Sea Buckthorn (Hippophae rhamnoides) Proanthocyanidins Inhibit In Vitro Enzymatic Hydrolysis of Protein

Effects of Covalent or Noncovalent Binding of Different Polyphenols to Acid-Soluble Collagen on Protein Structure, Functionality, and Digestibility

In this study, the structure, function, and digestibility of noncovalent complexes and covalent conjugates formed by acid-soluble collagen with polyphenols of different structures (quercetin, epicatechin, gallic acid, chlorogenic acid, procyanidin, and tannic acid) were investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that polyphenols were covalently bound to collagen by laccase catalytic oxidation. Biolayer interferometry revealed that the noncovalent binding strength of polyphenols to collagen from high to low was quercetin > gallic acid > chlorogenic acid > epicatechin, which was consistent with the trend of covalent polyphenol binding. Procyanidin and tannic acid had strong noncovalent binding, but their covalent binding ability was weak. Compared with the pure collagen, the complexes improved emulsification and antioxidant properties (more than 2.5 times), and the conjugates exhibited better thermal stability (99.4-106.8 °C) and antidigestion ability (reduced by more than 37%). The finding sheds new light on the use of collagen as a functional food ingredient in the food industry.

Impact of pomegranate fruit powder on dough, textural and functional properties of fresh noodle

BACKGROUND

Polyphenols are important functional food ingredients due to good performance in the prevention of chronic diseases and elongation of shelf-life. Numerous studies have shown that the addition of polyphenols of natural origin to wheat flour tends to have a contradictory effect on the physicochemical properties of the dough in the presence of different doses of polyphenols, also known as biphasic regulation. In the meantime, a promising and economic flour enhancer of natural origin is needed because of the short stability time of the dough. In this study, the impact of pomegranate fruit powder (PFP) on mixing and rheological properties of the dough and texture as well as nutritional characteristics of cooking noodles was studied.

RESULTS

The mixing and tensile properties as well as viscoelasticity of the dough were improved with the addition of 4%, 8% or 12% PFP; correspondingly, a more compact and ordered microstructure was observed in the dough. The addition of PFP maintained the best cooking time and water absorption of noodles. Moreover, the hardness, tensile strength and resilience of noodles were improved with the addition of 4% or 8% PFP. Furthermore, the antioxidant capacities of noodles with the addition of PFP were increased via quantification of iron ion reduction, DPPH and ABTS scavenging capacity. The noodles added with PFP showed a dose-dependent inhibitory effect on glucose release.

CONCLUSION

PFP improved the textural properties and nutrition value of noodles. The addition of PFP to the wheat four dough and noodles was suggested to be below 12%. © 2023 Society of Chemical Industry.

Implication of the Polymeric Phenolic Fraction and Matrix Effect on the Antioxidant Activity, Bioaccessibility, and Bioavailability of Grape Stem Extracts

The bioaccessibility and bioavailability of phenolics compounds of two grape stem extracts with different composition were studied. High polymeric extract (HPE) presented a higher content of total phenolics (TPC), procyanidins, hemicelluloses, proteins, and ashes, whereas low procyanidin extract (LPE) showed a higher fat, soluble sugars, and individual phenolic compounds content. Corresponding to its higher total phenolics content, HPE possesses a higher antioxidant activity (TEAC value). The digestion process reduced the antioxidant activity of the HPE up to 69%, due to the decrease of TPC (75%) with a significant loss of polymeric compounds. LPE antioxidant activity was stable, and TPC decreased by only 13% during the digestion process. Moreover, a higher antioxidant phenolic compounds bioavailability was shown in LPE in contrast to HPE. This behaviour was ascribed mainly to the negative interaction of polymeric fractions and the positive interaction of lipids with phenolic compounds. Therefore, this study highlights the convenience of carrying out previous studies to identify the better extraction conditions of individual bioavailable phenolic compounds with antioxidant activity, along with those constituents that could increase their bioaccessibility and bioavailability, such as lipids, although the role played by other components, such as hemicelluloses, cannot be ruled out.

Structural Characterization and Evaluation of Interfacial Properties of Pea Protein Isolate-EGCG Molecular Complexes

Highlights

Pea protein isolate (PPI) and EGCG spontaneously formed complexes.

Protein–polyphenol complexation was mainly driven by hydrogen bonding.

The binding of EGCG influenced the structure and functionality of PPI.

PPI-EGCG complexes had better emulsifier properties than PPI.

Abstract

There is increasing interest in using plant-derived proteins in foods and beverages for environmental, health, and ethical reasons. However, the inherent physicochemical properties and functional performance of many plant proteins limit their widespread application. Here, we prepared pea protein isolate (PPI) dispersions using a combined pH-shift/heat treatment method, and then, prepared PPI-epigallocatechin-3-gallate (EGCG) complexes under neutral conditions. Spectroscopy, calorimetry, molecular docking, and light scattering analysis demonstrated that the molecular complexes formed spontaneously. This was primarily ascribed to hydrogen bonds and van der Waals forces. The complexation of EGCG caused changes in the secondary structure of PPI, including the reduction in the α-helix and increase in the β-sheet and disordered regions. These changes slightly decreased the thermal stability of the protein. With the accretion of EGCG, the hydrophilicity of the complexes increased significantly, which improved the functional attributes of the protein. Optimization of the PPI-to-EGCG ratio led to the complexes having better foaming and emulsifying properties than the protein alone. This study could broaden the utilization of pea proteins as functional ingredients in foods. Moreover, protein–polyphenol complexes can be used as multifunctional ingredients, such as antioxidants or nutraceutical emulsifiers.

Dietary proanthocyanidins on gastrointestinal health and the interactions with gut microbiota

Many epidemiological and experimental studies have consistently reported the beneficial effects of dietary proanthocyanidins (PAC) on improving gastrointestinal physiological functions. This review aims to present a comprehensive perspective by focusing on structural properties, interactions and gastrointestinal protection of PAC. In brief, the main findings of this review are summarized as follows: (1) Structural features are critical factors in determining the bioavailability and subsequent pharmacology of PAC; (2) PAC and/or their bacterial metabolites can play a direct role in the gastrointestinal tract through their antioxidant, antibacterial, anti-inflammatory, and anti-proliferative properties; (3) PAC can reduce the digestion, absorption, and bioavailability of carbohydrates, proteins, and lipids by interacting with them or their according enzymes and transporters in the gastrointestinal tract; (4). PAC showed a prebiotic-like effect by interacting with the microflora in the intestinal tract, and the enhancement of PAC on a variety of probiotics, such as Bifidobacterium spp. and Lactobacillus spp. could be associated with potential benefits to human health. In conclusion, the potential effects of PAC in prevention and alleviation of gastrointestinal diseases are remarkable but clinical evidence is urgently needed.

Effect of Brine fermented Pickling to Physicochemical, Anti-nutritional, and Microbiological Attributes of Pickled gboma Eggplant (Solanum macrocarpon)

Gboma eggplant (Solanum macrocarpon) has low calorie, high phenolic and antioxidant, excellent dietary fibre and mineral content. Besides healthy effects, gboma eggplant also contained numerous anti-nutrients unbeneficial for human health. Due to high moisture content, gboma eggplant was highly perishable during post-harvest. This research observed the changes of nutritional proximate, mineral contents, acidification indexes, anti-nutrients, phytochemical and antioxidant properties, texture profiles, microbiological characteristics of both raw and pickled gboma eggplant. Gboma eggplant fruits were soaked in clean water for 2 minutes before cutting their calyx lobes. The pre-treated fruits were submerged in sterilized brine (5% salt) for 8 days. Periodically, pickled samples were taken to examine physicochemical, anti-nutritional, and microbiological attributes of pickled gboma eggplant. Results showed that nutritional proximate of moisture, ash, protein, fat, fibre, carbohydrate was varied slightly during fermentation. There was a decreasing trend of moisture and carbohydrate; meanwhile, there was an increasing trend of ash, protein, fibre during 8 days of fermentation. There was no significant difference of fat during pickling. There was a minor increment of mineral contents in all samples. There was accumulation of phenyllactic acid, ascorbic acid content and titratable acidity with exception of pH. Anti-nutrient contents like tannin, phytate, oxalate, steroidal glycoalkaloid greatly decreased in raw and pickled eggplant. Remarkable increments of total phenolic, flavonoid, DPPH free radical scavenging and FRAP ferric reducing antioxidant of raw and pickled eggplant was presented. Texture profiles of hardness, crispness, fracturability, crunchiness revealed a minor reduction of sensory scores during 8 days of fermentation. Lactic acid bacteria, Bacillus significantly proliferated; meanwhile, Micrococcus and S. aureus were absolutely retarded in pickled eggplant. Yeast and fungi increased in the first 4 days and decreased afterwards. There was no significant difference of proximate compositions; mineral contents; phenyllactic acid, ascorbic acid content, pH and titratable acidity; anti-nutritional contents; phytochemical and antioxidant properties; texture profile (sensory score); microbiological load (with exception of S. aureus) between pickled gloma eggplants at day 6th and day 8th of fermentation. At a quick glance, the length of fermentation could be shorted to 6 days instead of 8 days. However, at the 6th day, S. aureus load was still presented at 0.33±0.01 log CFU/g. The fermentation should be lasted to 8th day so that S. aureus load could be dropped down to zero to ensure microbial food safety. Raw gboma eggplant should be fermented in 8% brine solution for 8 days to obtain the best physicochemical, anti-nutritional, and microbiological properties of pickle. Findings of this research suggested that fermentation pickling would be an appropriate approach to improve nutritional, physicochemical and functional criteria while controlling toxic chemical residues, retarding the growth and proliferation of spoilage and pathogen microorganisms.

Interaction characterization of zein with cyanidin-3-O-glucoside and its effect on the stability of mulberry anthocyanins and protein digestion

Ingredient interactions usually occur in food matrix, which may affect their functions and properties. This study aimed to investigate the interactive effects of mulberry and corn protein on pigment stability and zein digestibility. The interaction of main compounds in both ingredients, that is, cyanidin-3-O-glucoside (C3G) and zein, was characterized via their structural, morphological, thermal stability, and digestible properties using multi-spectroscopic techniques, scanning electron microscopy, high performance liquid chromatography, and in vitro digestion models. Results showed that zein exhibited a strong binding affinity for C3G via van der Waals forces and hydrogen bonds determined in fluorescence assays. The secondary structure of zein changed due to C3G binding, with a decrease in α-helix and an increase in β-sheet. The particle size of zein decreased after interacting with C3G. The zein complexation with mulberry anthocyanin-rich extracts in a simulative food system did not affect the digestibility of zein significantly but enhanced the thermal stability of pigments slightly. Specifically, anthocyanins did not change the susceptibility of zein to pepsin proteolysis, suggesting that binding sites of C3G might not be the cleavage sites of pepsins. These results provide important insight into the binding mechanism of zein and anthocyanins and might help guide the design of anthocyanin-based functional food. PRACTICAL APPLICATION: Zein, as a storage protein widely distributed in corn flour, was commonly co-existing with anthocyanins in starchy food. This study provides insights into the molecular interactions between zein and cyanidin-3-O-glucoside. However, the interaction might not impact the zein digestion but enhance anthocyanin thermal stability. The findings of this work could throw light on the selection of ingredients rich in zein and anthocyanins in the food industry.

Health promoting properties and sensory characteristics of phytochemicals in berries and leaves of sea buckthorn (Hippophaë rhamnoides)

Sea buckthorn (Hippophaë rhamnoides L., SB), as a multi-functional plant, is widely grown in Asia, Europe and Canada. The berries and leaves of SB contain a diverse array of health-supporting phytochemicals, which are also related to the sensory qualities of berry and berry products. This review summarizes the biologically active key-compounds of the berries and leaves of SB, their health-promoting effects, as well as the contributions to the sensory quality of the berries. The target compounds consist of sugars, sugar derivatives, organic acids, phenolic compounds and lipophilic compounds (mainly carotenoids and tocopherols), which play an important role in anti-inflammatory and antioxidant functions, as well as in metabolic health. In addition, these compounds contribute to the orosensory qualities of SB berries, which are closely related to consumer acceptance and preference of the products. Studies regarding the bioavailability of the compounds and the influence of the processing conditions are also part of this review. Finally, the role of the sensory properties is emphasized in the development of SB products to increase utilization of the berry as a common meal component and to obtain value-added products to support human health.

Binding affinity, antioxidative capacity and in vitro digestion of complexes of grape seed procyanidins and pork, chicken and fish protein

Studies have reported that procyanidins can interact with proteins, thereby affecting their structure, function, and bioaccessibility. In this paper, we investigated the interaction between grape seeds procyanidins (GSP) and animal source protein (from pig, chicken and fish), and the effects on the protein structure, antioxidant capacity and bioaccessibility of GSP. Fluorescence results showed that the binding constant of GSP-protein complex was 10-10⁴ M^-1, and the main forces were van der Waals force, hydrogen bonds and hydrophobic interactions. The antioxidant capacity of GSP was masked by GSP-protein complexes formed. The circular dichroism indicated that GSP had an effect on the content of α-helix and β-sheet in the secondary structure of pork and chicken proteins, but had little effect on the secondary structure of fish protein. The results showed that the protein can bind to GSP and affect its antioxidant activity and bioaccessibility. This study can provide reference for further study on the digestion and absorption of the complexes and offer health guidance in the preparation of diets.

The Role of Dietary Phenolic Compounds in Protein Digestion and Processing Technologies to Improve Their Antinutritive Properties

Digestion is the key step for delivering nutrients and bioactive substances to the body. The way different food components interact with each other and with digestive enzymes can modify the digestion process and affect human health. Understanding how food components interact during digestion is essential for the rational design of functional food products. Plant polyphenols have gained much attention for the bioactive roles they play in the human body. However, their strong beneficial effects on human health have also been associated with a negative impact on the digestion process. Due to the generally low absorption of phenolic compounds after food intake, most of the consumed polyphenols remain in the gastrointestinal tract, where they then can exert inhibitory effects on enzymes involved in the degradation of saccharides, lipids, and proteins. While the inhibitory effects of phenolics on the digestion of energy-rich food components (saccharides and lipids) may be regarded as beneficial, primarily in weight-control diets, their inhibitory effects on the digestion of proteins are not desirable for the reason of reduced utilization of amino acids. The effect of polyphenols on protein digestion is reviewed in this article, with an emphasis on food processing methods to improve the antinutritive properties of polyphenols.

Protective Effect of Proanthocyanidins from Sea Buckthorn (Hippophae Rhamnoides L.) Seed against Visible Light-Induced Retinal Degeneration in Vivo

Dietary proanthocyanidins (PACs) as health-protective agents have become an important area of human nutrition research because of their potent bioactivities. We investigated the retinoprotective effects of PACs from sea buckthorn (Hippophae rhamnoides L.) seed against visible light-induced retinal degeneration in vivo. Pigmented rabbits were orally administered sea buckthorn seed PACs (50 and 100 mg/kg/day) for 14 consecutive days of pre-illumination and seven consecutive days of post-illumination. Retinal function was quantified via electroretinography 7 days after light exposure. Retinal damage was evaluated by measuring the thickness of the full-thickness retina and outer nuclear layer 7 days after light exposure. Sea buckthorn seed PACs significantly attenuated the destruction of electroretinograms and maintained the retinal structure. Increased retinal photooxidative damage was expressed by the depletion of glutathione peroxidase and catalase activities, the decrease of total antioxidant capacity level and the increase of malondialdehyde level. Light exposure induced a significant increase of inflammatory cytokines (IL-1β, TNF-α and IL-6) and angiogenesis (VEGF) levels in retina. Light exposure upregulated the expression of pro-apoptotic proteins Bax and caspase-3 and downregulated the expression of anti-apoptotic protein Bcl-2. However, sea buckthorn seed PACs ameliorated these changes induced by light exposure. Sea buckthorn seed PACs mediated the protective effect against light-induced retinal degeneration via antioxidant, anti-inflammatory and antiapoptotic mechanisms.