A novel film based on gluten, pectin, and polyphenols and its potential application in high-fat food.

BACKGROUND: A novel film based on some natural ingredients (wheat gluten, pectin, and polyphenols) was used to improve the quality and storage stability of high-fat food due to their good sustainable, mechanical, and edible properties. RESULTS: With the addition of polyphenols from Cedrus deodara (in the form of pine-needle extract (PNE)), the physicochemical properties (thickness, moisture content, and color), mechanical properties (tensile strength and elongation), barrier properties (water vapor, oil, and oxygen permeability, transmittance), and thermal stability of the composite film were improved. According to the analysis of infrared spectroscopy and molecular docking, the main compounds of PNE interacted with wheat gluten by hydrogen bonds and hydrophobic forces to form a compact and stable structure. In addition, the composite film showed a remarkable antioxidant capability to scavenge free radicals, and the film matrix could effectively protect the antioxidant activity of PNE. Furthermore, using cured meat as a model, the composite film exhibited a fine packaging performance in high-fat food during storage, which could obviously inhibit the excessive oxidation of fat and protein of cured meat and was beneficial in forming its special flavor. CONCLUSION: Our results suggest that the composite film possessed good properties and had potential for packing of high-fat foods, which could improve the quality and safety of food during processing and storage. © 2023 Society of Chemical Industry.

Establishing a novel ternary complex of soybean protein isolated-tannic acid-magnesium ion and its properties.

A ternary complex composed of soybean protein isolated (SPI), tannic acid (TA) and magnesium ion (M) was established to enhance the capability of protein carriers for TA delivery. SPI was firstly covalently bind with TA (TA-SPI) and then M was employed to form the ternary complex (M-TA-SPI). Their structures, gel and digestion properties were further investigated. TA was observed to covalently bind with SPI. TA-SPI and M-TA-SPI complexes showed different molecule size and spatial structures after binding with M and TA. The increasing of TA amount changed the intramolecular interactions, microstructure and texture properties of M-TA-SPI gels. Compared with TA-SPI, M retarded the gastric digestion of M-TA-SPI and caused higher TA release amount in intestinal tract. In this study, M-TA-SPI was determined to be a good carrier to protect and release TA in gastrointestinal digestion. This kind of complex may have potential applications for loading polyphenols in nutraceuticals.

Establishing a novel covalent complex of wheat gluten with tea polyphenols: Structure, digestion, and action mechanism.

Plant-based proteins represent a more sustainable alternative, the approaches to modify and enhance their functionality and application are focused on. Covalent interaction could significantly modify the structure and function properties of protein. This study investigated the effects of covalent interaction between wheat gluten and tea polyphenols on the structure, aggregation, stability, and digestive properties of their covalent complex, as well as the possible action mechanism. The results showed that tea polyphenols could interact with gluten via covalent bonds (CN and/or CS), while tea polyphenols also acted as a bridge connecting gluten molecules, thus making covalent complex to show the larger particle sizes. This covalent interaction significantly changed the secondary structure, tertiary structure, and surface hydrophobicity of gluten. Moreover, covalent complex exhibited the high polyphenols bioaccessibility during in vitro digestion. The peptide bonds of covalent complex were mainly broken in gastric digestion, while the covalent bonds between tea polyphenols and gluten were completely destroyed in intestinal digestion. In addition, their digestates exhibited excellent antioxidant capability. All results suggest that wheat gluten have potential to prepare functional carrier for transporting active compounds and protecting them during digestion.

Gel properties of Nicandra physalodes (Linn.) gaertn. seeds polysaccharides with tea polyphenols and its application.

The novel gelling polysaccharides (NPGP) were extracted and characterized from Nicandra physalodes (Linn.) Gaertn. seeds, while properties and potential application of NPGP gels with tea polyphenols were further explored. NPGP was composed of GalA, Glc, Rha, Gal, Xyl, Ara, and Man at a molar ratio of 71.87:17.13:3.10:2.55:2.19:1.64:1.52, with molecular weight of 6.32 × 104 Da and low methoxylation degree of 45.21%. The gelling properties of NPGP gel induced by tea polyphenols showed that tea polyphenols significantly improved the structural and rheological properties of NPGP gel, due to the formation of dense network by hydrogen bonds and the increase of crystalline degree of NPGP. NPGP gels with tea polyphenols could significantly ameliorated the texture, water-holding capacity, aggregation, leading force, and moisture distribution of surimi during freeze-thaw cycles. All results suggest that NPGP gels with tea polyphenols has fine properties and show potential to be applied as natural additives in food industry.

Creating and characteristics of a novel biomacromolecules complex of pea protein isolated-tannic acid-magnesium ion.

Pea protein isolate (PPI) was used as a carrier matrix to load tannic acid (TA) due to its multiple cavity structures and reaction sites, after that, magnesium ion (M) was further added to form more stable carrier structures. PPI was covalently bound with TA to form TA-PPI complexes in alkaline conditions, then M induced the aggregation of TA-PPI to produce M-TA-PPI complexes. TA mainly interacted with free amino groups and sulfhydryl groups of PPI, thereby decreasing their content in complexes. TA further decreased the α-helix content and increased the ß-sheet and ß-turn content in TA-PPI complexes correspondingly, nevertheless the M would decline these changes in M-TA-PPI complexes. As a result of binding, TA and M jointly increased the average molecular size of complexes. The higher TA addition amount (10-20 mg/g PPI) was conducive to the stronger intramolecular interactions (more hydrophobic interactions and disulfide bonds), gel structure (higher hardness value) and storage modulus in M-TA-PPI gels. Compared with TA-PPI complexes, M-TA-PPI complexes showed higher stability in gastric digestion and higher TA releasement and antioxidant capacity of its digesta in intestinal digestion. This kind of metal-phenolics-protein complexes may have potentials to be a stable and efficient carrier for loading gastric sensitive polyphenols.

A polysaccharide from Epiphyllum oxypetalum (DC.) Haw. and its immunomodulatory activity.

A polysaccharide (EOP) from Epiphyllum oxypetalum (DC.) Haw. was isolated and identified, and its immunomodulatory activity was evaluated both in vitro and in vivo. By using multispectral analysis, EOP was determined to be composed of rhamnose, arabinose, galactose, and galacturonic acid at a molar ratio of 26.65:11.48:53.79:6.04, and its molecular weight was 5.77 × 106 Da. In addition, backbone structure of EOP was determined to consist of (1 â†’ 4)-linked ß-Galp, (1 â†’ 2)-linked ß-Rhap, (1 â†’ 3,4)-linked ß-Galp, (1 â†’ 2,4)-linked ß-Rhap and (1 â†’ 4) -linked α-GalpA, terminating with t-ß-Arap and t-ß-Galp. The in vitro immunomodulatory activity assay on RAW 264.7 cell showed that EOP increased the proliferation of macrophages, enhanced its phagocytic capability, and promoted the production of cytokines including nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). Furthermore, the in vivo evaluation on zebrafish showed that EOP could reduce the residual content of fluorescent microspheres in zebrafish, which indicated that EOP had the capability to enhance the macrophage phagocytosis. All results suggested that EOP showed a complex structure and exhibited significant immunomodulatory activity both in vitro and in vivo that had the potential to be utilized valuably in food and medicine industries.

Cross-linking effects of EGCG on myofibrillar protein from common carp (Cyprinus carpio) and the action mechanism.

The cross-linking effects and action mechanism of epigallocatechin gallate (EGCG) on myofibrillar protein from common carp (Cyprinus carpio) were investigated. According to particle size, zeta potential, and atomic force microscopy, EGCG could cause the aggregation of myofibrillar protein, while hydrogen bonds and electrostatic interactions were the main molecular forces. With the measurement of Fourier transform infrared spectrum, surface hydrophobicity, fluorescence spectrum, circular dichroism spectrum, and molecular dynamics simulation, EGCG could make the spatial configuration of myofibrillar protein loose, enhance the exposure of amino acid residues, and further change its secondary and tertiary structures by forming intermolecular and intramolecular hydrogen bonds with myofibrillar protein. In addition, the gel properties of myofibrillar protein were improved by EGCG. All results suggested that EGCG had the cross-linking effects on myofibrillar protein in carp meat and could further improve its properties, which showed the potential to improve the qualities of fish meat in food industry. PRACTICAL APPLICATIONS: Compared with other meat, fish meat is particularly easy to break and deteriorate during its processing and sales due to the short length and low cross-linking degree of fish myofibrillar protein, which shows some negative impacts on the quality of fish meat. In the present study, epigallocatechin gallate (EGCG) showed the significant cross-linking effects on carp myofibrillar protein and further improved its physicochemical properties. All results suggested that EGCG had the potential to increase the cross-linking degree of fish myofibrillar protein and improve its properties, so as to ameliorate the quality of fish meat during processing and storage.

Structural and functional modifications of myofibrillar protein by natural phenolic compounds and their application in pork meatball.

Effects of different phenolic compounds on the structural and functional properties of myofibrillar protein (MP) were investigated, and the phenolic compounds were applied as natural modifiers in pork meatball. Interactions between MP and phenolic compounds were determined via molecular docking to elucidate the modification mechanisms. Tannic acid, gallic acid, (-)-epigallocatechin gallate, and epigallocatechin interacted with MP primarily through hydrogen bonds, which unfolded the secondary structures of MP and lowered surface hydrophobicity. Accordingly, the solubility, gel properties, and oxidation stability of MP were improved, while the emulsifying properties significantly decreased. Quercetin and quercitrin showed electrostatic interactions with MP, which preserved α-helix structures and increased surface hydrophobicity. While, the modifications lent MP the enhanced emulsifying properties, thermal stability, and oxidation stability, but the gel properties and solubility were mitigated. In addition, the incorporation of phenolic compounds prevented MP oxidation based upon their antioxidant abilities deriving from hydroxyl groups. Once the phenolic compounds were used in pork meatball, a minced meat model, they significantly improved the quality of meatball by bettering the texture properties and controlling the oxidation level. The results suggest that phenolic compounds have great potential to be employed as natural additives in minced meat products for the modification of functional properties.

Effect of Cedrus deodara extract on the physiochemical and sensory properties of salted meat and its action mechanism.

The effect of pine needle extract from Cedrus deodara (PNE) on the quality of salted meat was reported, and its action mechanism was further investigated. With the treatment of PNE, the physicochemical properties of salted meat were improved. The peroxide value decreased from 16.18 to 6.78 mmol O2 /kg, while the thiobarbituric acid value decreased from 0.79 to 0.40 mg MDA/kg. Moreover, the salted meat with PNE also had the better texture, color, and volatile compositions. The 0.2% PNE group showed the highest ΔE value (63.16 ± 0.56), hardness (813.5 ± 48.7 g), and volatility (45.86 ± 0.39), while the control group showed the lowest ΔE value (43.92 ± 2.13), hardness (515.8 ± 17.3 g) and volatility (29.97 ± 0.56). In addition, with the analysis of fluorescence and circular dichroism spectroscopy, the spatial structures of myofibrillar protein (MP) in salted meat were obviously changed by PNE. Meanwhile, methylconiferin, 1-O-feruloyl-ß-D-glucose, nortrachelogenin, secoxyloganin, 1-O-(4-coumaroyl)-ß-D-glucose and pelargonidin-3-O-glucoside were identified from PNE. Furthermore, according to the analysis of molecular docking, hydrogen bond, hydrophobic force, and electrostatic force were obtained as the main molecular forces between MP and the phenolic compounds of PNE, while arginine, glutamic acid, and glycine residues were the main binding sites. All results suggested that PNE might be a potential candidate to improve the quality of salted meat in the food industry. PRACTICAL APPLICATION: The quality deterioration of meat may not only affect its further processing and consumption but also may lead to some food safety problems. In present study, PNE exhibited the fine capability to inhibit the oxidation of meat, while it could ameliorate the texture, color, and physicochemical properties of meat due to its tightly interaction with myofibrillar protein. All result suggested that PNE could be potentially utilized to improve the quality of meat in food industry.