Effect of cellulase on dough structure and quality characteristics of tough biscuits enriched with potato whole flour.

Potato whole flour is a promising way to improve the nutrition of tough biscuits, while its gluten-free characteristic was difficult to form acceptable texture properties. In this study, cellulase was used to degrade the cellulose in dough enriched with potato whole flour, so as to mitigate the interference of cellulose with the gluten network, resulting in forming the potato whole flour biscuit with great characteristics. Results indicated that cellulase within 0.2% led to the gradually reduced G' and G'' values of dough from 5.50×104 to 4.00×104 and 2.66×104 to 1.35×104, respectively. Cellulase at 0.2% resulted in the significantly increased tensile properties of the dough compared to the control. The incorporation of cellulase within 0.2% also led to the tightly ordered and intact network structure base on the results of SEM, disulfide bonds determination and FTIR. Those results indicated that cellulase was beneficial to improve the baking quality of dough, which was conductive to form tough biscuit with great characteristics. The hardness, crunchiness, crispness and specific volume analysis results confirmed that 0.2% cellulase resulted in the significantly decreased hardness by 45.25% and the significantly increased specific volume, crunchiness and crispness by 24.74%, 121.20% and 156.47%, respectively. Overall, cellulase ultimately improved the quality of the biscuits by improving the properties and structure of the dough. It was of great significance for the utilization of potato whole flour resources and the industrial production of its tough biscuits. PRACTICAL APPLICATION: The results showed that inclusion of cellulase led to the reduced hardness and increased crunchiness, crispness, and specific volume of potato whole flour tough biscuits. Cellulase could be used as a potential improver of tough biscuits. This study will provide guidance for practical uses of cellulase in improving potato whole flour dough and tough biscuit quality.

Extrusion modification of prolamins from distiller's grains to facilitate the construction of biopolymer films.

BACKGROUND: Distiller's grains (DGs), which are rich in natural ingredients such as prolamins, are often used as low-value feed or discarded directly, resulting in great environmental pollution and resource waste. Prolamins from DGs (PDGs) were found to be a potential material for the construction of biopolymer films due to their good film-forming properties. In this study, extrusion processing was conducted to modify the physicochemical and structural properties of PDGs to facilitate the construction of biopolymer films with superior characteristics. RESULTS: Results indicated that extrusion led to improved solubility (17.91% to 39.95%) and increased disulfide bonds (1.46 to 6.13 µmol g-1) in PDGs. The total and sulfur amino acid contents of extruded PDGs were increased by 13.26% and 38.83%, respectively. New aggregation patterns were formed after extrusion according to the results of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Extrusion resulted in reduced surface hydrophobicity of PDGs (10 972 to 3632), sufficient evidence for which could be also found from structure analyses of PDGs. Finally, PDGs extruded at 110 °C were found to facilitate the forming of biopolymer films with superior mechanical properties, water resistance and thermal stability. CONCLUSIONS: Physicochemical and structural properties of PDGs were effectively modified by extrusion processing, and extrusion modification of PDGs could be a great way to facilitate the construction of biopolymer films with superior characteristics. It could provide more possibilities to extend the applications of DGs to alleviate the problems of environmental pollution and resource waste. © 2024 Society of Chemical Industry.

Insights into the modification of physicochemical properties and digestibility of pea starch gels with barley ß-glucan.

The influences of barley ß-glucan (BBG) on the physicochemical properties and in vitro digestibility of pea starch were investigated. BBG was found to decrease pasting viscosity in a concentration dependent manner and inhibited the aggregation of pea starch. After the presence of BBG, the gelatinization enthalpy of pea starch was decreased (from 7.83 ± 0.03 to 5.55 ± 0.22 J/g), whereas the gelatinization temperature was enhanced (from 62.64 ± 0.01 to 64.52 ± 0.14°C) according to the differential scanning calorimeter results. In addition, BBG inhibited the swelling of pea starch and amylose leaching. When amylose leached out from pea starch to form a BBG-amylose barrier, starch gelatinization was inhibited. The starch gels exhibited weak gels and shear thinning behaviors by rheological tests results. The interaction between BBG and amylose led to lower viscoelasticity and texture parameters in pea starch gels. The structure analysis results unveiled that the force between BBG and amylose was mainly hydrogen bonds. Pea starch hydrolysis was inhibited when BBG was present in the system, which was connected with the restricted starch gelatinization. These results obtained in the study would supply insights into incorporating BBG into various food systems.

Effects of different physical factors on potato protein-chitosan complexes considering Hofmeister series and Maillard reaction.

BACKGROUND: Potato protein possesses strong potential for application in the food industry due to its outstanding nutritional and functional properties. However, the inevitable industrial processing often brings adverse effects. The use of a polysaccharide and protein complex is a promising way to improve the performance of potato protein. This work aimed to investigate the effects of different physical factors on the potato protein/chitosan (PP/CS) complex system. RESULTS: The addition of NaCl was not conductive to the formation of PP/CS complexes, resulting in significantly decreased peak turbidities from 1.29 to 0.75. The effect of different ions on PP/CS system matched with the Hofmeister series in the following order: Li+ > Control > Na+ > K+ ; SCN- > I- > NO3 - > Br- ≈ Control > Cl- > SO4 2- , among which the salting-in ions (Li+ , Br- , NO3 - , I- and SCN- ) tended to promote the formation of PP/CS complexes. The turbidity increased significantly when the reaction temperature rose to 45 °C and above, and peak turbidity was obtained at lower pH values. The PP/CS system reaction at 45 °C led to the highest whiteness value, and the Maillard reaction could occur when the temperature was above 45 °C. CONCLUSIONS: The results of the present study confirmed that different physical factors led to strong influences on PP/CS complexes, especially when considering the Hofmeister series and the Maillard reaction. These findings could have significant implications for the utilization of potato protein in complex food systems. © 2023 Society of Chemical Industry.

MOF-Immobilized Two-in-One Engineered Enzymes Enhancing Activity of Biocatalytic Cascade for Tumor Therapy.

Biocatalytic systems based on enzyme cascade reactions have attracted growing interest in the field of biocatalytic medicine. However, it is a major challenge to reasonably construct enzyme cascade reactions with high stability, selectivity, and catalytic efficiency for the in vivo biocatalytic application. Herein, two-in-one engineered glucose oxidase (GOx-Fe0 ) is fabricated by a biomineralization strategy, through which a nanozyme (Fe0 NP) is anchored within the inner cavity of GOx. Then, GOx-Fe0 is immobilized in a pH-sensitive metal-organic framework (MOF) zeolitic imidazolate framework-8 (ZIF-8) to establish a stable and effective MOF-immobilized two-in-one engineered enzyme, GOx-Fe0 @ZIF-8. In vitro studies show that GOx-Fe0 @ZIF-8 exhibits excellent stability and high pH/glucose selectivity, and the shorter spacing between cascade enzymes can increase the cascade throughput and effectively improve the reaction efficiency of the enzyme cascade. In vivo experiments exhibit that GOx-Fe0 @ZIF-8 solves the instability and systemic toxicity of free enzymes, and achieves deep tumor penetration and significant chemodynamic therapeutic efficacy through a pH/glucose-selective enzyme cascade reaction in tumor site. Taken together, such an orchestrated enzyme engineering strategy can effectively improve enzyme stability, selectivity, and enzyme cascade reaction efficiency via chemical transformations, and also provide a promising strategy for the application of biocatalytic cascade reactions in vivo.

Study of ultrasonic treatment on the structural characteristics of gluten protein and the quality of steamed bread with potato pulp.

Physicochemical properties and microstructure of gluten protein, and the structural characteristics of steamed bread with 30 % potato pulp (SBPP) were investigated by ultrasonic treatments. Results showed that 400 W ultrasonic treatment significantly (P < 0.05) increased the combination of water and substrate in the dough with 30 % potato pulp (DPP). The contents of wet gluten, free sulfhydryl (SH), and disulfide bond (SS) were influenced by ultrasonic treatment. Moreover, UV-visible and fluorescence spectroscopy demonstrated that the conformation of gluten protein was changed by ultrasonic treatment (400 W). Fourier transform infrared (FT-IR) illustrated that the ß-sheet content was significantly (P < 0.05) increased (42 %) after 400 W ultrasonic treatment, and the surface hydrophobicity of gluten protein in SBPP increased from 1225.37 (0 W ultrasonic treatment) to 4588.74 (400 W ultrasonic treatment). Ultrasonic treatment facilitated the generation of a continuous gluten network and stabilized crumb structure, further increased the specific volume and springiness of SBPP to 18.9 % and 6.9 %, respectively. Those findings suggested that ultrasonic treatment would be an efficient method to modify gluten protein and improve the quality of SBPP.

Correlation analysis between extrusion process variables and quality of purslane leaf powder rice extrudates.

Extrusion has become one of the most popular techniques in food processing, and the process parameters are closely related to product quality. Purslane (Portulaca oleracea L.) can be used in medical and food products as a vegetable and herb. It has limited application in extrusion. The effects of extrusion process variables (screw speed, barrel temperature, and feed moisture) on system variables (specific mechanical energy [SME], die head pressure, and torque) and target variables (water absorption index, water solubility index, iodine blue value, color, pasting properties, and textural properties) of purslane powder compound rice were studied. The results showed that SME was moderately positively correlated with screw speed (r = 0.608, p < 0.05). However, torque was moderately negatively correlated with feed moisture (r = -0.574, p < 0.05), and die head pressure was moderately negatively correlated with barrel temperature (r = -0.635, p < 0.01). The target variables of extrudates were also correlated with the system parameters to varying degrees. These results are helpful to control and predict the texture, pasting properties, and other quality characteristics of extruded products containing purslane powder. PRACTICAL APPLICATION: The results showed that torque and die head pressure were moderately negatively related to barrel temperature, specific mechanical energy was moderately positively related to screw speed, peak viscosity and breakdown viscosity were moderately negatively related to specific mechanical energy, and water absorption index was moderately negatively related to torque and die head pressure. It provides a reference for the research of influencing system parameters and changing product quality by controlling extrusion process parameters. In this study, some possibilities for the application of broken rice and purslane in extrusion processing were proposed.

Changes of the main components, physicochemical properties of distiller's grains after extrusion processing with focus on modification mechanism.

Distiller's grains (DGs) possessed great potential utilization value due to their rich active ingredients. However, its utilization efficiency was limited by the large amount of lignocellulose components and water-insoluble proteins. In this work, single screw extrusion was applied to modify physicochemical properties of DGs. Results indicated that extruded distiller's grains (EDGs) exhibited the lower crude fiber content (26.01%), the higher soluble fiber (9.07%) and the smaller particle size when compared with those of Control, and subsequently achieving the increased bulk density, swelling capacity and water/oil holding capacity. The crude protein in EDGs decreased slightly, while the total amount of acid hydrolyzed amino acids showed a significant increase. Additionally, the looser, coarser and fragmentary microstructure of EDGs were observed. The main macromolecules in EDGs had been modified distinctly based on thermal analysis, crystallinity and functional groups analyses, while the possible schematic diagram was conducted to better understand the modification mechanism.

Microparticle prepared by chitosan coating on the extruded mixture of corn starch, resveratrol, and α-amylase controlled the resveratrol release.

Microcapsule was developed by chitosan coating on the microparticle which was prepared by smashing the extruded mixture of corn starch, resveratrol, and α-amylase. In the preparation process, the low-temperature extrusion and α-amylase were employed to overcome the disadvantages of low gelatinization, dissolution, and poor hydration of extruded starch. Chitosan-coating retarded starch aging, improved the stability of microcapsules, delayed the release of resveratrol. Considering the bioactive functions of chitosan, microcapsules also obtained the functions of chitosan by chitosan coating. The chitosan coating and α-amylase addition improved the release ratio of resveratrol. CESRA (chitosan solution (2%) coating on the extruded mixture of corn starch, resveratrol, and α-amylase) released 86.8% resveratrol at 25 °C in six days chasing, and 85.3% resveratrol at 37 °C in 48 h chasing. Chitosan coating slightly improved the free radical scavenging activity of ABTS+. The particle size variation, SEM, XRD, and FT-IR were also employed to investigate the variation of morphology, crystal structure, and chemical composition.

Influence of emulsifiers and enzymes on dough rheological properties and quality characteristics of steamed bread enriched with potato pulp.

The aim of this study was to evaluate whether processing characteristics of steamed bread enriched with potato pulp could be improved through the addition of different emulsifiers (soy lecithin-Soy L, sodium stearoyl lactate and diacetyl tartaric esters of monoglyceride) and enzymes (glucose oxidase-GOX and transglutaminase). Results showed that separate addition of each emulsifier at 1% concentration or each enzyme at 1.5 U/g could increase the viscoelasticity and strength of potato pulp dough due to enhancement of gluten network. Fermentation properties of dough showed that Soy L and GOX significantly (P < 0.05) increased the maximum dough height and the gas retention capacity during fermentation which promoting dough expansion. Moreover, Soy L and GOX increased specific volume and improved crumb structure and softness of steamed bread, which were consistent with the results of sensory analysis. In conclusion, Soy L and GOX could be used as improvers of potato pulp steamed bread.

Biopolymer films based on chitosan/potato protein/linseed oil/ZnO NPs to maintain the storage quality of raw meat.

Biopolymer films based on chitosan/potato protein/linseed oil/ZnO NPs were developed to maintain the storage quality of raw meat. Results indicated that the incorporation of ZnO NPs could effectively improve the transparency and tensile strength of the films, while addition of linseed oil could make the composite film maintain good elastic property. Films blended with chitosan/potato protein/linseed oil/ZnO NPs (Fcpzl) exhibited an excellent moisture barrier capability. SEM showed that ZnO NPs could harmoniously exist in various polymers matrix. FTIR analysis demonstrated that different components were bound together by intramolecular and intermolecular interactions, among which hydrogen bonds were the main force. Raw meat samples were wrapped with different films to evaluate the preservative effect during 4 °C storage. Results indicated that Fcpzl possessed best protective effect of raw meat with excellent acceptable sensory properties during 7 days storage, which could reduce the speed of increasing pH and total bacterial counts.

Characterization of sustained-release chitosan film loaded with rutin-ß-cyclodextrin complex and glucoamylase.

ABSTRACT: Edible chitosan film incorporated with rutin-ß-cyclodextrin was developed and characterized. The delivery of rutin was improved via the hydrolyzation function of glucoamylase, and the antioxidant activity of the chitosan film was enhanced by the addition of rutin. Sodium bicarbonate solution at different pHs (pH-adjusting reagent) was employed to afford the mild condition for the incorporated glucoamylase. The enzyme exhibited its hydrolyzation function to improve the release rate of rutin by destabilizing the rutin-ß-cyclodextrin complex (RCC) in chitosan film. The optimum pH of glucoamylase was achieved with 5 mL addition amount of 0.5 mol/L sodium bicarbonate solution, and the glucoamylase improved the radical scavenging ratio of chitosan film. The yellowness of chitosan film was enhanced with the addition of RCC solution. The films prepared without water demonstrated coarse and rough surface, while the water-based films had smoother and even surface as examined by scanning electron microscopy. In contrast, these observations disappeared in the water immersion groups. X-ray diffraction suggested that the hydrolyzation of ß-cyclodextrin and the interlinkage between ß-cyclodextrin and the chitosan chain exerted a negative function on maintaining the crystal structure of pure chitosan film. Further, the destabilization of RCC complex with the glucoamylase activity was evidenced by the absence of peak associated with ß-cyclodextrin as observed from Fourier transform infrared spectra. The enzyme improved the release of rutin and the addition of RCC successfully endowed antioxidant activity to the chitosan film.

Preparation and characterization of potato protein-based microcapsules with an emphasis on the mechanism of interaction among the main components.

BACKGROUND: Potato protein (PP) has promising potential for utilization in food applications due to its high nutritive value and functional properties. Grapeseed oil (GO) is rich in unsaturated fatty acids and antioxidant active ingredients. However, its application is limited because of low stability and high volatility. In order to overcome such problems, PP-based microcapsules encapsulating GO were produced by complex coacervation, and characterized using optical, thermodynamic and spectroscopic analyses. RESULTS: Results indicated that a ratio of GO/PP of 1:2 led to the best encapsulation effect with the maximum microencapsulation efficiency and yield. Intact and nearly spherical microcapsules were observed from scanning electron microscopy images. Results of thermogravimetry demonstrated that thermal resistance was increased in the microencapsulated GO, indicating that PP-based microcapsules could be a good way to protect the thermal stability of GO. Fourier transform infrared spectra indicated that hydrogen bonding and covalent crosslinking might occur among wall materials, but a physical interaction between GO and wall materials. CONCLUSIONS: PP can be successfully used to encapsulate GO when combined with chitosan, indicating that PP-based microcapsules have potential for application in encapsulating liquid oils with functional properties. A schematic diagram of possible interactions was constructed to better understand the mechanism of formation of the microcapsules. © 2020 Society of Chemical Industry.

Exploring Cycloreversion Reaction of Cyclobutane Pyrimidine Dimers Quantum Mechanically.

The cyclobutane pyrimidine dimer (CPD) is a major photoproduct of deoxyribonucleic acid (DNA) that is damaged by ultraviolet light. This DNA lesion can be repaired by DNA photolyase with the aid of UV light and two cofactors. To understand the repair mechanism of CPD and whether protonation of CPD participates in the DNA repair process, the cycloreversion reactions of four CPD models and proton transfers between the adjacent residue Glu283 and CPD models were explored through the quantum mechanical method. Two-dimensional maps of potential energy surface in a vacuum and in implicit water solution were calculated at the ωB97XD/6-311++G(2df,2pd) level. One-dimensional potential energy profiles were computed for proton transfer reactions. Among the models that have been considered, both in a vacuum and in water solution, the results indicate that the most likely repair mechanism involves CPD•2- radical anion splitting in a stepwise manner. C5-C5' splits first, and C6-C6' splits later. The computed free energies of activation of the two splitting steps are 0.9 and 3.1 kcal/mol, respectively. The adjacent Glu283 may stabilize the CPD•2- radical anion through hydrogen bond and increase the quantum yield; however, protonating the CPD radical anion by Glu283 cannot accelerate the rate of ring opening.

A pyrazolopyrimidine based fluorescent probe for the detection of Cu2+ and Ni2+ and its application in living cells.

A fluorescent sensor L based on a pyrazolopyrimidine core simultaneously detects Cu2+ and Ni2+ ions by photoluminescence quenching, even in the presence of other metal cations. Sensor L possesses high association constants of 5.24 × 103 M-1 and 2.85 × 104 M-1 and low detection limits of 0.043 µM and 0.038 µM for Cu2+ and Ni2+, respectively. The binding stoichiometry ratios of L to Cu2+ or Ni2+ is 1:1 as determined by Benesi-Hildebrand and Job's plots, and by crystal structures. DFT calculations on L-Cu2+ indicated reduced electron donation from the coordinated pyrazolopyridine to the fused pyrimidine and pendant phenyl group which, together with a smaller HOMO-LUMO orbital gap could favour non-radiative decay and explain the observed fluorescence quenching. Sensor L possessed low cytotoxicity and good imaging characteristics for Cu2+ and Ni2+ in living cells, suggesting potential applications for detecting Cu2+ and Ni2+in vivo.

Development of Water-Triggered Chitosan Film Containing Glucamylase for Sustained Release of Resveratrol.

There is a paradox when incorporating enzyme into an edible chitosan film that chitosan is dissolved in acid solution and enzyme activity is maintained under mild conditions. A method for maintaining the pH of the chitosan solution at 4-6 to prepare a chitosan film containing ß-cyclodextrin, resveratrol-ß-cyclodextrin inclusion (RCI), was developed, using glucamylase and acetic acid. A considerable amount of resveratrol was released by the glucamylase-incorporated film within 15 days, and the maximum amount released was 46% of the total resveratrol content. The highest resveratrol release ratio (released resveratrol/total resveratrol) was obtained in the film with 6 mL of RCI. Scratches and spores were generated on the surface of the glucamylase-added film immersed in water (GAFW) for 7 days because of ß-cyclodextrin hydrolysis during film drying and water immersion. RCI and ß-cyclodextrin were extruded from the film surface and formed teardrops, which were erased by water on the GAFW surface but appeared on the glucamylase-added film without water immersion (GAF). The bubbles generated by the reaction of acetic acid and residual sodium bicarbonate were observed in both glucamylase-free films immersed in water (GFFW) for 7 days and without water immersion (GFF). The FT-IR spectra illustrated that the covalent bond was not generated during water immersion and ß-cyclodextrin hydrolysis. The crystal structure of chitosan was destroyed by water immersion and ß-cyclodextrin hydrolysis, resulting in the lowest chitosan crystallization peak at 22°. The increasing of water holding capacity determined by EDX presented the following order: GAF, GFFW, GFF, and GAFW.