Fabrication of cinnamon essential oil nanoemulsions with high antibacterial activities via microfluidization.

The high volatility and hydrophobicity of cinnamon essential oils (CiEO) limited their practical application. To enhance their stability and antibacterial activity, nanoemulsions encapsulating CiEO were prepared using hydroxypropyl-ß-cyclodextrin/lauroyl arginate (HPCD/LAE) inclusion complexes through high-pressure microfluidization (HPM). Effects of HPM parameters on the stability and antibacterial properties of nanoemulsion were investigated. Results revealed that increased processing pressure and cycle numbers were associated with reduced droplet size and greater homogeneity in CiEO distribution. Storage and thermal stability were optimized at 100 MPa and seven cycles. Moreover, the nanoemulsions showed strong synergistic antibacterial against E. coli (19.79 mm) and S. aureus (23.61 mm) compared with LAE (11.52 mm and 12.82 mm, respectively) and CiEO alone (13.26 mm and 17.68 mm, respectively). This study provided new information for constructing CiEO nanoemulsion, which is suitable for use in the food industry.

New insights into how freeze-drying and cryo-milling affects the fine structure and digestibility of gelatinized starch.

Freeze-drying (FD) and cryo-milling (CM) are common methods for preparing powder gelatinized starch samples. This study investigates the structural characterization of raw/gelatinized maize starches and digestibility after FD/CM processes to elucidate their effect on starch digestibility determination. Results showed that FD slightly increased digestibility, while higher initial glucose content in CM samples, especially for gelatinized samples. Only FD retained the granular morphology and relative crystallinity (RC), while gelatinized-FD decreased RC by 75%. CM decreased RC by 12%, while gelatinized-CM decreased it by 97%. Combined with short-range and chain structural results, FD tended to disrupt internal connected chains through volume stress, while CM cleaved glycosidic bonds in external chain. Stretched chains in gelatinized starch promoted the breakage of chains during shearing and their efficient binding with digestive enzymes. These findings would provide a basis for pre-treatment of powder samples and processes of starch- rich foods.

Exploring the relationship between starch structure and physicochemical properties: The impact of extrusion on highland barley flour.

Highland barley (HB) is an intriguing plateau cereal crop with high nutrition and health benefits. However, abundant dietary fiber and deficient gluten pose challenges to the processing and taste of whole HB products. Extrusion technology has been proved to be effective in overcoming these hurdles, but the association between the structure and physicochemical properties during extrusion remains inadequately unexplored. Therefore, this study aims to comprehensively understand the impact of extrusion conditions on the physicochemical properties of HB flour (HBF) and the multi-scale structure of starch. Results indicated that the nutritional value of HBF were significantly increased (soluble dietary fiber and ß-glucan increased by 24.05%, 19.85% respectively) after extrusion. Typical underlying mechanisms based on starch structure were established. High temperature facilitated starch gelatinization, resulting in double helices unwinding, amylose leaching, and starch-lipid complexes forming. These alterations enhanced the water absorption capacity, cold thickening ability, and peak viscosity of HBF. More V-type complexes impeded amylose rearrangement, thus enhancing resistance to retrogradation and thermal stability. Extrusion at high temperature and moisture exhibited similarities to hydrothermal treatment, partly promoting amylose rearrangement and enhancing HBF peak viscosity. Conversely, under low temperature and high moisture, well-swelled starch granules were easily broken into shorter branch-chains by higher shear force, which enhanced the instant solubility and retrogradation resistance of HBF as well as reduced its pasting viscosity and the capacity to form gel networks. Importantly, starch degradation products during this condition were experimentally confirmed from various aspects. This study provided some reference for profiting from extrusion for further development of HB functional food and "clean label" food additives.

Preparation and characterization of starch/PBAT film containing hydroxypropyl-ß-cyclodextrin/ethyl lauroyl arginate/cinnamon essential oil microcapsules and its application in the preservation of strawberry.

Cinnamon essential oil (CEO) was emulsified by hydroxypropyl-ß-cyclodextrin/ ethyl lauroyl arginate (HPCD/LAE) complex to make nanoemulsions, which were then incorporated into maltodextrin (MD) to prepare HPCD/LAE/CEO/MD microcapsules by spray drying. The starch/polybutylene adipate terephthalate (starch/PBAT, SP) based extrusion-blowing films containing above microcapsules were developed and used as packaging materials for strawberry preservation. The morphology, encapsulation efficiency, thermal and antibacterial properties of microcapsules with different formulations were investigated. The effects of microcapsules on the physicochemical and antimicrobial properties of SP films were evaluated. When the formula was 4 % HPCD/LAE-3% CEO-10% MD (HL-3C-MD), the microcapsule had the smallest particle size (3.3 µm), the highest encapsulation efficiency (84.51 %) of CEO and the best antibacterial effect. The mechanical and antimicrobial properties of the SP film were enhanced while the water vapor transmittance and oxygen permeability decreased with the incorporation of HL-3C-MD microcapsules. The films effectively reduced the weight loss rate (49.03 %), decay rate (40.59 %) and the total number of colonies (2.474 log CFU/g) and molds (2.936 log CFU/g), thus extending the shelf life of strawberries. This study revealed that the developed SP films containing HPCD/LAE/CEO microcapsules had potential applications in degradable bioactive food packaging materials.

Structure, rheological properties, and biocompatibility of Laponite® cross-linked starch/polyvinyl alcohol hydrogels.

Hydrogels, owing to their unique porous structures, hydrophilic properties, and biocompatibility, are being developed as scaffolds for bone grafts. However, the use of toxic initiators or cross-linking agents is a drawback. To overcome this, we developed Laponite®/cross-linked starch/polyvinyl alcohol (PVA) hydrogels prepared by one-step solution mixing. The structure, rheological properties, and biocompatibility of the hydrogels were investigated. Zeta potential, Fourier transform infrared, and X-ray diffraction analyses showed that hydrogen bonding and electrostatic interactions jointly maintained the structure of the cross-linked hydrogel systems. At a Laponite® concentration of 10 %, the hydrogel with a starch/PVA ratio of 2:2 exhibited a uniform porous structure, the highest storage modulus (G'), and the lowest degradation rate. At a starch/PVA ratio of 2:2, the G' increased; however, the degradation rate decreased with the increase in Laponite® content from 5 % to 20 %. These results indicate that the mechanical strength and degradation rate of the hydrogels could be adjusted by altering the starch/PVA ratio and the amount of Laponite®. In vitro cytotoxicity experiments showed that the Laponite®/starch/PVA (LSP) hydrogels were non-toxic to MC3T3-E1 cells. The starch/PVA ratio had no obvious effect on the proliferation of MC3T3-E1 cells, but an increase in Laponite® content significantly promoted cell proliferation. In summary, the results suggest that these LSP hydrogels have great potential for applications in bone tissue engineering.

Effects of Lactic Acid Bacteria Fermentation on the Physicochemical Properties of Rice Flour and Rice Starch and on the Anti-Staling of Rice Bread.

In this study, Lactococcus lactis lactis subspecies 1.2472, Streptococcus thermophilus 1.2718, and thermostable Lactobacillus rhamnosus HCUL 1.1901-1912 were used to ferment rice flour for preparing rice bread. The characteristics of fermented rice bread were studied to elucidate the mechanism by which fermentation improves the anti-staling ability of rice bread. The amylose content of rice flour increased after fermentation. The peak viscosity, attenuation value, final viscosity, recovery value, and gelatinization temperature decreased. Amylopectin was partially hydrolyzed, and the amylose content decreased. The crystallinity of starch decreased, and the minimum crystallinity of Lactococcus lactis subsp. lactis fermented rice starch (LRS) was 11.64%. The thermal characteristics of fermented rice starch, including To, Tp, Tc, and ΔH, were lower than RS (rice starch), and the △H of LRS was the lowest. Meanwhile, LRS exhibited the best anti-staling ability, and with a staling degree of 43.22%. The T22 of the LRF rice flour dough was lower, and its moisture fluidity was the weakest, indicating that moisture was more closely combined with other components. The texture characteristics of fermented rice bread were improved; among these, LRF was the best: the hardness change value was 1.421 times, the elasticity decrease was 2.35%, and the chewability change was 47.07%. There, it provides a theoretical basis for improving the shelf life of bread.

Quinoa protein Pickering emulsion improves the freeze-thaw stability of myofibrillar protein gel: Maintaining protein composition, structure, conformation and digestibility and slowing down protein oxidation.

In this work, the effects of quinoa protein Pickering emulsion (QPPE) on protein oxidation, structure and gastrointestinal digestion property of myofibrillar protein gels (MPGs) after freeze-thaw (F-T) cycles are revealed. SDS-PAGE results indicated that 5.0 %-10.0 % QPPE addition slowed down the protein degradation. Meanwhile, 5.0 %-7.5 % QPPE maintained the stability of the protein secondary and tertiary structure of MPGs after F-T cycles. The sulfhydryl group, disulfide bond and dityrosine content increased with QPPE supplementation. The conformations of disulfide bond changed from g-g-t and t-g-t to g-g-g after F-T cycles, and 5.0 %-7.5 % QPPE stabilized the changes of t-g-t conformation. Furthermore, the increase of dityrosine content after F-T cycles was significantly reduced with 7.5 % QPPE addition, indicating its effect to slow down protein oxidation of MPGs. In addition, MPGs with 5.0 % and 7.5 % QPPE showed noticeably higher zeta potential values than other groups, indicating the enhanced electrostatic repulsion and weakened aggregation caused by F-T damage. This work showed that 7.5 % QPPE improved the F-T stability of MPGs and reduced the protein denaturation and oxidation caused by F-T treatments, exerting no side effect on the digestion property of MPGs. QPPE can be used as a green and effective antifreeze in meat industry.

Effects of different content of EGCG or caffeic acid addition on the structure, cooking, antioxidant characteristics and in vitro starch digestibility of extruded buckwheat noodles.

The effects of different types and content of polyphenol addition on the structure, cooking, antioxidant characteristics and in vitro starch digestibility of extruded buckwheat noodles were investigated in this study. The result showed epigallocatechin-3-gallate (EGCG) was more easily combined with starch to form complex than caffeic acid, and amylose tended to be combined with polyphenols to form more complex. Amylose had a protective effect on polyphenols during extrusion process, which led to a significant increase of polyphenol content and antioxidant activity of extruded noodles. The addition of polyphenol and high amylose corn starch (HACS) improved the cooking quality of extruded buckwheat noodles. The extruded buckwheat noodles with 20 % HACS and 1 % EGCG had the lowest cooking loss of 6.08 %. The addition of EGCG and HACS increased the content of resistant starch and reduced predicted glycemic index (pGI). The noodles with 20 % HACS and 3 % EGCG had the lowest pGI (63.38) and the highest resistant starch (RS) content (61.60 %). This study provides a theoretical basis for the development of low pGI extruded buckwheat noodles.

Preparation and characterization of carnauba wax-based particle with hierarchical structure and its use as hydrophobic coating for chitosan films.

To improve the hydrophobicity of polysaccharide-based films, hydrophobic carnauba wax-based particles were prepared by Pickering emulsion. The influence of the different size of the particles on the structure and hydrophobicity of the chitosan coating films were investigated. The results showed that micro-scale particles (average particle size 25.04 µm) with nano-scale (5-10 nm) TiO2 uniformly distributed on the surface of the particles were formed by Pickering emulsion. The chitosan coating films showed higher contact angle and lower sliding angle compared to the control due to the hierarchical structure, hydrophobicity and arrangement of the particles. In addition, the small particle (23-48 µm) coating film showed higher hydrophobicity than the large particle coating film (48-70 µm) due to the small particle size and the formation of more small gaps. The gaps were conducive to form "air cushion" which reduced the contact area between water and the coating films and thus increased contact angle and decreased sliding angle. The coating films showed high chemical stability and low residual rates of liquid food. The results suggest that Pickering emulsion is an effective method to create wax-based particles with hierarchical structure and the particles have potential to be used as hydrophobic coating materials.

Effects of frozen storage on the quality characteristics of frozen whole buckwheat extruded noodles.

The effects of frozen storage (-18 °C, 180 days) on the quality of frozen whole buckwheat extruded noodles (FWBEN) were investigated. The water content of FWBEN decreased, while the reheating time, water absorption, and dry consumption rate increased with prolonged storage time. Cooking loss increased from 3.20% to 4.31%. Texture analysis indicated that the hardness initially increased, then decreased. Microstructure results showed that the starch gel structure was damaged to a certain extent after storage for a longer period of time, whereas the porous structure became non-uniform with the appearance of cracks. The relative crystallinity gradually increased, and the freezable water content decreased with prolonged storage. These results demonstrated that FWBEN quality was affected by starch retrogradation and ice recrystallization. In general, FWBEN quality was relatively stable during 180 days of frozen storage at -18 °C.

Stability and Digestive Properties of a Dual-Protein Emulsion System Based on Soy Protein Isolate and Whey Protein Isolate.

The stability and digestive properties of a dual-protein emulsion consisting of soy protein isolate (SPI) and whey protein isolate (WPI) have been systematically studied. The results showed that the particle size and viscosity of the dual-protein emulsion system decreased continuously with the increase in WPI, and this might be related to the large amount of electric charge on the surface of the emulsion droplets. Dual-protein emulsions with ratios of 3:7 and 5:5 showed the highest emulsion activity, while emulsion stability increased with the increase in WPI. The thicker adsorption layer formed at the interface might have contributed to this phenomenon. After in-vitro-simulated digestion, the emulsion droplet particle size increased substantially due to the weakened electrostatic repulsion on the droplet surface, especially for the intestinal digestion phase. Meanwhile, WPI accelerated the release of free fatty acids in the digestion process, which played a positive role in the nutritional value of the dual-protein emulsion. In accelerated oxidation experiments, WPI also improved the antioxidant properties of the dual-protein emulsion system. This study will provide a new insight and necessary theoretical basis for the preparation of dual-protein emulsions.

Targeted delivery of food functional ingredients in precise nutrition: design strategy and application of nutritional intervention.

With the high incidence of chronic diseases, precise nutrition is a safe and efficient nutritional intervention method to improve human health. Food functional ingredients are an important material base for precision nutrition, which have been researched for their application in preventing diseases and improving health. However, their poor solubility, stability, and bad absorption largely limit their effect on nutritional intervention. The establishment of a stable targeted delivery system is helpful to enhance their bioavailability, realize the controlled release of functional ingredients at the targeted action sites in vivo, and provide nutritional intervention approaches and methods for precise nutrition. In this review, we summarized recent studies about the types of targeted delivery systems for the delivery of functional ingredients and their digestion fate in the gastrointestinal tract, including emulsion-based delivery systems and polymer-based delivery systems. The building materials, structure, size and charge of the particles in these delivery systems were manipulated to fabricate targeted carriers. Finally, the targeted delivery systems for food functional ingredients have gained some achievements in nutritional intervention for inflammatory bowel disease (IBD), liver disease, obesity, and cancer. These findings will help in designing fine targeted delivery systems, and achieving precise nutritional intervention for food functional ingredients on human health.

Fabrication of a metal organic framework (MOF)-modified Au nanoparticle array for sensitive and stable SERS sensing of paraquat in cereals.

A high-performance Au@MIL-101/PMMA/DT surface-enhanced Raman scattering (SERS) substrate was fabricated for sensitive and stable detection of paraquat by self-assembling metal organic framework-modified Au nanoparticles (Au@MIL-101) on a poly(methyl methacrylate) (PMMA) film and then immobilizing the formed substrate onto a duct tape (DT). The highly closely packed Au@MIL-101 array provided intensive hotspots for SERS sensing. The MIL-101 layer modified on the surface of Au nanoparticles could absorb paraquat to the electromagnetic enhancement area of Au nanoparticles. The DT on the bottom made the substrate smoother, which is beneficial for achieving a more stable detection performance. As a result, the constructed substrate exhibited outstanding uniformity with relative standard deviations of 9.47% and storage stability for 2 months. For detecting paraquat, the substrate showed a low detection limit of 7.1 × 10-9  M (1.83 µg/kg) and wide linear range from 10-8 to 10-2  M. Furthermore, the substrate showed good detection performance in real cereal samples with desirable recovery rates from 91.57% to 102.32%.

Effect of low temperature extrusion-modified potato starch addition on properties of whole wheat dough and texture of whole wheat youtiao.

In this study, low temperature extrusion-modified potato starch (MPS) was added to improve properties of whole wheat dough and textural quality of resulted youtiao. Extrusion temperature (60, 90 ℃) and barrel moisture content (30, 42 and 54%) were set as test variables. The results suggested that the low temperature extrusion processing caused moderate gelatinization and improved gel-forming properties of potato starch. MPS addition decreased the setback by up to 46%, and enhanced the viscoelasticity of whole wheat dough significantly. Compared to the whole wheat-based youtiao, the addition of 10% MPS decreased the hardness by up to 72%, and increased the springiness and specific volume by 32% and 22%, respectively. The addition of MPS prepared at lower extrusion temperature (60 ℃) and moderate moisture content (42%) resulted in the optimum textural qualities of whole wheat youtiao. This study will help better understand the role of MPS in whole wheat-based food product.

Effect of nano-TiO2 particle size on the bonding performance and film-forming properties of starch-based wood adhesives.

The effect of nano-TiO2 particle size on the properties of starch-based wood adhesives was studied in this work. Our findings indicate that a smaller size of nano-TiO2 particles corresponds with a larger specific surface area and more hydroxyl sites on the particle surface that interact with latex molecules, forming a more compact network structure. Therefore, the bonding performance and water resistance of the adhesive were enhanced. In addition, rheology results showed that the adhesive behaves as a pseudoplastic fluid. Small-angle X-ray scattering and energy dispersive spectroscopy confirmed the good compatibility and dispersion of nano-TiO2 in the adhesive films. Diffusing wave spectroscopy and scanning electron microscopy showed that smaller TiO2 particles were more favorable for the formation of smoother and denser films. These results are of great significance for improving the structure and properties of starch-based wood adhesives and preparing high-performance environmentally friendly biobased adhesives.

Toward a comprehensive understanding of various milling methods on the physicochemical properties of highland barley flours and eating quality of corresponding sugar-free cookies.

Highland barley (HB) was subjected to dry-, semidry-, wet-milling methods and assessed for flour physicochemical properties and eating quality of corresponding sugar-free cookies. Results showed that there were significant differences between different milled flours in damaged starch content, particle size, hydration, pasting properties, and color. High a* values and poor hydration/pasting properties of wet-milled flours were associated with its smallest particle size and lowest content of damaged starch (25.3%), ß-glucan (1.87%), and dietary fiber (10.87%), resulting in dark brown color, slightly high spread ratio, low hardness, and fast digestibility of the corresponding cookies. Conversely, the low digestibility of the cookies (predicted glycemic index 58.85) prepared from dry-milled flours was attributed to the higher content of dietary fiber, ß-glucan and V-type starch-lipid complex, which would affect enzyme accessibility and may be beneficial for making HB sugar-free cookies. This study is expected to promote the development of HB functional foods.

Gallic acid-fortified buckwheat Wantuo: characteristics of in vitro starch digestibility, antioxidant and eating quality.

Gallic acid (GA), presented in various plant sources, is increasingly used as a nutritional food ingredient due to its prominent bioactive. In this work, common buckwheat Wantuo (BWT, a Chinese traditional starch gel food) was fortified with 1,3,5% (w/w) GA and assessed for physicochemical properties of flour as well as in vitro starch digestibility, antioxidant and eating quality of BWT. The results clearly showed that the hydration, pasting properties as well as gel microstructure and texture of gel were influenced with addition of GA, while the color of flours showed no significantly change. Hydrogen bonds interaction between GA and starch, more hydrophilic groups exposure and more acid hydrolysis of the starch were thought to be main reasons. Furthermore, combined with structural analysis of starch, the significantly decreased rapidly digested starch (8.62%)/slowly digested starch (12.90%) and increased resistant starch (78.48%) in BWT with 5% addition amount can be mainly due to digestive enzymes inhibition, formation of V-type conformation and alteration in the local structure of starch-phenol-enzyme complex. Meanwhile, the antioxidant activity of BWT-GA improved, where as its texture properties softened due to suppressed starch retrogradation. This study demonstrated the potential use of polyphenol as food ingredient to improve the nutritional properties and eating qualities of starch gel food. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05614-x.

Quinoa protein Pickering emulsion: A promising cryoprotectant to enhance the freeze-thaw stability of fish myofibril gels.

In this work, the effects of different QPE addition on the freeze-thaw (F-T) stability of fish myofibrillar protein (MP) gels were revealed. During freezing process, QPE decreased the freezing point of MP gels and shortened the time to pass through the maximum-ice-crystal-formation zone. The occurrence of thermal hysteresis effect led to the formation of small ice crystals and alleviated the damage to MP gel network. The incorporation of 7.5% QPE also reduced the free water amount to 19.23% and improved the water holding capacity of MP gels. Furthermore, the incorporation of QPE decreased the carbonyl content of MP gels after F-T cycles and delayed the protein oxidation. Meanwhile, QPE addition maintained the stability of the tertiary structure of MP gels via stabilizing the microenvironment of tyrosine and tryptophan. Overall, QPE shows the potential as a new cryoprotectant to improve the F-T stability of MP gel products.

The Tunable Rhenium Effect on the Creep Properties of a Nickel-Based Superalloy.

Atomistic simulations on the creep of a nickel-based single-crystal superalloy are performed for examining whether the so-called rhenium effect can be tuned by changing the spatial distribution of rhenium in the nickel matrix phase. Results show that Rhenium dopants at {100} phase interfaces facilitate mobile partial dislocations, which intensify the creep, leading to a larger creep strain than that of a pure Ni/Ni3Al system containing no alloying dopants. If all the Re dopants in the matrix phase are far away from phase interfaces, a conventional retarding effect of Re can be observed. The current study implies a tunable Re effect on creep via dislocation triggering at the phase interfaces.

Insight into multi-scale structural evolution during gelatinization process of normal and waxy maize starch.

By using a mimicked heating with ex-situ liquid nitrogen flash freezing method, multi-scale structural evolution behaviors of normal maize starch (NMS) and waxy maize starch (WMS) during gelatinization process were studied. The results from SEM, X-ray diffraction (XRD), FTIR/solid state NMR spectroscopy and small angle X-ray scattering (SAXS) showed that NMS and WMS exhibited differently structural evolution behavior during gelatinization process. As the temperature increase, the proportion of the NMS granules with cavity gradually increased, while after heating beyond (peak gelatinization temperature (Tp) + conclusion gelatinization temperature (Tc))/2 the disappearance of starch granule integrity occurred for WMS. The relative crystallinity of NMS declined from 32.8 to 15.26% gradually, as that of WMS declined from 42.43 to 13.09% with a sharply descent when heated beyond (Tp + Tc)/2. The loss of short-range order structure of NMS and WMS showed same trends according to FTIR and NMR. Semicrystalline lamellae of NMS became thinner gradually while that of WMS showed an apparently narrowing after heating beyond (Tp + Tc)/2. These results suggest that the destruction of double helix in amylopectin structure had greatly influence on the larger scale structure of starch samples. This strategy is important for thorough understanding and profiting starch-based food processing. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05520-2.