The promoted hydrolysis effect of cellulase with ultrasound treatment is reflected on the sonicated rather than native brown rice

Brown rice is nutritionally superior to polished white rice, as it maintains a large content of external bran that involves a series of bioactive compounds. However, the presence of bran also restricts water diffusion and results in adverse quality of brown rice. In this work, ultrasound conditions were optimized for cellulase to improve its hydrolysis effect on rice bran, and combinations of enzymatic and ultrasound treatment in different manners were conducted on brown rice, to improve the textural attributes. The results showed significant improvements in the catalytic activity and efficiency of cellulase after ultrasonication at the optimal intensity of 1.67 W cm⁻³ and duration of 30 min, with the conformational variation of cellulase observed from the fluorescence spectra and circular dichroism (CD). Despite the enhanced activity of ultrasonicated cellulase, it leaded to a similar rice surface morphology and a comparable amount of released glucose, and equivalent textural parameters of brown rice treated by native cellulase. However, for the pre-sonicated brown rice, the ultrasonicated cellulase showed a significantly higher hydrolysis capacity than the untreated enzyme, suggesting the important influence of ruptured bran surface on amplifying the hydrolysis effect of cellulase. Compared to the successive ultrasound stimulation on both cellulase and brown rice, ultrasound-assisted cellulase treatment on brown rice produced less glucose from rice bran, but induced similar textural properties of brown rice, possibly resulting from the simultaneously promoting effect of ultrasonication on cellulase and water diffusion. Ultimately, this study highlighted that the mild rice surface rupture is a crucial factor to display the promoted hydrolysis effect of ultrasonicated cellulase on brown rice. Ultrasound-assisted cellulase treatment potentially provides an effective strategy to improve the edible quality of brown rice.     

Effect of ultrasound on structural and physicochemical properties of sweetpotato and wheat flours

Ultrasound technologies are increasingly used for modification of physicochemical properties of food systems. Effects of ultrasound (20 kHz, 750 W) up to 20 h on physicochemical properties of two varieties of sweetpotato flour were studied and compared with those of commercial wheat flour. Ultrasound induced structural modifications on starch granules mainly in the morphological changes of granules and reduction of the crystallinity. Longer treatment significantly decreased enthalpy change of gelatinization, pasting viscosities, gelling capacity, while increasing in vitro starch digestibility of raw flour. Besides, prolonged treatment reduced total phenolic contents and in vitro antioxidant activities of sweetpotato flours, mainly due to pyrolysis and release of hydroxyl radicals caused by cavitation. The extents of these changes were seen to depend on the treatment time and indicated degradation and modifications of the chemical components (e.g., starch and polyphenol) of flours. This study suggests that ultrasound processing as a non-thermal and energy-saving technique has potential to modify flour functionalities.     

Structural and physicochemical properties of lotus seed starch nanoparticles prepared using ultrasonic-assisted enzymatic hydrolysis

Lotus seed starch nanoparticles were prepared by ultrasonic (ultrasonic power: 200 W, 600 W, 1000 W; time: 5 min, 15 min, 25 min; liquid ratio (starch: buffer solution): 1%, 3%, 5%) assisted enzymatic hydrolysis (LS-SNPs represent lotus seed starch nanoparticles prepared by enzymatic hydrolysis and U-LS-SNPs represent lotus seed starch nanoparticles prepared by high pressure homogenization-assisted enzymatic hydrolysis). The structure and physicochemical properties of U-LS-SNPs were studied by laser particle size analysis, scanning electron microscope, X-ray diffraction, Raman spectroscopy, nuclear magnetic resonance and gel permeation chromatography system. The results of scanning electron microscopy showed that the surface of U-LS-SNPs was cracked and uneven after ultrasonic-assisted enzymolysis, and there was no significant difference from LS-SNPs. The results of particle size analysis and gel permeation chromatography showed that the particle size of U-LS-SNPs (except 5% treatment group) was smaller than that of LS-SNPs. With the increase of ultrasonic power and time, the weight average molecular gradually decreased. The results of X-ray diffraction and Raman spectroscopy showed that ultrasonic waves first acted on the amorphous region of starch granules. With the increase of ultrasonic power and time, the relative crystallinity of U-LS-SNPs increased first and then decreased. The group (600 W, 15 min, 3%) had the highest relative crystallinity. The results of nuclear magnetic resonance studies showed that the hydrogen bond and double helix structure of starch were destroyed by ultrasound, and the double helix structure strength of U-LS-SNPs was weakened compared with LS-SNPs. In summary, U-LS-SNPs with the small-sized and the highest crystallinity can be prepared under the conditions of ultrasonic power of 600 W, time of 15 min and material-liquid ratio of 3%.     

Ultrasound-chilling assisted annealing treatment to produce a lower glycemic index of white rice grains with different amylose content

White rice samples, Chai-Nat1 (CN1) and Jasmin rice (KDML105), were treated with the ultrasound-chilling (UC) and combined with annealing treatments (UC + ANN 45, UC + ANN50, and UC + ANN55). Their physicochemical properties and in vitro glycemic index of rice samples were analyzed. UC + ANN treatments presented pasting temperature, gelatinization temperature and crystallinity increased whereas the glycemic index of both rice samples was decreased as compared to its native. Especially, UC + ANN55 treated rice produced the lowest glycemic index and starch hydrolysis. Moreover, UC + ANN treated CN1 rice exhibited delayed gelatinization temperature, increased gelatinization enthalpy, and decreased glycemic index than KDML105 rice. In addition, Pearson’s correlation presented that UC + ANN and amylose content had a highly negative correlation with the glycemic index at p < 0.0.1. The result exhibited that UC followed by ANN show an effective way to modify starch granules with delayed starch hydrolysis reduced glycemic index and properties depending on annealing temperature and rice cultivar.     

Use of ultrasound for the determination of flour quality

Within the baking industry, the control of dough properties is required to achieve final product quality and consistency. Traditional methods for dough testing are slow and off-line and do not provide fundamental rheological information. There is therefore a need for the development of fast and on-line instruments capable of providing relevant data for baking. Ultrasonics provide a non-destructive, rapid and low cost technique for the measurement of physical food characteristics.In this work, the water content of dough is investigated using ultrasonic techniques. The capability of ultrasound measurements for discriminating flours for different purposes is also studied. Doughs from more than 30 flours were characterised rheologically using a Chopin Alveograph and a Brabender Extensograph. Ultrasound measurements on the doughs prepared from these flours were also performed. The measurements were correlated, showing that ultrasound was an alternative measurement method to discriminate types of flours for different purposes.     

Detection of Crude Protein,Crude Starch,and Amylose for Rice by Hyperspectral Reflectance

The contents of crude protein, crude starch, and amylose are three important indices to evaluate the nutrition and taste quality of rice. Studying the characteristics of crude protein, crude starch, and amylose of rice may provide a basis for monitoring rice quality by remote sensing. Different varieties and qualities of rice samples were selected through testing. The crude protein, crude starch, and amylose were extracted from rice. The hyperspectral reflectances of samples were measured for their crude protein, crude starch, and amylose as well as mixture with crude protein and crude starch by an Analytical Spectral Device FieldSpec Pro FR. The hyperspectral characteristics and their correlation with the contents of crude protein, crude starch, and amylose were analyzed. The results showed that the hyperspectral reflectance of crude protein was different from that of crude starch and amylose. Furthermore, the positions of peak and valley in the spectral curve of the mixture appeared “red shift” or “blue shift.” Nevertheless the contents (%) of crude protein, crude starch, and amylose in rice flour were significantly correlated to the absorbing area from 2020 to 2235 nm. The identified factors show a feasible method for monitoring rice quality by remote sensing.     

Combined ultrasound and germination treatment on the fine structure of highland barley starch

Highland barley is a grain crop grown in Tibet, China. This study investigated the structure of highland barley starch using ultrasound (40 kHz, 40 min, 165.5 W) and germination treatments (30℃ with 80% relative humidity). The macroscopic morphology and the barley's fine and molecular structure were evaluated. After sequential ultrasound pretreatment and germination, a significant difference in moisture content and surface roughness was noted between highland barley and the other groups. All test groups showed an increased particle size distribution range with increasing germination time. FTIR results also indicated that after sequential ultrasound pretreatment and germination, the absorption intensity of the intramolecular hydroxyl (–OH) group of starch increased, and hydrogen bonding was stronger compared to the untreated germinated sample. In addition, XRD analysis revealed that starch crystallinity increased following sequential ultrasound treatment and germination, but a-type of crystallinity remained after sonication. Further, the Mw of sequential ultrasound pretreatment and germination at any time is higher than that of sequential germination and ultrasound. As a result of sequential ultrasound pretreatment and germination, changes in the content of chain length of barley starch were consistent with germination alone. At the same time, the average degree of polymerisation (DP) fluctuated slightly. Lastly, the starch was modified during the sonication process, either prior to or following sonication. Pretreatment with ultrasound illustrated a more profound effect on barley starch than sequential germination and ultrasound treatment. In conclusion, these results indicate that sequential ultrasound pretreatment and germination improve the fine structure of highland barley starch.     

Ultrasonic-assisted binding of canistel (Lucuma nervosa A.DC) seed starch with quercetin

In order to provide a reference for improving the physicochemical properties of starch, the study of starch polyphenol complex interaction has aroused considerable interest. As a common method of starch modification, ultrasound can make starch granules have voids and cracks, and make starch and polyphenols combine more closely. In this research, canistel seed starch was modified by ultrasonic treatment alone or combined with quercetin. The molecular structure, particle characteristics and properties of starch were evaluated. With the increase of ultrasonic temperature, the particle size of the dextrinized starch granules increased, but the addition of quercetin could protect the destruction of starch granule size by ultrasonic; X-ray diffraction and infrared spectra indicated that quercetin was bound to the surface of canistel seed starch through hydrogen bonding, and the complex and the original starch had the same crystal structure and increased crystallinity; by molecular simulation, quercetin bound inside the starch molecular helix preserved the crystalline helical configuration of starch to some extent and inhibited the complete unhelicalization of starch molecules. Meanwhile, hydrogen bonding was the main driving force for the binding of starch molecules to quercetin, and van der Waals interactions also promoted the binding of both. In the physicochemical properties, as the temperature increased after the combination of ultrasonic modified starch combined with quercetin, the solubility, swelling force and apparent viscosity of the compound increased significantly, and it has higher stability and shear resistance.     

云南稻核心种质糙米功能成分栽培型差异及其地带性特征

采用Beckman公司DU640型紫外-可见分光光度计测定了五个稻作区16个州市的905份云南地方稻初级核心种质功能成分栽培型间差异及地带性特征,结果表明:糙米抗性淀粉(%)为0.75±0.29,籼稻(0.78±0.35)显著高于粳稻(0.74±0.24),粘稻(0.78±0.31)极显著高于糯稻(0.67±0.22),晚稻(0.77±0.35)极显著高于早中稻(0.75±0.26),红米(0.81±0.30)和紫米(0.70±0.30)极显著高于白米(0.69±0.27);稻作区依次为Ⅰ(0.83)Ⅱ(0.79)Ⅲ(0.76)Ⅴ(0.55)Ⅳ(0.50),即滇中南部(Ⅰ,Ⅱ,Ⅲ)糙米抗性淀粉含量极显著高于北部稻作区(Ⅴ,Ⅳ);滇西北的丽江和滇东北的昭通糙米抗性淀粉含量极显著低于除迪庆州外的13个州市。糙米γ-氨基丁酸含量[mg.(100 g)-1]为7.43±2.53,水稻(7.59±2.56)极显著高于陆稻(7.09±2.45),糯稻(8.55±2.88)极显著高于粘稻(7.10±2.32),晚稻(7.88±2.64)极显著高于早中稻(7.23±2.45),白米(8.38±2.66)极显著高于红米(6.63±2.14)和紫米(7.34±2.18);稻作区依次为Ⅱ(7.69)Ⅰ(7.40)Ⅳ(7.39)Ⅲ(7.33)Ⅴ(6.64),即滇南单双季籼稻区(Ⅱ)糙米γ-氨基丁酸含量明显高于滇西北高寒粳稻区;滇南的思茅、滇中的玉溪和保山糙米γ-氨基丁酸含量至少与5个州市差异显著。云南稻糙米总黄酮含量[mg.(100 g)-1]为306.98±192.75,陆稻(341.74±185.11)极显著高于水稻(290.41±193.72),粘稻(315.54±197.64)显著高于糯稻(171.68±11.76),早中稻(318.25±197.93)极显著高于晚稻(282.12±178.11),红米(379.22±197.70)和紫米(365.61±195.44)极显著高于白米(216.96±142.11),光壳稻(332.68±196.22)显著高于白壳稻(300.48±191.14);稻作区依次为Ⅲ(327.13)Ⅱ(324.23)Ⅳ(273.11)Ⅴ(270.16)Ⅰ(258.26),即滇南(Ⅱ,Ⅲ)糙米总黄酮含量极显著高于滇中;思茅糙米总黄酮含量显著高于8个州市而保山总黄酮含量则显著低于7个州市。这些既揭示了糙米抗性淀粉、γ-氨基丁酸和总黄酮、含量在水陆、沾糯、早中晚、米色间差异极显著(p0.01),而有无芒和米味间差异不大,又揭示了3种功能成分呈现明显的地带性特征。文章研究为解决人类慢性病问题以及功能稻米育种生产提供参考。     

Ultrasonic study of wheat flour properties

In this work, the wheat flour properties are investigated using ultrasound techniques. Moreover, the flour samples were also characterized by means of well established techniques such as protein content, Alveograph and Mixolab®. A set of 35 dough samples, made of wheat flours with diverse physical and quality properties, were studied. The obtained results shown that ultrasound measurements can detect changes in the dough consistency induced by proteins and also by gelatinization of the starch. Furthermore, ultrasound measurements can be related to parameters indicative of the proteolytic degradation or softening of the dough due to protease activity. Thus, ultrasound can be considered a low cost and rapid tool, complementary to conventional test, for wheat flour characterization.     

Impact of ultrasonic treatment on rice starch and grain functional properties: A review

As a green, nonthermal, and innovative technology, ultrasonication generates acoustic cavitation in an aqueous medium, developing physical forces that affect the starch chemistry and rice grain characteristics. This review describes the current information on the effect of ultrasonication on the morphological, textural, and physicochemical properties of rice starch and grain. In a biphasic system, ultrasonication introduced fissures and cracks, which facilitated higher uptake of water and altered the rice starch characteristics impacting textural properties. In wholegrain rice, ultrasonic treatment stimulated the production of health-related metabolites, facilitated the higher uptake of micronutrient fortificants, and enhanced the palatability by softening the rice texture. This review provides insights into the future direction on the utilization of ultrasonication for the applications towards the improvement of rice functional properties.     

Studies on Rheological Behavior and Structure Development of High‐Density Polyethylene in the Presence of Ultrasonic Oscillations During Extrusion

The effects of ultrasonic oscillations on properties and structure of extruded high‐density polyethylene (HDPE) were studied. The experimental results show that ultrasonic oscillations can improve the surface appearance of the HDPE extrudates; increase the productivity of the HDPE extrudates; and decrease the die pressure, melt viscosity, and flow activation energy of the HDPE. The processing properties of the HDPE improve greatly in the presence of ultrasonic oscillations. Linear viscoelastic properties tests show that dynamic shear viscosity and zero shear viscosity decrease in the presence of ultrasonic oscillations. Ultrasonic oscillations can improve crystal perfection and thermal stability of HDPE. At appropriate ultrasound intensity, ultrasonic oscillations could also increase the mechanical strength of extruded HDPE. The gel permeation chromatography (GPC) results show that at high ultrasound intensity and low rotation speed of extrusion, ultrasonic oscillations causes chain scission of HDPE, which result in a decrease of molecular weight and an increase of melt flow index.     

Effects of ultrasound treatment on the starch properties and oil absorption of potato chips

As a non-thermal processing method, the ultrasound treatment prior to the frying process has been demonstrated with great potential in reducing the oil absorption of fried food. This research aimed to evaluate the effect of ultrasound pretreatment on starch properties, water status, pore characteristics, and the oil absorption of potato slices. Ultrasound probe set with two power (360 W and 600 W) at the frequency of 20 kHz for 60 min was applied to perform the pretreatments. The results showed that ultrasound pretreatment led to the surface erosion of starch granules and higher power made the structure of starch disorganized. Moreover, the fraction of bound water and immobilized water were changed after ultrasonic pretreatment. Pores with the minor diameters (0.4–3 μm and 7–12 μm) were formed after ultrasound pretreatment. The penetrated surface oil (PSO) content, and structure oil (STO) content were reduced by 27.31% and 22.25% respectively with lower power ultrasound pretreatment. As the ultrasound power increased, the surface oil (SO) content and PSO content increased by 25.34% and 12.89% respectively, while STO content decreased by 38.05%. By using ultrasonic prior to frying, the quality of potato chips has been greatly improved.     

Enzymolysis kinetics and structural characteristics of rice protein with energy-gathered ultrasound and ultrasound assisted alkali pretreatments

This research investigated the structural characteristics and enzymolysis kinetics of rice protein which was pretreated by energy-gathered ultrasound and ultrasound assisted alkali. The structural characteristics of rice protein before and after the pretreatment were performed with surface hydrophobicity and Fourier transform infrared (FTIR). There was an increase in the intensity of fluorescence spectrum and changes in functional groups after the pretreatment on rice protein compared with the control (without ultrasound and ultrasound assisted alkali processed), thus significantly enhancing efficiency of the enzymatic hydrolysis. A simplified kinetic equation for the enzymolysis model with the impeded reaction of enzyme was deduced to successfully describe the enzymatic hydrolysis of rice protein by different pretreatments. The initial observed rate constants (K_in,0) as well as ineffective coefficients (k_imp) were proposed and obtained based on the experimental observation. The results showed that the parameter of k_in,0 increased after ultrasound and ultrasound assisted alkali pretreatments, which proved the effects of the pretreatments on the substrate enhancing the enzymolysis process and had relation to the structure changes of the pretreatments on the substrate. Furthermore, the applicability of the simplified model was demonstrated by the enzymatic hydrolysis process for other materials.     

Ultrasonic treatment on physicochemical properties of water-soluble protein from Moringa oleifera seed

Effect of ultrasonic power on the structure and functional properties of water-soluble protein extracted from defatted Moringa oleifera seed were explored. The results showed that ultrasonic treatment could reduce β-sheet and β-turn content of water-soluble protein from Moringa oleifera seed (MOWP) and increase the content of random coil and α-helix. Changes in intrinsic fluorescence spectra, surface hydrophobicity (H₀) and thermal behaviors indicated that ultrasonic had significant effect on the tertiary structure of MOWP. The results of SEM and SDS-PAGE showed that the MOWP was aggregated but not significantly degraded by ultrasound. The solubility, foaming properties and emulsifying properties of MOWP increased firstly and then decreased with the increase of ultrasonic power. Ultrasonic treatment altered the functional properties of MOWP, which might be attributed to the exposure of hydrophilic group and the change of and secondary and tertiary structure.     

Ultrasonic characterisation of flour-water systems: a new approach to investigate dough properties

The viscoelastic properties of dough are of great interest in the baking industry as they affect the quality of the final product. In this work, the viscoelastic properties of dough were investigated using ultrasonic techniques and then compared with traditional methods. It has been shown that ultrasonics provides a non-destructive, rapid and low cost technique for the measurement of physical food characteristics. A common protocol for dough preparation was used for each type of measurement. Experimental results on more than 30 different flour quality and dough processing were presented. The measurements were correlated and compared with traditional dough quality tests. In addition, the capability of ultrasound measurements for discriminating flours for different purposes was also studied, showing the potential of ultrasound as an alternative measurement method to discriminate types of flours for different purposes.     

Ultrasound-intensified laccase production from Trametes versicolor

An efficient intermittent ultrasonic treatment strategy was developed to improve laccase production from Trametes versicolor mycelia cultures. The optimized strategy consisted of exposing 2-day-old mycelia cultures to 5-min ultrasonic treatments for two times with a 12-h interval at the fixed ultrasonic power and frequency (120 W, 40 kHz). After 5 days of culture, this strategy produced the highest extracellular laccase activity of 588.9 U/L among all treatments tested which was 1.8-fold greater than the control without ultrasound treatment. The ultrasonic treatment resulted in a higher pellet porosity that facilitated the mass transfer of nutrients and metabolites from the pellets to the surrounding liquid. Furthermore, the ultrasonic treatment induced the expression of the laccase gene (lcc), which correlated with a sharp increase in both extracellular and intracellular laccase activity. This is the first study to find positive effects of ultrasound on gene expression in fungal cells. These results provide a basis for understanding the stimulation of metabolite production and process intensification by ultrasonic treatment in filamentous fungal culture.     

Effect of ultrasonic power on properties of edible composite films based on rice protein hydrolysates and chitosan

Rice protein hydrolysates (RPH) are incapable of film formation by self-crosslinking due to low molecular mass. Hence, we used chitosan (CS) as a modifier and developed rice protein hydrolysates/chitosan (RPH/CS) edible composite films by means of ultrasound. Results showed that ultrasound treatment decreased the particle size and the viscosity of film-forming solutions. The value of elongation at break of composite films was increased by 125% at 400 W compared with untreated film. The peroxide value of soybean oil was significantly reduced from 16.99 ± 0.78 meq/kg to 2.23 ± 0.09 meq/kg with the increase of ultrasonic power. Ultrasound treatment was efficient in keeping smooth on surface, and the films at ultrasound treatment of 200 W had better compatibility. Moreover, hydrogen bonds and covalent interactions were probably the main forces between RPH and CS and contributed to film formation under ultrasound treatment, which supported by analyses of Fourier transform infrared spectroscopy and X-ray diffraction. These results suggested that ultrasound was an effective method to improve the properties of edible composite films.     

Effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips

The effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips were investigated. The water medium system (distilled water and 5% NaCl osmotic solution) and oil medium system (90 °C) were designed with different power levels of ultrasound to simulate the ultrasonic conditions. Results showed that the changes of moisture content, water loss, solid gain and dielectric properties of potato slices were facilitated by the ultrasonic treatment. LF-NMR analysis showed the binding force between the moisture and structure in the material was significantly (p < 0.05) weakened. The changes become greater with the increase of ultrasonic power levels. Microscopic channels and disruptions were induced on the microstructure by the ultrasonic treatment. The effective moisture diffusivity of vacuum fried (VF) potato chips was increased by about 56.2%-67.0% and 53.9% with the combination of microwave energy and the ultrasonic pre-treatment in water and oil medium simulated system, respectively. The oil uptake, hardness, shrinkage, total color change and water activity of vacuum fried samples were significantly (p < 0.05) decreased by the assist of microwave energy combined ultrasonic pre-treatment.