A simple and green method for preparation of non-crystalline granular starch through controlled gelatinization

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.

Changes of crystalline structure and physicochemical properties of Pueraria lobata var. thomsonii starch under water deficit

Crystal type is an important physicochemical property of starch. However, it is currently unclear whether changes in crystal type affect other properties of starch. This study discovered that water deficit resulted in an increase in small starch granules and transparency in Pueraria lobata var. thomsonii, while causing a decrease in amylose content and swelling power. Additionally, the crystal type of P. Thomsonii starch changed from CB-type to CA-type under water deficit, without significantly altering the short-range ordered structure and chain length distribution of starch. This transformation in crystal type led to peak splitting in the DSC heat flow curve of starch, alterations in gelatinization behavior, and an increase in resistant starch content. These changes in crystalline structure and physicochemical properties of starch granules are considered as adaptive strategies employed by P. Thomsonii to cope with water deficit.

Improving the swelling capacity of granular cold-water rice starch by ultrasound-assisted alcoholic-alkaline treatment

The aim of this study was to determine the ability to improve the capacity of cold swelling and cold-water solubility of rice starch by ultrasonic-assisted alcohol-alkaline and alcohol-alkaline methods. To achieve this, ultrasound powers (U) were varied (30%, 70%, 100%) under the granular cold-water swelling starch (GCWSS) preparation (GCWSS + 30 %U, GCWSS + 70 %U, and GCWSS + 100 %U). The effects of these methods on morphological, pasting properties, amylose content, ratio of 1047/1022 spectra by FTIR, turbidity, freeze-thaw stability, and gel texture were also studied and compared. The results showed that the surface of GCWSS granules presented a honeycomb especially GCWSS + U treatments exhibited more porous on the surface of starch granules. The cold swelling power and solubility of GCWSS + U samples were increased which confirmed by reducing ratio of ordered structure to amorphous structure of starch, and turbidity was also decreased. Moreover, pasting temperature, breakdown, final viscosity, and setback decreased while peak viscosity increased as measured using a Rapid Visco Analyzer. The freeze-thaw stability of GCWSS + U was more resistant to syneresis than GCWSS under repeated freeze-thaw cycles. The reduction of gel hardness and springiness was observed using Texture Analyzer. These changes were enhanced with increasing ultrasound powers. Thus, the results indicate that the different ultrasound-assisted alcohol-alkaline treatments for preparing GCWSS show an effective use in the preparation of GCWSS with improved cold-water swelling and reduced retrogradation of rice starch.

Structure and properties of flexible starch-based double network composite films induced by dopamine self-polymerization

Starch-based packaging materials are being developed to alleviate environmental pollution and greenhouse gas emissions associated with plastic-based ones. However, the high hydrophilicity and poor mechanical properties of pure-starch films limit their widespread application. In this study, dopamine self-polymerization was used as a strategy to improve the performance of starch-based films. Spectroscopy analysis showed that strong hydrogen bonding occurred between polydopamine (PDA) and starch molecules within the composite films, which significantly altered their internal and surface microstructures. The composite films had a greater water contact angle (> 90°), which indicated that the incorporation of PDA reduced their hydrophilicity. Additionally, the elongation at break of the composite films was 11-fold higher than pure-starch films, indicating that PDA improved film flexibility, while the tensile strength decreased to some extent. The composite films also exhibited excellent UV-shielding performance. These high-performance films may have practical applications in food and other industries as biodegradable packaging materials.

Preparation and characterization of non-crystalline granular starch with low processing viscosity

Non-crystalline granular starch (NCGS) has advantages in the deep processing of starch owing to its unique structure and function. In this study, NCGS was successfully prepared at a baking temperature of 210 °C, and the morphology, structure, pasting properties, and rheological properties of the NCGS were systematically studied. Compared with native starch, NCGS showed a lower processing viscosity and rapid reduction in the peak viscosity from 3795 to 147 cP. Furthermore, NCGS exhibited impaired short- and long-range ordered structures, as indicated by the lower ratio of absorbance at 1047/1015 cm^-1 and decreased crystallinity compared to native starch. Additionally, amylose and amylopectin with long and medium chains in NCGS were degraded into short chains, resulting in an increase in amylose content and branch density. The analysis of the physicochemical properties of NCGS, especially the low processing viscosity, is of great importance for the industrial application of starch, particularly in terms of improving the yield, saving energy, and reducing environmental pollution.

Effect of Micronization on Panax notoginseng: In Vitro Dissolution and In Vivo Bioavailability Evaluations

Panax notoginseng (PN) has become the most widely used dietary supplement and herbal in Asian countries. The effect of micronization on PN is not entirely clear. The aim of this study was to investigate the effects of particle size of Panax notoginseng powder (PNP) and the potential to improve the bioavailability. The results showed that particle size reduction significantly changed the Panax notoginseng saponins (PNS) in vitro dissolution and in vivo pharmacokinetics. The size of the Panax notoginseng powder (PNP) ranges from 60 to 214 μm. The surface morphology and thermal properties of PNP were extensively characterized, and these changes in physicochemical properties of PNP provide a better understanding of the in vitro and in vivo release behaviors of PNS. The in vitro studies demonstrated that the dissolution of PNS and particle size were nonlinear (dose- and size-dependent). The pharmacokinetics parameters of PNP in rats were determined by UHPLC-MS/MS. Powder 4 (90.38 ± 8.28 μm) showed significantly higher AUC_0-T values in plasma (P < 0.05). In addition, we also investigated the influence of the hydrothermal treatment of PNP. The results showed that the PNS in vitro release and in vivo bioavailability of PNP pretreatment at 40°C were the highest. This suggests that PNP with a particle size of around 90 μm and heat pretreatment at 40°C would be beneficial. These results provided an experimental basis, and it was beneficial to choose an appropriate particle size and hydrothermal temperature when PNP was used in clinical treatment.

Effect of cooling rate on long-term recrystallized crystal of rice starch in the presence of flavor compounds

This study evaluated the effect of cooling rate on starch recrystallization in the presence of 2,3-butanedione and 2-acetyl-1-pyrroline, which could form B-type and V-type complexes with starch, respectively. Rapid cooling resulted in poor perfection and high heterogeneity of both B-type and V-type recrystallized crystal. For B-type crystal, rapid cooling changed nucleation mode from instantaneous (Avrami index n < 1) to continuous mechanism (1 ≤ n ≤ 2), and decreased recrystallization rate from 0.0502 to 0.0160 d^-n, indicating the increased retention of starch on 2,3-butanedione. V-type crystal was formed at initial stages of recrystallization, and inhibited the growth of B-type crystal. The loose crystalline obtained by rapid cooling is conducive to the retention of flavor compounds for B-type complexes (especially ≤14 days) and V-type complexes (especially ≤1 day). These results could provide guidance for maintaining fragrance of instant rice during long-term storage.

Insight into the biphasic transition of heat-moisture treated waxy maize starch through controlled gelatinization

Biphasic transition is an important behavior of starch caused by heat-moisture treatment (HMT). Starch may change from typical single endotherm to biphasic endotherm (G1, G2) by HMT which corresponded to two viscosity peaks (PV₁ and PV₂) in pasting analysis. During PV₁, remarkable disruption of birefringence occurred in the inner region of starch granules, accompanied by a decreased relative crystallinity from 20.59 to 14.73%. Native starch completely lost their birefringence at 73 °C, while the HMT starch still showed strong birefringence in granule periphery. The HMT starch only lost crystallites at 80 °C (PV₂). A crystallite stability hypothesis was developed that G1 was mainly due to the gelatinization of the inner crystalline lamellae of starch granule, and the newly formed G2 was caused by the peripheral ones enhanced by HMT. This work also provided details on the mechanism of HMT and a potential method for the thermal transition study on starch.

Effect of Mesona chinensis polysaccharide on the pasting, rheological, and structural properties of tapioca starch varying in gelatinization temperatures

The effects of Mesona chinensis polysaccharide (MCP) on the pasting, rheological properties, granule size, and water mobility of tapioca starch (TS) were investigated at different gelatinization temperatures (75 °C and 95 °C). The structures of tapioca starch-Mesona chinensis polysaccharide (TM) gels formed at different gelatinization temperatures were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that the peak, trough, and final viscosities of TM-95 mixtures were lower than that of TM-75 mixtures. Addition of MCP had a significant reduce (p < 0.05) on the granule size and transversal relaxation time of TM mixtures at the two gelatinization temperatures. Rheological analysis also showed that the addition of MCP increased the consistency indexes (K) and decreased the flow behavior indexes (n) of TM-95 and TM-75 gels. XRD results confirmed the diffraction peak of TM-95 gels became blunt and wider, and the diffraction peak at 17° and 23° of TM-75 gels could be observed after MCP added. In addition, the microstructures of TM-75 gels were more compact than that of TM-95 gels. These results can promote the development of TS-based products and application of MCP at different gelatinization temperatures.

Preparation, characterization and antitumor activity of a cationic starch-derivative membrane embedded with a β-cyclodextrin/curcumin inclusion complex

A membrane of cationic starch-derivative/poly(vinyl alcohol) was prepared and utilized as a support to immobilize a β-cyclodextrin/curcumin inclusion complex. The resulting material (denote as β-CD/CUR-MBN) was characterized in detail by different techniques. In vitro experiments revealed that β-CD/CUR-MBN enables the controlling of the curcumin release process, which is guided by the relaxation of the polymer matrix. Moreover, cytotoxic assays were performed to investigate the effect of β-CD/CUR-MBN on two cancer cell lines (melanoma and glioblastoma). The results showed that the polymeric membrane exerts higher cytotoxicity against these cells than free curcumin. Also, β-CD/CUR-MBN exerted a prolonged cytotoxic effect (up to 96 h), even using a low concentration (50 μg mL^-1), indicating that the curcumin in the polymeric membrane showed increased bioavailability under the tested condition. β-CD/CUR-MBN was non-cytotoxic against normal cells suggesting a specific action of this material against target cancer cells. The results reported here allow ranks β-CD/CUR-MBN as a promising biomaterial to act as a local drug delivery system to treat cancer.

A new characterization methodology for starch gelatinization

A gelatinization degree control system, with a combination of Artificial Neural Networks (ANNs) and computer vision, was successfully developed. An intelligent measurement framework was purposely designed to achieve a precise investigation on phase transition and morphology change of starch in real time, as well as a process control during gelatinization. Base on a variation of birefringence number, the degree of gelatinization (DG) control system provided a direct and fast methodology without subjective uncertainty in studying starch gelatinization. In the course, the whole system was a cascade structure with the hot-stage temperature chosen as the inner-loop parameter, thus the granule morphology and birefringence at different DG could be easily observed and compared in real time, and the relative transition temperature was simultaneously calculated.