The interactions between anthocyanin and whey protein: A review

Interactions with peanut protein isolate regulate the bioaccessibility of cyanidin-3-O-glucoside: Multispectral analysis, simulated digestion, and molecular dynamic simulation

Anthocyanins are susceptible to degradation owing to environmental factors. Combining them with proteins can improve their stability; however, the interaction mechanism is difficult to elucidate. This study used multispectral and molecular dynamics simulations and molecular docking methods to investigate the interaction mechanism between peanut protein isolate (PPI) and cyanidin-3-O-glucoside (C3G). The UV absorption peak and PPI turbidity increased, while the fluorescence intensity decreased with greater C3G content. Protein secondary structure changes suggested that PPI and C3G coexisted in spontaneous covalent and non-covalent interactions via static quenching. The complex structures were stable over time and C3G stably bound to the peanut globulin Ara h 3 cavity through hydrogen bonding and hydrophobic interactions. Furthermore, PPI enhanced the C3G antioxidant activity and bioaccessibility by increasing its retention rate during in-vitro simulated digestion. This study elucidates the binding mechanism of PPI and C3G and provides insight into applications of the complex in food development.

Study on stability of rose anthocyanin extracts and physicochemical properties of complex with whey protein isolate after spray drying

Pingyin rose is an edible flower rich in anthocyanins. In this study, antioxidant capacity and color were used as the main evaluation indexes to investigate the effects of common physical and chemical factors on the stability of rose anthocyanin extracts (RAEs). In addition, the physicochemical properties of the whey protein isolate (WPI)-RAEs complex after spray drying were studied. Vitamin C, temperature, and some metal ions can cause different degrees of discoloration of RAEs solution. More importantly, heat treatment, as well as most metal ions and sugars, had no significant effect on the antioxidant capacity of RAEs solution (p > 0.05). Moreover, compared to spray-dried pure WPI, the WPI-RAEs powder was delicate and uniform, and had higher particle size, bulk density, moisture activity, and better gel properties. The release rate of all WPI-RAEs sol/gel to RAEs reached about 89% in the intestinal digestion stage, but the WPI-RAEs interaction reduced the digestibility of protein in the intestinal digestion stage. We hope that this study can provide a theoretical basis for the development and utilization of WPI-RAEs as food ingredients.

A Review of Whey Protein-Based Bioactive Delivery Systems: Design, Fabrication, and Application

The efficacy of many edible bioactive agents is limited by their low water dispersibility and chemical instability in foods, as well as by their poor bioaccessibility, low absorption, and metabolism within the human gastrointestinal tract. Whey proteins are amphiphilic molecules that can be used to construct a variety of edible carrier systems that can improve the performance of bioactive ingredients. These carrier systems are being used by the food and biomedical industries to encapsulate, protect, and deliver a variety of bioactive agents. In this article, we begin by providing an overview of the molecular and functional characteristics of whey proteins, and then discuss their interactions with various kinds of bioactive agents. The ability of whey proteins to be used as building blocks to assemble different kinds of carrier systems is then discussed, including nanoparticles, hydrogels, oleogels, bigels, nanofibers, nanotubes, and nanoemulsions. Moreover, applications of these carrier systems are highlighted. Different kinds of whey protein-based carriers can be used to encapsulate, protect, and deliver bioactive agents. Each kind of carrier has its own characteristics, which make them suitable for different application needs in foods and other products. Previous studies suggest that whey protein-based carriers are particularly suitable for protecting chemically labile bioactive agents and for prolonging their release profiles. In the future, it is likely that the applications of whey protein-based carriers in the food and pharmaceutical fields will expand.

Unveiling the impact of high-pressure processing on anthocyanin-protein/polysaccharide interactions: A comprehensive review

Anthocyanins, natural plant pigments responsible for the vibrant hues in fruits, vegetables, and flowers, boast antioxidant properties with potential human health benefits. However, their susceptibility to degradation under conditions such as heat, light, and pH fluctuations necessitates strategies to safeguard their stability. Recent investigations have focused on exploring the interactions between anthocyanins and biomacromolecules, specifically proteins and polysaccharides, with the aim of enhancing their resilience. Notably, proteins like soy protein isolate and whey protein, alongside polysaccharides such as pectin, starch, and chitosan, have exhibited promising affinities with anthocyanins, thereby enhancing their stability and functional attributes. High-pressure processing (HPP), emerging as a non-thermal technology, has garnered attention for its potential to modulate these interactions. The application of high pressure can impact the structural features and stability of anthocyanin-protein/polysaccharide complexes, thereby altering their functionalities. However, caution must be exercised, as excessively high pressures may yield adverse effects. Consequently, while HPP holds promise in upholding anthocyanin stability, further exploration is warranted to elucidate its efficacy across diverse anthocyanin variants, macromolecular partners, pressure regimes, and their effects within real food matrices.

Microencapsulation with fructooligosaccharides and whey protein enhances the antioxidant activity of anthocyanins and their ability to modulate gut microbiota in vitro

Anthocyanins are the primary functional pigments in the diet. However, anthocyanins exhibit instability during digestion, coupled with limited bioavailability. Microencapsulation offers anthocyanins a sheltered environment, enhancing their stability and bioactivity. Fructooligosaccharides (FOS) and whey protein (WP) commonly serve as wall materials in microencapsulation and represent a significant source of probiotic functionality. Our prior research successfully established a robust microencapsulation system for anthocyanins utilizing FOS and WP. This study investigates the antioxidative capacity, stability during in vitro digestion, modulation on gut microbiota, and short-chain fatty acids (SCFAs) production of black soybean skin anthocyanins microencapsulated with FOS and WP (anthocyanin-loaded microencapsule particles, ALM). The results demonstrate that ALM exhibits a superior antioxidant capacity compared to free anthocyanins (ANCs) and cyanidin-3-glucoside (C3G). During simulated digestion, ALM exhibits enhanced anthocyanin retention compared with ANC in both gastric and intestinal phases. In comparison with ANC and even non-loaded microcapsules (NLM), in vitro fermentation demonstrates that ALM exhibits the highest gas production and lowered pH, indicating excellent fermentation activity. Furthermore, in comparison with ANC or NLM, ALM exerts a positive influence on the diversity and composition of gut microbiota, with potentially beneficial genera such as Faecalibacterium and Akkermansia exhibiting higher relative abundance. Moreover, ALM stimulates the production of SCFAs, particularly acetic and propionic acids. In conclusion, microencapsulation of anthocyanins with FOS-WP enhances their antioxidative capacity and stability during in vitro digestion. Simultaneously, this microencapsulation illustrates a positive regulatory effect on the intestinal microbiota community and SCFA production, conferring potential health benefits.

Carriers based on dairy by-products and dehumidified-air spray drying as a novel multiple approach towards improved retention of phenolics in powders: sour cherry juice concentrate case study

BACKGROUND

Sour cherry juice concentrate powder can serve as a modern, easy-to-handle, phenolics-rich merchandise; however, its transformation into powdered form requires the addition of carriers. In line with the latest trends in food technology, this study valorizes the use of dairy by-products (whey protein concentrate, whey, buttermilk, and mixes with maltodextrin) as carriers. A new multiple approach for higher drying yield, phenolics retention (phenolic acids, flavonols and anthocyanins) and antioxidant capacity of powders were tested as an effect of simultaneous decrease of drying temperature due to the drying air dehumidification and lower carrier content.

RESULTS

Dairy-based carriers were effective for spray drying of sour cherry-juice concentrate. The drying yield was increased and retention of phenolics was higher when compared with maltodextrin. The application of dehumidified air, which enabled the drying temperature to be reduced, affected drying yield positively, and also affected particle morphology and retention of phenolics (the phenolic content was approximately 30% higher than with spray drying).

CONCLUSIONS

The study proved that it is possible to apply dairy-based by-products to produce sour cherry juice concentrate powders profitably, lowering the spray-drying temperature and changing the carrier content. Dehumidified air spray drying can be recommended for the production of fruit juice concentrate powders with improved physicochemical properties. © 2023 Society of Chemical Industry.

Advanced application of nanotechnology in active constituents of Traditional Chinese Medicines

Traditional Chinese Medicines (TCMs) have been used for centuries for the treatment and management of various diseases. However, their effective delivery to targeted sites may be a major challenge due to their poor water solubility, low bioavailability, and potential toxicity. Nanocarriers, such as liposomes, polymeric nanoparticles, inorganic nanoparticles and organic/inorganic nanohybrids based on active constituents from TCMs have been extensively studied as a promising strategy to improve the delivery of active constituents from TCMs to achieve a higher therapeutic effect with fewer side effects compared to conventional formulations. This review summarizes the recent advances in nanocarrier-based delivery systems for various types of active constituents of TCMs, including terpenoids, polyphenols, alkaloids, flavonoids, and quinones, from different natural sources. This review covers the design and preparation of nanocarriers, their characterization, and in vitro/vivo evaluations. Additionally, this review highlights the challenges and opportunities in the field and suggests future directions for research. Nanocarrier-based delivery systems have shown great potential in improving the therapeutic efficacy of TCMs, and this review may serve as a comprehensive resource to researchers in this field.

Postprandial glycemic and lipidemic effects of black rice anthocyanin extract fortification in foods of varying macronutrient compositions and matrices

Anthocyanin (ACN) fortification of commonly consumed foods is significant as a dietary strategy against the development of metabolic complications by delivering ACNs at high doses. However, its bioactivity and translated metabolic effects in the presence of varying food matrices and macro-constituents is particularly unclear. This end-to-end study investigates the metabolic effects of black rice ACN extract (BRAE) fortification-from in-vitro enzyme inhibitory activities and digestibility, to downstream in vivo impacts on GI, postprandial glycemia and lipidemia. The in vivo effects were investigated in two separate crossover randomised controlled trials (RCT) of 24 healthy participants each-the first RCT determined the postprandial blood glucose, insulin, and ACN bioavailability to a starch-rich single food over 2 h, while the second RCT determined the postprandial blood glucose, insulin, lipid panel, and lipoprotein particles and subfractions to a starch- and fat-rich composite meal over 4 h. In-vitro findings confirmed the inhibitory activities of major black rice ACNs on carbohydrases (p = 0.0004), lipases (p = 0.0002), and starch digestibility (p < 0.0001). in vivo, a 27-point mean GI reduction of wheat bread was observed with BRAE fortification, despite a non-significant attenuation in postprandial glycemia. Conversely, there were no differences in postprandial glycemia when fortified bread was consumed as a composite meal, but acute lipid profiles were altered: (1) improved plasma HDL-c, ([0.0140 mmol/L, 95% CI: (0.00639, 0.0216)], p = 0.0028), Apo-A1 ([0.0296 mmol/L, 95% CI: (0.00757, 0.0515)], p = 0.0203), and Apo-B ([0.00880 mmol/L, 95% CI: (0.00243, 0.0152)], p = 0.0185), (2) modified LDL and HDL subfractions (p < 0.05), and (3) remodelled lipid distributions in HDL and LDL particles. This end-to-end study indicates the potential of ACN fortification in GI reduction and modulating postprandial lipoprotein profiles to starch- and fat-rich composite meals.

Anthocyanins' effects on diabetes mellitus and islet transplantation

The incidence of diabetes mellitus is dramatically increasing every year, causing a huge global burden. Moreover, existing anti-diabetic drugs inevitably bring adverse reactions, and the application of islet transplantation is often limited by the damage caused by oxidative stress after transplantation. Thus, new approaches are needed to combat the growing burden of diabetes mellitus. Anthocyanins are of great nutritional interest and have been documented that have beneficial effects on chronic diseases, including diabetes mellitus. Here, we describe the health effects of anthocyanins on diabetes mellitus and islet transplantation. Epidemiological studies demonstrated that moderate intake of anthocyanins leading to a reduction in risk of diabetes mellitus. Numerous experiments both animal and clinical studies also showed positive effects of anthocyanins on prevention and treatment of diabetes and diabetic complications. These effects of anthocyanins may be related to mechanisms of improving glucose and lipid metabolism and insulin resistance, antioxidant, and anti-inflammatory activities. In addition, damage and function of pancreatic islets after transplantation are also improved by anthocyanins. These findings suggest that daily intake of anthocyanins may not only improve nutritional metabolism in healthy individuals to prevent from diabetes, but also as a supplementary treatment of diabetes mellitus and islet transplantation. Thus, more evidence is needed to better understand the potential health benefits of anthocyanins.

Protein and Peptide-Based Nanotechnology for Enhancing Stability, Bioactivity, and Delivery of Anthocyanins

Anthocyanin, a unique natural polyphenol, is abundant in plants and widely utilized in biomedicine, cosmetics, and the food industry due to its excellent antioxidant, anticancer, antiaging, antimicrobial, and anti-inflammatory properties. However, the degradation of anthocyanin in an extreme environment, such as alkali pH, high temperatures, and metal ions, limits its physiochemical stabilities and bioavailabilities. Encapsulation and combining anthocyanin with biomaterials could efficiently stabilize anthocyanin for protection. Promisingly, natural or artificially designed proteins and peptides with favorable stabilities, excellent biocapacity, and wide sources are potential candidates to stabilize anthocyanin. This review focuses on recent progress, strategies, and perspectives on protein and peptide for anthocyanin functionalization and delivery, i.e., formulation technologies, physicochemical stability enhancement, cellular uptake, bioavailabilities, and biological activities development. Interestingly, due to the simplicity and diversity of peptide structure, the interaction mechanisms between peptide and anthocyanin could be illustrated. This work sheds light on the mechanism of protein/peptide-anthocyanin nanoparticle construction and expands on potential applications of anthocyanin in nutrition and biomedicine.

Effect of Preheating Whey Protein Concentrate on the Stability of Purple Sweet Potato Anthocyanins

Anthocyanins (ANs) have strong antioxidant activities and can inhibit chronic diseases, but the instability of ANs limits their applications. The conservation of preheating whey protein concentrate (WPC) on the stability of purple sweet potato ANs was investigated. The retention of ANs in WPC-ANs was 85.88% after storage at 25 °C for 5 h. WPC-ANs had higher retention of ANs in heating treatment. The retention rates of ANs in WPC-ANs exposed to light and UV lamps for 6 h were 78.72% and 85.76%, respectively. When the concentration of H2O2 was 0.50%, the retention rate of ANs in the complexes was 62.04%. WPC-ANs' stability and antioxidant activity were improved in simulated digestive juice. The WPC-ANs connection was static quenching, and the binding force between them was a hydrophobic interaction at one binding site, according to the fluorescence quenching spectroscopy. UV-visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis further indicated that the secondary structure and microenvironment of amino acid residues in WPC can be impacted by the preheating temperature and preheating times of WPC. In conclusion, preheating WPC can successfully preserve the stability of purple sweet potato ANs by binding to them through a non-covalent interaction.

Interaction of preheated whey protein isolate with rose anthocyanin extracts in beverage model system: Influence on color stability, astringency and mechanism

Preheating proteins have the potential to improve anthocyanin stability. Our aim was to investigate the effect of preheated whey protein isolate (WPI) on the color stability and astringency of the beverage model system in the presence of rose anthocyanin extracts (RAEs), and to explore the mechanism of interaction between preheated WPI and RAEs. The secondary structure, particle size and transparency of WPI were obviously changed by preheating. WPI preheated at 100°C  (WPI100) could effectively improve the color stability of RAEs in the beverage model system. Importantly, the WPI100-RAEs in the beverage model system exhibited the smallest particle size and the weakest astringency effect. In addition, different preheated WPIs could interact with RAEs non-covalently, and the interaction forces are hydrogen bonding and van der Waals forces, among which WPI100 had the strongest binding ability to RAEs. These results will provide a new insight into the development of protein-anthocyanin beverages.

The health-promoting anthocyanin petanin in Lycium ruthenicum fruit: a promising natural colorant

Acylated anthocyanins derived from dietary sources have gained significant attention due to their health-promoting properties and potential as natural colorants with high stability. However, exploration of the functional food products using acylated anthocyanins enriched in fruits and vegetables remains largely delayed in food industries. The black goji (Lycium ruthencium) fruit (LRF) is a functional food that is extensively used due to its exceptionally high levels of acylated anthocyanins, including petanin. This review provides a comprehensive summary of the functional properties and anthocyanin components of LRF. The stability, bioaccessibility, bioavailability, and bioactivities of petanin, the major anthocyanin component, are compared with those of LRF anthocyanin extracts and other food sources. Furthermore, the biosynthetic pathway and regulatory network of petanin in LRF are proposed and constructed, respectively. The key genes that could be potentially used for metabolic engineering to produce petanin are predicted. Finally, the potential application of petanin derivatives in the food industry is also discussed. This review presents comprehensive and systematic information about the dual-function of petanin as a bioactive component and a promising natural colorant for future food industrial applications.

Different protein-anthocyanin complexes engineered by ultrasound and alkali treatment: Structural characterization and color stability

Through alkali treatment (AT) and ultrasound (UT)-assisted processing producing covalent protein-anthocyanin complexes, we investigated the impact of treatment methods and protein types on conjugation efficiency, protein structure, and color stability. Our findings revealed the effective grafting of anthocyanins (ACNs) onto proteins, with myofibrillar protein (MP) exhibiting the highest conjugation efficiency of 88.33% after UT (p <.05). UT accelerated the structure unfolding of distinct protein samples, leading to the exposure of sulfhydryl, and hydrophobic groups in proteins, and enhanced the oxidation stability of ACNs. Notably, the modified ACNs maintained a favorable pH-color relationship, while U-MP showed a significantly higher absorbance (0.4998) than the other groups (p <.05) at pH 9.0, demonstrating an outstanding color improvement. UT-assisted processing also accelerated the NH₃ reaction. Thus, the combination of UT and MP holds the potential for pH-color-responsive intelligent packaging and increases the efficiency of UT processing.

Understanding the pH-dependent interaction of anthocyanin with two food-derived transferrins

The potential binding of cyanidin-3-O-glucoside (C3G) to bovine lactoferrin (BLF) and ovotransferrin (OTF) at pH 3, 5, and 7 was investigated for the first time. Multiple spectroscopic techniques demonstrated pH-dependent alterations in the conformational characteristics of BLF and OTF upon complexation with C3G. Fluorescence quenching assays showed that their highest binding affinity was at pH 7. Hydrophobic interactions and hydrogen bonds were found to be crucial in molecular dynamics simulations but with significantly lower probabilities of formation at pH 3 (p < 0.05). At pH 7, electrostatic attraction can occur for the negatively charged forms of C3G, and the well-maintained native structures of BLF and OTF may be favorable for stabilizing the C3G binding sites. This study sheds light on the stronger interaction of C3G with BLF/OTF at pH 7, which may have implications for future applications such as anthocyanin stabilization or the development of functional food ingredients.

Himalayan Sources of Anthocyanins and Its Multifunctional Applications: A Review

Anthocyanins, the colored water-soluble pigments, have increasingly drawn the attention of researchers for their novel applications. The sources of anthocyanin are highly diverse, and it can be easily extracted. The unique biodiversity of the Himalayan Mountain range is an excellent source of anthocyanin, but it is not completely explored. Numerous attempts have been made to study the phytochemical aspects of different Himalayan plants. The distinct flora of the Himalayas can serve as a potential source of anthocyanins for the food industry. In this context, this review is an overview of the phytochemical studies conducted on Himalayan plants for the estimation of anthocyanins. For that, many articles have been studied to conclude that plants (such as Berberis asiatica, Morus alba, Ficus palmata, Begonia xanthina, Begonia palmata, Fragaria nubicola, etc.) contain significant amounts of anthocyanin. The application of Himalayan anthocyanin in nutraceuticals, food colorants, and intelligent packaging films have also been briefly debated. This review creates a path for further research on Himalayan plants as a potential source of anthocyanins and their sustainable utilization in the food systems.

A natural strategy for astaxanthin stabilization and color regulation: Interaction with proteins

The pigment astaxanthin, one of the carotenoids, is regarded as a functional factor with various biological activities, widely applied in feed, nutraceutical, and cosmetic industries. However, its low stability and poor water solubility limit its application. Examples in nature suggest that binding to proteins is a simple and effective method to improve the stability and bioavailability of astaxanthin. Proteins from algae, fish, and crustaceans have all been demonstrated to have astaxanthin-binding capacity. Inspired by nature, artificial astaxanthin-protein systems have been established in foods. Binding to proteins could bring aquatic species various colors, and changes in the conformation of astaxanthin after binding to proteins leads to color changes. The review innovatively summarizes multiple examples of proteins as means of protecting astaxanthin, giving a reference for exploring and analyzing pigment-protein interactions and providing a strategy for carotenoids stabilization and color regulation, which is beneficial to the broader and deeper applications of carotenoids.

Boosting the Bioaccessibility of Dietary Bioactives by Delivery as Protein-Polyphenol Aggregate Particles

Protein-polyphenol aggregate particles concurrently fortify a functional food product with healthy dietary proteins and concentrated polyphenols. However, what impact does ingestion of aggregate particles have on ultimate health relevance of either the polyphenolic molecules in the matrix or the protein molecules? Because human health benefits are contingent on bioavailability after ingestion, the fate of these molecules during transit in the gastrointestinal tract (GIT) will dictate their utility as functional food ingredients. This brief review explores diverse applications of protein-polyphenol particles in the food industry and the bioaccessibility of both bioactive polyphenolic compounds and edible proteins. Evidence to date suggests that complexation of phytoactive polyphenolics effectively enhances their health-relevant impacts, specifically because the phytoactives are protected in the protein matrix during transit in the GIT, allowing intact, non-degraded molecules to reach the colon for catabolism at the gut microbiome level, a prerequisite to realize the health benefits of these active compounds.

Enzymatic hydrolysates of soy protein promote the physicochemical stability of mulberry anthocyanin extracts in food processing

Soy protein papain hydrolysate (SPAH) and soy protein pepsin hydrolysate (SPEH) were used as protective agents for mulberry anthocyanin extracts (MAEs) to inhibit its color fading and enhance the anthocyanin stability at pH 6.3. Both SPAH and SPEH showed a significant protective effect on total anthocyanins in MAEs solutions. 1.0 mg/mL of SPEH presented the best protective effect on MAEs by increasing its half-life from 1.8 to 5.7 days. SPAH/SPEH-cyaniding-3-O-glucoside (C3G) interactions were investigated at pH 6.3 by fluorescence, Fourier-transform infrared spectroscopy (FT-IR), and Circular Dichroism (CD). Their association was mainly driven by hydrophobic interactions, and SPEH showed a higher binding affinity for C3G than SPAH, with a KA value of 2.62 × 105 M-1 at 300 K. The second structures of SPAH and SPEH were altered by C3G, with a decrease in the β-sheets and an increase in the turns and random coils.

Proteomic and computational characterisation of 11S globulins from grape seed flour by-product and its interaction with malvidin 3-glucoside by molecular docking

Grape seed flour by-product (GSBP) is an economic and renewable source of proteins, increasingly being explored due to interesting technological application such as colour protection in rich-anthocyanins beverages. Globulin-like proteins from GSBP were characterised by proteomic and computational studies. MALDI TOF/TOF analysis revealed the presence of two 11S globulins (acid and basic), whose 3D structures have been elucidated for the first time in Vitis vinifera L. grape seeds by using homology models and molecular dynamics. The secondary structure showed 11 α-helices and 25 β-sheets for acid and 12 α-helices and 24 β-sheets for basic 11S globulins. Molecular docking results indicate that both grape seed 11S globulins could establish different types of non-covalent interactions (π-π) with malvidin 3-O-glucoside (wine anthocyanin), which suggest a possible colour protection similar to that occurring in copigmentation phenomenon. These findings provide valuable information of globulin family proteins that could be relevant in food industry applications.

Onion anthocyanins: Extraction, stability, bioavailability, dietary effect, and health implications

Anthocyanins are high-value compounds, and their use as functional foods and their natural colorant have potential health benefits. Anthocyanins seem to possess antioxidant properties, which help prevent neuronal diseases and thereby exhibit anti-inflammatory, chemotherapeutic, cardioprotective, hepatoprotective, and neuroprotective activities. They also show different therapeutic effects against various chronic diseases. Anthocyanins are present in high concentrations in onion. In recent years, although both conventional and improved methods have been used for extraction of anthocyanins, nowadays, improved methods are of great importance because of their higher yield and stability of anthocyanins. In this review, we compile anthocyanins and their derivatives found in onion and the factors affecting their stability. We also analyze different extraction techniques of anthocyanins. From this point of view, it is very important to be precisely aware of the impact that each parameter has on the stability and subsequently potentiate its bioavailability or beneficial health effects. We present up-to-date information on bioavailability, dietary effects, and health implications of anthocyanins such as antioxidant, antidiabetic, anticancerous, antiobesity, cardioprotective, and hepatoprotective activities.

Advances in dietary proteins binding with co-existed anthocyanins in foods: Driving forces, structure-affinity relationship, and functional and nutritional properties

Anthocyanins, which are the labile flavonoid pigments widely distributed in many fruits, vegetables, cereal grains, and flowers, are receiving intensive interest for their potential health benefits. Proteins are important food components from abundant sources and present high binding affinity for small dietary compounds, e.g., anthocyanins. Protein-anthocyanin interactions might occur during food processing, ingestion, digestion, and bioutilization, leading to significant changes in the structure and properties of proteins and anthocyanins. Current knowledge of protein-anthocyanin interactions and their contributions to functions and bioactivities of anthocyanin-containing foods were reviewed. Binding characterization of dietary protein-anthocyanins complexes is outlined. Advances in understanding the structure-affinity relationship of dietary protein-anthocyanin interaction are critically discussed. The associated properties of protein-anthocyanin complexes are considered in an evaluation of functional and nutritional values.

Advancement of Protein- and Polysaccharide-Based Biopolymers for Anthocyanin Encapsulation

Although evidence shows that anthocyanins present promising health benefits, their poor stability still limits their applications in the food industry. Increasing the stability of anthocyanins is necessary to promote their absorption and metabolism and improve their health benefits. Numerous encapsulation approaches have been developed for the targeted release of anthocyanins to retain their bioactivities and ameliorate their unsatisfactory stability. Generally, choosing suitable edible encapsulation materials based on biopolymers is important in achieving the expected goals. This paper presented an ambitious task of summarizing the current understanding and challenges of biopolymer-based anthocyanin encapsulation in detail. The food-grade edible microencapsulation materials, especially for proteins and polysaccharides, should be employed to improve the stability of anthocyanins for effective application in the food industry. The influence factors involved in anthocyanin stability were systematically reviewed and highlighted. Food-grade proteins, especially whey protein, caseinate, gelatin, and soy protein, are attractive in the food industry for encapsulation owing to the improvement of stability and their health benefits. Polysaccharides, such as starch, pectin, chitosan, cellulose, mucilages, and their derivatives, are used as encapsulation materials because of their satisfactory biocompatibility and biodegradability. Moreover, the challenges and perspectives for the application of anthocyanins in food products were presented based on current knowledge. The proposed perspective can provide new insights into the amelioration of anthocyanin bioavailability by edible biopolymer encapsulation.

Analyzing the Interaction between Anthocyanins and Native or Heat-Treated Whey Proteins Using Infrared Spectroscopy

The color stability of anthocyanins (ACN) has been shown to be improved by interaction with whey proteins (WP). In this study, we explore the ACN–WP interaction using Fourier transform infrared spectroscopy (IR). ACN from purple corn, grape, and black carrot (50 μM) were evaluated. IR spectra (4000–700 cm⁻¹) were collected for native and preheated (40–80 °C) WP (5 mg/mL) and ACN–WP mixtures at pH 7.4. Soft independent modeling of class analogy was used to analyze the IR data. The WP secondary structure changed after heat treatments and after interaction with ACN. As expected, the WP α-helices decreased, and β-sheet increased after heat treatment. The intensities of the WP amide I and II bands decreased after ACN addition, revealing a decrease in the WP α-helix content. Higher preheating temperatures (70–80 °C) resulted in a more disordered WP structure that favored stronger WP–ACN interactions related to amide III changes. Addition of ACN stabilized WP structure due to heat denaturation, but different ACN structures had different binding affinities with WP. WP structure had less change after interaction with ACN with simpler structures. These results increase our understanding of ACN–WP interactions, providing a potential strategy to extend anthocyanin color stability by WP addition.