Acid Heat Treatment Research Articles

Melanin resistance of heat-processed ginsenosides from Panax ginseng berry treated with citric acid through autophagy pathway

GFRS is the conversion product of Panax ginseng Meyer berry after citric acid heat treatment, which is rich in rare ginsenosides. However, the anti-melanin role of GFRS in the regulation of skin pigmentation and its material basis remains unclear. To compare the anti-melanin activity before and after citric acid heat treatment, we determined the effects of GFS and GFRS on tyrosinase activity and melanin lever under α-MSH stimulation and found the potential anti-melanin effect of GFRS. Further, Western blot and immunofluorescence methods were used to reveal the mechanism by which GFRS detects anti-melanin activity by promoting autophagy flux levels. In zebrafish models, GFRS inhibited endogenous melanin and tyrosinase better than arbutin and promoted the accumulation of autophagy levels in vivo. To determine the material basis of the anti-melanin effect of GFRS, HPLC was used to isolate and prepare 12 ginsenosides from GFRS, and their activity evaluation and structure–activity relationship analysis were performed. The results showed that the inhibitory effect of GFRS on melanin was Rg3 > Rg5 > Rk1 > Rd. Molecular docking showed that their docking fraction with mushroom tyrosinase was significantly better than that of arbutin, but the presence of C-20 glycosylation decreased the anti-melanin activity of Rd. To maximize the content of Rg3, Rg5, and Rk1, we optimized the process by using citric acid heat treatment of ginsenoside Rd and found that citric acid heat treatment at 100°C almost completely transformed Rd and obtained a high content of active ingredients. In summary, our data demonstrated that GFRS exerted anti-melanin effects by inducing autophagy. It was further revealed that Rg3, Rg5, and Rk1, as effective active components, could be enriched by the improved process of converting ginsenoside Rd by citric acid heat treatment.

Oil in water emulsion stabilized by glycated rice bran protein aggregates: Effect on interfacial behavior and in vitro digestion of emulsion

To investigate the effect of molecular weight of saccharides and heating time on interfacial behavior of protein, glycated rice bran protein aggregates (gRBPAs) were obtained by incubating rice bran protein (RBP) with glucose (Glu), maltose (Mal) and dextran (Dex) via acid-heat treatment (pH 2.0, 90 °C). Subsequently, the stability and in vitro simulated digestion properties of oil in water (O/W) emulsion stabilized by gRBPAs were analyzed. Structural analysis (circular dichroism and fluorescence spectra) proved that the tertiary structure and secondary structure of RBP changed after glycation, and the contents of β-sheet structure of gRBPAs increased significantly. Besides, the glycation improved the interfacial activity and emulsification of protein obviously. Compared with Glu or Mal, the grafting of Dex could produce larger steric hindrance, which better inhibited the aggregation of emulsion droplets. Furthermore, glycation enhanced the pancreatic lipase (PL) inhibitory activity of gRBPAs obviously, and the emulsions stabilized by gRBPAs exhibited higher anti-digestion ability (62.12–75.00%) compared with RBP (95.27%). Moreover, the free fatty acid (FFA) rate of O/W emulsion was closely related to the surface hydrophobicity, degree of glycation, PL inhibitory activity and interfacial behavior of gRBPAs. Therefore, these findings would be enlightening to intuitively tailor the physicochemical stability and digestibility of O/W emulsion system according to heating time and molecular weight of saccharides. Meanwhile, this work would facilitate the application of O/W emulsion stabilized by glycated protein aggregates in functional foods.

Synthesis and full-spectrum-responsive photocatalytic activity from UV/Vis to near-infrared region of S-O decorated YMnO3 nanoparticles for photocatalytic degradation of ibuprofen.

The oxalic acid complexation method and sulfuric acid heat treatment method were used to synthesize the YMnO3 (YMO) and YMO-SO4 2- (YMO-SO) photocatalysts. The YMO-SO photocatalyst maintained the crystal structure of YMO, but the particle size increased slightly and the optical band gap decreased significantly. The YMO-SO photocatalyst demonstrates a wide range of light absorption capabilities, covering ultraviolet, visible and near-infrared light. The photocatalytic activity of YMO-SO was investigated with ibuprofen as the target pollutant. The YMO-SO photocatalyst exhibits high ultraviolet (UV), visible and near-infrared photocatalytic activity. Experiments with different environmental parameters confirmed that the best catalyst content was 1g/L, the best drug concentration was 75mg/L and the best pH value was 7. The capture experiment, free radical detection experiment and photocatalytic mechanism analysis confirmed that the main active species of YMO-SO photocatalyst were hole and superoxide free radical.

Structure Identification of Ganoderma lucidum Spore Polysaccharides and Their Antitumor Activity In Vivo.

Ganoderma lucidum spore powder, valued for its nutritional and medicinal properties, contains polysaccharides crucial for its efficacy. However, the complex structural nature of these polysaccharides necessitates further investigation to fully realize their potential. This study aimed to investigate the effects of acid heat treatment on Ganoderma lucidum spore polysaccharides (GLSPs) to enhance their properties and application in antitumor activity. The GLSP was obtained via acid heat treatment, concentration, and centrifugal separation. This process led to a notable reduction in polysaccharide molecular weight, increasing water solubility and bioavailability. Analytical techniques including NMR spectroscopy and methylation analysis revealed a polysaccharide composition comprising four distinct monosaccharides, with molecular weights of 3291 Da (Mw) and 3216 Da (Mn). Six different linkage modes were identified, with a molar ratio of 1:5:2:3:4:3. In vivo experiments demonstrated the GLSP's significant inhibitory effect on the growth of four tumor models (sarcoma S180, Lewis lung cancer, liver cancer H22, and colon cancer C26) in mice, with no observed toxicity. These findings suggest the GLSP's potential as an antitumor therapeutic agent for clinical use.

Ginseng fruit rare saponins (GFRS), a promising anti-wrinkle agent: Evidence of its antioxidant effect and its capacity to prevent matrix metalloproteinase (MMPs) expression in vitro and in vivo

Rare saponins show numerous significant biological activities, however, there has been no research on using ginseng fruit rare saponins (GFRS) to minimize skin wrinkles. This paper studied the anti-wrinkle effect, related mechanism, material basis of efficacy, and structure-activity relationship of GFRS in vivo and in vitro. The findings demonstrate that GFRS has potent collagenase and elastase inhibition capabilities in addition to superior ultraviolet absorption properties. Secondly, GFRS can strengthen the endogenous antioxidant defense system, thus lessening the UVB-induced ultraviolet damage that L929 cells and zebrafish experience. Matrix metalloproteinases (MMPs) studies have shown that GFRS could significantly inhibit the UVB-induced MMP1 and MMP9 proteins production. Finally, the main ginsenoside component in GFRS was identified by LC-MS, and 16 kinds of ginsenoside were analyzed, including rare ginsenoside such as Rg6, F4, and R/S-Rg3, which may be caused by the transformation of prototype saponins Re and Rd caused by citric acid heat treatment (CAHT). After doing a quantitative HPLC analysis on twelve of them, it was discovered that CAHT could enrich the content of rare saponins in GFS. By evaluating these ginsenoside’s anti-wrinkle properties. It is found that the main material basis for GFRS’s anti-wrinkle action may be ginsenoside Rg6 or F4. In summary, GFRS exhibits promising properties as an anti-wrinkle treatment because of its robust anti-oxidation, anti-collagenase, anti-elastase activity, favorable ultraviolet absorption effect, and capacity to regulate MMPs in vivo and in vitro models.

Co-encapsulation of curcumin and piperine in whey protein isolate fibrils improves their water dispersibility and antioxidant activity

In this study, whey protein isolate (WPI) fibrils prepared by acid heat treatment for different times (5, 10, 15, or 20 h) were used for the co-encapsulation and co-delivery of curcumin (Cur) and piperine (Pip). Co-encapsulation of both nutraceuticals in the fibrils significantly improved their water dispersibility, chemical stability, and antioxidant activity. For instance, the water dispersibility of Cur and Pip in native WPI solutions was around 47.0% and 47.5%, respectively. In contrast, the water dispersibility of the same two nutraceuticals in WPI fibrils (15 h treatment) was 94.3% and 66.6%, respectively. The nutraceutical-loaded WPI fibrils did not undergo significant flocculation or precipitation after 14 d storage at 25 °C. After encapsulation, the DPPH free radical scavenging ability of the Cur-Pip combination experienced a surge, rising from approximately 35.4% to 72.0%. The Stern-Volmer quenching constants (Ksv) of Cur-WPI (3.03 × 104 M−1) and Pip-WPI (7.08 × 104 M−1) were much smaller than those of Cur-WPI fibrils (3.88 × 104–4.69 × 104 M−1) and Pip-WPI fibrils (8.26 × 104–9.41 × 104 M−1), indicating that the nutraceuticals bind stronger to the protein fibrils than to the native protein molecules. In summary, WPI fibrils have the capability to encapsulate, protect, and deliver hydrophobic nutraceuticals, suggesting their suitability for application in functional foods and beverages.

Study on the formation mechanism of pea protein nanofibrils and the changes of structural properties of fibril under different pH and temperature

The functional performance of plant proteins can be enhanced by converting them into nanofibrils using controlled acid-heat treatments. Initially, the impact of heating time on the morphology and properties of nanofibrils prepared from pea proteins was assessed. The pea protein nanofibrils (PPF) were formed by heating at 85 °C and pH 2.0 for different times (0–24 h). Multiple analytical methods were then used to characterize the properties of the nanofibrils, including transmission electron microscopy (TEM), gel electrophoresis (SDS-PAGE), thioflavin T (ThT) fluorescence spectroscopy, molecular flexibility, and surface hydrophobicity. With increasing heating time, the protein molecules were gradually decomposed into small molecular weight peptides, which then assembled into nanofibrils. Initially, the length of the PPFs increased with heating time, but then it decreased, which was attributed to fibril fragmentation. In the food processing industry, pH and temperature are important factors affecting food preparation. For this reason, the effects of pH (2–9) and temperature (55, 85, 100 °C) on the properties of the nanofibrils were explored. These environmental conditions had a strong influence on the morphology and properties of PPFs. For instance, their flexibility increased with increasing pH, whereas their surface hydrophobicity decreased with increasing pH and temperature. Moreover, their charge went from positive to negative as the pH was ascended from below to above their isoelectric point. The findings of the structural properties of protein nanofibrils could provide some new insights into the wider application of nanofibrils in the food industry.

Malic acid-heat treatment of oil cakes enhances rumen undegradable protein for effective protein utilization in buffaloes (Bubalus bubalis)

Malic acid-heat treatment of oil cakes enhances rumen undegradable protein for effective protein utilization in buffaloes (Bubalus bubalis)

Untreated vs. Treated Carbon Felt Anodes: Impacts on Power Generation in Microbial Fuel Cells.

This research sought to enhance the efficiency and biocompatibility of anodes in bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs), with an aim toward large-scale, real-world applications. The study focused on the effects of acid-heat treatment and chemical modification of three-dimensional porous pristine carbon felt (CF) on power generation. Different treatments were applied to the pristine CF, including coating with carbon nanofibers (CNFs) dispersed using dodecylbenzene sulfonate (SDBS) surfactant and biopolymer chitosan (CS). These processes were expected to improve the hydrophilicity, reduce the internal resistance, and increase the electrochemically active surface area of CF anodes. A high-resolution scanning electron microscopy (HR-SEM) analysis confirmed successful CNF coating. An electrochemical analysis showed improved conductivity and charge transfer toward [Fe(CN)6]3-/4- redox probe with treated anodes. When used in an air cathode single-chamber MFC system, the untreated CF facilitated quicker electroactive biofilm growth and reached a maximum power output density of 3.4 W m-2, with an open-circuit potential of 550 mV. Despite a reduction in charge transfer resistance (Rct) with the treated CF anodes, the power densities remained unchanged. These results suggest that untreated CF anodes could be most promising for enhancing power output in BESs, offering a cost-effective solution for large-scale MFC applications.

Precise control of aggregation morphology: Effective strategy to tune the properties of ovotransferrin particles

Different aggregation morphologies of ovotransferrin (OVT) aggregates were successfully obtained through precise control, and the effects on structural, physical, liquid–liquid and gas–liquid interfacial characteristics as well as mechanisms were explored for the first time. It was observed that the surface hydrophobicity of OVT fibrils was higher than OVT spheres due to the acid-heat treatment. The exploration of liquid–liquid interface behaviors indicated that OVT fibrils possessed higher adsorption capacity at the interface, revealing the higher surface activity at the oil-water interface. During adsorption process, fibrils exhibited higher diffusion rate, while spheres were easier to penetrate and rearrange at the interface. The interfacial film composed of fibrils possessed more elastic solid-like behaviors owing to the higher surface activity of individual fibrous aggregates and rapid fibril-fibril interactions. The analysis of gas–liquid interface characteristics presented that OVT spheres possessed lower interfacial tension and higher interfacial viscoelasticity, and showed significantly higher FC and FS values in comparation to fibrils. These findings will facilitate the reader's understanding of the relationship between protein aggregate structure and properties, and lay a foundation for broadening the application of OVT and even other proteins.

Comparison of Dietary Fiber Characteristics Prepared from Cassava Pulp Using Acid-Heat Treatment and Extrusion Process

Cassava pulp is used to develop dietary fiber from prospective local resources to boost its added value and applications. Extrusion and an acid-heat treatment were used to alter cassava pulp into nutritional fiber. The goal of this study was to characterize the chemical compositions, physical-chemical functional features, and yield of dietary fiber products produced by the extrusion and acid-heat processes. Total dietary fiber (TDF) content was 89.24%, starch content was 9.7%, water holding capacity (WHC) was 12.07 g/g, oil holding capacity (OHC) was 3.99 g/g, swelling capacity (SC) was 17.8 ml/g, bulk density (BD) was 0.2 g/ml, and yield was 50% for the dietary fiber produced by the acid-heat treatment. While the extrusion process produced dietary fiber with TDF content of 50.86%, starch content of 47.28%, WHC of 9.96 g/g, OHC of 0.81 g/g, SC of 12.99 ml/g, BD of 0.6 g/ml, and a yield of 90%. Acid-heat treatment was successful in eliminating starch constituents, raising TDF, and raising WHC and OHC values. The extrusion procedure did not raise TDF or OHC and could not eliminate components of starch, however, it might increase WHC by swelling the starch granules.

Fabrication mechanism and functional properties of ovalbumin fibrils prepared by acidic heat treatment.

Ovalbumin (OVA), accounting for 50% of proteins in egg white, is a kind of high-quality protein with excellent nutritional and processing functions. Acid heat treatment will induce the deformation and filtration of OVA, endowing it with improved functionality. However, the molecular kinetic process during the fibrillation of OVA and the application of the fabricated OVA fibrils (OVAFs) have not been thoroughly studied and revealed. In this study, the fabrication mechanism and the application OVAFs as an interfacial stabilizer and polyphenol protector were investigated. Acidic (pH 3.0) heat treatment was used to induce the fibrillation of OVA, and thioflavin T fluorescence intensity, molecular weight distribution, and the tertiary and secondary structures of OVAF samples were recorded to determine the fibrillation efficiency and the molecular mechanism. The results showed that, in the initial stage of fibrillation, OVA first hydrolyzed to oligopeptides, accompanied by the exposure of hydrophobic domains. Then, oligopeptides were connected by disulfide bonds to form primary fibril monomers. Hydrophobic interaction and hydrogen bonding may participate in the further polymerization of the fibrils. The fabricated OVAFs were characterized by a β-sheet-rich structure and possessed improved emulsifying, foaming, and polyphenol protection ability. The research work was meaningful for exploring the application of globular water-soluble OVA in an emerging nutritious food with novel texture and sensory properties. © 2023 Society of Chemical Industry.

High-performance films fabricated by food protein nanofibrils loaded with vanillin: Mechanism, characterization and bacteriostatic effect

A viable platform for food packaging applications has evolved in the form of protein nanofibers with material properties. Through this work, a simple, extensible process of protein for amyloid fibrils formation was proposed. The addition of polyphenol was expected to improve its synergistic antibacterial properties. The isolate protein of soy and whey (SPI and WPI) were selected as model proteins with an acid-heat treatment for 5 h to prepare the nanofibrils. Protein molecules eventually lost their intrinsic structure, which was also followed by aggregation and degeneration. Atomic force microscopy was used to investigate how proteins' spherical and linear shapes changed over time. As the protein unfolded and intermolecular aggregation occurred, circular dichroism (CD) demonstrated that the protein's secondary structure altered from a-helix to β-sheet and random coils. Furthermore, the fibrous protein films' mechanical characteristics were enhanced, particularly the elongation (E) of amyloid SPI films, which increased from 33.50 % to 100.57 %. Additionally, the films' water solubility (WS) and water vapor permeability (WVP) were both decreased. In order to create an antibacterial edible film, vanillin was also added to the fibrous protein solution as a bacteriostatic agent. The results showed that the fibrous protein film demonstrated a great bacteriostatic action and retained good shape. Here we present this simple and efficient method to obtain robust, flexible films, which not only provides a strategy for films with good mechanical properties but also extends their antibacterial by adding a bacteriostatic agent to further provide a new idea for food packaging.

Enhancement of emulsification properties by modulation of egg white protein fibril structure with different heating times

Egg white protein (EWP) has poor emulsification ability due to the hydrophobic groups buried in the molecular structure. In contrast, the protein fibrils produced by acidic heat treatment are able to expose the hydrophobic groups and firmly adsorb to the surface of oil droplets. Therefore, the preparation of egg white protein fibrils (EWPF) can broaden the range of applications of EWP, such as low-fat emulsion-based foods. Since the heating time affects the growth condition of the fibrils and thereby the properties of their stabilized emulsions. The effect of treatment time on the structure properties and emulsification properties of EWP during fibrillation, also the effect of different environments on the stability of EWPF emulsion were investigated. The EWPF content increased with heating time. During the heating of EWP under acidic condition, proteins were hydrolyzed into peptides, subsequently peptides aggregated unidirectionally to form fibrils due to electrostatic repulsive forces at low pH. Compared with EWP, EWPF had larger particle size, higher ζ-potential, higher β-sheet content and greater surface hydrophobicity. In addition, the emulsifying activity and emulsification stability of the EWPF emulsion increased nearly two-fold compared with that of the EWP emulsion. Furthermore, it had smaller droplets, higher ζ-potential, and better thermal and ionic stability. This study could provide insights into the improvement of EWP emulsifying properties and fibril-modified EWP as stabilizing ingredients for emulsion-based foods. • EWP rich in acidic amino acids is an excellent material for fibrils preparation. • EWPF morphology gradually prolonged and aggregated with heating time. • The fine curled structure of EWPF can better encapsulate the oil droplets. • EWPF had the best emulsification properties when heated for 8 h. • Thermal stability and ionic stability of emulsion with EWPF were increased.

Apple pomaces derived from mono-varietal Asturian ciders production are potential source of pectins with appealing functional properties

Comprehensive chemical characterization of nine mono-varietal apple pomaces obtained from the production of ciders with PDO is described. They were rich in essential minerals, fibers (35–52.9 %), and polyphenols. High levels in GalA (11.8–21.6 %), revealed the suitability of these apple pomaces as efficient sources of pectins. Extracted pectins showed high variability in monomer composition, with degrees of methylesterification, strongly associated with pectins functional properties, ranging from 58 to 88 %. For a subset of apple pomace varieties, pectin extraction was accomplished by conventional acid heat treatment or ultrasound. Despite ultrasound-assisted extraction did not improve pectin yield, it minimized levels of “non-pectin” components as revealed by the low content of Glc/Man, leading to the obtainment of high-purity pectin. Our work highlights the key role played by the selection of the apple variety to streamline the potential food applications (gelling/thickening agents or prebiotics) of the extracted pectins that largely depend on their structural features.

The effect of the nitric acid heat treatment time on the ELECTROCHEMICAL PROPERTIES OF NiCo2S4/CARBON CLOTH composites as supercapacitor electrode materials

The effect of the nitric acid heat treatment time on the ELECTROCHEMICAL PROPERTIES OF NiCo2S4/CARBON CLOTH composites as supercapacitor electrode materials

A dimensional stable hydrogel-born foam with enhanced mechanical and thermal insulation and fire-retarding properties via fast microwave foaming

Hydrogel-born foam materials have been intensively developed because of great potential in various fields and environmental friendliness with water as foaming agent. However, the energy-consuming nature and pore collapse in the preparing and using process limit their application. Herein, a facile strategy is present to fabricate a dimensional stable hydrogel-born foam by simple acid-heat treatment and subsequent fast microwave foaming. The microwave heating rapidly evaporates and expands water into cells in the gel while the heat softening of the hydrogel further facilitates the formation of the cells. Moreover, the hydrophilicity/hydrophobicity and the crosslinking degree of the foam can be regulated by controllable conversion of amide groups of the hydrogel to the imide groups during the acid-heat treatment. As a result, it successfully avoids the pore collapse in both of the preparation and use process. With hierarchical pore structure and controllable moisture absorption, the foam shows with excellent dimensional and thermal insulation. In addition, the foam provides superior mechanical properties and fire retardance over traditional foams. The flame-retardant mechanism was proposed. The fabrication of this hydrogel-born foam is facile, flexible and can be adapted for extensive applications in building structures.

Preparation of sea cucumber (Stichopus variegates) peptide fraction with desired organoleptic property and its anti-aging activity in fruit flies and D-galactose-induced aging mice

Abstract Sea cucumber-derived peptide, a potential candidate for combating aging, is currently under-developed. In the present study, we reported the development of a green approach to efficiently prepare a high-value anti-aging oligopeptide fraction with desired color and low viscosity from a low-edible-value sea cucumber (Stichopus variegates) containing highly viscous polysaccharide using enzymatic hydrolysis, acid-heat treatment and ultrafiltration. The analysis by UPLC-MS/MS revealed the peptide composition characteristic of S. variegates peptide fraction, suggesting the acceptable stabilities of oligopeptides during citric acid-heat processing. In vivo studies demonstrated that S. variegates peptide fraction effectively promoted longevity in normal and D-galactose-induced aging fruit flies and attenuated D-galactose-induced oxidative injury in mice via up-regulating Klotho expression, activating SOD and GSH-Px, and inhibiting lipid peroxidation and protein oxidation. Our results also validated the stability of longevity promoting efficacy and anti-oxidative stress action of S. variegates peptide after citric acid-heat treatment.

OBTAINING MICROCRYSTALLINE CELLULOSE FROM MELON CROPS AND STUDYING ITS STRUCTURE

The aim of the study was to obtain microcrystalline cellulose from gourds. Cellulose was isolated from the stems of watermelon and pumpkin by acid and alkaline heat treatment. Microcrystalline cellulose was obtained from cellulose by hydrolysis. Cellulose was hydrolyzed in a mixture of sulfuric acid and hydrogen peroxide. The optical parameters of the microcrystalline cellulose sample, ash content, bulk density, water swelling, and moisture sorption were determined. The structural features of the obtained microcrystalline cellulose were studied by IR spectroscopy. The functional groups present under various conditions for the production of microcrystalline cellulose were determined. The influence of the duration of cellulose treatment on the degree of ordering of microcrystalline cellulose was established.

Microstructure, gelatinization and pasting properties of rice starch under acid and heat treatments

Microstructure of starch plays a vital role in the physicochemical properties. In this study, the microstructure, gelatinization and pasting properties of rice starches after acid, heat and acid-heat treatments were investigated. In our findings, molecular weight and size, amylopectin chain length distribution, degree of branching, amylose content, relative crystallinity, and hot water-solubility of rice starch were varied significantly after acid-heat treatment, showing a synergy between acid and heat. Correspondingly, acid-heat treatment markedly changed gelatinization and pasting properties of rice starch by sharply decreasing gelatinization and pasting temperatures as well as pasting viscosities. Pearson correlation analysis was performed, showing that molecular weight, size, amylopectin chain length distribution, and amylose content were significantly correlated to gelatinization temperatures, and crystallinity was remarkably correlated to gelatinization enthalpy. As for pasting properties, molecular weight and size as the major factors were substantially correlated to pasting viscosities and pasting temperature. This study provides a structure-property correlation for acid-heat treated rice starch, giving scientific basis for the application of starch in food industry.