Assessing Starch Retrogradation from the Perspective of Particle Order.

Starch retrogradation is a complex process involving changes in the multi-scale structure. In particular, the particle order of retrograded starch is unclear. In this study, we measured the radius of gyration (Rg) and radius of particles (R) of retrograded starch using small-angle X-ray scattering. Retrograded starch included various Rg, and the values of Rg depended on the length and state of the starch chains. With time, the standard deviations of R decreased due to the increase in particle uniformity. Based on these results, a new method for assessing the degree of starch retrogradation was established from the perspective of the particle order. The accuracy of the new method was verified through differential scanning calorimetry and scanning electron microscopy. The microstructures of the samples indicated that the retrograded starch granules contained substructures (primary particles) of different sizes. This study provides a new perspective for analyzing the structure of retrograded starch.

Improvement of resistant starch content and thermal-stability of starch-linoleic acid complex: An attempt application in extruded recombinant rice.

The utilization of resistant starch in food industry is restricted due to its susceptibility to thermal degradation. This work aimed to address this issue by preparing a starch-linoleic acid complex (RS5) via extrusion method combined with heat moisture treatment, obtaining VII-type crystal (melting temperature âˆ¼110 °C). The complex obtained through an 8-hour heat moisture treatment exhibited a high RS content of 46.7 %. The glycemic index (pGI) values predicted by two different methods for this complex were 54.5 and 64.2. The complex was further processed into recombinant rice, which exhibited similar textural properties to commercial rice products after cooking. Notably, the recombinant rice maintained an anti-enzyme structure (VII-type complex) as evidenced by its significant resistant starch content of 38.1 %, the lowest pGI values of 59.6 and 72.5. These findings could serve as a useful reference to aid in developing low glycemic index foods based on starch.

Structural properties of the intra- and interhelical cavities of V6-type crystalline starches.

V-type crystalline starch is known for its property to enhance aroma retention. Intra- and interhelical cavities are the first-order characteristics of V-type crystalline starch, which can affect its properties from microscopic level. This work aims to provide a detailed analysis of structural attributes of intra- and interhelical cavities and their influence on the properties of V-type crystalline starches. Helix deformation was caused due to the formation of interhelical cavities, which was reflected by the downfield shift of the signals for C1 and C4 as well as the appearance of an independent signal for C3 in 13C CP/MAS NMR spectra. Unit cell and lamellar structure formed by the aggregation of intrahelical cavities exhibited relatively low cell volume and high fractal dimension at crystal cell and lamellar levels. Toward a larger crystal, d-spacing increased with the formation of interhelical cavities, causing low-angle shifts of V-type crystalline starches in X-ray diffraction profiles. Intrahelical cavities enabled V6I-type crystalline starch to show high crystallinity per unit volume and a favorable short-range order, contributing greatly to the stable thermal properties. The flavor quality improvement in starch-based food is attributed to the structural characteristics of helical cavities and their relationship with the properties of V-type crystalline starches.

Recrystallized resistant starch by encapsulation with konjac glucomannan: Structural changes, digestibility, and its effect on glucose response and short-term satiety in mice.

The effects of the structure and digestibility of konjac glucomannan (KGM)-recrystallized resistant starch complex (KRS3) on the glycemic response and short-term satiety in mice were investigated. KRS3 samples were prepared by recrystallized debranched starch (RS3) at 50 °C, and then combined with KGM. The RS3 and KRS3 samples displayed an A-type pattern and maintained peak temperature values above 110 °C. With an increase in KGM, the swelling power and apparent viscosity of KRS3 increased. The results of in vitro and in vivo digestion revealed that KRS3 with a resistant starch content ranging from 69.4 % to 78.8 % could effectively maintain postprandial blood glucose levels. KRS3, particularly with 0.5 % KGM, slowed gastric emptying of mice from 82.7 % to 36.6 % and intestinal propulsion rate from 60.9 % to 35.3 %, resulting in strong satiety. RS3 combined with KGM could serve as a new approach to develop RS3 based foods with low glycemic responses and high-satiety.

Recrystallized Resistant Starch: Structural Changes in the Stomach, Duodenum, and Ileum and the Impact on Blood Glucose and Intestinal Microbiome in Mice.

The structure and properties of resistant starch (RS) and its digestive products were assessed in mice. Digestion of recrystallized (group RS3, including RS3a and RS3b) and control RS (RS2, RS4, and RS5) in the stomach, duodenum, and ileum of mice was systematically analyzed along with in vivo digestive degradation of RS3. RS3a and RS3b significantly reduced the release of blood glucose. During in vivo digestion, the proportion of ultrashort and A chains in the RS3a and RS3b digestive residues gradually increased, whereas the proportion of B1 and B2 chains gradually reduced. B3+ chain proportions did not change. The final digestive residues in the ileum (RS3a-I90 and RS3b-I90) maintained a high proportion of suitable chain length, accounting for more than 60%. The crystalline structure of RS3a-I90 was weakened, indicating the hydrolysis of partial crystal structure. In comparison, RS3b-I90 maintained an orderly crystalline structure, indicating its higher resistance to enzymatic hydrolysis. In vivo experiments showed that RS could maintain the normal growth of mice and effectively control weight gain. RS3a significantly increased the concentrations of acetic, propionic, and butyric acids, while reducing the abundance of Firmicutes to Bacteroidetes ratio, further confirming the benefits of RS3 in gastrointestinal health.

Structural changes of thermally treated starch during digestion and the impact on postprandial glucose homeostasis.

Intake of foods upon thermal treatment is typically associated with an elevated postprandial glycemic response, which is one of the risk factors for type 2 diabetes development and progression. In this study, rice starch was thermally treated using aqueous phase (boil), air phase (bake), and lipid phase (fry). Peak blood glucose levels in C57 mice increased by 16.94 %, 12.60 %, and 8.1 % after ingestion of thermally treated starch (20.23, 19.48, and 18.70 mmol/L), compared with raw starch (17.30 mmol/L). The insulin response to the intake of thermally treated starch increased (4.73 %-6.83 % higher than the control), whereas the concentration of GLP-1, a hormone used to promote insulin secretion, decreased (1.54 %-8.56 % lower than the control). Furthermore, thermally treated starch accelerated food absorption by enhancing gastrointestinal digestion, exacerbating postprandial glucose fluctuation at the next meal. Structural characterization showed thermal treatment reduced starch branching density and degree of structure order, which were not conducive to preventing the attack of enzymes. During digestion, they were highly hydrolyzed into low-molecular-weight fragments, and the proportion of ultrashort chains substantially increased. These findings provide a better understanding of the fine structure of starch that promotes hypoglycemia and initially explain how diets high in thermally treated starch impair glucose balance.

Simultaneous improvement of the physical and biological properties of starch films by incorporating steviol glycoside-based solid dispersion.

Bioactive compounds are frequently incorporated into polysaccharides (e.g., starch) to form active biodegradable films for food packaging, but some of them are water insoluble (e.g., curcumin, CUR) that will make the films have undesirable performance. Herein, CUR was successfully solubilized into the aqueous starch film solution by steviol glycoside (STE, a natural sweetener)-based solid dispersion. The mechanisms of solubilization and film formation were explored through molecular dynamic simulation and various characterization methods. The results showed that the amorphous state of CUR combined with micellar encapsulation of STE achieved the solubilization of CUR. STE and starch chains cooperated to form the film via hydrogen bonding, while CUR was uniformly and densely distributed within the film in the form of needle-like microcrystals. The as-prepared film exhibited high flexibility, great moisture barrier, and excellent UV barrier (UV transmittance: ∼0 %). Compared with the film containing CUR alone, the as-prepared film possessed higher release efficiency, antibacterial activity, and pH response sensitivity due to the assistance of STE. Hence, the introduction of STE-based solid dispersion can simultaneously improve the biological and physical properties of starch films, which provides a green, nontoxic, and facile strategy for the perfect integration of hydrophobic bioactive compounds and polysaccharide-based films.

The Fluorescence Response of Four Crystalline Starches According to Ultrasound-Assisted Starch-Salicylic Acid Inclusions.

Fluorescence has shown its superior performance in the fields of starch physicochemical properties, starch-based materials, and the interactions of starch with small molecules. However, it has not been well explored in the fluorescence characteristics of starch. Herein, the fluorescence properties of four crystalline starches (A-type tapioca starch, B-type potato starch, C-type pea starch, and V-type starch, prepared with corn starch and stearic acid) were investigated using salicylic acid (SA) as an indicator. The results of inverted fluorescence microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis indicated that SA could be included by starch. X-ray diffraction analysis further demonstrated that the inclusion of SA did not change the crystalline of the four crystal types of starches, which could provide a prerequisite for comparing the different fluorescence properties of the four crystal types of starches. Fluorescence enhancements of the four inclusions were 264.5 (B-type), 206 (C-type), 51.2 (V-type), and 28 (A-type). These results provide new insights for analyzing the fluorescence response of starch.

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.

Structure, thermal stability, and in vitro digestibility of rice starch-protein hydrolysate complexes prepared using different hydrothermal treatments.

In this study, rice starch-protein hydrolysate (WPH-S) complexes with high resistant starch (RS) content were prepared by heat-moisture treatment (HMT) and annealing (ANN). The effects of different hydrothermal treatments on the structure and thermal stability of the WPH-S complexes and their relationship with starch digestibility were further discussed. The results showed that RS contents of ANN-WPH-S complexes (35.09-40.26 g/100 g) were higher than that of HMT-WPH-S complexes (24.15-38.74 g/100 g). Under hydrothermal treatments, WPH decreased the hydrolysis kinetic constant (k) of starch form 4.07 × 10-2-4.63 × 10-2 min-1 to 3.29 × 10-2-3.67 × 10-2 min-1. HMT and ANN promoted hydrogen bonding between WPH and starch molecules, thus increasing the molecular size of starch. In addition, the shear stability of WPH-S mixture was improved with the hysteresis loop area decreased after HMT/ANN treatments, resulting in a more stable structure. Most importantly, the hydrothermal treatment made the scatterers of WPH-S complexes denser and the surface smoother. Especially after ANN treatment, the WPH60-S complex formed a denser aggregate structure, which hindered the in vitro digestion of starch to a certain extent. These results enrich our understanding of the regulation of starch digestion by protein hydrolysates under different hydrothermal treatments and have guiding significance for the development of foods with a low glycemic index.

Starch digestion retarded by wheat protein hydrolysates with different degrees of hydrolysis.

Wheat protein hydrolysates (WPH) were prepared by pepsin hydrolysis for 30, 60, and 120 min (WPH30, WPH60, and WPH120). The mixed system of rice starch and WPH was hydrothermally treated to explore the effect of WPH with different degrees of hydrolysis on starch digestion. WPH reduced the first-order rate coefficient (k) of starch digestion. Especially, WPH30 reduced the k value the most and formed the highest slowly digestible starch content due to the entanglement of starch chains and long-chain peptides. WPH60 and WPH120 with more hydrophobic peptides and polar amino acids than WPH30 tended to form hydrogen bonds with starch molecules due to less steric hindrance. Particularly, the complexation of WPH60 promoted the formation of dense aggregate structure and hindered the enzymatic hydrolysis of starch to a certain extent, thereby increasing the resistant starch content. These findings provide significant guidance for the preparation of hypoglycemic reformed food.

An overview of the nutritional profile, processing technologies, and health benefits of quinoa with an emphasis on impacts of processing.

Consumers are becoming increasingly conscious of adopting a healthy lifestyle and demanding food with high nutritional values. Quinoa (Chenopodium quinoa Willd.) has attracted considerable attention and is consumed worldwide in the form of a variety of whole and processed products owing to its excellent nutritional features, including richness in micronutrients and bioactive phytochemicals, well-balanced amino acids composition, and gluten-free properties. Recent studies have indicated that the diverse utilization and final product quality of this pseudo-grain are closely related to the processing technologies used, which can result in variations in nutritional profiles and health benefits. This review comprehensively summarizes the nutritional properties, processing technologies, and potential health benefits of quinoa, suggesting that quinoa plays a promising role in enhancing the nutrition of processed food. In particular, the effects of different processing technologies on the nutritional profile and health benefits of quinoa are highlighted, which can provide a foundation for the updating and upgrading of the quinoa processing industry. It further discusses the present quinoa-based food products containing quinoa as partial or whole substitute for traditional grains.

Enzymatic preparation and potential applications of agar oligosaccharides: a review.

Oligosaccharides derived from agar, that is, agarooligosaccharides and neoagarooligosaccharides, have demonstrated various kinds of bioactivities which have been utilized in a variety of fields. Enzymatic hydrolysis is a feasible approach that principally allows for obtaining specific agar oligosaccharides in a sustainable way at an industrial scale. This review summarizes recent technologies employed to improve the properties of agarase. Additionally, the relationship between the degree of polymerization, bioactivities, and potential applications of agar-derived oligosaccharides for pharmaceutical, food, cosmetic, and agricultural industries are discussed. Engineered agarase exhibited general improvement of enzymatic performance, which is mostly achieved by truncation. Rational and semi-rational design assisted by computational methods present the latest strategy for agarase improvement with greatest potential to satisfy future industrial needs. Agarase immobilized on magnetic Fe3O4 nanoparticles via covalent bond formation showed characteristics well suited for industry. Additionally, albeit with the relationship between the degree of polymerization and versatile bioactivities like anti-oxidants, anti-inflammatory, anti-microbial agents, prebiotics and in skin care of agar-derived oligosaccharides are discussed here, further researches are still needed to unravel the complicated relationship between bioactivity and structure of the different oligosaccharides.

Mechanism of peptides from rice hydrolyzed proteins hindering starch digestion subjected to hydrothermal treatment.

Clarifying the interactions between food components is critical in designing carbohydrate-based foods with low digestibility. To date, the hindering effect of starch-protein interactions on starch digestion has attracted extensive attention. In this study, rice proteins were further hydrolyzed, and rice peptides (RP) with different molecular weights were obtained by ultrafiltration. The effects and possible mechanisms of RP with different molecular weights on the structure, thermal properties, and in vitro digestibility of cooked rice starch were investigated. All peptides slowed the digestion of rice starch in a concentration-dependent manner. A concentration of 10% RP>10 decreased the rapidly digestible starch content from 68.02 to 45.90 g/100 g, and increased the resistant starch content from 17.54 to 36.54 g/100 g. The addition of RP improved the thermal stability of the starch and reduced the amount of leached amylose. Infrared analysis shows that strong hydrogen bonds formed between RP (especially RP>10) and starch during co-gelatinization. In addition, RP improved the compactness of aggregated structure and played an important role in hindering the enzymatic hydrolysis of starch. These results enrich the theory of starch-protein interactions and have important implications for the development of carbohydrate-based foods with low digestibility and protein functional foods.

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.

Enzymatically modified starch for paper surface sizing: Enzymes with different action modes and sites.

Enzymatically modified starch is frequently applied as a kind of superior surface sizing agent to improve paper quality, but the available options for various enzyme types, except for α-amylases, are limited. Herein, starch was modified using various commercial enzymes with different action modes and sites, namely, α-amylase (CSTWA), ß-amylase (CSTWB), pullulanase (CSTWP), glucoamylase (CSTWG), and compound enzyme (α-/ß-amylase, CSTWAB), for sizing paper. The performance of the paper and the properties of the sizing agents were comprehensively determined. Moreover, the molecules of the modified starch were characterized to explore the enzymolysis mechanism. Results showed that enzymatic hydrolysis should be performed ahead of gelatinization. Compared with CSTWA, CSTWB and CSTWP endowed the paper with higher strength owing to their apposite viscosity and molecular mass distribution. CSTWG and CSTWAB contained excess low-molecular-mass molecules, making them weakly effective as surface-sizing agents. Therefore, pullulanase and ß-amylase have better application prospects as surface-sizing agents than α-amylase.

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.

The formation of starch-lipid complexes by microwave heating.

This study investigated the impact of microwave treatment on the formation of starch-lipid complexes, and physicochemical properties of wheat starch (WS) fortified with lipids, such as lauric acid (LA), glycerol monolaurate (GML), and stearic acid (SA). Specimens were prepared using a conventional water bath and microwave heating and evaluated using macrostructural and microstructural analyses. Iodine staining and scanning electron microscopy revealed interplay between WS and LA. Diffraction peaks around 7.5°, 13°, and 20° and the absence of the absorption band in the 2850 cm-1 were observed in microwave treated WS-lipid samples than conventional water bath samples. Further, more type I complexes were formed in WS-LA microwave-assisted samples, as demonstrated by differential scanning calorimetry. Additionally, more resistant starch was formed in specimens treated by microwave than water bath treated counterparts, the finding that was proved by in vitro enzymatic hydrolysis. In short, the current study may suggest the applications of microwave treatment in foods for hypoglycemia.

Facile fabrication of thermostable and colorimetric starch-based waterproof coating with edible organic materials.

With the attention to pollution and human health, nontoxic food grade superhydrophobic coating as a strategy to reduce food waste has aroused wide interest. Herein, a food grade colorimetric starch-based waterproof coating was achieved using starch nanoparticle (SNP), stearic acid (STA) and anthocyanin. The as-prepared coating exhibited considerable thermostability and remarkable water repellency due to the low-surface-energy pomegranate pulp-like micro/nanostructure assembled by STA and SNP. The certain mechanical and chemical durability, prominent self-cleaning property and liquid food repellency in the coating had been thoroughly verified. Additionally, anthocyanin was creatively introduced to the coating via SNP loading, which endowed the coating with color response to different pH solutions. Thus, the coating is applicable to freshness monitoring without being disabled by water. This thermostable and colorimetric starch-based waterproof coating shows promising application prospects in advanced bio-based food-contact material field.