Construction of TiO2/starch nanocomposite cryogel for ethylene removal and banana preservation.

Perishability caused by natural plant hormone ethylene has attracted great attention in the field of fruit and vegetable (F&V) preservation. Various physical and chemical methods have been applied to remove ethylene, but the eco-unfriendliness and toxicity of these methods limit their application. Herein, a novel starch-based ethylene scavenger was developed by introducing TiO2 nanoparticles into starch cryogel and applying ultrasonic treatment to further improve ethylene removal efficiency. As a porous carrier, the pore wall of cryogel provided dispersion space, which increased the area of TiO2 exposed to UV light, thereby endowing starch cryogel with ethylene removal capacity. The photocatalytic performance of scavenger reached the maximum ethylene degradation efficiency of 89.60 % when the TiO2 loading was 3 %. Ultrasonic treatment interrupted starch molecular chains and then promoted their rearrangement, increasing the material specific surface area from 54.6 m2/g to 225.15 m2/g and improving the ethylene degradation efficiency by 63.23 % compared with the non-sonicated cryogel. Furthermore, the scavenger exhibits good practicability for removing ethylene as a banana package. This work provides a new carbohydrate-based ethylene scavenger, utilizing as a non-food contact inner filler of F&V packaging in practical applications, which exhibits great potential in F&V preservation and broadens the application fields of starch.

The inhibitory mechanism of amylase inhibitors and research progress in nanoparticle-based inhibitors.

Type 2 diabetes is caused by persistently high blood sugar levels, which leads to metabolic dysregulation and an increase in the risk of chronic diseases such as diabetes and obesity. High levels of rapidly digestible starches within foods may contribute to high blood sugar levels. Amylase inhibitors can reduce amylase activity, thereby inhibiting starch hydrolysis, and reducing blood sugar levels. Currently, amylase inhibitors are usually chemically synthesized substances, which can have undesirable side effects on the human body. The development of amylase inhibitors from food-grade ingredients that can be incorporated into the human diet is therefore of great interest. Several classes of phytochemicals, including polyphenols and flavonoids, have been shown to inhibit amylase, including certain types of food-grade nanoparticles. In this review, we summarize the main functions and characteristics of amylases within the human body, as well as their interactions with amylase inhibitors. A strong focus is given to the utilization of nanoparticles as amylase inhibitors. The information covered in this article may be useful for the design of functional foods that can better control blood glucose levels, which may help reduce the risk of diabetes and other diet-related diseases.

Superhydrophobic starch-based nanocomposite cryogel for oil removal underwater and magnetically guided oil slick cleanup.

Low-cost and eco-friendly carbohydrate-based absorbents have attracted great attention for cleaning oil spill that poses a serious threat to the ecosystem. Porous starch-based materials have been proven to have good oil absorption performance, but the hydrophilicity of these materials limits their application in oil spill cleanup. Herein, a novel starch-based superhydrophobic absorbent (HMS-SiO2@MSC) was achieved by introducing nanoparticles into starch cryogel. Fe3O4 and silylated SiO2 nanoparticles endowed the adsorbent with magnetism (saturation magnetization: 4.36 emu/g) and superhydrophobicity (water contact angle: 154.4°), respectively. In addition, the surface chemical composition and microstructure of the adsorbent were investigated in detail. Some crucial properties of HMS-SiO2@MSC were also comprehensively confirmed, including water-repellent, self-cleaning, anti-fouling, and durability. Furthermore, HMS-SiO2@MSC exhibited good practicability of removing oil underwater and magnetically guided cleaning oil slick on the water surface. This work provided a new carbohydrate-based adsorbent, which would broaden the application fields of starch.

Superhydrophobic starch-based adsorbent with honeycomb coral-like surface fabricated via facile immersion process for removing oil from water.

The development of novel superhydrophobic adsorbents is highly demanded for tackling frequent oil spill accidents. Porous starch-based materials have been proven to possess good oil absorption performance, but their superhydrophobicity has not yet been reported, thus limiting their application in oil spill cleanup. Herein, a superhydrophobic starch-based adsorbent (MSC) was fabricated through the facile immersion process of starch cryogel (SC) into toluene solution of methyltrichlorosilane (MTS). Low-surface-energy and honeycomb coral-like micro/nanostructures, which contribute to high water contact angle (>151.0°) and low sliding angle (<15.0°), were provided simultaneously to SC by the hydrolysis-condensation reaction of MTS. MSC exhibited excellent water repellent, self-cleaning, and anti-fouling properties, as well as passable mechanical and chemical durability. The reasonable oil adsorption performance and selective wettability toward oil and water allowed this absorbent to be applied for heavy oil removal underwater and oil slick cleaning from the water surface. It is expected that the facile strategy provided by this work will accelerate the application of superhydrophobic starch-based materials in oil contamination removal and other industrial activities.

Superhydrophobic modular cryogel with variable magnetic-actuated motion direction for discrete small-scale oil spill cleanup.

Smart superhydrophobic sorbents are in high demand for cleaning oil spills that could endanger the aquatic ecosystem. Herein, we demonstrated the fabrication of a superhydrophobic and magnetic modular cryogel (SNS@Fe-PSC) containing three starch-based modules, namely, a superhydrophobic nano-coating, a magnetic nanocomposite insertion, and a high-strength starch/polyvinyl alcohol composite substrate. The surface chemical composition and hierarchical micro/nanostructures of this material were investigated in detail. The modular cryogel had a high water contact angle (>151°) and low sliding angle (<9°), as well as excellent water-repellent, self-cleaning, and anti-fouling properties. This material also exhibited good durability owing to its stable chemical bonding and structural support. SNS@Fe-PSC could be applied to remove oil from water effectively. Moreover, the magnetic module (saturation magnetization, 5.04 emu/g) allowed the as-obtained material to be propelled and controlled by a magnet on the surface of water. Variable magnetic-actuated motion direction could be realized by adjusting the position and amount of magnetic modules inserted to the cryogel.

Eco-friendly and superhydrophobic nano-starch based coatings for self-cleaning application and oil-water separation.

High-performance nano-based superhydrophobic coatings have attracted tremendous attention in a wide range of sectors. As a biodegradable and low-cost natural polymer, starch nanoparticles (SNPs) exhibit significant potential for use in many advanced materials. However, nano-starch based superhydrophobic coatings have not yet been reported. Herein, SNPs/polydimethylsiloxane composites were applied to fabricate these coatings using an environmentally friendly approach. The coating exhibited superhydrophobic (water contact angle >152.0° and sliding angle <9.0°) and self-cleaning properties owing to the hierarchical micro and nanostructures formed by coralloid SNP aggregates combined with the low surface energy of the PDMS covering. Meanwhile, the strong adhesion of PDMS and chemical bonding of SNPs with PDMS endowed the coatings with mechanical and chemical robustness. The excellent oil-water separation abilities of the coating were also comprehensively confirmed. This coating shows the potential application in the development of eco-friendly self-cleaning materials and oily wastewater treatment.

Effect of annealing and heat-moisture pretreatments on the oil absorption of normal maize starch during frying.

The impacts of two hydrothermal pretreatments, annealing (ANN) and heat moisture treatment (HMT), on oil-absorption by normal maize starch (NMS) during frying were investigated using low-field nuclear magnetic resonance (LF-NMR). The structural organizations of the fried samples were also evaluated using SEM, XRD, ATR-FTIR, and DSC, respectively. Both hydrothermal pretreatments significantly reduced the total oil content in the starch after frying, with the magnitude of the effect depending on the treatment conditions used. SEM showed that the pretreated fried starch granules preserved more of their original morphology. XRD, FTIR, and DSC showed that both pretreatments preserved more of the short-range double helices and long-range organizations within the orthorhombic crystalline structure for NMS during frying. The promoting effect of ANN/HMT on the interactions of starch molecules and the rearrangement of double helices were hypothesized to be responsible for the increased thermal stability of starch granules in the present work. As a result, fried starch pretreated by ANN/HMT were more organized and more compact than fried NMS, thus inhibiting oil absorption during frying.

Structural modification and functional improvement of starch nanoparticles using vacuum cold plasma.

Starch nanoparticles (SNPs) have become one of the most interesting nanocarriers due to their relatively easy synthesis, biocompatibility, and biodegradability. However, the practical applications of SNPs are limited, as their aggregation reduce their functionality. Here, SNPs obtained by recrystallizing debranched waxy maize starch were modified using oxygen and ammonia vacuum cold plasma (CP). The modified SNPs were measured using Fourier transform infrared spectroscopy, showing a new carbonyl or carboxyl peak at 1720 cm-1. SNPs modified with oxygen CP treatment have negative charges (-21.6 to -15.1 mV). Modified SNPs with diameter ranging from 75.94 to 159.72 nm had good dispersibility without much aggregation. The relative crystallinity of modified SNPs decreased from 44.13% to 33.80%. Moreover, modified SNPs showed high absorption of tea polyphenols, indicating that as nanocarriers, they can accommodate more cargo molecules than primary SNPs. CP modification of SNPs is simple, green, and inexpensive. Modified SNPs can be used as nanocarriers to deliver drug or food components in the food and pharmaceuticals industries.

Effect of pullulan on oil absorption and structural organization of native maize starch during frying.

The oil-absorption behavior of native maize starch (NMS) during frying was investigated in the presence or absence of pullulan (PUL) using a LF-NMR method. The morphology, long-range order, short-range order, and thermal properties of fried NMS-PUL mixtures were further evaluated using SEM, XRD, ATR-FTIR, and DSC, respectively. Pullulan addition significantly reduced the oil content of the fried starch samples: 0.395, 0.310, 0.274, and 0.257 g/g in NMS with addition of 0, 1, 3, and 5% PUL, respectively (p < 0.05). SEM analysis showed that the intact granular morphology of the starch granules was preserved upon addition of pullulan. The XRD, FTIR, and DSC results showed that pullulan protected both the short-range double helices and long-range crystalline structure of the granules during frying. As a result, fried NMS-PUL mixtures were denser than fried NMS, thus inhibiting oil absorption during frying. These results may have important implications for creating healthier reduced-fat fried food products.

Impact of amylose content on structural changes and oil absorption of fried maize starches.

The absorption of oil during frying has important implications for food quality, cost, and nutrition. Maize starches with low (WMS), intermediate (NMS), and high amylose (HAMS) contents were therefore heated in oil to mimic the frying process, and the impact of amylose content on the hierarchical structures and oil absorption of the fried starches was evaluated. Amylose affected the oil absorption by interfering with the structural evolution of the starch or by directly interacting with the lipids during frying. At low moisture level (20%), the granular state was preserved after frying and so the size and porosity of the granules played a dominant role in the oil absorption process, explaining why the highest oil absorption occurred in WMS. At 40% moisture content, NMS absorbed the most oil because of its granular morphology and lower crystallinity. At 60% moisture content, HAMS absorbed more oil than NMS, because more amylose molecules in HAMS provided more hydrophobic helical cavities available for lipids.

Measurement and characterization of external oil in the fried waxy maize starch granules using ATR-FTIR and XRD.

Concerns regarding increased dietary oil uptake have prompted efforts to investigate the oil absorption and distribution in fried starchy foods. In the present study, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, together with a chloroform-methanol method, was used to analyze the external and internal oil contents in fried starchy samples. The micromorphology of fried starchy samples was further investigated using scanning electron microscope (SEM), polarized light microscope (PLM) and confocal laser scanning microscopy (CLSM). The results indicated that large amounts of oil were absorbed in or within waxy maize starch, but the majority of oil was located near the surface layer of the starch granules. After defatting, the internal oil was thoroughly removed, while a small amount of external oil remained. As evidenced by the changes of the crystalline characteristics with the help of X-ray diffraction (XRD), the interaction between starch and lipids on the surface was confirmed to form V-type complex compounds during frying at high moisture.

Rapid, accurate, and simultaneous measurement of water and oil contents in the fried starchy system using low-field NMR.

Fried starchy food is rich in oil that may pose a risk to health. For controlling of the oil uptake, a rapid and accurate method for the determination of oil content in the fried starchy food is important. In this study, low-field nuclear magnetic resonance (LF-NMR) was applied to simultaneously determine water and oil contents in the model fried starchy system. The proton signals from oil and water were verified and distinguished by desiccation at 105°C. There was no superposition between oil and water signals in the fried starch, making it possible for quantitative analysis of water and oil in a single test. Compared with Soxhlet extraction, the LF-NMR analysis provided a more accurate result of oil content in the fried starchy system, confirming the practicability of the application of LF-NMR technology as a fast and accurate method for the quantification of water and oil in the fried starchy system.

Inhibition of wheat starch retrogradation by tea derivatives.

The effect of four industrial tea derivatives (tea polyphenols [TPS], tea water-soluble extracts [TSE], tea polysaccharides [TSS], and green tea powder [GTP]), on the retrogradation of wheat starch was investigated using texture profile analysis (TPA), differential scanning calorimetry (DSC), rapid viscosity analysis (RVA), and the α-amylase-iodine method. The addition of the four tea derivatives resulted in decreased hardness and increased cohesiveness of the starch gel as shown by the TPA test. The DSC data demonstrated an increase in the enthalpy change of starch gelatinization and a decrease in the enthalpy change of starch recrystallite dissociation. The RVA results indicated that the peak viscosity, representing the intermolecular forces of wheat starch, was reduced after addition of TPS, TSE, and TSS, respectively, but was increased by GTP. Furthermore, the half crystallization time in the Avrami equation almost doubled after the separate addition of the tea derivatives.

Synthesis of pH- and ionic strength-responsive microgels and their interactions with lysozyme.

Microgels composed of carboxymethyl cellulose (CMC) polymers via chemical crosslinking with sodium trimetaphosphate were synthesized and characterized using thermogravimetric analysis (TGA), swelling, and rheological analysis. The effects of pH, ionic strength, and crosslinking density on lysozyme loading in microgels were also studied. The microgel particle size ranged primarily from 10 to 20 µm. TGA revealed that the crosslinking increased the thermal stability of CMC. The swelling degree increased as pH increased from 3 to 5, and remained almost constant from pH 5 to 8. However, the swelling degree decreased with increasing ionic strength. The rheological analysis was in good agreement with the results of swelling degree. The protein uptake decreased with increasing ionic strength and crosslinking density. The pH 6 was the optimal pH for lysozyme absorption at ionic strength 0.05 M. The lysozyme-microgel complex was identified by confocal laser scanning microscopy, and the lysozyme distribution in the microgel was observed to be rather homogeneous.

Preparation and characterization of carboxymethyl starch microgel with different crosslinking densities.

Microgels synthesized with different crosslinking densities were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry analysis (TGA), swelling, and rheological analyses. The lysozyme uptake capacity of these microgels was evaluated through the effects of lysozyme concentration, pH, and ionic strength. The microgel particle size mostly ranged within 25µm to 45µm. FT-IR analysis results suggested that sodium trimetaphosphate reacted with the hydroxyl groups of carboxymethyl starch (CMS), thereby forming ester linkages. TGA data indicated that crosslinking increased the thermal stability of CMS. Swelling degree increased with increasing pH before pH 5, and then remained almost constant. However, swelling degree decreased with increasing ionic strength and crosslinking density. The microgels behaved as viscoelastic solids because the storage modulus was higher than the loss modulus over the entire frequency range of dispersions with polymer concentrations of 3% (W/W) at 25°C. The data for the uptake of lysozyme by microgels demonstrated that the protein uptake increased with increasing pH and lysozyme concentration, as well as with decreasing ionic strength and crosslinking density. The lysozyme-microgels complex was identified by CLSM, and the distribution of lysozyme in microgels with low crosslinking density was rather homogeneous.

Polyphenols from blueberries modulate inflammation cytokines in LPS-induced RAW264.7 macrophages.

Polyphenols including 3-glucoside/arabinoside/galactoside-based polymers of delphinidins, petunidins, peonidins, malvidins and cyanidins are one type of biological macromolecules, which are extraordinarily rich in blueberries. Anti-inflammatory activity of blueberry polyphenols (BPPs) was investigated by using lipopolysaccharide (LPS) induced RAW264.7 macrophages. The results showed that BPPs suppressed the gene expression of IL-1ß (interleukin-1ß), IL-6 and IL-12p35. The inhibition effect on IL-1ß and IL-6 mRNA was most obvious at the concentration of 10-200µg/mL BPPs. But the inhibition effect on IL-12p35 mRNA was increased with the increasing concentration of BPPs. When fixed at 100µg/mL BPPs, the most significant inhibition on IL-1ß, IL-6 and IL-12p35 mRNA expression was detected at 12-48h. In conclusion, BPPs exhibit anti-inflammation activity by mediating and modulating the balances in pro-inflammatory cytokines of IL-1ß, IL-6, and IL-12.

Acid-thermal dextrin prepared from rice starch: structure and encapsulation properties.

In this study, acid-thermal dextrin (ATD) was prepared from rice starch using hydrochloric acid in combination with heat treatment. The structure and encapsulation properties of ATD were examined. The results showed that three fractions (Fraction I, Fraction II, and Fraction III) in ATD were obtained based on the distribution of molecular weight (M(w)) in high-performance size-exclusion chromatographic (HPSEC) spectra. The Fraction II (M(w)≈10,000 Da) was identified using high-performance anion exchange chromatography (HPAEC), indicating that it consisted of three major groups: DP=2-5, DP=6-15, and DP=25-36. This distribution in chains led to good encapsulating ability of Fraction II to cinnamaldehyde (CIN) and a maximum encapsulation rate reached 41.2 µL/g (CIN/Fraction II) with a molar ratio of about 3:1. The encapsulating mechanism was proposed due to a single helical V-conformation (single resonance at 102.7 ppm) of Fraction II present and observed in solid-state NMR spectra.