic acid, caprylic acid, and capric acid increased from 0 to 20.0%, the ΔH of DBS decreased from 11.38 ± 0.01 to 3.90 ± 0.63, 1.39 ± 0.21, and 3.98 ± 0.83 J/g, respectively. The interactions between emulsifiers, polyphenols, and fatty acids and DBS could affect physiochemical properties of DBS in varying degrees.

Application of cyclodextrinase in non-complexant production of γ-cyclodextrin.

The production of γ-cyclodextrin usually includes the utilization of organic complexants. However, the non-complexant production of γ-cyclodextrin is always being explored due to the defects of organic complexants. However, in non-complexant production, the separation of γ-cyclodextrin from α- and ß-cyclodextrin is still a challenge. Here, the selective hydrolysis ability of a cyclodextrinase designated PpCD (cyclodextrinase from Palaeococcus pacificus) on α-cyclodextrin, ß-cyclodextrin, and γ-cyclodextrin was proved. The kcat /Km values of PpCD for α-cyclodextrin and ß-cyclodextrin were roughly 12-fold and 5-fold higher than that of γ-cyclodextrin. It was proved that PpCD had selective hydrolysis ability and its γ-cyclodextrin purification performance was apparent on various simulated cyclodextrin mixtures with reported proportions derived from different CGTases. Besides, the hydrolysis temperature was optimized and it could be seen that 85°C was appropriate for the production of γ-cyclodextrin. In addition, the production of γ-cyclodextrin was achieved by using PpCD in the γ-CGTase reaction products.

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.

Green preparation and characterization of starch nanoparticles using a vacuum cold plasma process combined with ultrasonication treatment.

In this study, starch nanoparticles (SNPs) were fabricated via a facile and green method involving a vacuum low-temperature plasma process combined with rapid ultrasonication treatment using waxy corn starch (WCS) and potato starch (PS). Morphology, size, crystalline structure, thermal property, and stability analyses of the SNPs were systematically performed. The obtained SNPs exhibited good uniformity and almost perfect spherical and square shapes. The zeta potential and Fourier transform infrared spectroscopy results confirmed that the SNPs were covered with negative carboxyl groups (zeta potential ranging from -21.8 ±â€¯1.06 to -9.78 ±â€¯0.89 mV). The gelatinization enthalpy of SNPs from PS significantly decreased, changing from 16.63 ±â€¯0.91 to 9.81 ±â€¯0.19 J/g. However, the crystal patterns of SNPs from the WCS and PS after plasma and ultrasonic treatments did not change. The crystallinity of SNPs from PS decreased from 45.2% to 16.5%. This novel approach to preparing SNPs is low cost, simple and green. The developed SNPs could have great potential in the food, biomedical, and material industries.

Retrogradation behavior of debranched starch with different degrees of polymerization.

Retrogradation is inevitable during the storage of starchy products. Retrogradation behavior of starches (e.g., amylopectin and amylose) has been widely investigated. We firstly studied the retrogradation behavior of short linear glucan debranched from amylopectin with different degrees of polymerization (DP). With increasing DP, the retrogradation enthalpy change (ΔH) of debranched starch (DBS) increased. At a DBS to water ratio of 1:2 and a storage time of 0 min, the retrogradation ΔH of DBS samples (DP 11.96, 12.62, and 13.36) reached up to 6.03 ±â€¯0.41, 8.03 ±â€¯0.53, and 12.80 ±â€¯1.57 J/g, respectively. The greater the short-chain length, the more rapid the retrogradation of DBS. The peak temperature of retrograded DBS (101.95-111.53 °C) with a DBS to water ratio of 1:2 stored at 50 °C was greater than that stored at 4 °C. The retrogradation of DBS was rapid, taking only 0-120 min, corresponding to ultra-short-term retrogradation.

The co-plasticization effects of glycerol and small molecular sugars on starch-based nanocomposite films prepared by extrusion blowing.

In this study, starch-based nanocomposite films (SNF) made with small molecular sugars (sucrose, fructose and glucose) and glycerol as co-plasticizers were prepared by extrusion blowing. The incorporation of sugars into SNF inhibited the formation of intercalated structures, as shown by X-ray diffraction (XRD) data. XRD analysis also showed that the relative crystallinity of the films decreased after the addition of sugars. Compared to control films, SNF made with sugars showed higher water vapor permeability (WVP, 4.78 × 10-10 g.m/m2.s.Pa), as well as a lower tensile strength and glass transition temperature (Tg, -14.2 °C). Fourier transform infrared (FTIR) analysis revealed that there were high levels of hydroxyl groups and water molecules aggregated around the starch polymer chains. Sugars played an important role in the melting and fracturing of starch granules, as confirmed by scanning electronic microscopy (SEM) data. For the films with sugars especially for glucose, the vertical elongation at break achieved 142%, representing approximately 76% enhancement in elongation at break value compared to the control film, which has almost reached basic standard of traditional plastics (V/H-E ≥ 150%). Thermoplastic starch films co-plasticized with sucrose (TPS-suc) presented better performance than those co-plasticized with fructose (TPS-fru) or glucose (TPS-glu).

Structural changes of chemically modified rice starch by one-step reactive extrusion.

Structural changes of chemically modified rice starch (CMRS) by one-step reactive extrusion (REX) via esterification, acetylation, hydroxypropylation, and cross-linking or dual-modification (hydroxypropylation-cross-linking and acetylation-cross-linking) were investigated. REX treatments exhibited a significant effect on the structure of rice starch granules, resulting in the destruction of the starch crystalline structure and formation of new crystalline complexes. The original A-type crystalline structure was transformed to VH-type after REX treatments, which were further confirmed by DSC experiments since a new endotherm at 100-122 °C was detected. Due to the susceptibility differences in shear-induced breakdown of amylopectin and amylose, the molecular degradation was heterogeneous and retarded by esterification but enhanced by cross-linking. Morphology analysis showed that the original starch granular structure was lost and replaced with a rougher and more irregular structure. In consequence, REX process exerted significant influences on rice starch granules which enhanced its resistance to enzyme hydrolysis.

Effect of annealing on the structural and physicochemical properties of waxy rice starch nanoparticles: Effect of annealing on the properties of starch nanoparticles.

Annealing offers a facile and green approach to the modification of starch. This study was the first to investigate the effect of annealing on the properties of waxy rice starch nanoparticles (SNPs). The spherical morphology of SNPs hardly changed after annealing, and the nanoscale size of the SNPs was maintained in the range of 50-120 nm. The relative crystallinity of modified SNPs increased from 53.71% to 63.46% after annealing at 55 °C for 48 h. The annealing treatment increased the melting temperature from 78.3 °C to 95.7 °C, but decreased the melting range from 30.8 °C to 25.3 °C. The increased 1047 cm-1:1022 cm-1 ratio suggested that annealing resulted in an efficient packing of double helices. This work suggests that annealing, a safe and green method, produces modifications which can improve the properties of SNPs and therefore expand their applications in the fields of food, nutraceuticals, and other materials.

Preparation of Borax Cross-Linked Starch Nanoparticles for Improvement of Mechanical Properties of Maize Starch Films.

Recently, starch nanoparticles have attracted widespread attention from various fields. In this study, a new strategy for preparing covalent-cross-linked starch nanoparticles was developed using boron ester bonds formed between debranched starch (DBS) and borax. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The obtained nanoparticles were spherical with a size of 100-200 nm. The formation of boron ester bonds was confirmed by FTIR. The as-prepared starch nanoparticle exhibited a low relative crystallinity of 13.6%-23.5%. Compared with pure starch film, the tensile strength of starch film with 10% starch nanoparticles increased about 45%, and the elongation at break percentage of starch film with 5% starch nanoparticles increased about 20%. The new strategy of forming starch nanoparticles by using boron ester bonds will advance the research of carbohydrate nanoparticles.

Characterization of Cationic Modified Debranched Starch and Formation of Complex Nanoparticles with κ-Carrageenan and Low Methoxyl Pectin.

The functional modifications of debranched starch (DBS) has been attracting the interest of researchers. This study marks the first time that DBS was modified by cationization through the use of (3-chloro-2-hydroxypropyl) trimethylammonium chloride with the introduction of cationic functional groups. The physicochemical properties and structural characteristics of cationized debranched starch (CDBS) were systematically assessed. The results demonstrate that the maximum degree of substitution (DS) value obtained was as high as 1.14, and the corresponding CDBS exhibited significantly higher zeta potential values: approximately +35 mV. The minimal inhibitory concentration values of the CDBS of DS 1.14 against Escherichia coli and Staphylococcus aureus were 6 and 8 mg mL-1, respectively. In addition, nanoparticles were successfully prepared with a combination of CDBS and low methoxyl pectin (LMP) and a combination of CDBS and κ-carrageenan (CRG). The maximum encapsulation efficiency of nanoparticles for (-)-epigallocatechingallate can reach 87.8%.

Fabrication and Characterization of Starch Nanohydrogels via Reverse Emulsification and Internal Gelation.

Biopolymer-based nanohydrogels have great potential for various applications, including in food, nutraceutical, and pharmaceutical industries. Herein, starch nanohydrogels were prepared for the first time via reverse emulsification coupled with internal gelation. The effects of starch type (normal corn, potato, and pea starches), amylose content, and gelation time on the structural, morphological, and physicochemical properties of starch nanohydrogels were investigated. The diameter of starch nanohydrogel particles was around 100 nm after 12 h of retrogradation time. The relative crystallinity and thermal properties of starch nanohydrogels increased gradually with an increasing amylose content and gelation time. The swelling behavior of starch nanohydrogels was dependent upon the amylose content, and the swelling ratios were between 2.0 and 14.0, with the pea starch nanogels exhibiting the lowest values and the potato starch nanogels exhibiting the highest values.