Effect of pulsed electric field on assembly structure of α-amylase and pectin electrostatic complexes

Distinctive activation of β-galactosidase by carboxymethylated β-glucan in vitro and mechanism study: Critical role of hydrophobic and electrostatic interactions

β-galactosidase (lactase) is commercially important as a dietary supplement to alleviate the symptoms of lactose intolerance. This work investigated a unique activation of CMP (carboxymethylated (1 → 3)-β-d-glucan) on lactase and its mechanism by comparing it with carboxymethyl chitosan (CMCS), an inhibitor of lactase. The results illustrated that the secondary and tertiary structures of lactase were altered and its active sites exposed after complexation with CMP, and dissociation of lactase aggregates was also observed. These changes favored better accessibility of the substrate to the active sites of lactase, resulting in a maximum increase of 60.5 % in lactase activity. Furthermore, the hydrophobic and electrostatic interactions with lactase caused by the carboxymethyl group of CMP were shown to be crucial for its activation ability. Thus, the improvement of lactase activity and stability by CMP shown here is important for the development of new products in the food and pharmaceutical industries.

Enhancing storage and gastroprotective viability of Lactiplantibacillus plantarum encapsulated by sodium caseinate-inulin-soy protein isolates composites carried within carboxymethyl cellulose hydrogel

Probiotics are subjected to various edible coatings, especially proteins and polysaccharides, which serve as the predominant wall materials, with ultrasound, a sustainable green technology. Herein, sodium caseinate, inulin, and soy protein isolate composites were produced using multi-frequency ultrasound and utilized to encapsulateLactiplantibacillus plantarumto enhance its storage, thermal, and gastrointestinal viability. The physicochemical analyses revealed that the composites with 5 % soy protein isolate treated with ultrasound at 50 kHz exhibited enough repulsion forces to maintain stability, pH resistance, and the ability to encapsulate larger particles and possessed the highest encapsulation efficiency (95.95 %). The structural analyses showed changes in the composite structure at CC, CH, CO, and amino acid residual levels. Rheology, texture, and water-holding capacity demonstrated the production of soft hydrogels with mild chewing and gummy properties, carried the microcapsules without coagulation or sedimentation. Moreover, the viability attributes ofL. plantarumevinced superior encapsulation, protecting them for at least eight weeks and against heat (63 °C), reactive oxidative species (H2O2), and GI conditions.

Pectin as a biofunctional food: comprehensive overview of its therapeutic effects and antidiabetic-associated mechanisms

Pectin is a complex polysaccharide found in a variety of fruits and vegetables. It has been shown to have potential antidiabetic activity along with other biological activities, including cholesterol-lowering properties, antioxidant activity, anti-inflammatory and immune-modulatory effects, augmented healing of diabetic foot ulcers and other health benefits. There are several pectin-associated antidiabetic mechanisms, such as the regulation of glucose metabolism, reduction of oxidative stress, increased insulin sensitivity, appetite suppression and modulation of the gut microbiome. Studies have shown that pectin supplementation has antidiabetic effects in different animal models and in vitro. In human studies, pectin has been found to have a positive effect on blood glucose control, particularly in individuals with type 2 diabetes. Pectin also shows synergistic effects by enhancing the potency and efficacy of antidiabetic drugs when taken together. In conclusion, pectin has the potential to be an effective antidiabetic agent. However, further research is needed to fully understand its detailed molecular mechanisms in various animal models, functional food formulations and safety profiles for the treatment and management of diabetes and associated complications in humans. The current study was carried out to provide the critical approach towards therapeutical potential, anti-diabetic potential and underlying molecular mechanisms on the basis of existing knowledge.

Structure-based modification of a-amylase by conventional and emerging technologies: Comparative study on the secondary structure, activity, thermal stability and amylolysis efficiency

α-Amylase is an endo-enzyme that catalyzes the hydrolysis of starch into shorter oligosaccharides. α-Amylase plays a crucial role in various industries. Manipulated α-amylases are of particular interest due to their remarkable amylolysis efficiency and thermostability for large-scale biotechnological processes. The retained catalytic activity of enzymes is decreased according to extreme pH, temperature, pressure, and chemical reagents. Broad industrial applications of α-amylases need special properties such as stability against temperature, pH, and chelators, and also attain reusability, desirable enzymatic activity, efficiency, and selectivity. Considering the biotechnological importance of α-amylase, its high stability is the most critical challenge for its economic viability. Therefore, improving its functionality and stability recently gained much interest. To achieve this purpose, various emerging technologies in combination with conventional methods on α-Amylases with different sources have been conducted. The present review is an attempt to summarize the effect of various conventional methods and emerging technologies employed to date on α-amylase secondary structure, thermal stability, and performance.

Fabrication and characterization of pectin-zein nanoparticles containing tanshinone using anti-solvent precipitation method

Tanshinone compounds are secondary metabolites which their application in food and pharmaceutical industry is limited due to the low solubility in water and sensitivity to heat. This study aimed to develop a novel biopolymer nanocarriers system based on pectin/zein for the encapsulation of tanshinone compounds using the anti-solvent precipitation method. The concentration of pectin and mass ratio of tanshinone/zein in the final formulation of nanoparticles were optimized. According to the results, a pectin concentration of 1 g/L and a tanshinone/zein ratio of 0.1:1 g/g were considered the optimal nanoparticle formulation. The resulting nanoparticles exhibited a spherical core-shell structure, with approximate values for size, zeta potential, TSI, and encapsulation efficiency of 132 ± 0.002 nm, -38.6 ± 0.019 mV, 0.600 ± 0.084, and 79.41 ± 0.62 %, respectively. The FTIR test confirmed the presence of hydrophobic, hydrogen, and electrostatic interactions among the constituents within the nanoparticles. Additionally, XRD and DSC tests verified the amorphous nature of the nanoparticles. Morphological examination conducted through TEM, and SEM revealed the characteristics of the resulting nanoparticles. Furthermore, this carrier system significantly enhanced the solubility of tanshinone compounds in water.

Relationships of pulsed frequency and anammox bacteria growth rate, at low temperatures

This study explored pulsed frequency that could enhance the anammox bacteria growth rate and TN removal rate at low temperatures (16 ± 1°C). The results showed that the growth rate of anammox bacteria in R1 (1000 Hz) was significantly higher than in R2 (30 Hz) and R3 (106Hz). The relative abundance values of anammox bacteria R1 were higher by 52.21% and 172.41% than R2 and R3, while that of MLSS were as high as 241.07% and 471.36% than R2 and R3, with the nitrogen loading rate was 6.84 kg-N/m³/d. Besides, the dynamics also showed that the specific anammox activity (SAA) and the cellular yield of R1 were higher than R2 and R3. The intermediate frequency could enhance the cell division by stimulating the anammoxosome and reduce the ionic hydration layer to accelerate the ion migration rate, further improving the number of anammox bacteria even at low temperatures. The pulsed frequency could enhance the anammox growth rate and the doubling time is just 5 d.

Impact of ultrasound treatment on the structural modifications and functionality of carbohydrates - A review

Carbohydrates are crucial in food as essential biomolecules, serving as natural components, ingredients, or additives. Carbohydrates have numerous applications in the food industry as stabilizers, thickeners, sweeteners, and humectants. The properties and functionality of the carbohydrates undergo alterations when exposed to various thermal or non-thermal treatments. Ultrasonication is a non-thermal method that modifies the structural arrangement of carbohydrate molecules. These structural changes lead to enhanced gelling and viscous nature of the carbohydrates, thus enhancing their scope of application. Ultrasound may improve carbohydrate functionality in an environmentally sustainable way, leaving no chemical residues. The high-energy ultrasound treatments significantly reduce the molecular size of complex carbohydrates. Sonication parameters like treatment intensity, duration of treatment, and energy applied significantly affect the molecular size, depolymerization, viscosity, structural modifications, and functionality of carbohydrate biomolecules. This review provides a comprehensive analysis of ultrasound-assisted modifications in carbohydrates and the changes in functional properties induced by sonication.

Electrochemistry in sensing of molecular interactions of proteins and their behavior in an electric field

Electrochemical methods can be used not only for the sensitive analysis of proteins but also for deeper research into their structure, transport functions (transfer of electrons and protons), and sensing their interactions with soft and solid surfaces. Last but not least, electrochemical tools are useful for investigating the effect of an electric field on protein structure, the direct application of electrochemical methods for controlling protein function, or the micromanipulation of supramolecular protein structures. There are many experimental arrangements (modalities), from the classic configuration that works with an electrochemical cell to miniaturized electrochemical sensors and microchip platforms. The support of computational chemistry methods which appropriately complement the interpretation framework of experimental results is also important. This text describes recent directions in electrochemical methods for the determination of proteins and briefly summarizes available methodologies for the selective labeling of proteins using redox-active probes. Attention is also paid to the theoretical aspects of electron transport and the effect of an external electric field on the structure of selected proteins. Instead of providing a comprehensive overview, we aim to highlight areas of interest that have not been summarized recently, but, at the same time, represent current trends in the field.

Preparation of core-shell hordein/pectin nanoparticles as quercetin delivery matrices: Physicochemical properties and colon-specific release analyses

Quercetin (Que) is a hydrophobic flavanol that has the potential to prevent colon diseases. This study aimed to design hordein/pectin nanoparticle as a colon-specific delivery system for quercetin. The encapsulation efficiency, physicochemical stability and release properties of the nanoparticles were estimated. The FTIR and secondary structure analysis indicated that hydrogen bonds, hydrophobic interactions and electrostatic attractions were formed in the quercetin-loaded hordein/pectin nanoparticles (Que-hordein/pectin NPs). In comparison to Que-hordein NPs, Que-hordein/pectin NPs exhibited better colloidal stability (physical, UV light, heating and salt). Furthermore, the release properties studies showed that pectin coating restrained the premature release of Que from hordein NPs in gastric fluid and intestinal fluid. In-vitro release, when the Que-hordein/pectin NPs were exposed to simulated colonic fluid (SCF) for 6 h, quercetin was greatly released from the hordein/pectin NPs (15.29 ± 1.17% - 80.60 ± 1.78%). In-vivo release, the concentration of Que (μg/g) in Que-hordein/pectin NPs was 2.18 times higher than Que-hordein NPs in colon tissue after 6 h of oral administration. This study suggests that Que-hordein/pectin NPs have promising applications in the specific delivery and release of quercetin to the colon.

Combination with litchi procyanidins under PEF treatment alters the physicochemical and processing properties of inulin

A novel alternative to prepare the inulin-procyanidin complex assisted by pulsed electric field (PEF) treatment was explored in this study. Results showed that the optimal condition of PEF treatment enhanced the adsorption rate of procyanidins to inulin from 78.56 to 103.46 μg/mg. Based on well fitted by Redlich-Peterson model and spectral analysis including UV and FT-IR, the interaction between inulin and procyanidin was evidenced to be dominated by hydrogen bonds. The DSC curve and the SEM spectrum displayed better stability of the PEF-treated inulin-procyanidin complex than the untreated complex. The PEF-treated complex had lower solubility but higher water-holding capacity than inulin, which exhibited stronger shear-thinning property and more stable flow behavior referring to rheological analysis. Furthermore, the gel formed from the PEF-treated complex possessed greater hardness, chewiness and viscosity, with no significant effects noted in terms of springiness, cohesiveness and resilience.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

Structural Transitions of Alpha-Amylase Treated with Pulsed Electric Fields: Effect of Coexisting Carrageenan

Pulsed electric field (PEF) is an effective way to modulate the structure and activity of enzymes; however, the dynamic changes in enzyme structure during this process, especially the intermediate state, remain unclear. In this study, the molten globule (MG) state of α-amylase under PEF processing was investigated using intrinsic fluorescence, surface hydrophobicity, circular dichroism, etc. Meanwhile, the influence of coexisting carrageenan on the structural transition of α-amylase during PEF processing was evaluated. When the electric field strength was 20 kV/cm, α-amylase showed the unique characteristics of an MG state, which retained the secondary structure, changed the tertiary structure, and increased surface hydrophobicity (from 240 to 640). The addition of carrageenan effectively protected the enzyme activity of α-amylase during PEF treatment. When the mixed ratio of α-amylase to carrageenan was 10:1, they formed electrostatic complexes with a size of ~20 nm, and carrageenan inhibited the increase in surface hydrophobicity (<600) and aggregation (<40 nm) of α-amylase after five cycles of PEF treatment. This work clarifies the influence of co-existing polysaccharides on the intermediate state of proteins during PEF treatment and provides a strategy to modulate protein structure by adding polysaccharides during food processing.

Pulsed Electric Field: Fundamentals and Effects on the Structural and Techno-Functional Properties of Dairy and Plant Proteins

Dairy and plant-based proteins are widely utilized in various food applications. Several techniques have been employed to improve the techno-functional properties of these proteins. Among them, pulsed electric field (PEF) technology has recently attracted considerable attention as a green technology to enhance the functional properties of food proteins. In this review, we briefly explain the fundamentals of PEF devices, their components, and pulse generation and discuss the impacts of PEF treatment on the structure of dairy and plant proteins. In addition, we cover the PEF-induced changes in the techno-functional properties of proteins (including solubility, gelling, emulsifying, and foaming properties). In this work, we also discuss the main challenges and the possible future trends of PEF applications in the food proteins industry. PEF treatments at high strengths could change the structure of proteins. The PEF treatment conditions markedly affect the treatment results with respect to proteins' structure and techno-functional properties. Moreover, increasing the electric field strength could enhance the emulsifying properties of proteins and protein-polysaccharide complexes. However, more research and academia-industry collaboration are recommended to build highly effective PEF devices with controlled processing conditions.

Maillard-Type Protein-Polysaccharide Conjugates and Electrostatic Protein-Polysaccharide Complexes as Delivery Vehicles for Food Bioactive Ingredients: Formation, Types, and Applications

Due to their combination of featured properties, protein and polysaccharide-based carriers show promising potential in food bioactive ingredient encapsulation, protection, and delivery. The formation of protein–polysaccharide complexes and conjugates involves non-covalent interactions and covalent interaction, respectively. The common types of protein–polysaccharide complex/conjugate-based bioactive ingredient delivery systems include emulsion (conventional emulsion, nanoemulsion, multiple emulsion, multilayered emulsion, and Pickering emulsion), microcapsule, hydrogel, and nanoparticle-based delivery systems. This review highlights the applications of protein–polysaccharide-based delivery vehicles in common bioactive ingredients including polyphenols, food proteins, bioactive peptides, carotenoids, vitamins, and minerals. The loaded food bioactive ingredients exhibited enhanced physicochemical stability, bioaccessibility, and sustained release in simulated gastrointestinal digestion. However, limited research has been conducted in determining the in vivo oral bioavailability of encapsulated bioactive compounds. An in vitro simulated gastrointestinal digestion model incorporating gut microbiota and a mucus layer is suggested for future studies.

Structural characterization and antibacterial properties of konjac glucomannan/soluble green tea powder blend films for food packaging

Antimicrobial activity is a promising property for food packaging which could prolong the shelf life of food products. In this paper, the physicochemical and antimicrobial properties of konjac glucomannan (KGM)/soluble green tea powder (SGTP) edible films were firstly prepared and analyzed through light barrier properties, Fourier transform infrared spectroscopy (FT-IR), tensile strength (TS), X-ray diffraction (XRD), thermogravimetric analysis and scanning electron microscope (SEM). The results showed that appropriate addition of SGTP could improve the TS of composite films. With the increase of SGTP content, the transmittance of the films in the ultraviolet region decreased obviously, and the thermal stability was improved in a SGTP dependent manner. KGM/SGTP films present a fairly smooth and flat surface without any fracture when 0.5% SGTP was provided. The bacteriostatic test showed that the bacteriostatic performance of the composite films against Staphylococcus aureus and Escherichia coli was also significantly enhanced. When 1% SGTP was provided, the zones of inhibition for Escherichia coli and Staphyloccocus aureus reached to 13.45 ± 0.94 mm and 13.76 ± 0.92 mm, respectively. Overall, the KGM/SGTP films showed great potential as bioactive packaging materials to extend food shelf life.

Internal cavity amplification of shell-like ferritin regulated with the change of the secondary and tertiary structure induced by PEF technology

In this study, the effect of pulsed electric field (PEF) on apparent morphology and molecular structure of shell-like ferritin obtained from horse spleen was determined by circular dichroic (CD), fluorescence spectroscopy, Raman spectroscopy, cold field emission scanning electron microscopy (CF-SEM) and transmission electron microscopy (TEM), and verified by molecule dynamics (MD) simulation. After PEF treatment, the α-helix content of the samples reached a minimum value at 10 kV/cm, which indicated that the ferritin structure has been partially unfolded. However, the α-helix content peaked again after resting for 2 h at 25 ± 1 °C. This indicated that the PEF-treated ferritin tended to restore its original spherical morphology probably owing to the reversible assembly characteristic of ferritin. In addition, microstructure analysis revealed that ferritin particles aggregated after PEF treatment. Therefore, PEF treatment could induce the "exposure" of hydrophobic amino acids and conversion of disulfide bond configuration, and consequently, regulate the internal cavity stability of ferritin. The research will be beneficial to expand the application of PEF treatment in the modification of protein structure, and provide a theoretical basis for the application of ferritin as a carrier of bioactive molecules in food.

Anion carboxymethylated β-glucan alleviates undesirable binding between procyanidins and β-galactosidase

To solve the potential problem of hindered β-galactosidase activity by procyanidins, carboxymethylated Pachyman (CMP), a negatively-charged carboxymethylated (1 → 3)-β-d-glucan, was applied to mitigate inhibition by procyanidins. The mechanisms underlying this effect were explored through enzyme kinetic analysis, fluorescence quenching assays, circular dichroism, and molecular docking studies. The results indicated that the introduction of CMP could decrease the inhibition rate of high-concentration lotus seedpod oligomeric procyanidins (LSOPC) from 98.7 to 46.5%, and enabled low-concentration LSOPC to activate β-galactosidase in vitro and in vivo. The competitive/noncompetitive inhibition constants, fluorescence quenching constants, and molecular docking results indicated that the mechanism of this effect might be CMP competing with β-galactosidase to bind procyanidins, resulting in restoration of the catalytic centre and key active site of procyanidin-bound lactase. Additionally, it was affected by procyanidin-CMP noncovalent interactions. This study illustrates a promising strategy for mitigating the anti-nutritional properties of procyanidins and activating β-galactosidase to promote intestinal health.