Characteristics and ethylene encapsulation properties of V-type linear dextrin with different degrees of polymerisation

Structural characteristics of linear dextrin and in vitro digestion of lauric acid complexes generated via gradient alcohol precipitation

Linear dextrin (LD), a low-molecular-weight carbohydrate, regarded as a type of short amylose, can form resistant starch when combined with fatty acids. This study investigated the structural properties and in vitro digestion of linear dextrins and their complexes with lauric acid (LA). Four groups of linear dextrins were prepared by pretreating gelatinized high-amylose maize starch (HAMS) with pullulanase followed by gradient ethanol precipitation at concentrations of 0 %, 50 %, 60 %, and 70 % (v/v). The GPC results showed that the weight average molecular weight (Mw) of these linear dextrins were 425.88 kDa, 189.68 kDa, 3.77 kDa and 2.01 kDa, respectively. After linear dextrins were complexed with lauric acid through co-precipitation treatment, the X-ray diffraction data revealed that, except for LD-70-LA, all other complexes formed a V-type structure. The complexing index of the complexes initially increased and then declined with increasing ethanol concentration, reaching a peak value of 41.54 % for LD-50-LA. The LD-0-LA, LD-60-LA and LD-70-LA complexes exhibited weaker anti-digestion properties compared to LD-50-LA, which demonstrated the highest resistant starch content at 52.43 %. This study offers a new approach and application potential for the efficient production of resistant starch.

Modulation of V-type starch structures using aqueous ethanol solutions of different polarities for controlled curcumin encapsulation and release

This study investigated the effect of different-polarity aqueous ethanol solutions on the formation of V-type starch originating from corn starch. Scanning electron microscopy revealed that the morphology of starch transformed from a random lamellar structure to a granular structure with decreasing solution polarity. When the ethanol concentration increased from 40 % to 60 %, the crystallinity and single-helix ratio of V-type starch increased from 9.66 % and 6.90 % to 29.77 % and 12.84 %, respectively. When the ethanol concentration was 100 %, the aforementioned parameters decreased to 21.31 % and 11.07 %, respectively. The crystallinity and curcumin encapsulation efficiency of the V-type starch reached their maximum values when this starch was prepared using 60 % aqueous ethanol. Furthermore, curcumin release experiments indicated that the produced starch-curcumin complex could resist gastric acid, and V-type starch with higher crystallinity exhibited a better sustained release effect in intestinal fluid. These results indicate that the formation of V-type starch can be finely regulated using aqueous ethanol solutions with different polarities, and such regulation is beneficial for the application of V-type starch in the oral delivery of guest molecules.

Formation of the rosette-like starch with enhanced V-type crystallization via modified solvent-shifting method

This research investigated the effect modified solvent-shifting method on the formation, ordered structure, and morphology of V-type starch. Ionic liquid (IL) dissolution and hot ethanol aqueous incubation in gradient concentrations from 30 % to 80 % (v/v) were applied to optimize the relative crystallinity of V-type starch. The results showed that this new method worked in producing V-type conformation, and higher ethanol concentration tended to yield V-type starch with higher crystallinity and more disk-like shape structure within the ethanol range of 30-50 % (v/v). Notably, the crystalline order of V-type starch reached the maximum with a specific rosette-like morphology under the condition of an ethanol concentration of 50 % (v/v). While the grown crystals organized into small-size flower-like assemblies and this morphology even disappeared accompanied by the V-type crystallization weakening when starch chains co-crystallized with the ethanol concentrations of 60 %-80 % (v/v). The molecular structure analysis indicated no significant correlation between the relative crystallinity of V-type starch and its fine structure. IL served to promote the formation of V-type starch, while it didn't participate in the formation process and could be removed during the washing process. The findings can provide new insights into developing a bottom-up pathway for regulating crystallization and morphology of V-type starch.

A novel efficient liquefaction process for corn starch through ternary deep eutectic solvent: Products characterization and liquefaction mechanism

A novel approach for the solvothermal liquefaction of corn starch (CS) was investigated, using ternary deep eutectic solvent (TDES) as both an acidic catalyst and a source of liquefaction reagent. Synergistic effects from multi-component TDES were observed, leading to milder reaction conditions (110 °C, 35 min) and improved product selectivity (relative content of polyhydroxy compounds up to 97.83 %). As a result, a viscosity of 351.76 mPa·s, hydroxyl number of 131.98 mg KOH/g, and acid number of 5.56 mg KOH/g of LP-60 with comparable polyol properties were obtained. Liquefaction residue analysis revealed a significant enhancement in the reactivity of CS by disrupting its recalcitrant structure through electrostatic interactions and hydrogen bonding in TDES, as evidenced by the significant reduction of short-range ordering (R1047/1022 and R995/1022) and C1 (C-C/C-H), C3 (C=O/O-C-O) components of the starch granule surface. According to the gas chromatography-mass spectroscopy result, the reaction pathway and mass balance for CS liquefaction in the TDES system were proposed. This study provides an efficient and mild route for starch liquefaction using TDES.

Metal-anchored oxidized starch-pullulan nanofiber films enhance ethylene adsorption and banana preservation

The development of novel strategies to control ethylene accumulation of fruit is crucial for improving food preservation and reducing spoilage-related losses. In this study, an oxidized starch-pullulan (OS-PUL) nanofiber films were prepared with silver, copper, and iron to control ethylene accumulation. The starch nanofiber film exhibited an average diameter of 96 nm at an OS-PUL concentration of 25 % (wt/wt). Adsorption test showed the maximum ethylene adsorption capacity (21.86 mg·m-2) of metal-nanofiber film with typical hierarchical microporous and mesoporous structure. Oxidized starch-pullulan-metal-nanofiber film extended the shelf life of bananas from 8 to 15 days by efficiently absorbing ethylene. This work will contribute to the development of innovative packaging materials with ethylene adsorption properties, which can help reduce food waste.

Application of the molecular dynamics simulation GROMACS in food science

Food comprises proteins, lipids, sugars and various other molecules that constitute a multicomponent biological system. It is challenging to investigate microscopic changes in food systems solely by performing conventional experiments. Molecular dynamics (MD) simulation serves as a crucial bridge in addressing this research gap. The Groningen Machine for Chemical Simulations (GROMACS) is an open-source, high-performing molecular dynamics simulation software that plays a significant role in food science research owing to its high flexibility and powerful functionality; it has been used to explore the molecular conformations and the mechanisms of interaction between food molecules at the microcosmic level and to analyze their properties and functions. This review presents the workflow of the GROMACS software and emphasizes the recent developments and achievements in its applications in food science research, thus providing important theoretical guidance and technical support for obtaining an in-depth understanding of the properties and functions of food.

Insights into formation and stability mechanism of V7-type short amylose-resveratrol complex using molecular dynamics simulation and molecular docking

Pre-formed V-type amylose as a kind of wall material has been reported to carry polyphenols, while the interaction mechanism between V-type amylose and polyphenol is still elusive. In this work, the formation and stability mechanism of a V7-type short amylose-resveratrol complex was investigated via isothermal titration calorimetry, molecular dynamics, and molecular docking. The results presented that two stoichiometric ratios of resveratrol to short amylose were calculated to 0.120 and 0.800, and the corresponding main driving force was hydrogen bonding and hydrophobic interaction, respectively. The folding and unfolding conformation of V7-type short amylose chains appeared alternately during the simulation. Resveratrol tended to be bound in the short amylose helix between 40 ns and 80 ns to form a more stable complex. Hydrogen bonds between resveratrol molecule and O6 at the 22nd glucose molecule/O2 at the 24th glucose molecules and hydrophobic interaction between resveratrol molecule and glucose molecules (19th, 20th, 21st and 23rd) could be found.

Stabilization and release of thymol in pre-formed V-type starch: A comparative study with traditional method

Recently, pre-formed V-type starch has become popular as a versatile carrier in encapsulation systems of containing starch-guest inclusion complexes (ICs). However, the differences in stabilizing and dissociating guests between ICs prepared by either the traditional method or the pre-formed "empty" helix method have not yet been elucidated. Here, starch-thymol ICs were prepared using the traditional high temperature-water method and the pre-formed method, covering different complexation temperatures and solvents, to compare the loading capacity, crystalline structure, thermal stability, and release properties. The highest content of thymol in ICs prepared by the pre-formed and the traditional method was 74.2 and 65.3 mg/g, respectively. Different from ICs prepared by the traditional method (V7-type crystal), ICs prepared by the pre-formed method mostly exhibited a V6a structure with larger crystallinities and a better short-range ordered structure. ICs prepared at 90 °C were type II complexes and efficiently protected thymol from rapid heat loss. A slow release was observed in both cases: about 45 % and 75 % of thymol were released from ICs prepared by the pre-formed and traditional methods, respectively, after two weeks of storage at 25 °C.

Molecular rotor as an in-situ fluorescent probe for the degree of polymerization of α-D-1,4-glucans

Various starch synthesis and tailoring processes involve prevailing adjustments in the degree of polymerization (DP) of linear α-D-1,4-glucan chains (LGCs) for the improved functional performances. Previous studies indicated that LGCs might hinder the twisted relaxation of 9-(2-carboxy-2-cyanovinyl)-julolidine (CCVJ, a hydrophilic molecular rotor), highlighting CCVJ as a potential in-situ structural probe for LGC. In this study, glucose and its α-D-1,4 oligomers and polymers with molecular weights ranging from 0.18 kDa to 70.00 kDa were prepared as the model molecules (MM). The fluorescent emission behavior of CCVJ in various concentrations (1-5 g/L) of MM solutions or dispersions were analyzed. Results showed that for the low-DP MMs (≤ 3.98 kDa) with good aqueous stability, CCVJ emission increased by about 20 times with the DP of MMs. In contrast, CCVJ generally emitted weak DP-relevant but glucan content-dependent fluorescence in response to the interaction with high-DP MMs (> 3.98 kDa). Furthermore, a double-logarithmic linear relationship was found between the emission intensity of CCVJ and the molar-based molecular weight of glucan. The result combined with the molecular dynamic simulation suggested that CCVJ underwent surface-to-surface interaction with MMs. This study may contribute to the real-time analysis of the DP of α-D-1,4 oligoglucosides in maltodextrin and starch syrup.

Modified porous starch for enhanced properties: Synthesis, characterization and applications

Native starches have low water solubility at room temperature and poor stability, which demand modifications to overcome. Porous starch as a modified one shows enhanced adsorptive efficiency and solubility compared with its native starch. In contrast, some inherent disadvantages exist, such as weak mechanical strength and low thermal resistance. Fortunately, modified porous starches have been developed to perform well in adsorption capacity and stability. Modified porous starch can be prepared by esterification, crosslinking, oxidation and multiple modifications to the porous starch. The characterization of modified porous starch can be achieved through various analytical techniques. Modified porous starch can be utilized as highly efficient adsorbents and encapsulants for various compounds and applied in various fields. This review dealt with the progress in the preparation, structural characterization and application of modified porous starch. The objective is to provide a reference for its development, utilization, and future research directions.

Development, application and future trends of starch-based delivery systems for nutraceuticals: A review

As a natural biopolymer, starch is ideally adapted as an encapsulant material for nutraceutical delivery systems due to its unique nature of extensive sources, versatility and high biocompatibility. This review offers an outline of recent advances in the development of starch-based delivery systems. The structure and functional properties of starch in encapsulating and delivering bioactive ingredients are first introduced. Structural modification of starch improves the functionalities and extends the applications of starch in novel delivery systems. Then, various nutraceutical delivery systems are systematically summarized, which include porous starch, starch particle, amylose inclusion complex, cyclodextrin, gel, edible film and emulsion. Next, the delivery process of nutraceuticals is discussed in two parts: digestion and release. Intestinal digestion plays an important role during the whole digestion process of starch-based delivery systems. Moreover, controlled release of bioactives can be achieved by porous starch, starch-bioactive complexation and core-shell structure. Finally, the challenges of the existing starch-based delivery systems are deliberated, and the directions for future research are pointed out. Composite delivery carriers, co-delivery, intelligent delivery, delivery in real food systems, and reuse of agricultural wastes may be the research trends for starch-based delivery systems in the future.

Multiscale structure and precipitation mechanism of debranched starch precipitated by different alcohols

Alcohol solution is a cheap, simple, and effective precipitating solvent frequently used for separating debranched starch (DBS), yet little is known about the precipitation mechanism of DBS by different alcohols. This study precipitated DBS from pullulanase-hydrolyzed starch using ethanol, n-butanol, and isopentanol. The multiscale structures of DBS were characterized, including chain length, single/double helix, and crystalline. The chain conformation and precipitation mechanism of DBS in different alcohols was investigated using molecular dynamics (MD) simulation. DBS precipitated by n-butanol contained the largest proportion of short chain (DP6-24, 83.2 %), the highest V-type crystallinity (21.1 %), and the largest single-helix content (24.7 %). A single helix conformation of DBS chain was determined in alcohols, where alcohol molecules entered the helix cavity. Intra/inter-molecular hydrogen bonds stabilized the helix, with a large number of hydrogen bonds leading to strong molecular interaction and stable helical structure. The solvent accessible surface area of DBS chain decreased by 7.88-19.32 % in alcohols, and the radial distribution function revealed that the first solvent layer of DBS chain at 0.29 nm was closely related to hydrogen bonding. This study provides a basis for the choice of precipitation solvent for preparing DBS with different chain lengths and physicochemical properties.