Preparation and characterization of porous starch reinforced with halloysite nanotube by solvent exchange method

Formation, influencing factors, and applications of internal channels in starch: A review

Starch, a natural polymer, has a complex internal structure. Some starches, such as corn and wheat starches, have well-developed surface pores and internal channels. These channel structures are considered crucial in connecting surface stomata and internal cavities and have adequate space for loading guest molecules. After processing or modification, the starch-containing channel structures can be used for food and drug encapsulation and delivery. This article reviews the formation and determination of starch internal channels, and the influence of different factors (such as starch species and processing conditions) on the channel structure. It also discusses relevant starch preparation methods (physical, chemical, enzymatic, and synergistic), and the encapsulation effect of starch containing internal channels on different substances. In addition, the role of internal channels in regulating the starch digestion rate and other aspects is also discussed here. This review highlights the significant multifunctional applications of starch with a channel structure.

Expanded porous-starch matrix as an alternative to porous starch granule: Present status, challenges, and future prospects

Exposing the hydrated-soft-starch matrix of intact grain or reconstituted flour dough to a high-temperature-short-time (HTST) leads to rapid vapor generation that facilitates high-pressure build-up in its elastic matrix linked to large deformation and expansion. The expanded starch matrix at high temperatures dries up quickly by flash vaporization of water, which causes loss of its structural flexibility and imparts a porous and rigid structure of the expanded porous starch matrix (EPSM). EPSM, with abundant pores in its construction, offers adsorptive effectiveness, solubility, swelling ability, mechanical strength, and thermal stability. It can be a sustainable and easy-to-construct alternative to porous starch (PS) in food and pharmaceutical applications. This review is a comparative study of PS and EPSM on their preparation methods, structure, and physicochemical properties, finding compatibility and addressing challenges in recommending EPSM as an alternative to PS in adsorbing, dispersing, stabilizing, and delivering active ingredients in a controlled and efficient way.

Ultrasound-assisted acid/enzymatic hydrolysis preparation of loquat kernel porous starch: A carrier with efficient palladium loading capacity

Porous starch, with excellent renewal and thermodynamic stability characteristics, could be utilized as a novel carrier for metals. In this research, starch was obtained from wasted loquat kernel (LKS) and converted into loquat kernel porous starch (LKPS) through ultrasound-assisted acid/enzymatic hydrolysis. Then, LKS and LKPS were utilized for loading with palladium. The porous structures of LKPS were evaluated by the results of water/oil absorption rate and N2 adsorption analysis, and the physicochemical properties of LKPS and starch@Pd were analyzed by FT-IR, XRD, SEM-EDS, ICP-OES, and DSC-TAG. LKPS prepared by the synergistic method formed a better porous structure. Its specific surface area was 2.65 times that of LKS, and the water/oil absorption capabilities were considerably improved to 152.28 % and 129.59 %, respectively. XRD patterns showed that the presence of diffraction peaks at 39.7° and 47.1°, indicating successful palladium loading onto LKPS. The EDS and ICP-OES results revealed that the palladium loading capacity of LKPS was superior to that of LKS, with a significantly increased loading ratio of 2.08 %. In addition, LKPS@Pd exhibited excellent thermal stability, with a temperature range of 310-320 °C. Therefore, LKPS was a palladium carrier with highly efficient loading ratio, and LKPS@Pd had promising properties as a competent catalyst.

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.

Combining pulsed electric field and cross-linking to enhance the structural and physicochemical properties of corn porous starch

In this study, corn porous starch (CPS) was firstly prepared using enzymatic hydrolysis, followed by pore formation enhancement using the treatment of a pulsed electric field (PEF). Subsequently, the PEF treated porous starch (CPS-PEF) was cross-linked with sodium trimetaphosphate (STMP) to investigate its structural and functional properties. The results showed PEF treatment increased the oil absorption of CPS by 26.92% and improved its specific surface area, total pore volume value, solubility and swelling power. After cross-linking of the CPS-PEF, C-O-P covalent bonds were formed between CPS-PEF molecules, resulting in a further increase in oil absorption and specific surface area properties. Moreover, the covalent bonds enhanced the intermolecular forces, resulting in increased thermal stability of the cross-linked porous starch (ScPS). The double modification resulted in significantly improved adsorption properties and better thermal stability of the ScPS, indicating that the double modification is an effective method for the preparation of porous starches.

New Techniques in Structural Tailoring of Starch Functionality

Inherent characteristics of native starches such as water insolubility, retrogradation and syneresis, and instability in harsh processing conditions (e.g., high temperature and shearing, low pH) limit their industrial applications. As starch properties mainly depend on starch composition and structure, structural tailoring of starch has been important for overcoming functional limitations and expanding starch applications in different fields. In this review, we first introduce the basics of starch structure, properties, and functionalities and then describe the interactions of starch with lipids, polysaccharides, and phenolics. After reviewing genetic, chemical, and enzymatic modifications of starch, we describe current progress in the areas of porous starch and starch-based nanoparticles. New techniques, such as using the CRISPR-Cas9 technique to tailor starch structures and using an emulsion-assisted approach in forming functional starch nanoparticles, are only feasible when they are established based on fundamental knowledge of starch. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Antidiabetic effect of fucoxanthin extracted from Sargassum angustifolium on streptozotocin-nicotinamide-induced type 2 diabetic mice

This work aimed to study the antidiabetic effect of encapsulated fucoxanthin with porous starch (PS) in streptozotocin and nicotinamide-induced type 2 diabetic mice. Fucoxanthin was extracted and purified from Sargassum angustifolium and encapsulated in porous starch (PS). Diabetic mice groups were gavaged daily with fucoxanthin (400 mg/kg), either free or encapsulated into PS, and metformin (50 mg/kg) for three weeks. The results exhibited that the fucoxanthin and fucoxanthin-loaded PS markedly prevented the weight gain in treated groups (p < .05). Moreover, both free and encapsulated fucoxanthin could decrease the fasting blood glucose and increase the plasma insulin level similar to metformin (p < .05). In addition, total cholesterol, triglyceride, and low-density lipoprotein were lower in the treated groups. These results confirm antiobesity effect of fucoxanthin by regulating lipid profile parameters. Moreover, the histopathology evaluation of pancreatic tissue in diabetic mice exhibited that oral administration of metformin and fucoxanthin caused regeneration of pancreatic beta cells. This study revealed the healthy effect of seaweed pigment as a suitable bioactive compound which can be used in functional foods for natural diabetes therapy.

Starch-based materials encapsulating food ingredients: Recent advances in fabrication methods and applications

Encapsulation systems have gained significant interest in designing innovative foods, as they allow for the protection and delivery of food ingredients that have health benefits but are unstable during processing, storage and in the upper gastrointestinal tract. Starch is widely available, cheap, biodegradable, edible, and easy to be modified, thus highly suitable for the development of encapsulants. Much efforts have been made to fabricate various types of porous starch and starch particles using different techniques (e.g. enzymatic hydrolysis, aggregation, emulsification, electrohydrodynamic process, supercritical fluid process, and post-processing drying). Such starch-based systems can load, protect, and deliver various food ingredients (e.g. fatty acids, phenolic compounds, carotenoids, flavors, essential oils, irons, vitamins, probiotics, bacteriocins, co-enzymes, and caffeine), exhibiting great potentials in developing foods with tailored flavor, nutrition, sensory properties, and shelf-life. This review surveys recent advances in different aspects of starch-based encapsulation systems including their forms, manufacturing techniques, and applications in foods.

A Carrier-Free Folate Receptor-Targeted Ursolic Acid/Methotrexate Nanodelivery System for Synergetic Anticancer Therapy

PURPOSE

To avoid undefined metabolic mechanisms and to eliminate potential side effects of traditional nanocarriers, new green carriers are urgently needed in cancer treatment. Carrier-free nanoparticles (NPs) based on ursolic acid (UA) have attracted significant attention, but the UA NPs targeting the folate receptor have never been explored. We designed a novel self-assembled UA-Methotrexate (MTX) NPs targeting the folate-receptor and its synergetic anticancer activity was studied in vitro and in vivo.

METHODS

UA-MTX NPs were prepared using the solvent precipitation method. Characterization of the UA-MTX NPs preparation was performed using a size analyzer, transmission electron microscopy, and UV-vis spectrophotometry. The in vitro pH-responsive drug release capability of UA-MTX NPs was tested at different pH values. The UA-MTX NPs targeting of folates was determined by comparing the endocytosis rates of cell lines with low or overexpression of the folate receptor (A549 and MCF-7 cells). The cytotoxicity and cell apoptosis of UA-MTX NPs were also studied to determine the in vitro synergistic effects. Combination chemotherapy of UA-MTX NPs in vivo was evaluated using MCF-7 xenografted tumor models.

RESULTS

Compared with free UA or MTX, the water solubility of UA-MTX NPs improved significantly. Drug-release from the UA-MTX NPs was faster at pH 5.0 than pH 7.4, suggesting MTX-UA NPs could rapidly release MTX in the acidic conditions of the tumor microenvironment. Confocal laser scanning microscopy revealed the excellent folate receptor targeting of UA-MTX NPs in MCF-7 cells. Cytotoxicity and cell apoptosis results demonstrated greater antiproliferative capacity of UA-MTX NPs than that of free drug in folate receptor overexpressing MCF-7 cells. Anticancer effects in vivo suggested MTX-UA NPs exhibited good biological safety and could enhance antitumor efficacy due to the combination therapy.

CONCLUSION

Our findings indicate that the UA-MTX NPs targeting folate-receptors is an efficient strategy for combination chemotherapy.

Double encapsulation of fucoxanthin using porous starch through sequential coating modification with maltodextrin and gum Arabic

This study aims to assess the effect of gum Arabic (GA), maltodextrin (MD), or their combination as a coating agent at different ratios (1/3, 1/5, and 1/7 w/w) to encapsulate fucoxanthin. For this purpose, fucoxanthin was initially extracted and purified from Sargassum angustifolium brown seaweed and then loaded into porous starch (PS). The fucoxanthin-loaded PS samples were further contributed in another encapsulation process using the coating materials. All samples were evaluated in terms of encapsulation efficiency, Fourier-transform infrared (FTIR) spectroscopy and stability under light, dark and low or high temperature (4 and 50°C) exposure over a certain time period. Purification of fucoxanthin was verified through HPLC and NMR spectroscopy. It was shown that the subsequent coating with MD + GA (1/7 w/w) caused an enhanced encapsulation of fucoxanthin-loaded PS, reaching to about 96%. In addition, the stability of fucoxanthin-loaded PS was greatly influenced by light and high temperature exposure and decreased from 85% to 58% using the GA-coated material (1/3 w/w). First-order kinetic model was found to be fitted well on thermal degradation data of fucoxanthin. Interestingly, the mixture of MD + GA (1/7 w/w) exhibited the highest fucoxanthin prevention at the end of the storage period. Conclusively, the findings of this study can provide simple and facile protocol for food chemists in protecting the food ingredients using encapsulation process.

Understanding the mechanism of ultrasonication regulated the digestibility properties of retrograded starch following vacuum freeze drying

The digestibility properties and structural changes of retrograded starch (RS3) induced by ultrasonic treatment (UT) were investigated. The digestion profiles showed that UT increased the slowly digestible starch (SDS) or resistant starch (RS) of RS3 as an effective green process, corresponding to a change in hydrolysis kinetic parameters (equilibrium starch hydrolysis percentage and kinetic constant). SEM analysis showed that ultrasound led to breakage of RS3 particles followed by cracking, reorientation and crystallization. Differences in amylose content, granule size, and ζ-potential were found for native RS3 and ultrasound-treated RS3 (UT-RS3). UT decreased the relative crystallinity and gelatinization enthalpy but enhanced short-range order of RS3 based on the results of XRD, DSC, and FT-IR, respectively. Surprisingly, diffractive peaks at 13°and 20° (V-type crystalline structure) and a new exothermic peak were also observed for UT-RS3. The outcome was believed to open new pathways for regulating the digestibility properties of RS3 by UT and development of low glycemic response food.

Advances in Halloysite Nanotubes-Polysaccharide Nanocomposite Preparation and Applications

Halloysite nanotubes (HNTs), novel 1D natural materials with a unique tubular nanostructure, large aspect ratio, biocompatibility, and high mechanical strength, are promising nanofillers to improve the properties of polymers. In this review, we summarize the recent progress toward the development of polysaccharide-HNTs composites, paying attention to the main existence forms and wastewater treatment application particularly. The purification of HNTs and fabrication of the composites are discussed first. Polysaccharides, such as alginate, chitosan, starch, and cellulose, reinforced with HNTs show improved mechanical, thermal, and swelling properties. Finally, we summarize the unique characteristics of polysaccharide-HNTs composites and review the recent development of the practical applications.