Inhibition of Lipid and Protein Oxidation in Whey-Protein-Stabilized Emulsions Using a Natural Antioxidant: Black Rice Anthocyanins

Application of poly(L-lactic acid)-based films for equilibrium modified atmosphere packaging of "Kyoho" grapes and its favorable protection for anthocyanins

Grapes were packaged by different Poly (L-lactic acid)-based packaging films (PLTL-PLEL) and stored at 5 °C for 35 days to investigate the effects of equilibrium modified atmosphere packaging on the quality of "Kyoho" grapes during storage. Changes in physiochemical quality, antioxidant content and senescence of grapes were studied. Furthermore, UPLC-Q-TOF-MS/MS was used to observe and identify key factors influencing the variation of grape anthocyanins under different atmosphere conditions. Alterations in gas components and enzyme activities significantly impacted anthocyanin levels, highlighting oxygen concentration as the primary influence on total anthocyanin levels. The PLTL-PLEL50 packaging resulted in an approximate 5.7% lower weight loss and increased soluble solids by approximately 14.4%, vitamin C, total phenols and flavonoids reaching 60.2 mg/100 g, 8.4 mg/100 g and 7.2 mg/100 g, respectively. This packaging also preserved higher anthocyanin levels, with malvidin-3-glucoside and peonidin-3-glucoside at 0.55 μg/mL and 1.62 μg/mL, respectively, on the 35th day of storage.

Young apple polyphenols confer excellent physical and oxidative stabilities to soy protein emulsions for effective β-carotene encapsulation and delivery

Protein emulsions' poor physical and oxidative stabilities restrict their use in functional foods. Soy protein isolate (SPI) emulsions' physical stability was enhanced by adding young apple polyphenols (YAP) in this study, but decreased when YAP was 0.12%. YAP binding prefolded SPI's structure, which promotes efficient SPI stacking at the interface. YAP also improved SPI emulsions' oxidation resistance in a dose-dependent manner. SPI-YAP interaction promoted more YAP adsorption (>80%) at the interface, which increased emulsions' antioxidant capacities twofold. Furthermore, over 90% of unsaturated fatty acids were preserved, and the oxidation of lipid-SPI-β-carotene appeared to be reduced as YAP increased. In addition, SPI-YAP emulsions were effective in encapsulating and safeguarding β-carotene during emulsion storage and in vitro digestion, leading to a delayed and maximum release of β-carotene. This study improves the understanding of polyphenols inhibition on lipid-protein oxidation through interface strengthening and broadens the potential applications of YAP and SPI in functional foods.

Research Progress on the Extraction and Purification of Anthocyanins and Their Interactions with Proteins

Anthocyanins, as the most critical water-soluble pigments in nature, are widely present in roots, stems, leaves, flowers, fruits, and fruit peels. Many studies have indicated that anthocyanins exhibit various biological activities including antioxidant, anti-inflammatory, anti-tumor, hypoglycemic, vision protection, and anti-aging. Hence, anthocyanins are widely used in food, medicine, and cosmetics. The green and efficient extraction and purification of anthocyanins are an important prerequisite for their further development and utilization. However, the poor stability and low bioavailability of anthocyanins limit their application. Protein, one of the three essential nutrients for the human body, has good biocompatibility and biodegradability. Proteins are commonly used in food processing, but their functional properties need to be improved. Notably, anthocyanins can interact with proteins through covalent and non-covalent means during food processing, which can effectively improve the stability of anthocyanins and enhance their bioavailability. Moreover, the interactions between proteins and anthocyanins can also improve the functional characteristics and enhance the nutritional quality of proteins. Hence, this article systematically reviews the extraction and purification methods for anthocyanins. Moreover, this review also systematically summarizes the effect of the interactions between anthocyanins and proteins on the bioavailability of anthocyanins and their impact on protein properties. Furthermore, we also introduce the application of the interaction between anthocyanins and proteins. The findings can provide a theoretical reference for the application of anthocyanins and proteins in food deep processing.

Enhancing the properties of soy protein isolate and dialdehyde starch films for food packaging applications through tannic acid crosslinking

The utilization of naturally derived biodegradable polymers, including proteins, polysaccharides, and polyphenols, holds significant promise in addressing environmental concerns and reducing reliance on nonrenewable resources. This study aimed to develop films with enhanced UV resistance and antibacterial capabilities by covalently cross-linking soy protein isolate (SPI) with dialdehyde starch (DAS) through the incorporation of tannic acid (TA). The covalent crosslinking of TA with DAS and SPI was shown to establish a stable chemical cross-linking network. The tensile strength of the resulting SPI/DAS/15TA film exhibited a remarkable increase of 208.27 % compared to SPI alone and 52.99 % compared to SPI/DAS film. Notably, the UV absorption range of SPI/DAS/10TA films extended from 200 nm to 389 nm. This augmentation can be attributed to the oxidation of TA's phenolic hydroxyl groups to quinone under alkaline conditions, which then facilitated cross-linking with the SPI chain via Michael addition and Schiff base reactions. Furthermore, the film demonstrated robust antibacterial properties due to the incorporation of TA. Collectively, the observed properties highlight the significant potential of the SPI/DAS/10TA film for applications in food packaging, where its enhanced mechanical strength, UV resistance, and antibacterial characteristics can contribute to improved product preservation and safety.

Anthocyanin of Black Highland Barley Alleviates H2O2-Induced Cardiomyocyte Injury and Myocardial Infarction via Activating the Phosphatase and Tensin Homolog/Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

Cardiovascular disease (CVD) represents a substantial global health challenge, with its impact on mortality and morbidity rates surpassing that of cancer. The present study was designed to explore the cardioprotective properties of anthocyanin (ACN), a compound derived from black barley, against oxidative stress-induced damage in myocardial cells and to uncover the molecular mechanisms at play. Utilizing both in vitro and in vivo experimental models, our findings indicate that ACN notably reduced cell damage caused by oxidative stress and effectively prevented apoptosis. High-throughput RNA sequencing analysis has shed light on the mechanism by which ACN achieves its antioxidative stress effects, implicating the PTEN-Akt signaling pathway. ACN was found to modulate PTEN expression levels, which in turn influences the Akt pathway, leading to a reduction in apoptotic processes. This novel insight lays the groundwork for the potential clinical utilization of ACN in the management of CVD. While this study has shed light on some of the functions of ACN, it is important to recognize that natural compounds often interact with multiple molecular targets and engage in intricate signaling cascades. Future research endeavors will concentrate on further elucidating the regulatory mechanisms by which ACN influences PTEN expression, with the goal of enhancing our comprehension and expanding the therapeutic potential of ACN in the treatment of cardiovascular conditions.

Heritability and amylose content in hybrid lines of late-generation rice with colored pericarp

Improving grain quality in rice breeding is one of the main tasks. This concerns the creation of rice varieties with colored pericarp uncommon in the Republic of Kazakhstan, and the assessment of its quality is an important stage of breeding. Rice with colored pericarp is an important dietary crop, more useful for the human body than white rice. Regardless of the type of rice, the amount of amylose in rice grain is a crucial indicator that determines the quality of rice. The paper presents the results of electrophoretic separation of spare grain proteins of rice hybrids and dihaploids with colored pericarp and their parent forms obtained as a result of the hybridization of varieties with colored pericarp (Black Rice (China), Mavr (Russia), and Yir 5815 (Ukraine)) with white rice varieties zoned in Kazakhstan. The hybridization of the rice varieties with colored pericarp with white rice varieties was carried out to obtain rice varieties with colored pericarp oriented to the soil and climate of Kazakhstan. Analyzing the results of electrophoresis and the amount of amylose, it was found that hybrid lines differed in amylose content. One of the studied hybrids was high in amylose, four had a medium amylose content, ten had a low amylose content, three had a very low amylose content, and six were glutinous. According to the results of electrophoretic separation of spare rice grain proteins, the spectrum of the enzyme determining amylose was detected in five hybrids, which corresponds to the results of spectrophotometric determination of amylose: high amylose in one hybrid and medium amylose content in four. The results show that the hybrids obtained as a result of hybridization are true hybrids and as a result of long-term selection, the amylose content in the F7-F8 hybrids stabilized. The hybrids can be used in further breeding of rice with colored pericarp.

Effect of Different Temperatures on the Storage Stability of Flaxseed Milk

In this study, the physical and oxidative stability of flaxseed milk without food additives at different temperatures (25 °C and 37 °C) was assessed. Over in 206 days in storage, the particle size, Turbiscan stability index (TSI), centrifugal sedimentation rate, and primary and secondary oxidation products of flaxseed milk increased, viscosity decreased, and the absolute value of the potential first decreased and then increased. These phenomena indicated a gradual decrease in the physical stability of flaxseed milk, accompanied by drastic oxidative changes. The antioxidant capacity of flaxseed milk was related to the location of the physical distribution of flaxseed lignin, which was more effective in the aqueous phase compared to the non-aqueous phase. Interestingly, after 171 days in storage at 37 °C, the particle size of flaxseed milk was approximately doubled (6.98 μm → 15.27 μm) and the absolute value of the potential reached its lowest point (-13.49 mV), when the content of primary oxidation products reached its maximum (8.29 mmol/kg oil). The results showed that temperature had a significant effect on the stability of flaxseed milk and that stability decreased with increasing temperature and shortened shelf life. This work provides a theoretical basis for elucidating the stabilization-destabilization mechanism of flaxseed milk.

Pickering emulsion stabilized by Haematococcus pluvialis protein particles and its application in dumpling stuffing

In this study, the oil-in-water Pickering emulsions were prepared using Haematococcus Pluvialis protein (HPP) particles as an emulsifier by a simple one-step emulsification method. The internal oil phase was as high as 70 % due to the excellent emulsifying properties of HPP, and the average size of oil droplets in the emulsion was around 20 μm. The emulsion prepared by 2.5 % HPP with the oil phase ratio of 70 % showed the best stability after 14 days of storage, and the emulsion could maintain stability at acidic condition, high ionic strength, low and high temperatures. However, all emulsion samples exhibited shear thinning phenomenon, and the higher HPP concentration and oil phase ratio led to greater G' and G″ modulus. NMR relaxation results showed that high concentration HPP could limit the mobility of free water in the emulsion and improve the emulsion stability. The HPP-stabilized emulsion could inhibit the oxidation of oil phase during storage due to the DPPH and ABTS radical scavenging activity of astaxanthin (AST) in HPP. Finally, the nutritional microspheres based on HPP-stabilized emulsion showed good stability in traditional dumplings and could reduce the loss of AST and DHA in algae oil during the boiling of dumplings.

Designing ultra-stable linseed oil-in-water Mickering emulsions using whey protein isolate cold-set microgels containing marjoram aqueous extract: Effect of pH and extract on rheological, physical, and chemical properties

In this study, whey protein isolate (WPI) cold-set microgels containing marjoram (Origanum majorana) aqueous extract (MAE) were prepared at different pHs (4.0, 5.0, and 6.0). After characterization, the microgel dispersion was used to stabilize linseed oil-in-water Mickering emulsions (MEs). The resultant MEs were then characterized in terms of physicochemical and rheological properties under the effect of pH and MAE addition. The morphology, particle size, zeta potential, and interfacial tension of microgels were affected by pH and MAE. XRD patterns showed the amorphous structure. Microgel-stabilized MEs did not reveal any significant sign of instability under gravity during 6 months of storage. All MEs had dominant elastic character. Despite the lowest zeta potential values, MEs prepared at pH 4 showed the highest physical stability against gravity but the lowest centrifugal stability against oiling off, which indicated that both viscous and elastic components are required for MEs stability. This sample had the highest apparent viscosity and the strongest viscoelastic properties. Rheological data were best fitted with Herschel-Bulkley and Power Law models. An increase in pH and presence of MAE improved the oxidative stability of MEs. The results of this study showed that WPI microgels are appropriate candidate for long-term stabilization of linseed oil-in-water MEs. The presence of MAE is useful in designing special emulsions in which the aqueous phase is partially replaced by the aqueous extract of medicinal plants.

Integral Valorization of Grape Pomace for Antioxidant Pickering Emulsions

Full harnessing of grape pomace (GP) agricultural waste for the preparation of antioxidant Pickering emulsions is presented herein. Bacterial cellulose (BC) and polyphenolic extract (GPPE) were both prepared from GP. Rod-like BC nanocrystals up to 1.5 µm in length and 5-30 nm in width were obtained through enzymatic hydrolysis (EH). The GPPE obtained through ultrasound-assisted hydroalcoholic solvent extraction presented excellent antioxidant properties assessed using DPPH, ABTS and TPC assays. The BCNC-GPPE complex formation improved the colloidal stability of BCNC aqueous dispersions by decreasing the Z potential value up to -35 mV and prolonged the antioxidant half-life of GPPE up to 2.5 times. The antioxidant activity of the complex was demonstrated by the decrease in conjugate diene (CD) formation in olive oil-in-water emulsions, whereas the measured emulsification ratio (ER) and droplet mean size of hexadecane-in-water emulsions confirmed the physical stability improvement in all cases. The synergistic effect between nanocellulose and GPPE resulted in promising novel emulsions with prolonged physical and oxidative stability.

Robust microfluidic construction of polyvinyl pyrrolidone microfibers incorporated with W/O emulsions stabilized by amphiphilic konjac glucomannan

In this work, we prepared polyvinyl pyrrolidone (PVP) microfibers incorporated water-in-oil (W/O) emulsions. The W/O emulsions were fabricated by hexadecyl konjac glucomannan (HKGM, emulsifier), corn oil (oil phase) and purple corn anthocyanins (PCAs, water phase). The structures and functions of emulsions and microfibers were characterized by confocal laser scanning (CLSM) and scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Raman and nuclear magnetic resonance (NMR) spectroscopy. The results showed that W/O emulsions exhibited good storage stability for 30 d. Microfibers presented ordered and uniform arrays. Compared with pure PVP microfiber films, the addition of W/O emulsions with PCAs improved the water resistance (WVP from 1.28 to 0.76 g mm/m² day kPa), mechanical strength (Elongation at break from 18.35 % to 49.83 %), antioxidation (free radical scavenging rate from 2.58 % to 16.37 %), and antibacterial activity (inhibition zone against E. coli: 27.33 mm and inhibition zone against S. aureus: 28.33 mm) of microfiber films. Results showed that microfiber film exhibited controlled release of PCAs in W/O emulsions, and about 32 % of the PCAs were released from the microfiber film after 340 min. The as-prepared microfiber films exhibited potential applications for food packaging.

Epicatechin Inhibited Lipid Oxidation and Protein Lipoxidation in a Fish Oil-Fortified Dairy Mimicking System

In this study, a typical tea polyphenol epicatechin (EC) was investigated for its impact on the oxidative stability of whey protein isolate (WPI) in a fish oil-fortified emulsion. The oil-in-water emulsion system consisted of fish oil (1%, w/w), WPI (6 mg/mL), and EC (0.1, 1, and 2 mM), and the oxidation reaction was catalyzed by Fenton's reagent at 25 °C for 24 h. The results showed EC exhibited a dose-dependent activity in the reduction of lipid oxidation (TBARS) and protein carbonylation. A Western blot analysis demonstrated that protein lipoxidation was inhibited by EC via interrupting the covalent binding of lipid secondary oxidation products, MDA, onto proteins. In addition, protein lipoxidation induced a loss of tryptophan fluorescence, and protein hydrolysis was partially recovered by EC. The findings of this study provide an in-depth understanding of the performance of phenolic antioxidants in relieving lipid oxidation and subsequent protein lipoxidation in oil-containing dairy products.

Improvement of Oxidative Stability of Fish Oil-in-Water Emulsions through Partitioning of Sesamol at the Interface

The susceptibility of polyunsaturated fatty acids to oxidation severely limits their application in functional emulsified foods. In this study, the effect of sesamol concentration on the physicochemical properties of WPI-stabilized fish oil emulsions was investigated, focusing on the relationship between sesamol-WPI interactions and interfacial behavior. The results relating to particle size, zeta-potential, microstructure, and appearance showed that 0.09% (w/v) sesamol promoted the formation of small oil droplets and inhibited oil droplet aggregation. Furthermore, the addition of sesamol significantly reduced the formation of hydrogen peroxide, generation of secondary reaction products during storage, and degree of protein oxidation in the emulsions. Molecular docking and isothermal titration calorimetry showed that the interaction between sesamol and β-LG was mainly mediated by hydrogen bonds and hydrophobic interactions. Our results show that sesamol binds to interfacial proteins mainly through hydrogen bonding, and increasing the interfacial sesamol content reduces the interfacial tension and improves the physical and oxidative stability of the emulsion.

Optimization of Extrusion Treatments, Quality Assessments, and Kinetics Degradation of Enzyme Activities during Storage of Rice Bran

Over the years, extrusion has been a multi-step thermal technique that has proven to be the most effective process to stabilize rice bran (RB). This study aimed to investigate the effects of extrusion treatment and temperature (15, 25, and 40 °C) on the storage stability, lipid oxidation, peroxidase, and peroxide values, free fatty acids, fatty acid composition, and protein variations of RB over 60 days. The study offers novel insights into the changes in RB’s protein and amino acid compositions during extrusion and storage, which has not been extensively explored in prior research. After extrusion processing, peroxidase activity (POD) and lipase activity (LPS) were significantly reduced. However, peroxide value (PV), free fatty acids (FFA), and malondialdehyde content (MDA) observed a significantly increased by 0.64 mEqO2/kg, 8.3 mg/100 g, and 0.0005 μmol/L respectively. The storage stability of RB after extrusion shows that the POD, LPS, FFA, PV, and MDA were positively correlated with storage duration and temperature. The oleic acid/linoleic acid ratio in processed RB by extrusion had no significant changes during storage. The total and essential/non-essential amino acid ratios showed a downward trend of 5.26% and 8.76%, respectively. The first-order kinetics was the best-fitting model to describe the enzymatic inactivation and degradation of extruded RB during storage. The extrusion treatment did not affect the crude protein and the essential subunits of protein. Overall, the optimized extrusion procedure exhibited promising results in stabilizing the RB.

Complexation of anthocyanins, betalains and carotenoids with biopolymers: An approach to complexation techniques and evaluation of binding parameters

Natural pigments are bioactive compounds that can present health-promoting bioactivities in the human body. Due to their strong coloring properties, these compounds have been widely used as color additives as an alternative to artificial colorants. However, since these pigments are unstable under certain conditions, such as the presence of light, oxygen, and heat, the use of complexation and encapsulation techniques with biopolymers is in demand. Moreover, some functional properties can be achieved by using natural pigments-biopolymers complexes in food matrices. The complexation and encapsulation of natural pigments with biopolymers consist of forming a complex with the aim to make these compounds less susceptible to oxidative and degrading agents, and can also be used to improve their solubility in different media. This review aims to discuss different techniques that have been used over the last years to create natural pigment-biopolymers complexes, as well as the recent advances, limitations, effects, and possible applications of these complexes in foods. Moreover, the understanding of thermodynamic parameters between natural pigments and biopolymers is very important regarding the complex formation and their use in food systems. In this sense, thermodynamic techniques that can be used to determine binding parameters between natural pigments and potential wall materials, as well as their applications, advantages, and limitations are presented in this work. Several studies have shown an improvement in many aspects regarding the use of these complexes, including increased thermal and storage stability. Nonetheless, data regarding the biological effects on the human body and the sensory acceptance of natural pigments-biopolymers complexes in food systems are scarce in the literature.

A review of protein-phenolic acid interaction: reaction mechanisms and applications

Phenolic acids (PA) are types of phytochemicals with health benefits. The interaction between proteins and PAs can cause minor or extensive changes in the structure of proteins and subsequently affect various protein properties. This study investigates the protein/PA (PPA) interaction and its effects on the structural, physicochemical, and functional properties of the system. This work particularly focused on the ability of PAs as a subgroup of phenolic compounds (PC) on the modification of proteins. Different aspects including the influence of structure affinity relationship and molecular weight of PA on the protein interaction have been discussed in this review. The physicochemical properties of PPA change mainly due to the change of hydrophilic/hydrophobic parts and/or the formation of some covalent and non-covalent interactions. Furthermore, PPA interactions affecting functional properties were discussed in separate sections. Due to insufficient studies on the interaction of PPAs, understanding the mechanism and also the type of binding between protein and PA can help to develop a new generation of PPA. These systems seem to have good capabilities in the formulation of low-fat foods like high internal Phase Emulsions, drug delivery systems, hydrogel structures, multifunctional fibers or packaging films, and 3 D printing in the meat processing industry.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

The impact of konjac glucomannan on the physical and chemical stability of walnut oil-in-water emulsions coated by whey proteins

BACKGROUND

Walnut oil, which is rich in polyunsaturated fatty acids (PUFAs), can be incorporated into food emulsions to increase their nutritional value. However, these emulsions are highly susceptible to deterioration during storage due to lipid oxidation. Konjac glucomannan (KGM) is a neutral plant polysaccharide used as a stabilizer, thickener or gelling agent in foods. The goal of this study was to incorporate KGM into oil-in-water emulsions containing walnut oil droplets coated by whey protein isolate (WPI) and then determine its effects on their physical and oxidative stability.

RESULTS

At pH 3, inclusion of KGM (0.1-1 g kg^-1 ) reduced the positive surface potential on the droplets in the emulsions and modified the secondary structure of the adsorbed whey proteins, suggesting an interaction between KGM and WPI at the droplet surfaces. The physical stability of the emulsions was enhanced when 0.1-0.6 g kg^-1 KGM was added but reduced at higher levels. Lipid oxidation was inhibited in the emulsions in a dose-dependent manner when 0.2-0.6 g kg^-1 KGM was added but protein oxidation was promoted at higher KGM levels. The steric hindrance provided by the thick WPI-KGM interfaces, as well as the ability of the polysaccharides to modify the antioxidant properties of the adsorbed proteins, may account for these effects.

CONCLUSION

These results suggest that KGM can be used to inhibit lipid oxidation in emulsified foods containing protein-coated oil droplets. However, its level must be optimized because higher doses can result in droplet aggregation and protein oxidation. © 2022 Society of Chemical Industry.

Dual stabilization of Pickering emulsion with epigallocatechin gallate loaded mesoporous silica nanoparticles

Oxidation in food emulsions remains challenging to keep food quality and shelf-life. In this paper, a dual stabilization to both oil phase and antioxidant in Pickering emulsion is presented. Mesoporous silica nanospheres (MSN) were prepared to incorporate epigallocatechin gallate (EGCG), a typical plant-based antioxidant. EGCG loaded MSN were used to emulsify Litsea cubeba essential oil, a model oil, with olfactory investigation of the chemical stability. The emulsions improved the physical and chemical stabilization. The emulsions were uniformly stable with various parameters with one-month observation. Olfactory evaluation and GC-MS-O investigation reveal that the odors and odorous compounds of essential oil were well preserved in Pickering emulsions and much better than those in conventional emulsion with Tween 80. EGCG loaded MSN Pickering emulsion efficiently protect essential oil from oxidation. EGCG was also well retained in Pickering emulsion. This strategy could inspire new designs for food functional Pickering emulsions with efficient protective effect.

Review on the Regulation of Plant Polyphenols on the Stability of Polyunsaturated-Fatty-Acid-Enriched Emulsions: Partitioning Kinetic and Interfacial Engineering

The plant polyphenols are normally presented as natural functional antioxidants, which also possess the potential ability to improve the physicochemical stability of polyunsaturated fatty acid (PUFA)-enriched emulsions by interface engineering. This review discussed the potential effects of polyphenols on the stability of PUFA-enriched emulsions from the perspective of the molecular thermodynamic antioxidative analysis, the kinetic of interfacial partitioning, and the covalent and non-covalent interactions with emulsifiers. Recently, research studies have proven that the interfacial structure of emulsions can be concurrently optimized via promoting interfacial partitioning of polyphenols and further increasing interfacial thickness and strength. Moreover, the applied limitations of polyphenols in PUFA-enriched emulsions were summarized, and then some valuable and constructive viewpoints were put forward in this review to provide guidance for the use of polyphenols in constructing PUFA-enriched emulsions.

Proposed Methods for Testing and Comparing the Emulsifying Properties of Proteins from Animal, Plant, and Alternative Sources

The food industry is trying to reformulate many of its products to replace functional ingredients that are chemically synthesized or isolated from animal sources (such as meat, fish, eggs, or milk) with ingredients derived from plant or microbial sources. This effort is largely a result of the demand for foods that are better for the environment, human health, and animal welfare. Many new kinds of plant- or microbial-derived proteins are being isolated for potential utilization as functional ingredients by the food industry. A major challenge in this area is the lack of standardized methods to measure and compare the functional performance of proteins under conditions they might be used in food applications. This information is required to select the most appropriate protein for each application. In this article, we discuss the physicochemical principles of emulsifier functionality and then present a series of analytical tests that can be used to quantify the ability of proteins to form and stabilize emulsions. These tests include methods for characterizing the effectiveness of the proteins to promote the formation and stability of the small droplets generated during homogenization, as well as their ability to stabilize the droplets against aggregation under different conditions (e.g., pH, ionic composition, temperature, and shearing). This information should be useful to the food industry when it is trying to identify alternative proteins to replace existing emulsifiers in specific food applications.

Effect of Purple Corn Anthocyanin on Antioxidant Activity, Volatile Compound and Sensory Property in Milk During Storage and Light Prevention

The aim of this study was to observe the effect of purple corn anthocyanin on the light-induced antioxidant activity, free radicals, volatile compounds, color parameters, and sensory properties of milk during storage. There were four groups: (1) negative control, no addition of anthocyanins + exposure to fluorescent light (NC); (2) positive control 1, no addition of anthocyanins + protected from fluorescent light (PC1); (3) positive control 2, the addition of 0.3% (w/v) anthocyanins + exposure to fluorescent light (PC2); and (4) the addition of 0.3% anthocyanins + protected from fluorescent light (AC). The results indicated that the concentration of antioxidant activity parameters in the NC group decreased during the entire storage period, whereas antioxidant activity parameters were unchanged except for the glutathione peroxidase (GSH-Px) in the AC group. Moreover, the NC group showed lower levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and higher levels of superoxide anion and hydrogen peroxide than the other groups after 1 d of storage period. The extent of malondialdehyde accumulation and lipid peroxidation in the control groups were greater than that of the AC group. Twenty-two volatile compounds were determined in milk, which consisted of eight alcohols, three ketones, five aldehydes, two esters, and four hydrocarbons by headspace gas chromatography mass spectrometer analysis. Specifically, individual aldehydes, esters and hydrocarbons in the AC group remained at relatively stable values during storage relative to the other three groups. Stronger positive correlations were detected between several antioxidant activities (superoxide dismutase, GSH-Px) and DPPH scavenging activity as well as total ketones in milk. Adding of anthocyanin did not impact on the color values of L^*, a^* and b^* in light-protected milk during the entire storage period. Some sensory evaluation parameters (flat, garlic/onion/weedy, oxidized-light, oxidized-metal, rancid) in AC group were significantly higher than that of the control group at the end of the period. In conclusion, the current study revealed that the addition of purple corn anthocyanin pigment to light-protected milk had the potential to prevent lipid oxidation, enhance antioxidant activity, maintain volatile compounds and increase the sensory scores.

Lipid oxidation and in vitro digestion of pickering emulsion based on zein-adzuki bean seed coat polyphenol covalent crosslinking nanoparticles

This study first used adzuki bean seed coat polyphenol (ABSCP) to modify zein and form covalent nanoparticles (ZAP) and used ZAP as an emulsifier to stabilize Pickering emulsion (ZAE). The results showed that the ratio of zein-ABSCP controlled the physicochemical properties of the two compounds. ZAP could be absorbed on the water-oil surface and stabilized ZAE, which presented as a non-Newtonian fluid state with good rheological properties. The addition of ABSCP inhibited lipid oxidation in a dose-dependent manner, as verified through the analysis of accelerated oxidation experiments (50 °C, 20 days). In in vitro gastrointestinal digestion of ZAE showed that free fatty acids (FFA) release gradually decreased with ABSCP concentration increasing. Moreover, ABSCP gave ZAE a strong red-yellow color, which allowed ZAE to be used for specific applications (e.g., natural pigments). Our findings make it feasible to develope functional food and food-grade delivery systems made of protein-plant polyphenols nanoparticles.

Formation of Antioxidant Multilayered Coatings for the Prevention of Lipid and Protein Oxidation in Oil-in-Water Emulsions: Lycium barbarum Polysaccharides and Whey Proteins

The impact of Lycium barbarum polysaccharides (LBPs) on the physical and chemical stability of oil-in-water emulsions coated by a whey protein isolate (WPI) was investigated. At pH 3.0, the anionic LBP (0.2-0.6 wt %) molecules were electrostatically deposited onto the cationic surfaces of the WPI-coated oil droplets, leading to the formation of stable multilayered emulsions containing WPI-/LBP-coated oil droplets. However, increasing the LBP concentration to 0.8 wt % led to oil droplet aggregation, which was attributed to charge neutralization, bridging flocculation, and/or depletion flocculation. For subsequent experiments, a low (0.2%) and an intermediate (0.6%) LBP dose was used to prepare the secondary emulsions, and then their physical and oxidative stability was studied during 8 days of storage at 37 °C. The presence of the multilayer WPI/LBP coatings around the oil droplets inhibited lipid oxidation (reduced levels of lipid hydroperoxides and 2-thiobarbituric acid-reactive substances), as well as protein oxidation (reduced levels of carbonyl formation, sulfhydryl consumption, molecular weight modifications, intrinsic fluorescence loss, and Schiff-base fluorescence gain). The antioxidant effects of the multilayer coatings were greater at the higher LBP concentration. These results suggest that LBP, a natural plant-based polysaccharide isolated from a traditional Chinese medicine, can be used to improve the quality of emulsion-based foods. However, the level used should be optimized to ensure good physical and oxidative stability of the emulsions.

Anti-ageing peptides and proteins for topical applications: a review

Skin ageing is a cumulative result of oxidative stress, predominantly caused by reactive oxygen species (ROS). Respiration, pollutants, toxins, or ultraviolet A (UVA) irradiation produce ROS with 80% of skin damage attributed to UVA irradiation. Anti-ageing peptides and proteins are considered valuable compounds for removing ROS to prevent skin ageing and maintenance of skin health. In this review, skin ageing theory has been illustrated with a focus on the mechanism and relationship with anti-ageing peptides and proteins. The effects, classification, and transport pathways of anti-ageing peptides and proteins across skin are summarized and discussed. Over the last decade, several novel formulations and advanced strategies have been developed to overcome the challenges in the dermal delivery of proteins and peptides for skin ageing. This article also provides an in-depth review of the latest advancements in the dermal delivery of anti-ageing proteins and peptides. Based on these studies, this review prospected several semi-solid dosage forms to achieve topical applicability for anti-ageing peptides and proteins.

Laccase-catalyzed soy protein and gallic acid complexation: Effects on conformational structures and antioxidant activity

The ability of laccase to oxidize polyphenols arouses our interest that laccase can be applied for protein-polyphenol cross-linking. In this study, laccase promoted the cross-linking of gallic acid (GA) and soy protein isolate (SPI) under neutral pH. SPI-GA complexes changed the secondary structures with a decrease in β-fold and an increase in α-helix and β-turn. The free-radical scavenging activity and reducing power determination results suggested that GA elevated the SPI antioxidant activity significantly. Specifically, DPPH free radical scavenging rate and ABTS free radical scavenging ability increased almost 5- and 1.5-fold compared with unmodified SPI, respectively. Moreover, the reducing power had more than 3-fold compared to the SPI control. This study provided a novel enzyme-induced approach to modulate the physicochemical properties of SPI binding polyphenol.

Supersmall Dendritic Mesoporous Silica Nanospheres as Antioxidant Nanocarriers for Pickering Emulsifiers

Encapsulation of flavor and aromatic compounds in emulsions holds great potential for development of novel formulations in food applications. In this paper, supersmall dendritic mesoporous silica nanospheres (DMSNs) were fabricated by the one-pot strategy. The morphologies of DMSNs were directly tuned in terms of diameter from 35 ± 2 to 85 ± 4 nm. The obtained DMSNs are nanocarriers for hydrophilic or hydrophobic antioxidants with superior loading performance. Both DMSNs and antioxidant-loaded ones can emulsify the flavor and aromatic compounds yielding stable Pickering emulsions with droplets of approximately 2 μm in diameter. The emulsions possess excellent physical stability for at least half a year. More importantly, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) analysis shows that antioxidant-loaded DMSNs provide outstanding protective functionalities to the encapsulated flavoring oil. A universality study reveals that DMSNs are an ideal platform for stable Pickering emulsions for aromatic compounds. Our design could provide a new path for flavor and sensitive bioactives for codelivery with excellent stability in food, medicine, cosmetics, etc.

Effects of tocopherols on the stability of flaxseed oil-in-water emulsions stabilized by different emulsifiers: Interfacial partitioning and interaction

The potential effects of tocopherols (100 μM in emulsions) on the physicochemical stability of whey protein isolate (WPI), soy lecithin (SL), or Tween 20 (TW) stabilized flaxseed oil (FO)-in-water emulsions were investigated. During the storage (18 days at 55 ℃), the particle size, microstructure, and multiple light scattering results showed WPI-stabilized emulsions exhibited better physical stability when tocopherols were added hydroperoxides and TBARS concentration in TW-stabilized emulsions were higher than those of SL or WPI, which were suppressed differently by tocopherols. Among homologues, δ-tocopherol was more effective in inhibiting lipid oxidation than α-tocopherol, which was related to the higher interface partitioning. Moreover, the increased interfacial tension indicated tocopherols, especially δ-tocopherol, were adsorbed on the interface and interacted with WPI or SL via hydrophobic or electrostatic interactions determined by isothermal titration calorimetry. Our results suggest tocopherols are more applicable in WPI emulsion systems to achieve steady-state delivery of ALA.

Antioxidant and prooxidant activities of tea polyphenols in oil-in-water emulsions depend on the level used and the location of proteins

We studied the impacts of protein location (interface or aqueous phase) on the antioxidant and prooxidant activities of tea polyphenols (TP) in model oil-in-water emulsions (pH 7) at a low (0.01% w/v) or high (0.04 % w/v) concentration. TP at 0.01% reduced the levels of both lipid and protein oxidation markers in emulsions, independent of the protein location. However, TP were more potent when proteins were located at the interface. At 0.04%, TP were only weakly antioxidant towards lipids but were prooxidant towards proteins in emulsions with proteins at the interface, whereas they were still somewhat antioxidant for aqueous phase proteins. These results indicate that TP may act as either antioxidants or prooxidants depending on their concentration and also on the location of the proteins in emulsions. The level of TP should be optimized for emulsion-based foods or beverages to achieve optimum antioxidant activity.

The interactions between anthocyanin and whey protein: A review

Anthocyanins (ACN) are natural pigments that produce bright red, blue, and purple colors in plants and can be used to color food products. However, ACN sensitivity to different factors limits their applications in the food industry. Whey protein (WP), a functional nutritional additive, has been shown to interact with ACN and improve the color, stability, antioxidant capacity, bioavailability, and other functional properties of the ACN-WP complex. The WP's secondary structure is expected to unfold due to heat treatment, which may increase its binding affinity with ACN. Different ACN structures will also have different binding affinity with WP and their interaction mechanism may also be different. Circular dichroism (CD) spectroscopy and Fourier transform infrared (FTIR) spectroscopy show that the WP secondary structure changes after binding with ACN. Fluorescence spectroscopy shows that the WP maximum fluorescence emission wavelength shifts, and the fluorescence intensity decreases after interaction with ACN. Moreover, thermodynamic analysis suggests that the ACN-WP binding forces are mainly hydrophobic interactions, although there is also evidence of electrostatic interactions and hydrogen bonding between ACN and WP. In this review, we summarize the information available on ACN-WP interactions under different conditions and discuss the impact of different ACN chemical structures and of WP conformation changes on the affinity between ACN and WP. This summary helps improve our understanding of WP protection of ACN against color degradation, thus providing new tools to improve ACN color stability and expanding the applications of ACN and WP in the food and pharmacy industries.

Effects of resveratrol on lipid and protein co-oxidation in fish oil-enriched whey protein isolate emulsions

In this study, the impact of resveratrol (RES) on co-oxidation of lipid and protein in a fish oil-fortified whey protein isolate (WPI) emulsion was investigated. Oil-in-water (O/W) emulsions containing 1% fish oil, 6 mg/mL of WPI and RES (0.08 ~ 2 mM) were oxidatively stressed using a Fenton system at 25 °C for 24 h. The incorporation of RES significantly suppressed lipid oxidation (TBARS) and protein carbonylation. Oxidation-induced decrease on protein sulfhydryl content and surface hydrophobicity were partially attenuated by RES, but protein tryptophan fluorescence was further decreased with the increased concentration of RES. Visualization of protein patterns and MDA-bound protein suggested that RES is capable of inhibiting protein modification induced by secondary products of lipid oxidation. Significant decrease in protein digestibility under oxidizing condition was also mitigated by RES. Our study contributes to the exploration of complicated interactions between oxidized lipids and proteins when phenolic compounds are present.

Impact of Tetrapeptide-FSEY on Oxidative and Physical Stability of Hazelnut Oil-In-Water Emulsion

This study investigates the antioxidant behaviors of a hazelnut tetrapeptide, FSEY (Phe-Ser-Glu-Tyr), in an oil-in-water emulsion. The emulsion was prepared with stripped hazelnut oil at a ratio of 10%. O/W emulsions, both with and without antioxidants (FSEY and TBHQ), were incubated at 37 °C. The chemical stabilities, including those of free radicals and primary and secondary oxidation productions, along with the physical stabilities, which include particle size, zeta-potential, color, pH, and ΔBS, were analyzed. Consequently, FSEY displayed excellent antioxidant behaviors in the test system by scavenging free lipid radicals. Both primary and secondary oxidation products were significantly lower in the FSEY groups. Furthermore, FSEY assisted in stabilizing the physical structure of the emulsion. This antioxidant could inhibit the increase in particle size, prevent the formation of creaming, and stabilize the original color and pH of the emulsion. Consequently, FSEY may be an effective antioxidant additive to use in emulsion systems.

The Potential of High-Anthocyanin Purple Rice as a Functional Ingredient in Human Health

Purple rice is recognized as a source of natural anthocyanin compounds among health-conscious consumers who employ rice as their staple food. Anthocyanin is one of the major antioxidant compounds that protect against the reactive oxygen species (ROS) that cause cellular damage in plants and animals, including humans. The physiological role of anthocyanin in plants is not fully understood, but the benefits to human health are apparent against both chronic and non-chronic diseases. This review focuses on anthocyanin synthesis and accumulation in the whole plant of purple rice, from cultivation to the processed end products. The anthocyanin content in purple rice varies due to many factors, including genotype, cultivation, and management as well as post-harvest processing. The cultivation method strongly influences anthocyanin content in rice plants; water conditions, light quantity and quality, and available nutrients in the soil are important factors, while the low stability of anthocyanins means that they can be dramatically degraded under high-temperature conditions. The application of purple rice anthocyanins has been developed in both functional food and other purposes. To maximize the benefits of purple rice to human health, understanding the factors influencing anthocyanin synthesis and accumulation during the entire process from cultivation to product development can be a path for success.

Structural changes of rice starch and activity inhibition of starch digestive enzymes by anthocyanins retarded starch digestibility

The effects of anthocyanins on in vitro and in vivo digestibility of rice starch were evaluated in this study. Then, the effects of anthocyanins on physicochemical properties of rice starch and on starch digestive enzymes (α-amylase and α-glucosidase) were investigated to understand the mechanism of the effects of anthocyanins on starch digestibility. Characterization of physicochemical properties of rice starch indicates a structural change due to the presence of anthocyanins, hindering its access to starch digestive enzymes. Besides, anthocyanins inhibited the activities of starch digestive enzymes by binding to their active sites, competing with the substrates and changing the secondary structure of the enzymes. The above stated changes of rice starch and starch digestive enzymes due to the presence of anthocyanins both contributed to retarding the digestibility of rice starch. This study could offer some theoretical guidance to the development of new type rice-based food with low glycemic index.

Differential Antioxidant Compounds and Activities in Seedlings of Two Rice Cultivars Under Chilling Treatment

Variations in antioxidant compounds were examined in seedlings of two rice cultivars (Qiutianxiaoting and 93-11) exposed to low temperature (4°C) for 0, 12, 36, and 48 h. Antioxidant activity was identified by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The concentrations of total phenols, flavonoids, chlorophyll, and anthocyanins (ACNs) were determined by spectrophotometry. In addition, high-performance liquid chromatography (HPLC) was used to reveal the changes in phenolic compound concentrations in rice seedlings under chilling treatment. Results showed that antioxidant concentrations and antioxidant activity after chilling treatment were higher in 93-11 compared to Qiutianxiaoting, reaching the highest level at 36 h chilling treatment in 93-11. Phenolic compounds in Qiutianxiaoting decreased between 12 and 36 h but then increased at 48 h, whereas the corresponding levels in 93-11 increased as chilling time increased. Moreover, 10 phenolic compounds were detected and quantified by HPLC, of which gallic acid and caffeic acid tended to only exist in 93-11, whereas rutin was observed only in Qiutianxiaoting. The results of this study could be leveraged to optimize the antioxidant potential of rice in the context of healthy food choices.