Effect of ultrasound pretreatment on enzymolysis and physicochemical properties of corn starch

Enhancing enzymatic resistance of starch through strategic application of food physical processing technologies

The demand for clean-label starch, perceived as environmentally friendly in terms of production and less hazardous to health, has driven the advancement of food physical processing technologies aimed at modifying starch. One of the key objectives of these modifications has been to reduce the glycaemic potency and increase resistant starch content of starch, as these properties have the potential to positively impact metabolic health. This review provides a comprehensive overview of recent updates in typical physical processing techniques, including annealing, heat-moisture, microwave and ultrasonication, and a brief discussion of several promising recent-developed methods. The focus is on evaluating the molecular, supramolecular and microstructural changes resulting from these modifications and identifying targeted structures that can foster enzyme-digestion resistance in native starch and its forms relevant to food applications. After a comprehensive search and assessment, the current physical modifications have not consistently improved starch enzymatic resistance. The opportunities for enhancing the effectiveness of modifications lie in (1) identifying modification conditions that avoid the intensive disruption of the granular and supramolecular structure of starch and (2) exploring novel strategies that incorporate multi-type modifications.

Ultrasound-assisted annealing treatment to improve physicochemical and digestive properties of banana flour

BACKGROUND

Banana flour can provide a solution to people with gluten intolerance, as it is gluten-free. Native banana flour may have limited functionality in certain applications. In this study, banana flour was modified by ultrasonic (US) and annealing (ANN) treatments at four incubation time spans, namely 12, 24, 36 and 72 h, separately or combined sequentially (US-ANN) to enhance the physicochemical and digestive properties.

RESULTS

US led to exposed granular surfaces and damaged non-starch components. Both treatments, at extended incubation time, increased crystallinity, resulting in a narrower starch gelatinization temperature range. The swelling power was significantly lower for ANN and US-ANN compared to US alone, providing a delay of gelatinization temperature. However, none of the treatments affected the gelatinization enthalpy. Furthermore, US increased peak viscosity, breakdown, final viscosity and setback whereas the opposite results were obtained for ANN and US-ANN. Additionally, US prior to ANN significantly increased the resistant starch (RS) content for annealing times over 24 h, especially for the US-ANN treatment for 72 h, which provided the highest RS content (49.3%) compared to ANN treatment for 72 h (44.0%) and native flour (36.3%).

CONCLUSIONS

US prior to ANN treatment offers an alternative method to improve the functional and digestive properties of banana flour, extending the range of applications. © 2024 Society of Chemical Industry.

Enhanced flexibility of high-yield bamboo pulp fibers via cellulase immobilization within guar gum/polyacrylamide/polydopamine interpenetrating network hydrogels

Softness is a crucial criterion in assessing the comfort and usability of tissue paper. Flexible fibers contribute to the softness of the tissue paper by allowing the sheets to conform to the contours of the skin without feeling rough or abrasive. This study focuses on developing innovative CGG/APAM/PDA hydrogels with interpenetrating networks consisting of cationic guar gum, anionic polyacrylamide, and polydopamine for cellulase immobilization, aimed at improving bamboo fiber flexibility. Cellulase biomolecules are efficiently immobilized on CGG/APAM/PDA hydrogels through the Schiff base reaction. Immobilized cellulases have a wider pH applicability than free cellulases, good storage stability, and can maintain high relative activity at relatively high temperatures. The treatment of bamboo fibers with immobilized cellulase results in a significant increase in flexibility, reaching 6.90 × 1014 N·m2, which is 7.18 times higher than that of untreated fibers. The immobilization of cellulases using CGG/APAM/PDA hydrogels as carriers results in a substantial enhancement of storage stability, pH applicability, and inter-fiber bonding strength, as well as the capacity to sustain high relative enzymatic activity at elevated temperatures. The immobilization of cellulase within CGG/APAM/PDA interpenetrating network hydrogels presents a viable strategy for enhancing bamboo fiber flexibility, thereby expanding the accessibility of tissue products.

Effects of plasma-activated water combined with ultrasonic treatment of corn starch on structural, thermal, physicochemical, functional, and pasting properties

In this study, corn starch was used as the raw material, and modified starch was prepared using a method combining plasma-activated water and ultrasound treatment (PUL). This method was compared with treatments using plasma-activated water (PAW) and ultrasound (UL) alone. The structure, thermal, physicochemical, pasting, and functional properties of the native and treated starches were evaluated. The results indicated that PAW and UL treatments did not alter the shape of the starch granules but caused some surface damage. The PUL treatment increased the starch gelatinization temperature and enthalpy (from 11.22 J/g to 13.13 J/g), as well as its relative crystallinity (increased by 0.51 %), gel hardness (increased by 16.19 %) compared to untreated starch, without inducing a crystalline transition. The PUL treatment resulted in a whitening of the samples. The dual treatment enhanced the thermal stability of the starch paste, which can be attributed to the synergistic effect between PAW and ultrasound (PAW can modify the starch structure at a molecular level, while ultrasound can further disrupt the granule weak crystalline structures, leading to improved thermal properties). Furthermore, FTIR results suggested significant changes in the functional groups related to the water-binding capacity of starch, and the order of the double-helical structure was disrupted. The findings of this study suggest that PUL treatment is a promising new green modification technique for improving the starch structure and enhancing starch properties. However, further research is needed to tailor the approach based on the specific properties of the raw material.

Ultrasonication: An Efficient Alternative for the Physical Modification of Starches, Flours and Grains

Ultrasonic (USC) treatments have been applied to starches, flours and grains to modify their physicochemical properties and improve their industrial applicability. The extent of the modification caused by USC treatment depends on the treatment conditions and the natural characteristics of the treated matter. Cavitation leads to structural damage and fragmentation and partial depolymerization of starch components. The amorphous regions are more susceptible to being disrupted by ultrasonication, while the crystalline regions require extended USC exposure to be affected. The increased surface area in USC-treated samples has a higher interaction with water, resulting in modification of the swelling power, solubility, apparent viscosity, pasting properties and gel rheological and textural properties. Starch digestibility has been reported to be modified by ultrasonication to different extents depending on the power applied. The most important treatment variables leading to more pronounced modifications in USC treatments are the botanical origin of the treated matter, USC power, time, concentration and temperature. The interaction between these factors also has a significant impact on the damage caused by the treatment. The molecular rearrangement and destruction of starch structures occur simultaneously during the USC treatment and the final properties of the modified matrix will depend on the array of treatment parameters. This review summarizes the known effects of ultrasonic treatments in modifying starches, flours and grains.

Highly Efficient Production of Cellulosic Ethanol from Poplar Using an Optimal C6/C5 Co-Fermentation Strain of Saccharomyces cerevisiae

Cellulosic ethanol is the key technology to alleviate the pressure of energy supply and climate change. However, the ethanol production process, which is close to industrial production and has a high saccharification rate and ethanol yield, still needs to be developed. This study demonstrates the effective conversion of poplar wood waste into fuel-grade ethanol. By employing a two-step pretreatment using sodium chlorite (SC)-dilute sulfuric acid (DSA), the raw material achieved a sugar conversion rate exceeding 85% of the theoretical value. Under optimized conditions, brewing yeast co-utilizing C6/C5 enabled a yield of 35 g/L ethanol from 10% solid loading delignified poplar hydrolysate. We increased the solid loading to enhance the final ethanol concentration and optimized both the hydrolysis and fermentation stages. With 20% solid loading delignified poplar hydrolysate, the final ethanol concentration reached 60 g/L, a 71.4% increase from the 10% solid loading. Our work incorporates the pretreatment, enzymatic hydrolysis, and fermentation stages to establish a simple, crude poplar waste fuel ethanol process, expanding the range of feedstocks for second-generation fuel ethanol production.

Ultrasonication followed by aqueous two-phase system for extraction, on-site modification and isolation of microalgal starch with reduced digestibility

Microalgae are new and sustainable sources of starch with higher productivity and flexible production modes than conventional terrestrial crops, but the downstream processes need further development. Here, ultrasonication (with power of 200 W or 300 W and duration of 10, 15, 20, or 25 min) was applied to simultaneously extract and modify starch from a marine microalga Tetraselmis subcordiformis for reducing the digestibility, and an aqueous two-phase system (ATPS) of ethanol/NaH2PO4 was then used to isolate the starches with varied properties. Increasing ultrasonic duration facilitated the partition of starch into the bottom pellet, while enhancing the ultrasonic power was conducive to the allocation in the interphase of the ATPS. The overall starch recovery yield reached 73 ∼ 87 % and showed no significant difference among the ultrasonic conditions tested. The sequential ultrasonication-ATPS process successfully enriched the starch with purities up to 65 % ∼ 88 %, which was among the top levels reported in microalgal starch isolated. Ultrasonication produced more amylose which was mainly fractionated into the interface of the ATPS. The digestibility of the starch was altered under different ultrasonic conditions and varied from different ATPS phases as well, with the one under the ultrasonic power of 200 W for 15 min at the bottom pellet having the highest resistant starch content (RS, 39.7 %). The structural and compositional analysis evidenced that the ultrasonication-ATPS process could exert impacts on the digestibility through altering the surface roughness and fissures of the starch granules, modulating the impurity compositions (protein and lipid) that could interact with starch, and modifying the long- and short-range ordered structures. The developed ultrasonication-ATPS process provided novel insights into the mechanism and strategy for efficient production of functional starch from microalgae with a potential in industrial application.

Physicochemical properties and in vitro digestibility of ginseng starches under citric acid-autoclaving treatment

In this study, the effects of citric acid-autoclaving (CA-A) treatment on physicochemical and digestive properties of the native ginseng starches were investigated. The results showed that ginseng starch exhibited a B-type crystal structure with a low onset pasting temperature of 44.23 ± 0.80 °C, but high peak viscosity and setback viscosity of 5897.34 ± 53.72 cP and 692.00 ± 32.36 cP, respectively. The granular morphology, crystal and short-range ordered structure of ginseng starches were destroyed after CA-A treatment. The more short-chain starches were produced, resulting in the ginseng starches solubility increased. In addition, autoclaving, citric acid (CA) and CA-A treatment promoted polymerization and recrystallization of starch molecules, increased the proportion of amylopectin B1, and B3 chains, and improved molecular weight and resistant starch (RS) content of ginseng starches. The most significant multi-scale structural change was induced by CA-A treatment, which reduced the relative crystallinity of ginseng starch from 28.26 ± 0.24 % to 2.75 ± 0.08 %, and increased the content of RS to 54.30 ± 0.14 %. These findings provided a better understanding of the structure and properties of Chinese ginseng starches and offered new ideas for the deep processing of ginseng foods.

Impact of ultrasound treatment on the physicochemical and rheological properties of acid hydrolyzed sorghum starch

The present study aimed to evaluate the influence of ultrasonication on the physicochemical properties of native and acid-hydrolyzed white sorghum starch. Sorghum starch exhibited improved freeze-thaw stability, solubility, swelling power, and paste clarity after mild sonication. Starches sonicated at 30 % amplitude for 10 and 20 min increased the peak viscosity to 249 and 240 BU, gel firmness to 140.23 and 131.62 (g), ΔH to 13.4 and 13.1 (J/g), crystallinity to 29.51 and 29.10 (%), double helix content to 1.11 and 1.07 and degree of ordered structures to 1.16 and 1.09. The sonicated dual-treated samples (sonicated-acid hydrolyzed) exhibited reduced swelling power, peak viscosity, gelatinization temperatures and gel firmness. In contrast, the solubility, paste clarity, ΔH, percentage of crystallinity, double helix content and degree of ordered structures improved. Ultrasonic treatment made cracks and holes in the granule surface, whereas dual-treated starches were more porous and rougher, with deep depressions. All sorghum starches displayed shear-thinning behavior (n < 1). The pseudoplastic behavior and consistency indices of the starch paste decreased with increasing sonication time and amplitude. The G' was always higher than G" and tanδ was <1 for all samples, indicating a more solid/elastic behavior. The increased sonication time and amplitude, as well as the dual-treatment, caused the gel to become more susceptible to shear forces, which resulted in a decrease in G' and G" and an increase in tanδ.

Lotus starch/bamboo shoot polysaccharide composite system treated via ultrasound: Pasting, gelling properties and multiscale structure

This study investigated the effects of ultrasound treatment on the physicochemical properties, digestion properties, and multiscale structure of a lotus root starch (LS) and bamboo shoot polysaccharide (BSP) composite system. It also preliminarily revealed the mechanism underlying the modification effect of ultrasound treatment. After 180-360 W ultrasound treatment, the viscosity, thixotropy, and gel viscoelasticity of the LS/BSP paste increased. However, treatment with the ultrasound power of 540 and 720 W decreased viscoelasticity. After 14 days of retrogradation, the hardness and cohesiveness of the LS/BSP gel increased under 180 and 360 W ultrasound treatment but decreased under 540 and 720 W ultrasound treatment. After 540 W ultrasound treatment, RDS content decreased by 17.2 % and resistant starch content increased by 32.5 %. After 180 min of in vitro digestion, the hydrolysis rate of LS/BSP decreased from 97.82 % to 93.13 % as the ultrasound power increased to 540 W. Ultrasound promoted the uniform dispersion of BSP in the starch paste and the movement, orientation, rearrangement, and aggregation of starch and BSP molecular chains. These effects further enhanced the interaction between BSP and starch, resulting in the formation of a dense paste structure with strong resistance to digestive enzymes. This work revealed the mechanism of the effects of ultrasound treatment on LS/BSP and found that 360-540 W ultrasound treatment could improve the physicochemical properties and digestion properties of LS/BSP.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Insights into the structural characteristics and in vitro starch digestibility on parboiled rice as affected by ultrasound treatment in soaking process

This study investigated ultrasound treatment as a protective parboiling technology for producing low GI rice. Indica and Japonica rice with different amylose contents were subjected to different ultrasound times (15 min, 30 min, and 60 min) and amplitudes (30, 60, and 100%) under soaking conditions for parboiling applications. Starch granules merged and lost their shape when ultrasound treatment time and amplitudes were increased up to 15 min and 30%, respectively. It increased the crystallinity, gelatinization temperatures and decreased pasting viscosity, promoting more resistant starch. The predicted glycemic index (GI) was reduced from 62.9 and 57.6 to 51.3 and 47.1 for Japonica and Indica, respectively. These results suggested that ultrasound soaking is a promising physical method to produce parboiled rice with a lower GI by promoting the formation of amylose chains and decreasing enzyme penetration efficiency.

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.

Effect of ultrasound-microwave and microwave-ultrasound treatment on physicochemical properties of corn starch

Natural starch is an agricultural sourced biopolymer being low cost, biodegradable, high efficiently, renewable and easy available. Despite these advantages, phisochemical properties of native starch are limited for most industrial applications and must be modified. Ultrasound and microwave treatment have been widely applied separately for starch modification. Ultrasound treatment, with high efficiency and low cost, and microwave treatment, which produces homogeneous and high quality products, are short proceesing time technologies that can be used together to change the structure and properties of starches obtained from various plants. In this study the effects of ultrasound and microwave combined treatment on the physicochemical properties of natural corn starch were investigated. Corn starch was irritated using different combination of ultrasound-microwave and microwave-ultrasound treatment; using 90, 180, 360 and 600 W microwave power during 1, 2, 3 min, and using ultrasound at 35 °C constant temperature for 20, 30, 40 min. The structural changes of modified corn starches were determined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analyses. Nowadays, many physical methods are used for starch modification, but limited studies were on ultrasound-microwave and microwave-ultrasound combined treatment method. As a result of this study, it was observed that ultrasound and microwave combination is an efficient, fast and environmentally friendly method for natural corn starch modification.

Characterization of hawthorn pectin gained via different ethanol concentrations

Pectin is identified as an effective delivery material due to its excellent gel-forming ability, low immunogenic properties, biocompatibility, and biodegradability. These excellent properties depend on the preparation method of pectin. In the study, four pectin fractions (named: CAHP30, CAHP40, CAHP50, and CAHP60, respectively) were obtained by different ethanol precipitations (30%, 40%, 50%, and 60%). Physicochemical properties, antioxidant activity, and emulsifying ability of HP were investigated and analyzed. Results showed that the surface structure of pectin was changed by ethanol fractional precipitation, and four fractions were low methoxy pectin. They had different monosaccharide compositions, but all rich in GalA. The Mw/Mn of CAHP30, CAHP40, CAHP50, and CAHP60 were 3.29, 2.57, 2.66, and 2.77, respectively. CAHP30 and CAHP60 had excellent emulsifying ability; moreover, CAHP60 was endowed with additional lipid antioxidant capacity and had the best thermal stability. E-CAHP40 exhibited a property between the entangled network structure. Overall, pectin with specific properties could be obtained by different ethanol concentrations.

Different multi-scale structural features of oat resistant starch prepared by ultrasound combined enzymatic hydrolysis affect its digestive properties

In this research, oat resistant starch (ORS) was prepared by autoclaving-retrogradation cycle (ORS-A), enzymatic hydrolysis (ORS-B), and ultrasound combined enzymatic hydrolysis (ORS-C). Differences in their structural features, physicochemical properties and digestive properties were studied. Results of particle size distribution, XRD, DSC, FTIR, SEM and in vitro digestion showed that ORS-C was a B + C-crystal, and ORS-C had a larger particle size, the smallest span value, the highest relative crystallinity, the most ordered and stable double helix structure, the roughest surface shape and strongest digestion resistance compared to ORS-A and ORS-B. Correlation analysis revealed that the digestion resistance of ORS-C was strongly positively correlated with RS content, amylose content, relative crystallinity and absorption peak intensity ratio of 1047/1022 cm^-1 (R_1047/1022), and weakly positively correlated with average particle size. These results provided theoretical support for the application of ORS-C with strong digestion resistance prepared by ultrasound combined enzymatic hydrolysis in the low GI food application.

Structural and physicochemical properties of resistant starch under combined treatments of ultrasound, microwave, and enzyme

The structural characteristics and physicochemical properties of native corn starch (NCS) and resistant starch (RS) prepared by enzymatic hydrolysis (RS-E), microwave-enzymatic hydrolysis (RS-ME), ultrasound assisted enzymatic hydrolysis (RS-UE), and microwave-ultrasound assisted enzymatic hydrolysis (RS-MUE) were investigated. The results showed that the combined treatments of ultrasound, microwave, and enzyme resulted in increases in RS content, amylose content, and solubility with a decrease in swelling power. RS-MUE exhibited the lowest digestibility, with a 41.71 % RS content. Particle-size distribution and scanning electron microscopy analyses demonstrated that RS samples exhibited larger granule sizes and rougher surfaces with irregular shapes. The Fourier transform infrared spectroscopy and X-ray diffraction pattern analysis demonstrated that no new groups were created during the modification processes, the crystal structure of all RS samples changed from A to B + V, and the short-range order and relative crystallinity of RS-E, RS-ME, RS-UE, and RS-MUE increased. RS-MUE exhibited the highest molecular order R_1047/1022 value (0.8769) and relative crystallinity (45.54 %). These results suggested that the new technology combining microwave, ultrasound, and enzyme for improving RS content is effective and has potential for application in the production of RS and low glycemic index foods.

In-situ and real-time monitoring of two-stage enzymatic preparation of ACE inhibitory peptides from Cordyceps militaris medium residues by ultrasonic-assisted pretreatment

A protocol for the preparation of angiotensin-Ⅰ-converting enzyme (ACE) inhibitory peptides from Cordyceps militaris medium residues (CMMR) was established by two-stage enzymatic hydrolysis (amylase and protease). In a combination (mono-, dual-, and tri-frequency) of five different frequencies (20, 28, 35, 40 and 50 kHz), ultrasound-assisted pretreatment increased ACE inhibition rate in hydrolysate by 63.30 % under the mode of 20/28 kHz. Afterwards, near-infrared (NIR) spectrometer combined with spectral preprocessing methods and multivariate analysis like partial least square (PLS), synergy interval-PLS (Si-PLS), random frog-PLS (RF-PLS) and competitive adaptive reweighted sampling (CARS-PLS) was used to monitor the ACE inhibitory activity. The performance of models was evaluated by the correlation coefficient (R_p) and root mean square error (RMSEP). CARS-PLS models achieved optimal results for both amylase and protease hydrolysis with R_p = 0.9693, RMSEP = 0.01 for the former and R_p = 0.9454, RMSEP = 0.03 for the latter. NIR spectrometer combined with CARS-PLS models may be employed for in-situ and real-time monitoring of the preparation of ACE inhibitory peptides under ultrasonic-assisted pretreatment.

Designing liquefaction and saccharification processes of highly concentrated starch slurry: Challenges and recent advances

Starch-based sugars are an important group of starch derivatives used in food, medicine, chemistry, and other fields. The production of starch sugars involves starch liquefaction and saccharification processes. The production cost of starch sugars can be reduced by increasing the initial concentration of starch slurry. However, the usage of the highly concentrated starch slurry is characterized by challenges such as low reaction efficiency and poor product performance during the liquefaction and saccharification processes. In this study, we endeavored to provide a reference guide for improving high-concentration starch sugar production. Thus, we reviewed the effects of substrate concentration on the starch sugar production process and summarized several potential strategies. These regulation strategies, such as physical field pretreatment, complex enzyme-assisted, and temperature control, can significantly increase the starch concentration and mitigate the challenges of using highly concentrated starch slurry. We believe that highly concentrated starch sugar production will achieve a qualitative leap in the future. This review provides theoretical guidance and highlights the importance of high concentration in starch-based sugar production. Further studies are needed to explore the fine structure and enzyme attack mode during the liquefaction and saccharification processes to regulate the production of more targeted products.

Impact of Solubilized Substances on the Techno-Functional, Pasting and Rheological Properties of Ultrasound-Modified Rice, Tef, Corn and Quinoa Flours

The modification of flours by ultrasound (US) treatments requires excess water to suspend the sample to be treated, which must be removed after treatment to recover the ultrasonicated flour. The aim of this study was to determine the influence that the water removal method has on the final characteristics of US-treated gluten-free flours (rice, brown tef, corn and quinoa). US treatment parameters were constant, and two water removal methods were studied: freeze-drying and centrifugation + drying. The elimination of water by centrifugation resulted in the loss of solubilized compounds from the treated flours, which led to important differences between the final characteristics of US-treated flours. Ultrasonication resulted in the reduction of flours' particle size and modification of their color parameters. Techno-functional properties were modified by US treatment, where the water removal method was more influential in whole grain samples (brown tef and quinoa). Few differences were found in thermal properties among pairs of US-treated samples, indicative that the effect caused to starch was mainly attributed to ultrasonication conditions than to the drying method. The water removal method markedly influenced the pasting properties of US-treated flours, resulting in lower profiles when freeze-drying was applied and higher profiles when flours were retrieved by centrifugation. Gels made with tef, corn and quinoa presented reduced tan(δ)₁ values after sonication, while gels made with rice did not show any modification. The water removal method is a decisive step in US treatments, defining the final characteristics of the treated matter, and having a great influence in the modification attributed to ultrasonication.

Reduction of Aflatoxin B1 and Zearalenone Contents in Corn Using Power Ultrasound and Its Effects on Corn Quality

The degradation of aflatoxin B1 (AFB1) and zearalenone (ZEA) is investigated using power ultrasound to identify suitable methods to reduce the mycotoxin content of corn. AFB1 and ZEA in corn are simultaneously degraded via power ultrasound; thus, this method has a significant effect on corn quality. The power intensity, solid-liquid ratio, and ultrasonic treatment modes significantly affect the degradation rates of AFB1 and ZEA. The dissolution of AFB1 and ZEA in water also facilitates their degradation. At the initial stage of ultrasonic treatment, power ultrasound promotes the dissolution of mycotoxins in water, whereupon they are partially oxidized by free radicals. With a treatment time of 10 min, the reduction rates decreased owing to the dissolution of combined-state mycotoxins. After ultrasonic treatment, the contents of the essential amino acids, the total number of amino acids, and the fatty acids in corn decreased; however, ΔH values decreased during starch gelatinization. In contrast, the amylose content and viscosity of corn significantly increased during gelatinization. Therefore, this method is potentially suitable for the reduction of AFB1 and ZEA contents in corn.

Effect of ultrasound on the physical properties and processing of major biopolymers-a review

Designing and developing modern techniques to facilitate the extraction and modification of functional properties of biopolymers are key motivations among researchers. As a low-cost, sustainable, non-toxic, and fast process, ultrasound has been considered a method to improve the processing of carbohydrate and protein-based biopolymers such as cellulose, chitin, starch, alginate, carrageenan, gelatine, and guar gum. A better understanding of the complex physicochemical behavior of biopolymers under ultrasonication may fortify the eminence of this technology in advanced-level applications. This review summarizes the recent advances in biopolymer processing and the effect of ultrasound on the physical properties of the selected biopolymers. A major focus will be given to the mechanisms of action and their impact on the properties and extraction. At the end, some possible suggestions are highlighted which need future investigation for amending the physical properties of biopolymers using ultrasonication.

Physicochemical, structural, and digestive properties of pea starch obtained via ultrasonic-assisted alkali extraction

As a new and clean extraction technology, ultrasonic extraction has been demonstrated with great potential in the preparation of modified starch. In order to increase its added value, it is necessary to modify pea starch to enlarge its application. In this study, the efficiency of combining ultrasonic with alkali in the extraction of pea starch was evaluated and compared to conventional alkali extraction. Ultrasonic-assisted alkali extraction conditions were optimized using single-factor experiments and response surface methodology. The results revealed that maximum yield of pea starch (54.43 %) was achieved using ultrasound-assisted alkali extraction under the following conditions: sodium hydroxide solution with a concentration of 0.33 %, solid/alkali solution ratio of 1:6 (w/v), ultrasonic power of 240 W, temperature of 42 °C, and extraction time of 22 min. The ultrasound-assisted alkali extraction yielded 13.72 % greater pea starch than conventional alkali extraction. On the other hand, morphological, structural, and physicochemical properties of the obtained starch isolates were evaluated. The ultrasound-assisted alkali extraction resulted in pea starch with greater amylose content, water-solubility, swelling power, and viscosity compared with conventional alkali extraction. Furthermore, ultrasonication influenced the morphological properties of pea starch granules, while the molecular structure and crystal type were not affected. Moreover, the ultrasonic-assisted extraction produced starch with a slightly greater resistant starch content. Therefore, ultrasonic-assisted extraction can be suggested as a potential method for extracting pea starch with improved functional properties.

Modification in structural, physicochemical, functional, and in vitro digestive properties of kiwi starch by high-power ultrasound treatment

Kiwi starch (KS) is a fruit-derived starch; in order to improve its processing performance and increase its added value, it is necessary to modify KS to enhance the positive attributes and to enlarge its application. In this study, KS was modified by high-power ultrasound treatment (HUT) to reveal the relationship between the structure and function of KS with different treatment powers (0, 200, 400, and 600 W) and different treatment times (0, 10, 20, and 30 min). The results showed that HUT destroyed the granular morphology of KS, formed holes and cracks on the surface, and reduced the particle size and the short-range molecular order of KS. After different HUTs, the apparent amylose content (AAC), swelling power (SP), water solubility index (WSI), viscosity and setback value (SB) of KS were significantly increased, while the gelatinization temperature was significantly decreased. In addition, HUT significantly reduced the content of rapidly digestible starch (RDS) and slowly digestible starch (SDS), while it significantly enhanced the content of resistant starch (RS) (64.08-72.73%). In a word, HUT as a novel physical modification method for KS, enlarged its application, and fulfilled different demands of a starch-based product, which introduces another possibility for kiwi fruit further processing.

Impact of low-frequency ultrasound technology on physical, chemical and technological properties of cereals and pseudocereals

Cereals (CE) and pseudocereals (PSCE) play a pivotal role in nourishing the human population. Low-frequency ultrasound (LFUS) modifies the structure of CE and PSCE macromolecules such as starch and proteins, often improving their technological, functional and bioactive properties. Hence, it is employed for enhancing the traditional processes utilized for the preparation of CE- and PSCE-based foods as well as for the upcycling of their by-products. We report recent advances in LFUS treatments for hydration, germination, extraction of bioactive compounds from by-products, and fortification of CEs and PSCE, including kinetic modelling and underlying action mechanisms. Meta-analyses of LFUS influence on compounds extraction and starch gelatinization are also presented. LFUS enhances hydration rate and time lag phase of CE and PSCE, essential for germination, extraction, fermentation and cooking. The germination is improved by increasing hydration, releasing promoters and eliminating inhibitors. Furthermore, LFUS boosts the extraction of phenolic compounds, polysaccharides and other food components; modifies starch structure, affecting pasting properties; causes partial denaturation of proteins, improving their interfacial properties and their peptides availability. Overall, LFUS has an outstanding potential to improve transformation processes and functionalities of CE and PSCE.

Nonthermal physical modification of starch: An overview of recent research into structure and property alterations

To tailor the properties and enhance the applicability of starch, various ways of starch modification have been practiced. Among them, physical modification methods (micronization, nonthermal plasma, high-pressure, ultrasonication, pulsed electric field, and γ-irradiation) are highly potential for starch modification considering its safety, environmentally friendliness, and cost-effectiveness, without generating chemical wastes. Thus, this article provides an overview of the recent advances in nonthermal physical modification of starch and summarizes the resulting changes in the multi-level structures and physicochemical properties. While the effect of these techniques highly depends on starch type and treatment condition, they generally lead to the destruction of starch granules, the degradation of molecules, decreases in crystallinity, gelatinization temperatures, and viscosity, increases in solubility and swelling power, and an increase or decrease in digestibility, to different extents. The advantages and shortcomings of these techniques in starch processing are compared, and the knowledge gap in this area is commented on.

The multi-scale structure and physicochemical properties of mung bean starch modified by ultrasound combined with plasma treatment

Plasma is a simple, effective and promising food processing technology with great potential for starch modification. Mung bean starch was subjected to ultrasound (300 W, 10, 30 and 50 min), plasma (40 V, 1, 3 and 9 min) and the synergistic treatment, as well as investigating its effects on the morphology, chain length distribution, molecular weight, crystalline structure and physicochemical properties of starch. Ultrasound and plasma treatment did not change the granule shape, but caused some corrosions on the surface, and dual treatment increased the damage degree of starch granules surface. All treatments decreased the molecular weight (Mw), amylopectin long chains and crystallinity but increased the gelatinization temperatures and enthalpy. Different from ultrasound irradiation, single plasma treatment significantly reduced the swelling power and pasting viscosities. Furthermore, dual treatment increased the thermal stability of starch paste, owing to the reinforcement effect between ultrasound and plasma. Thus, dual modification displayed an excellent ability to modify starch with specific characteristics and expand the potential application of mung bean starch in the food industry.

Brain Delivery of Curcumin Through Low-Intensity Ultrasound-Induced Blood-Brain Barrier Opening via Lipid-PLGA Nanobubbles

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Owing to the presence of blood-brain barrier (BBB), conventional pharmaceutical agents are difficult to the diseased nuclei and exert their action to inhibit or delay the progress of PD. Recent literatures have demonstrated that curcumin shows the great potential to treat PD. However, its applications are still difficult in vivo due to its poor druggability and low bioavailability through the BBB.

Methods

Melt-crystallization methods were used to improve the solubility of curcumin, and curcumin-loaded lipid-PLGA nanobubbles (Cur-NBs) were fabricated through encapsulating the curcumin into the cavity of lipid-PLGA nanobubbles. The bubble size, zeta potentials, ultrasound imaging capability and drug encapsulation efficiency of the Cur-NBs were characterized by a series of analytical methods. Low-intensity focused ultrasound (LIFU) combined with Cur-NB was used to open the BBB to facilitate curcumin delivery into the deep brain of PD mice, followed by behavioral evaluation for the treatment efficacy.

Results

The solubility of curcumin was improved by melt-crystallization methods, with 2627-fold higher than pure curcumin. The resulting Cur-NBs have a nanoscale size about 400 nm and show excellent contrast imaging performance. Curcumin drugs encapsulated into Cur-NBs could be effectively released when Cur-NBs were irradiated by LIFU at the optimized acoustic pressure, achieving 30% cumulative release rate within 6 h. Importantly, Cur-NBs combined with LIFU can open the BBB and locally deliver the curcumin into the deep-seated brain nuclei, significantly enhancing efficacy of curcumin in the Parkinson C57BL/6J mice model in comparison with only Cur-NBs and LIFU groups.

Conclusion

In this work, we greatly improved the solubility of curcumin and developed Cur-NBs for brain delivery of curcumin against PD through combining with LIFU-mediating BBB. Cur-NBs provide a platform for these potential drugs which are difficult to cross the BBB to treat PD disease or other central nervous system (CNS) diseases.

Modification in physicochemical, structural and digestive properties of pea starch during heat-moisture process assisted by pre- and post-treatment of ultrasound

Ultrasound is increasingly used for physicochemical modification of food systems as a green technology. Effects of heat-moisture treatment (HMT) assisted by pre- and post-treatment of ultrasound on physicochemical, structural and digestive properties of pea starch was investigated. Pea starch maintained the original morphology and C-type of crystalline after ultrasound treatment (UT), but 4 h or more of HMT and HMT assisted by UT changed the crystalline from C-type to A-type. All treatments decreased the crystallinity, molecular weight, swelling power and solubility at 70-90 °C, and elevated the content of resistant starch. Moreover, HMT assisted by pretreatment of UT was found to increase the viscosity and high-temperature stability of starch paste compared with others by the orderly combined effect of UT-induced depolymerization and HMT-induced depolymerization and rearrangement of starch chains. These results may promote the appropriate use of ultrasound in food industries and the production of starch materials for potential applications.

Resistant starch type 2 from lotus stem: Ultrasonic effect on physical and nutraceutical properties

Resistant starch type 2 (RS) was isolated from lotus stem using enzymatic digestion method. The isolated RS was subjected to ultrasonication (US) at different sonication power (100-400 W). The US treated and untreated RS samples were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), light microscopy and Fourier transform infrared spectroscopy (FT-IR). DLS revealed that particle size of RS decreased from 12.80 µm to 413.19 nm and zeta potential increased from -12.34 mV to -26.09 mV with the increase in sonication power. SEM revealed smaller, disintegrated and irregular shaped RS particles after ultrasonication. FT-IR showed the decreased the band intensity at 995 cm-1 and 1047 cm-1 signifying that US treatment decreased the crystallinity of RS and increased its amorphous character. The bile acid binding, anti-oxidant and pancreatic lipase inhibition activity of samples also increased significantly (p < 0.05) with the increase in sonication power. Increase in US power however increased the values of hydrolysis from 23.11 ± 1.09 to 36.06 ± 0.13% and gylcemic index from 52.39 ± 0.38 to 59.50 ± 0.11. Overall, the non-thermal process of ultrasonic treatment can be used to change the structural, morphological and nutraceutical profile of lotus stem resistant starch which can have great food and pharamaceutical applications.

Impact of thermo-sonication on quality indices of starch-based sauces

In this study, ultrasonication, a physical, relatively cheap, and environmentally benign technology, was investigated to characterize its effect on functional properties of rice starch and rice starch-based sauces. Temperature-assisted ultrasound treatment improved the granular swelling power, fat and water absorption capacities, and thermal properties of rice starch, signifying its suitability in the formulation of starch-based sauces. Rheological characterization of the formulated sauces revealed a shear-thinning flow behavior, well described by the Ostwald de Waele model, while viscoelastic properties showed the existence of a weak gel. Results indicated that ultrasonication significantly enhanced the pseudoplastic behavior of starch-based sauces. Additionally, textural analysis showed that textural attributes (stickiness, stringiness, and work of adhesion) were also improved with ultrasonication. Moreover, enhanced freeze/thaw stability was also achieved with ultrasound-treated starch-based sauces. Overall, the results from this study show that ultrasound-treated starches can be used in the formulation of sauces and potentially other food products, which meets the requirements for clean label and minimally processed foods.

Ultrasound-assisted acid hydrolysis of cassava (Manihot esculenta) bagasse: Kinetics, acoustic field and structural effects

Improving the actual acid hydrolysis of cassava bagasse (CB) with the assistance of high-intensity ultrasound (US) was aimed in comparison with mechanical agitation (AG). The kinetics of reducing and total sugar release were mathematically modeled. The acoustic field characterization and apparent viscosity of the suspensions were correlated. Moreover, microscopic analyses (visible, fluorescence and polarized light) were carried out to identify changes produced by the treatments. Both AG and US-treatments showed themselves to be effective at hydrolyzing CB. However, US-experiments reached equilibrium in the reducing sugar release process earlier and obtained slightly higher values of total sugars released. The Naik model fitted the experimental data with good accuracy. A greater loss in the birefringence of the starch granules and the degradation of lignocellulosic matter was also observed in US-assisted hydrolysis. The actual acoustic power applied was reduced after hydrolysis, probably due to the increase in the apparent viscosity of the resulting suspensions.

Dextran degradation by sonoenzymolysis: Degradation rate, molecular weight, mass fraction, and degradation kinetics

To study dextran degradation by sonoenzymolysis, the degradation rate, the change of molecular weight, the mass fractions of fragments of certain molecular weight, and the degradation kinetics were analyzed and compared with the corresponding parameters under ultrasonic and enzymolysis treatments. The degradation rate improved greatly and the time required to stabilize the rate was shortened compared with ultrasonic treatment, for example, more than 120 min was needed at 4 W/mL for ultrasonic treatment before stabilization with the degradation rate of 77.41%, whereas 80 min was needed for sonoenzymolysis treatment with the degradation rate of 91.44%. A lower molecular weight limit was established (7.15 × 10⁴ Da at 4 W/mL for sonoenzymolysis treatment compared with 19.61 × 10⁴ Da at 4 W/mL for ultrasonic treatment), with decreased time to approach the new limiting molecular weight (80 min compared with more than 120 min). The mass fraction of 10⁴-10⁵ Da fragment increased (61.02% at 4 W/mL for sonoenzymolysis treatment compared with 42.98% at 4 W/mL for ultrasonic treatment) and the dextran degradation kinetics for sonoenzymolysis under lower ultrasonic intensity fitted the Malhotra model well. Sonoenzymolysis treatment at the ultrasonic intensity of 4 W/mL for 80 min resulted in more 10⁴-10⁵ Da fragments in a shorter time. The results indicated that sonoenzymolysis can be applied as an efficient method to obtain clinical dextran.

Effect of drying treatment on the structural characterizations and physicochemical properties of starch from canistel (Lucuma nervosa A.DC)

This work investigated the effects of hot air drying pretreatment (HAD), freeze drying pretreatment (FD) and vacuum drying pretreatment (VD) on the physicochemical properties and structural characterizations of starch isolated from canistels. X-ray diffraction displayed that the starches separated from canistel by different drying pretreatments showed a typical A-type crystal structure. The SEM image showed that cracks and debris appeared on the surface of HVD and VD particles. The molecular structure of starches obtained by different drying pretreatments was studied using Fourier infrared and solid state ¹³C CP/MAS NMR analysis. The results indicated that vacuum drying pretreatment could promote the formation of the double helix of starch granules, and hot air drying and freeze drying destroyed the ordered structure of starch granules. These structural changed to affect the physicochemical properties of starch granules. The study of different drying pretreatments to separate starches provided practical value for drying pretreatments. Furthermore, the current study affords information for canistel starches cultivated in China that would be convenient for commercial applications.

Determination of the effect of high energy ultrasound application in tempering on flour quality of wheat

This research has been carried out under laboratory conditions. To determine the effect of soaking with ultrasound application to dampen hard wheat samples at one stage in tempering process was the prior goal. In the experiments, Bezostaya-1 wheat samples in different hardness levels (45, 65 and 75%) are used as material. The milling quality and qualitative properties of the flour were investigated. Results compared with the classic tempering process which has two stages tempering for hard and semi-hard wheat at the industrial applications. Ultrasonication of the samples has been applied by a probe-type ultrasound device. Because of experimental deviations, inevitable positive effect of ultrasonic tempering had not seen in the quality parameters of milling experiments like flour yield and energy consumption. But tempering with ultrasound application increased the speed of water intake and diffusion into the grain center. In the study, the wet gluten rates of the flour obtained by classical tempering process were 24.52% and the gluten index rate was 87.17%, while the results obtained by ultrasonic tempering were 22.70% and 93.33%, respectively. Thus it raised flour quality a little, possibly, due to low amount but better quality gluten coming from central endosperm in the flour obtained. Other analysis results in flour showed significant differences in some values of classical and ultrasonic tempering processes. As a result of ultrasonic tempering, the fineness rate (granulation) increased from 73.27% to 79.77%, ash content decreased from 0.61% to 0.55%, Zeleny sedimentation value decreased from 25.0 mL to 23.67 mL, flour stability increased from 9.76 min to 12.06 min, water absorption 59.1% decreased from 61.28%, softening resistance increased from 400.33 BU to 504.50 BU, maximum resistance increased from 420.50 BU to 536.16 BU. In bread trials, bread volume increased from 328.3 mL to 347.3 mL, and specific volume increased from 2.39 mL / g to 2.57 mL / g. These issues have been confirmed by some analysis such as fine granulation, low ash content, high gluten index, some farinogram, and extensigram properties, and finally better performance in bread making was observed.

Modification methods toward the production of porous starch: a review

Starch is a complex carbohydrate formed by the repeating units of glucose structure connected by the alpha-glycosidic linkages. Starch is classified according to their derivatives such as cereals, legumes, tubers, palms, fruits, and stems. For decades, native starch has been widely utilized in various applications such as a thickener, stabilizer, binder, and coating agent. However, starches need to be modified to enhance their properties and to make them more functional in a wide range of applications. Porous starch is a modified starch product which has attracted interest of late. It consists of abundant pores that are distributed on the granule surface without compromising the integrity of its granular structure. Porous starch can be produced either by enzymatic, chemical, and physical methods or a combination thereof. The type of starch and selection of the modification method highly influence the formation of pore structure. By carefully choosing a suitable starch and modification method, the desired morphology of porous starch can be produced and applied accordingly for its intended application. Innovations and technologies related to starch modification methods have evolved over the years in terms of the structure, properties and modification effects of different starch varieties. Therefore, this article reviews recent modification methods in developing porous starch from various origins.

Effects of high power ultrasound on the enzymolysis and structures of sweet potato starch

BACKGROUND

The general enzymatic method for producing reducing sugar is liquefaction followed by saccharification of starch. This method results in lower yields, consuming high energy and time. Therefore, the present study evaluated a new approach for producing reducing sugar from sweet potato starch (SPS), including simultaneous liquefaction (by α-amylase) and saccharification (by glucoamylase) of SPS pretreated with high power ultrasound. The effects of ultrasound parameters on the conversion rate of SPS and mechanism were investigated.

RESULTS

The optimum ultrasound pretreatment conditions were a frequency of 20 kHz, SPS concentration of 125 g L^-1 , temperature of 30 °C, pulsed on-time of 3 s, pulsed off-time of 5 s, power density of 8 W mL^-1 and sonication time of 15 min. The ultrasound assisted enzymolysis resulted in a SPS conversion rate of 59.10%, which was improved by 56.35% compared to the control. The results of pasting properties and thermal analysis showed that ultrasound pretreatment decreased the peak viscosity, breakdown temperature, setback viscosity, gelatinization range (T_C  - T_O ) and enthalpy of gelatinization (ΔH) of SPS significantly (P < 0.05) by 12.1%, 7.6%, 6.6%, 18.8% and 44.4%, respectively. Fourier-transform infrared spectroscopy indicated that ultrasound damaged the ordered structures and crystallization zone. This was confirmed by X-ray diffraction analysis, which showed that the relative crystallinity was reduced by 15.0%. Scanning electron microscopy showed that ultrasound destroyed the surfaces and the linkages between starch granules.

CONCLUSION

Prior to simultaneous liquefaction and saccharification of SPS, high power ultrasound pretreatment is a promising method for improving the conversion rate of starch. © 2020 Society of Chemical Industry.