Effects of low-methoxyl amidated pectin and ionic calcium on rheology and microstructure of acid-induced sodium caseinate gels

Passion fruit peel-derived low-methoxyl pectin: De-esterification methods and application as a fat substitute in set yogurt

Passion fruit pectin, originally high methoxyl pectin, undergoes substantial conversion into low methoxyl pectin (LMP) through de-esterification. This de-esterification is significance for reducing the application of sugar in food, as calcium ions can replace excessive sugar during gel formation. In this study, LMPs derived from passion fruit pectin were prepared using four methods: low-temperature alkali, room temperature alkali, enzymatic, and dielectric barrier discharge plasma (DBD)-assisted enzyme (DBDE). The de-esterification conditions were optimized, leading to the selection of LMPs with a degree of esterification for the analysis of molecular weight, monosaccharide composition, and gel properties. The results revealed significant differences in the structure and properties of LMPs depending on the de-esterification method applied. The galacturonic acid content of LMPs significantly increased, with LMP from DBDE (LMP-DBDE) exhibiting the highest increase at 47.81 %. Additionally, the molecular weights of LMPs significantly decreased, with LMP-DBDE showing the smallest decrease. LMP-DBDE demonstrated higher apparent viscosity, thermal stability, and gel properties, facilitating the formation of gels. After 21 days of storage, 0.40 % LMP-DBDE yogurt showed no whey separation, significantly extending its shelf life. Therefore, LMP-DBDE exhibits potential as a fat substitute, combining the advantages of LMP with enhanced water-holding capacity, and presenting promising applications in low-fat dairy products.

Recent advances in dietary polysaccharides from Allium species: Preparation, characterization, and bioactivity

Allium plants, including garlic, onions, shallots, and leeks, belong to the Alliaceae family and are utilized as vegetable, medicinal, and ornamental plants. These plants are consumed both raw and cooked and are noted in traditional medicine for their antibacterial, antitumor, and diuretic properties. Allium plants are a rich source of polyphenols, organosulfur compounds, flavonoids, alkaloids, and polysaccharides, which contribute to their health benefits. As consumer interest in the association between diet and health grows, there is an increasing market demand for foods that promote health, particularly those rich in dietary fiber or non-starch polysaccharides. Allium polysaccharides (APS) have molecular weights of 1 × 103-1 × 106 Da containing small amounts of pectin, glucofructan, or glycoproteins and large amounts of fructans. APS, despite its complex structure, is one of the principal active components of Allium plants but is often overlooked, which restricts its practical application. This paper provides a comprehensive overview of the extraction and purification, structural and functional characteristics, bioactivities, structure-function relationships, and chemical modifications of APS, as well as the effects of APS processing and storage. Additionally, this paper outlines future research directions for APS, which will inform its development and application in the food, pharmaceutical, and cosmetic industries.

Tuning whey protein isolate/hyaluronic acid emulsion gel structure to enhance quercetin bioaccessibility and in vitro digestive characteristics

Quercetin (Que), a health-promoting polyphenol, has limited applicability in food products due to its susceptibility to degradation in the gastrointestinal tract. To overcome this problem, Que-loaded emulsion gels were produced using whey protein isolate (WPI) and hyaluronic acid (HA) by combining heating and CaCl2 treatment. The effects of HA addition on the structural and rheological properties of the emulsion gels were evaluated, and the protective effect of the gel on Que under simulated digestion was investigated in vitro. Microstructural observations indicated that HA leads to a more compact and uniform network structure, which significantly enhances the textural and rheological properties of emulsion gels. In vitro digestion experiments revealed that WPI-HA emulsion gels exhibited a higher Que bioaccessibility (55.01%) compared to that produced by WPI alone (21.26%). This innovative delivery carrier has potential applications in food products to accomplish sustained nutrient release along with improved stability.

Caseinate-reinforced pectin hydrogels: Efficient encapsulation, desirable release, and chemical stabilization of (-)-epigallocatechin

(-)-Epigallocatechin (EGC) has good health benefits, but its chemical stability is low. Pectin hydrogels have potential for the encapsulation and delivery of EGC, but they are limited by porous networks and poor mechanical properties. In this study, protein (whey protein isolate and caseinate)-reinforced pectin hydrogel beads (HB_PEC-WPI and HB_PEC-CAS) were developed to overcome these limitations. The results showed that HB_PEC-CAS was a superior delivery system for EGC. HB_PEC-CAS had a compact network structure, mainly because of the hydrogen bonds that formed between caseinate and pectin. Moreover, the EGC encapsulation efficiency of HB_{PEC-CAS (2.4%)} reached 92.23 %; HB_{PEC-CAS (2.4%)} could also delay the release of EGC in an aqueous environment, while ensuring its sufficient release in a simulated gastrointestinal environment. Notably, EGC was chemically stabilized in HB_{PEC-CAS (2.4%)} during a 6-day storage period at 37 °C through the inhibition of its epimerization, oxidation, dimerization, and trimerization. The numerous hydroxyl groups in EGC readily interacted with the exposed amino acid residues in caseinate and created more protective sites. This study developed a strategy for protein-reinforced pectin hydrogel development and approaches for the protection of tea polyphenols; the findings offer useful insights for the tea-based food and beverage industry.

High-Protein Foods for Dysphagia: Manipulation of Mechanical and Microstructural Properties of Whey Protein Gels Using De-Structured Starch and Salts

This study focuses on understanding the effect of ionic strength on the mechanical and microstructural properties of novel composite gels containing 13% whey protein isolate (WPI) and 4% de-structured waxy potato starch (DWPS). The DWPS is a physically modified waxy potato starch treated at 140 °C for 30 min under constant shear. Thermodynamic incompatibility between WPI and DWPS was observed upon the addition of NaCl (~75 mM) or CaCl₂ (10–75 mM). The combined effects of such thermodynamic incompatibility with the changes in protein connectivity induced by varied ionic strength led to the formation of distinctive gel structures (inhomogeneous self-supporting gels with a liquid centre and weak gels with paste-like consistency) that were different from thermodynamic compatible homogeneous self-supporting gels (pure WPI and WPI + maltodextrin gels). At ≥ 250 mM NaCl, instead of a paste-like texture, a recovered soft and creamy self-supporting gel structure was observed when using DWPS. The ability to generate a range of textures in WPI gelation-based foods by using DWPS under different ionic conditions, is a feasible strategy for formulating high-protein foods for dysphagia—aimed to be either thickened fluids or soft solids. Additionally, this acquired knowledge is also relevant when formulating food gels for 3-D printing.

Preparation and Characterization of a Novel Soy Protein Isolate-Sugar Beet Pectin Emulsion Gel and Its Application as a Multi-Phased Nutrient Carrier

Emulsion gel, a novel oral delivery carrier, provides the possibility to co-load hydrophilic and lipophilic nutrients simultaneously. In this study, duo-induction methods of laccase and glucono-δ-lactone (L&GDL) or laccase and transglutaminase (L&MTG) were used to prepare the soy protein isolate-sugar beet pectin (SPI-SBP) emulsion gel. The textural data of the emulsion gel was normalized to analyze the effect of different induction methods on the gel property of the SPI-SBP emulsion gels. The characterization studies showed the structure of L&MTG emulsion gel was denser with a lower swelling ratio and reduced degree of digestion, compared with L&GDL emulsion gel. Moreover, the release profiles of both β-carotene and riboflavin co-loaded in the SPI-SBP emulsion gels were correlated to the digestion patterns of the gel matrix; the controlled-release of encapsulated functional factors was regulated by a gel network induced by different induction methods, mainly due to the resulting porosity of the structure and swelling ratio during digestion. In conclusion, SPI-SBP emulsion gels have the capability of encapsulating multiple functional factors with different physicochemical properties.

Effect and Mechanism of Acid-Induced Soy Protein Isolate Gels as Influenced by Cellulose Nanocrystals and Microcrystalline Cellulose

The effects of cellulose nanocrystals (CNC) and microcrystalline cellulose (MCC) on the gel properties and microstructure of glucono-δ-lactone-induced soy protein isolate (SPI) gels were investigated. The water-holding capacity, gel strength, and viscoelastic modulus of CNC-SPI gels were positively associated with CNC concentration from 0 to 0.75% (w/v). In contrast, MCC-SPI gels exhibited decreased water-holding capacity, gel strength, and viscoelastic modulus. All composite gels displayed high frequency dependence and the typical type I (strain thinning) network behavior. Changes in viscoelasticity under large strain were correlated with differences in the microstructure of SPI composite gels. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) showed that CNC were more evenly and steadily distributed in the protein matrix and formed a compact network structure. In contrast, MCC-SPI gels exhibited a discontinued and rough gel network with some large aggregates and pores, in which MCC was randomly entrapped. Fourier transform infrared spectroscopy (FTIR) and molecular forces results revealed that no new chemical bonds were formed in the gelation process and that the disulfide bond was of crucial importance in the gel system. With the addition of CNC, electrostatic interactions, hydrophobic interactions, and hydrogen bonds in the SPI gel network were significantly strengthened. However, the incorporation of MCC might obstruct the connection of the protein network. It is concluded that both cellulose type and concentration affect gelling properties.

Recent advances in utilization of pectins in biomedical applications: a review focusing on molecular structure-directing health-promoting properties

The numerous health benefits of pectins justify their inclusion in human diets and biomedical products. This review provides an overview of pectin extraction and modification methods, their physico-chemical characteristics, health-promoting properties, and pharmaceutical/biomedical applications. Pectins, as readily available and versatile biomolecules, can be tailored to possess specific functionalities for food, pharmaceutical and biomedical applications, through judicious selection of appropriate extraction and modification technologies/processes based on green chemistry principles. Pectin's structural and physicochemical characteristics dictate their effects on digestion and bioavailability of nutrients, as well as health-promoting properties including anticancer, immunomodulatory, anti-inflammatory, intestinal microflora-regulating, immune barrier-strengthening, hypercholesterolemia-/arteriosclerosis-preventing, anti-diabetic, anti-obesity, antitussive, analgesic, anticoagulant, and wound healing effects. HG, RG-I, RG-II, molecular weight, side chain pattern, and degrees of methylation, acetylation, amidation and branching are critical structural elements responsible for optimizing these health benefits. The physicochemical characteristics, health functionalities, biocompatibility and biodegradability of pectins enable the construction of pectin-based composites with distinct properties for targeted applications in bioactive/drug delivery, edible films/coatings, nano-/micro-encapsulation, wound dressings and biological tissue engineering. Achieving beneficial synergies among the green extraction and modification processes during pectin production, and between pectin and other composite components in biomedical products, should be key foci for future research.

The viability of complex coacervate encapsulated probiotics during simulated sequential gastrointestinal digestion affected by wall materials and drying methods

The objective of this study was to investigate the impact of protein type (sodium caseinate and pea protein isolate) and protein to sugar beet pectin mixing ratio (5 : 1 and 2 : 1) on complex coacervate formation, as well as the impact of the finishing technology (freeze-drying and spray-drying) for improving the viability of encapsulated Lactobacillus rhamnosus GG (LGG) in complex coacervates during simulated sequential gastrointestinal (GI) digestion. The physicochemical properties of LGG encapsulated microcapsules in liquid and powder form were evaluated. The state diagram and ζ-potential results indicated that pH 3.0 was the optimum pH for coacervate formation in the current systems. Confocal laser scanning microscopy (CLSM), viscoelastic analysis, and Fourier transform infrared spectroscopy (FTIR) confirmed that the gel-like network structure of the complex coacervates was successfully formed between the protein and SBP at pH 3.0 through electrostatic interaction. In terms of physiochemical properties and viability of LGG encapsulated in the microcapsule powder, the drying method played a crucial role on particle size, microstructure and death rate of encapsulated LGG during simulated sequential GI digestion compared to protein type and biopolymer mixing ratio. For example, the microstructure of spray-dried microcapsules exhibited smaller spherical particles with some cavities, whereas the larger particle size of freeze-dried samples showed a porous sponge network structure with larger particle sizes. As a result, spray-dried LGG microcapsules generally had a lower death rate during simulated sequential gastrointestinal digestion compared to their freeze-dried counterparts. Among all samples, spray-dried PPI-SBP microcapsules demonstrated superior performance against cell loss and maintained more than 7.5 log CFU per g viable cells after digestion.

Extraction, Characterization, and Applications of Pectins from Plant By-Products

Currently, pectins are widely used in the cosmetic, pharmaceutical, and food industries, mainly as texturizing, emulsifying, stabilizing, and gelling agents. Pectins are polysaccharides composed of a large linear segment of α-(1,4) linked d-galactopyranosyluronic acids interrupted by β-(1,2)-linked l-rhamnoses and ramified by short chains composed of neutral hexoses and pentoses. The characteristics and applications of pectins are strongly influenced by their structures depending on plant species and tissues but also extraction methods. The aim of this review is therefore to highlight the structures of pectins and the various methods used to extract them, including conventional ones but also microwave heating, ultrasonic treatment, and dielectric barrier discharge techniques, assessing physico-chemical parameters which have significant effects on pectin characteristics and applications as techno-functional and bioactive agents.

Size Modulation of Enzymatically Cross-Linked Sodium Caseinate Nanoparticles via Ionic Strength Variation Affects the Properties of Acid-Induced Gels

Enzymatic cross-linking by microbial transglutaminase is a prominent approach to modify the structure and techno-functional properties of food proteins such as casein. However, some of the factors that influence structure-function-interrelations are still unknown. In this study, the size of cross-linked sodium caseinate nanoparticles was modulated by varying the ionic milieu during incubation with the enzyme. As was revealed by size exclusion chromatography, cross-linking at higher ionic strength resulted in larger casein particles. These formed acid-induced gels with higher stiffness and lower susceptibility to forced syneresis compared to those where the same number of ions was added after the cross-linking process. The results show that variations of the ionic milieu during enzymatic cross-linking of casein can be helpful to obtain specific modifications of its molecular structure and certain techno-functional properties. Such knowledge is crucial for the design of protein ingredients with targeted structure and techno-functionality.

Gelation and microstructural properties of a millet-based yogurt-like product using polymerized whey protein and xanthan gum as thickening agents

Cereal-based fermented products are becoming popular in the world. A millet-based yogurt-like product (MYP) using polymerized whey protein (PWP) and xanthan gum (XG) as thickeners was developed. The present study aimed to investigate the effects of PWP (0.3 to 0.5%, w/v) and XG (0 to 0.2%, w/v) on the gelation properties and microstructure of MYP. All samples were analyzed for rheological properties, textural properties, microstructure, and pH value during fermentation. The MYP Ⅲ (0.4% PWP and 0.1% XG) registered the highest elastic modulus (G') throughout the fermentation and cooling steps (P < 0.05), but MYP Ⅳ (0.35% PWP and 0.15% XG) had the highest apparent viscosity compared with the other samples. No significant differences in the pH values among the samples were observed during the fermentation process (P > 0.05). The hardness value of MYP Ⅳ reached a maximum after 4 hr and then stabilized during fermentation. Scanning electron microscopy showed a compact and uniform network for the MYP with PWP and XG. MYP Ⅳ had the best texture properties (hardness, springiness, and gumminess). Overall, PWP (0.35%, w/v) and XG (0.15%, w/v) were the best combination for MYP as a thickening system. PRACTICAL APPLICATION: Cereal-based fermented products have attracted much attention in the food industry. However, due to absence of a natural protein network, it is hard to produce a set-type millet-based yogurt with a firm texture under the studied conditions without adding any thickening agents. In this study, PWP (0.35%, w/v) and XG (0.15%, w/v) can be used for fermentation of millet-based yogurt-like products. The new cereal-based fermented product would be a promising food in the market.

Vegetable-Milk-Based Yogurt-Like Structure: Rheological Properties Influenced by Gluten-Free Carob Seed Flour

There is a constant increase in the attention being paid to food quality and the effects of food on human health among consumers. Vegetable milk is among the foods whose consumption worldwide has increased because, when compared to animal-derived milk, it offers numerous benefits for human health. The aim of this research work was to use vegetable milk to obtain yogurt-like products enriched with different concentrations of carob seed flour, which has a double function: to modify, and thus perfect, the rheological characteristics of vegetable-milk-based yogurt-like samples and to increase their nutritional value. The rheological parameters of the obtained samples were studied both in static and dynamic conditions, confirming that carob seed flour, especially at the highest used concentrations (0.75%; 1%), allows one to obtain products characterized by a good stability and suitable rheological characteristics. The obtained yogurt-like products may also be consumed by celiac subjects, since carob seed flour is a gluten-free flour, and allow celiac consumers to combine a gluten-free diet with a diet free of animal derivatives. Furthermore, the addition of carob flour allows one to obtain a tasty product thanks to the sweet taste of the carob seed flour.

Physicochemical and rheological changes of acidified camel milk added with commercial low methoxyl-pectin

The influence of the addition of low methoxyl amidated pectin (LMA) on acid milk gels from whole camel milk (WCM) on physicochemical and rheological proprieties were studied. The zeta potential, particle size, viscosity, dynamic oscillatory rheology and isothermal titration calorimetry were monitored. The presence of LM-pectin in milk had an impact on the average size of the casein micelles and a large and dominant influence on rheological behavior during acidification. Zeta potential and viscosity of gels with 0.5% pectin were not affected. However, milk gels containing 1%, 1.5% and 2% of LM-pectin showed highest values of particle size at pH4. This modification of the structure of the casein micelles induces a significant improvement (p<0.05) on its acid gelation behavior. Therefore, the addition of pectin enhanced the rheological proprieties. Higher pectin concentration led to a strong gel with higher G' values. This result could be attributed to the formation of complexes and the mechanical spectra prove the hypothesis that pectin forms strands with caseins micelles. Isothermal titration calorimetry results showed that pectin concentration had a marked influence on the gels structure and that this polysaccharide stabilizes caseins micelles in acidified camel milk gel due to electrostatic interaction and steric repulsion.

Gastrointestinal Fate of Fluid and Gelled Nutraceutical Emulsions: Impact on Proteolysis, Lipolysis, and Quercetin Bioaccessibility

Fluid and gelled nutraceutical emulsions were formulated from quercetin-loaded caseinate-stabilized emulsions by the addition of gellan gum with or without acidification with glucono-δ-lactone. Gellan gum addition increased the viscosity or gel strength of the fluid and gelled emulsions, respectively. The behavior of the nutraceutical emulsions in a simulated gastrointestinal tract depended upon their initial composition. Fluid emulsions containing different gellan gum levels (0-0.2%) had similar protein and lipid hydrolysis rates as well as similar quercetin bioaccessibility (∼51%). Conversely, proteolysis, lipolysis, and quercetin bioaccessibility decreased with an increasing gellan gum level in the gelled emulsions. In comparison to gelled emulsions, fluid emulsions were digested more rapidly and led to higher quercetin bioaccessibility. There was a good correlation between quercetin bioaccessibility and the lipolysis rate. These findings are useful for designing nutraceutical-loaded emulsions that can be used in a wide range of food products with different rheological properties.

Insulin Inclusion into a Tragacanth Hydrogel: An Oral Delivery System for Insulin

Nanoparticles or microparticles created by physical complexation between two polyelectrolytes may have a prospective use as an excipient for oral insulin administration. Natural polymers such as tragacanth, alginate, dextran, pullulan, hyaluronic acid, gelatin and chitosan can be potential candidates for this purpose. In this research, insulin particles were prepared by the inclusion of insulin into a tragacanth hydrogel. The effect of the pH and concentration relationship involving polyelectrolytes offering individual particle size and zeta potential was assessed by zetasizer and scanning electron microscopy (SEM). Insulin-tragacanth interactions at varying pH (3.7, 4.3, 4.6, or 6), and concentration (0.1%, 0.5%, or 1% w/w) were evaluated by differential scanning calorimetry (DSC) and ATR Fourier transform infrared (ATR-FTIR) analysis. Individual and smaller particles, approximately 800 nm, were acquired at pH 4.6 with 0.5% of tragacanth. The acid gelation test indicated that insulin could be entrapped in the physical hydrogel of tragacanth. DSC thermograms of insulin-tragacanth showed shifts on the same unloaded tragacanth peaks and suggested polyelectrolyte-protein interactions at a pH close to 4.3-4.6. FTIR spectra of tragacanth-insulin complexes exhibited amide absorption bands featuring in the protein spectra and revealed the creation of a new chemical substance.

Scale-down models to optimize a filter train for the downstream purification of recombinant pharmaceutical proteins produced in tobacco leaves

The extraction of biopharmaceutical proteins from intact leaves involves the release of abundant particulate contaminants that must be removed economically from the process stream before chromatography, for example, using disposable filters that comply with good manufacturing practice. We therefore scaled down an existing 200-kg process for the purification of two target proteins from tobacco leaves (the monoclonal antibody 2G12 and the fluorescent protein DsRed, as monitored by surface plasmon resonance spectroscopy and fluorescence imaging, respectively) and screened different materials on the 2-kg scale to reduce the number of depth filtration steps from three to one. We assessed filter cost and capacity, filtrate turbidity, and protein recovery when the filter materials were challenged with extracts from different tobacco varieties and related species grown in soil or rockwool. PDF4 was consistently the most suitable depth filter because it was the least expensive, it did not interact significantly with the target proteins, and it had the greatest overall capacity. The filter capacity was generally reduced when plants were grown in rockwool, but this substrate has a low bioburden, thus improving process safety. Our data concerning the clarification of plant extracts will help in the design of more cost-effective downstream processes and accelerate their development.

Preparation and characterization of microcapsules based on biodegradable polymers: pectin/casein complex for controlled drug release systems

Controlled release of drugs is an important strategy to diminish the drug dose and adverse side effects. Aqueous mixtures of polysaccharides and proteins are usually unstable above a certain biopolymer concentration and phase separation occurs either because of repulsive (segregative) or attractive (associative) interactions. Herein, pectin/casein microcapsules were prepared by complex coacervation aiming at prolonged drug release. The morphological characteristics, particle size, distribution, and release kinetics of microcapsules were studied using as a model the hydrophilic drug acetaminophen. It was detected that complexation of pectin/casein particles occurs at pH values lower than 6, resulting in the formation of spherical particles after spray drying. Microcapsules had a mean diameter of 3.138 and 4.929 μm without drug, and of 4.680 and 5.182 μm with drug using USP and 8003 pectin, respectively. The in vitro release of acetaminophen from microcapsules was slow and the drug release mechanism was controlled by diffusion following first-order kinetics. There was greater release of acetaminophen in simulated gastric fluid than simulated intestinal fluid conditions. Concluding, the polymeric system present herein seemed to be appropriate for a prolonged release of acetaminophen throughout the gastrointestinal tract. Nevertheless, it is likely that it is a promising pectin/casein complex for lipossoluble drugs, which merits further investigation.

General analytical schemes for the characterization of pectin-based edible gelled systems

Pectin-based gelled systems have gained increasing attention for the design of newly developed food products. For this reason, the characterization of such formulas is a necessity in order to present scientific data and to introduce an appropriate finished product to the industry. Various analytical techniques are available for the evaluation of the systems formulated on the basis of pectin and the designed gel. In this paper, general analytical approaches for the characterization of pectin-based gelled systems were categorized into several subsections including physicochemical analysis, visual observation, textural/rheological measurement, microstructural image characterization, and psychorheological evaluation. Three-dimensional trials to assess correlations among microstructure, texture, and taste were also discussed. Practical examples of advanced objective techniques including experimental setups for small and large deformation rheological measurements and microstructural image analysis were presented in more details.