Rheological, thermal and microstructural properties of casein/κ-carrageenan mixed systems

High-pressure homogenization to improve the stability of liquid diabetes formula food for special medical purposes: Structural characteristics of casein-polysaccharide complexes

The stability of diabetes formula food for special medical purposes (D-FSMP) was improved by high-pressure homogenization (HPH) at different homogenization pressures (up to 70 MPa) and number of passes (up to 6 times). The process at 60 MPa/4 times was the best. Casein had the highest surface hydrophobicity in this condition. The casein-polysaccharide complexes were endowed with the smallest size (transmission electron microscopy images). The complex particles exhibited nearly neutral wettability (the three-phase contact angle was 90.89°), lower interfacial tension, and the highest emulsifying activity index (EAI) and emulsifying stability index (ESI). The prepared D-FSMP system exhibited the narrowest particle size distribution range, the strongest interfacial deformation resistance and the best storage stability. Therefore, an appropriate intensity of HPH could enhance the stability of D-FSMP by improving the interfacial and emulsifying properties of casein-polysaccharide complexes. This study provides practical guidance on the productions of stable D-FSMP.

Effect of low degree succinylation on properties of enzyme-induced casein hydrogel

This study examines the impact of succinic anhydride (SA) modification (0-9 %) on the gel properties of casein. Upon succinylation, the surface hydrophobicity (H0) of casein initially increased before decreasing, achieving its peak at a degree of succinylation of 5.22 ± 0.16 %. The α-helix content rose to 14.13 ± 2.60 %, and the -OH peak shifted towards lower wavenumbers, suggesting enhanced hydrogen bonding within intra/intermolecular structures. The storage modulus in the rheological test escalated from 2160.11 Pa to 5047.60 Pa, and SEM analysis revealed that the optimally succinylated casein gel formed a denser and more stable gel network structure. Moreover, succinylated casein hydrogels demonstrated superior texture properties, swelling ability, and thermal stability. Molecular dynamics simulation (MD) results suggest that SA preferentially binds to LYS27 and LYS28 of β-casein via hydrogen bonds and amide bonds, respectively. The interaction between modified proteins is primarily governed by hydrogen bonds, aligning with FT-IR findings. PCA analysis identified a positive correlation between the ordered structure and gel performance. This research offers theoretical insights and reference data for modulating casein hydrogel properties through succinylation.

Effect of Fucoidan on Conformation of Xanthan Gum and Its Tribo-Rheological Properties

This study sought to explore the rheological and tribological properties of fucoidan-xanthan gum (XG) mixtures at different fucoidan concentrations. A conformational transition of XG from disordered to ordered forms was observed with an increasing fucoidan concentration, as determined by intrinsic viscosity measurements and Fourier transform infrared analysis. All mixtures exhibited non-Newtonian flow behavior with the yield stress. The mixture sample with 0.5% fucoidan displayed higher apparent viscosity at 100 s-1, yield stress, and viscoelastic moduli values than XG alone, suggesting viscoelastic synergism between the two biopolymers. However, these values exhibited a decreasing trend with higher fucoidan concentrations (0.5-2.0%), indicating a nullification of synergism. While XG alone exhibited antithixotropic behavior, fucoidan-XG mixtures showed thixotropic behavior, most pronounced at 1.0% fucoidan. A decreasing trend was observed in the maximum friction coefficient as the fucoidan concentration increased, indicating better lubricant properties. Collectively, our findings may enable widespread adoption and application of fucoidan in various industries.

Effect of xanthan gum (XG) and carrageenan (CG) ratio on casein (CA)-XG-CG ternary complex: Used to improve the stability of liquid diabetes formula food for special medical purposes

Poor storage stability limits the application of liquid diabetes formula food for special medical purposes (L-D-FSMP) in maintaining blood sugar stability in diabetic patients. This work aims to improve the stability of L-D-FSMP by adjusting the ratio of xanthan gum (XG) and carrageenan (CG) in casein (CA)-XG-CG ternary complex. The centrifugal sedimentation rate results showed that the compound ratio of XG and CG had a greater impact on L-D-FSMP storage stability. Transmission electron microscopy (TEM) results showed that the combination of CA, XG and CG occurred. Fourier transform infrared spectroscopy (FTIR) results showed that CA, XG and CG were mainly combined through hydrogen bonds and ionic bonds to form a CA-XG-CG ternary complex. When the ratio of XG and CG was 1:1, the number of disulfide bonds was the largest. The results of three-phase contact angle and emulsifying ability confirmed that when the ratio of XG and CG was 1:1, CA-XG-CG had the strongest emulsifying ability. The particle size distribution and zeta-potential results showed that when the ratio of XG and CG was 1:1, L-D-FSMP had the narrowest particle size distribution range and the strongest stability. These results may provide valuable information for the production of stable L-D-FSMP.

Effects and mechanisms of different κ-carrageenan incorporation forms and ionic strength on the physicochemical and gelling properties of myofibrillar protein

The present work was aimed to investigate the effects of incorporating κ-carrageenan into myofibrillar protein (MP) as a dry powder (CP) or water suspension (CW) and the ionic strength (0.3 or 0.6 M sodium chloride (NaCl)) on MP physicochemical and gelling properties. The results indicated that incorporation of either CP or CW significantly increased turbidity, surface hydrophobicity, particle size and rheological behaviour of MP. In contrast, the protein solubility and fluorescence intensity of MP decreased when added with each form of κ-carrageenan (P < 0.05). These observed effects improved MP's gelling properties and produced a more compact and homogenous gel network after heating treatment. Moreover, the addition of CW rendered higher gel strength, water holding capacity and intermolecular interactions, such as ionic, hydrogen and disulphide bonds and hydrophobic interactions in MP gel compared with those added with CP, especially for 0.3 M NaCl (P < 0.05). Furthermore, addition of CW significantly decreased the α-helix content of MP gels (P < 0.05), which mainly contributing to the transformation from a random structure to an organised configuration. In addition, a higher NaCl concentration (0.6 M) enhanced the gelling properties of MP gels compared with 0.3 M NaCl concentration in the presence of each form of κ-carrageenan. Therefore, our present study indicated that incorporation form of κ-carrageenan and ionic strength have distinctive effects on regulating physicochemical characteristics and improves gelling properties of MP.

Effect of simulated saliva on rheological and tribological properties of oleogel-in-water HIPEs during oral processing

HYPOTHESIS

High internal phase emulsions (HIPEs) have great potentials in the food industry to control fat consumption. Textural perception of HIPEs during oral processing is strongly influenced by saliva, which has not been systematically investigated. Therefore, we investigated the roles of saliva in the rheological and tribological properties of HIPEs during oral processing.

EXPERIMENTS

HIPEs (O/W) stabilized by oleogel and a protein were fabricated. Small (SAOS) and large (LAOS) amplitude oscillatory shearing measurements and tribological tests were performed, in combination with structural characterization of the emulsions.

FINDINGS

Particle size and CLSM observation indicated that saliva induced coalescence of droplets by weakening the interface and more EC resulted in faster clustering. SAOS tests revealed that emulsions mixed with saliva had weaker structural strength and lower resistance to deformation. Particularly in large deformation, the HIPEs mixed with saliva presented an acceleration in the droplet-droplet structure breakdown, which led to the pronounced strain-thinning behavior and energy dissipation. Tribological curves further revealed that the corporation of saliva contributed to the release of oil to reduce friction coefficient.

Fabrication and Characterization of Complex Coacervation: The Integration of Sesame Protein Isolate-Polysaccharides

The exceptional biocompatibility of emulsion systems that rely on stabilizing protein-polysaccharide particles presents extensive possibilities for the transportation of bioactive carriers, making them highly promising for various biological applications. The current work aimed to explore the phenomenon of complex coacervation between sesame protein isolate (SPI) and four distinct polysaccharides, namely, Arabic gum (GA), carrageenan (CAR), sodium carboxymethyl cellulose (CMC), and sodium alginate (SA). The study objective was achieved by fabricating emulsions through the blending of these polymers with oil at their maximum turbidity level (φ = 0.6), followed by the measurement of their rheological properties. The turbidity, ζ-potential, and particle size were among the techno-parameters analyzed to assess the emulsion stability. The microstructural characterization of the emulsions was conducted using both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Furthermore, the functional properties were examined using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SPI incorporated with SA, CMC, and CAR reached the maximum turbidity (0.2% w/v) at a ratio of 4:1, corresponding to the pH values of 4.5, 3, or 3.5, respectively. The SPI-GA mixture exhibited the maximum turbidity at a ratio of 10:1 and pH 4.5. Results from the FTIR and XRD analyses provided evidence of complex formation between SPI and the four polysaccharides, with the electrostatic and hydrogen bond interactions facilitating the binding of SPI to these polysaccharides. SPI was bound to the four polysaccharides through electrostatic and hydrogen bond interactions. The SPI-CMC and SPI-SA emulsions were more stable after two weeks of storage.

Influence of Some Hydrocolloids and Sterilization Conditions on the Physical Properties of Texture-Modified Foods Developed for the Swallow Training of Dysphagia Patients

This research aimed to develop jelly soup for dysphagia patients at the International Dysphagia Diet Standardization Initiative (IDDSI) Framework levels 4 (puree) and 5 (minced and moist), who require swallow training to regain normal swallowing ability due to neurological issues. The study comprised three main parts: (1) an investigation of hydrocolloid types and concentrations for texture-modified foods to aid dysphagia patients during training; (2) a study of sterilization conditions and ascorbic acid's impact on physical properties (e.g., texture, viscosity, color) of the texture-modified foods; and (3) an evaluation of changes in physical, chemical, and microbial properties of the product during storage. Results revealed that the ideal recipe involved using pork bone broth with 1% κ-carrageenan for texture modification, which closely matched the properties of hospital jelly samples in terms of hardness, adhesiveness, and viscosity. Sterilization at 110 °C for 109 min effectively eliminated microorganisms without affecting the product's appearance or texture, albeit causing a slight increase in brownness. Adding ascorbic acid helped to prevent the Maillard reaction but reduced the gel strength of the sample and induced milk protein denaturation, leading to aggregation. During storage at room temperature for 9 weeks, the product became browner and less firm. Notably, no bacteria were detected throughout this period. In conclusion, this heating process is suitable for producing jelly soup to support swallow training for dysphagia patients with neurological problems. It offers invaluable assistance in their daily training to regain normal swallowing function.

Nanostructural changes in Polysaccharide-Casein Gel-Like structures upon in vitro gastrointestinal digestion

This work reports on the nanostructural changes taking place during the in vitro gastrointestinal digestion of polysaccharide-casein gel-like structures through the use of small angle X-ray scattering (SAXS). The results indicated that during the gastric phase, the hydrolysis of casein led to a swelling of the micellar structure, yielding peptide clusters. The presence of sulphated polysaccharides such as agar and κ-carrageenan was seen to limit the hydrolysis of casein during the gastric phase, hence decreasing the size of the formed clusters. After the intestinal phase, the produced peptidic fragments appeared to interact with the bile salts present in the digestion medium, yielding a mixture of bile salt lamellae/micelles and vesicular structures. However, in the presence of polysaccharides, which can interact with bile salts, the formation of vesicular structures was limited. Interestingly, the inclusion of casein within hybrid gel-like structures led to the formation of strong polysaccharide-protein interactions, especially in the case of κ-carrageenan. As a result, in some of the formulations, polysaccharide-peptide complexes were released towards the liquid medium, which formed larger vesicular structures. This was related to the greater protective effect of these particular gel-like structures. Furthermore, κ-carrageenan hindered the formation of bile salt lamellae/micelles. These results are of high relevance to understand the intestinal transport mechanism of the digestion products from protein-based ingredients and will allow a rational design of novel products with optimum nutritional and functional properties.

Comparative investigations of various modification methods on the gelling, rheological properties and mechanism of fish gelatin

In this study, κ-carrageenan(κC) and Transglutaminase (TG) were used to modify fish gelatin (FG). Three types of modified gelatin groups FG-κC, FG-TG and FG-κC-TG were prepared. The results showed that the gel strength and textural properties of FG gels were greatly enhanced by κC modification and κC-TG complex modification, whilst pure TG modification weakened the gelling properties. And the pure 0.1 % κC modified FG had the highest gel strength and hardness, respectively. Rheological behavior showed that the complex modified FG samples had the highest viscosity, gelling points, melting points and G'∞. Fourier infrared spectra and LF-NMR analysis showed that κC and κC-TG modification respectively improved the contents of hydrogen and isopeptide that decreased the water mobility but stabilized the helical structure of gelatin gels. Fluorescence intensity showed that three types of modification decreased fluorescence intensity. While, the formation of aggregates and denser gel networks decreased in vitro digestibility of FG.

A comprehensive review on yogurt syneresis: effect of processing conditions and added additives

Yogurt, produced by the lactic fermentation of milk base, is an important dairy product worldwide. One of the essential sensory properties of yogurt is the texture, and some textural defects such as weak gel firmness and syneresis likely occur in various types of yogurts, affecting consumer acceptance. In this regard, various strategies such as enrichment of milk-based with different additives and ingredients such as protein-based components (skimmed milk powder (SMP), whey protein-based powders (WP), casein-based powders (CP), and suitable stabilizers, as well as modification of processing conditions (homogenization, fermentation, and cooling), can be applied in order to reduce syneresis. The most effective proteins and stabilizers in syneresis reduction are CP and gelatin, respectively. Furthermore, yogurt's water holding capacity and syneresis can be affected by the type of starter cultures, the protolithic activity, production of extracellular polysaccharides, and inoculation rate. Moreover, optimizing the heat treatment process (85 °C/30 min and 95 °C/5 min), homogenization (single or dual-stage), incubation temperature (around 40 °C), and two-step cooling process can decrease yogurt syneresis. This review is aimed to investigate the effect of fortification of the milk base with various additives and optimization of process conditions on improving texture and preventing syneresis in yogurt.

Structural modification of zein-based oil-in-glycerol emulsion gels for improved textural and digestion behaviors

Zein can dissolve in glycerol, and can be developed into oil-in-glycerol emulsion gels to widen its applications. The current study focused on modulating the structures of zein-based emulsion gels by the addition of a surface active ingredient (Span 20, SP) to improve textural and digestion behaviors. Microstructural observation indicated that the addition of SP replaced zein from the oil-glycerol interface, and allowed a higher level of oil droplet aggregation. After adding SP, the gel hardness decreased from 3.43 ± 0.14 N to 1.62 ± 0.01 N, and the storage modulus also decreased with the increase of SP content. Viscoelasticity of the gels was thermo-responsive, and the presence of SP contributed to a higher recovery of the storage modulus after the heating-cooling process. The addition of SP reduced the oil-binding capacity of zein gel from 97.61 ± 0.19% to 82.00 ± 0.92% and the solvent-binding capacity from 75.97 ± 3.05% to 62.25 ± 0.22%, indicating that the zein network was weakened. Then, gels were mixed with simulated digestive juices to track the changes of gel structures and the release of free fatty acids. The addition of SP accelerated the digestion process, especially intestinal digestion. SP contributed to a higher fluorescence intensity in the digesta, which was a sign of a higher level of digestion of zein. Subsequently, the addition of SP increased the release content of free fatty acids from 4.27 ± 0.71% to 5.07 ± 1.27%. The above findings would be useful in designing zein-based functional food products with favored textural and digestion properties.

Acid-Mediated Formation of Soybean Isolate Protein Emulsion Gels with Soybean Oil as an Active Component

In this study, the effect of soybean oil concentration on the rheology, water-holding capacity, and thermal stability of acid-mediated soy protein isolate (SPI) emulsion gels was investigated. The microstructure was analyzed and interpreted by CLSM and SEM observations. The results showed that the addition of soybean oil improved the elastic properties of the acid-mediated SPI emulsion gels. The storage modulus increased from 330 Pa (2% soybean oil concentration) to 545 Pa (8% soybean oil concentration) with a significant increase (p < 0.05). The increase in soybean oil concentration resulted in more SPI-coated oil droplets acting as active particles, enhancing the gel network. The acid-mediated SPI emulsion gels became more disordered as the soybean oil concentration increased, with the fractal dimension increasing from 2.92 (2%) to 2.95 (8%). The rheological properties, thermal analysis, and microstructure of 6% SPI gel and acid-mediated SPI emulsion gels with 2% to 8% soybean oil concentration were compared. The acid-mediated SPI emulsion gels with soybean oil as the active filler showed improved gel properties, greater thermal stability, and a homogeneous network structure compared to the acid-mediated SPI emulsion gels.

Novel Colloidal Food Ingredients: Protein Complexes and Conjugates

Food proteins, polysaccharides, and polyphenols are natural ingredients with different functional attributes. For instance, many proteins are good emulsifiers and gelling agents, many polysaccharides are good thickening and stabilizing agents, and many polyphenols are good antioxidants and antimicrobials. These three kinds of ingredients can be combined into protein, polysaccharide, and/or polyphenol conjugates or complexes using covalent or noncovalent interactions to create novel multifunctional colloidal ingredients with new or improved properties. In this review, the formation, functionality, and potential applications of protein conjugates and complexes are discussed. In particular, the utilization of these colloidal ingredients to stabilize emulsions, control lipid digestion, encapsulate bioactive ingredients, modify textures, and form films is highlighted. Finally, future research needs in this area are briefly proposed. The rational design of protein complexes and conjugates may lead to the development of new functional ingredients that can be used to create more nutritious, sustainable, and healthy foods.

Preparation and characterization of astaxanthin-loaded microcapsules and its application in effervescent tablets

BACKGROUND

Astaxanthin is a type of keto-carotene with potential health benefits. However, astaxanthin has poor solubility and stability, resulting in its low oral bio-availability. Microcapsules can be used to improve the water solubility, stability and oral bio-availability of lipophilic bioactive compounds. Effervescent tablets can further improve the stability, smell and taste of microcapsules, and are more easily accepted by consumers.

RESULTS

Astaxanthin-loaded microcapsules were prepared by layer-by-layer assembly and freeze-drying technologies. Sodium caseinate and κ-carrageenan were applied as wall materials. The prepared microcapsules had good flow properties and encapsulation efficiencies (> 85%). Fourier transform infrared spectroscopy demonstrated that the mechanisms of layer-by-layer self-assembly between sodium caseinate and κ-carrageenan might be electrostatic adsorption and hydrogen bonding. The preparation process and excipients did not affect the antioxidant effect of astaxanthin. The in vitro simulated digestion study showed that microcapsules were mainly dissolved and digested in the simulated intestinal solution. Compared with its raw material, microencapsulation could improve the bio-accessibility of astaxanthin greatly. Then, astaxanthin-loaded microcapsules were incorporated into effervescent tablets by wet granulation and tablet-pressing methods. The dissolution of astaxanthin from effervescent tablets was over 90% in 2 h, which indicated a good dissolution effect. A cytotoxicity study revealed that astaxanthin loaded effervescent tablets had a good biocompatibility. Encapsulating astaxanthin-loaded microcapsules in effervescent tablets can improve its chemical stability.

CONCLUSION

Effervescent tablets containing microcapsules could be used to improve the solubility, stability and bio-accessibility of lipophilic bioactive compounds. © 2022 Society of Chemical Industry.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

Effect of physiological pH on the molecular characteristics, rheological behavior, and molecular dynamics of κ-carrageenan/casein

Introduction

During gastrointestinal digestion, κ-carrageenan (κ-CGN) undergoes physicochemical changes, which associated with the risk of colitis.

Methods

To understand the effect of physiological pH on the conformational transition and binding stability of κ-CGN and κ-carrageenan/casein (κ-CC), we conducted experiments at pH 3.0 (gastric environment) and pH 7.0 (intestinal environment). We evaluated zeta potential, free sulfate group content, Fourier transform infrared spectroscopy, thermodynamic properties, microstructure, and molecular mechanism.

Results and Discussion

Our results revealed that the helical conformation of κ-CGN and κ-CC were more ordered and stable, and sulfate group exposure both lower in the intestinal environment (pH 7.0). However, in gastric environment (pH 3.0), the charge density of κ-CGN decreased, accompanied by random curling conformation and free sulfate group content increased. In contrast, the intermolecular interactions between κ-CGN and casein increased in gastric acid environments due to casein flocculation and secondary structure folding, and significantly reduced the exposure of free sulfate groups of κ-CGN. Our research results provide an important theoretical basis for elucidating the molecular mechanism and structure-activity relationship of κ-CGN under casein matrix to protect the mucosal barrier and inhibit colitis, and are of great significance for guiding and expanding the safe application of κ-CGN, thus assisting food nutrition to be absorbed.

Static stability of partially crystalline emulsions: Impacts of carrageenan and its blends with xanthan gum and/or guar gum

In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s^-1 (10.12-25.32 Pa·s), particle sizes (3.12-4.06 μm), as well as interfacial protein concentrations (22.60-27.01 mg/m²), which were much lower than those with single CG (35.98 Pa·s, 6.72 μm, and 47.74 mg/m², respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24-0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.

Hydrogels as promising carriers for the delivery of food bioactive ingredients

The burden of public health challenges associated with the western dietary and living style is growing. Nutraceuticals have been paid increasing attentions due to their effects in promotion of health. However, in the gastrointestinal (GI) tract, the nutraceuticals suffer from not only the harsh acidic environment of the stomach and a variety of digestive enzymes, but also the antibacterial activity of intestinal bile salts and the action of protease from the gut microbiota. The amount of the nutraceuticals arriving at the sites in GI tract for absorption or exerting the bioactivities is always unfortunately limited, which puts forward high requirements for protection of nutraceuticals in a certain high contents during oral consumption. Hydrogels are three-dimensional polymeric porous networks formed by the cross-linking of polymer chains, which can hold huge amounts of water. Compared with other carries with the size in microscopic scale such as nanoparticle and microcapsules, hydrogels could be considered to be more suitable delivery systems in food due to their macroscopic bulk properties, adjustable viscoelasticity and large spatial structure for embedding nutraceuticals. Regarding to the applications in food, natural polymer-based hydrogels are commonly safe and popular due to their source with the appealing characteristics of affordability, biodegradability and biocompatibility. Although chemical crosslinking has been widely utilized in preparation of hydrogels, it prefers the physical crosslinking in the researches in food. The reasonable design for the structure of natural polymeric hydrogels is essential for seeking the favorable functionalities to apply in the delivery system, and it could be possible to obtain the enhanced adhesive property, acid stability, resistant to bile salt, and the controlled release behavior. The hydrogels prepared with proteins, polysaccharides or the mix of them to deliver the functional ingredients, mainly the phenolic components, vitamins, probiotics are discussed to obtain inspiration for the wide applications in delivery systems. Further efforts might be made in the in situ formation of hydrogels in GI tract through the interaction among food polymers and small-molecular ingredients, elevation of the loading contents of nutraceuticals in hydrogels, development of stomach adhesive hydrogels as well as targeting modification of gut microbiota by the hydrogels.

Characterization and stability of peppermint oil emulsions using polyglycerol esters of fatty acids and milk proteins as emulsifiers

Three peppermint oil emulsions using polyglycerol esters of fatty acids-casein (PGFE-CN), polyglycerol esters of fatty acids-sodium caseinate (PGFE-NaCN), and polyglycerol esters of fatty acids-whey protein isolate (PGFE-WPI) as emulsifiers were fabricated, and the droplet size, zeta potential, viscosity, and stability of emulsions were determined. The experimental results showed that the emulsion containing PGFE-CN has relatively smaller droplet size of 231.77 ± 0.49 nm. No significant changes were observed on the average particle size, polydispersity index and zeta potential during 4-week of storage, indicating that the emulsions kept stable against pH, salt ion, freeze-thaw, and storage. Fourier transform infrared spectrometer (FTIR) results showed that the electrostatic interaction occurs between CN and PGFE in the emulsion. The confocal laser scanning microscope (CLSM) was used to observe the microstructure of the emulsion, proving that droplets were evenly distributed throughout the aqueous phase by PGFE-CN emulsifier. The protein-stabilized emulsions can be used as potential carriers for the delivery of the lipophilic nutrients such as peppermint oil. PRACTICAL APPLICATION: PGFE-CN emulsifier can be directly added to the beverage systems containing oil or protein, such as coconut milk, peanut milk, and walnut milk. It can enhance the stability of beverage, prevent the precipitation, stratification, and oil floating, improve the homogeneity of the system and therefore extend the shelf life.

Research progress on polysaccharide/protein hydrogels: Preparation method, functional property and application as delivery systems for bioactive ingredients

Some bioactive ingredients in foods are unstable and easily degraded during processing, storage, transportation and digestion. To enhance the stability and bioavailability, some food hydrogels have been developed to encapsulate these unstable compounds. In this paper, the preparation methods, formation mechanisms, physicochemical and functional properties of some protein hydrogels, polysaccharide hydrogels and protein-polysaccharide composite hydrogels were comprehensively summarized. Since the hydrogels have the ability to control the release and enhance the bioavailability of bioactive ingredients, the encapsulation and release mechanisms of polyphenols, flavonoids, carotenoids, vitamins and probiotics by hydrogels were further discussed. This review will provide a comprehensive reference for the deep application of polysaccharide/protein hydrogels in food industry.

Textural and structural properties of a κ-carrageenan-konjac gum mixed gel: effects of κ-carrageenan concentration, mixing ratio, sucrose and Ca2+ concentrations and its application in milk pudding

BACKGROUND

Mixtures of carrageenan and konjac gum are useful for specific applications in gel-based foods. Focusing on the changes of textural and structural properties, the effects of κ-carrageenan and konjac ratio and sucrose and Ca²⁺ concentrations on mixed gels were studied in this research. Furthermore, application of κ-carrageenan-konjac gum mixed gel to milk puddings was investigated.

RESULTS

There was a better synergistic effect when the ratio of κ-carrageenan and konjac was 7:3. The mixed gel containing 10 g kg^-1 κ-carrageenan-konjac gum was characterized by higher hardness, chewiness, adhesiveness and resilience and denser network structure. Besides, the addition of 5-10 wt% sucrose or 0.02 wt% Ca²⁺ could enhance the hardness, chewiness and adhesiveness of the mixed gel, as well as affording a denser network structure. For milk pudding, moderate hardness, chewiness and resilience could be obtained by adding 1.5 g kg^-1 κ-carrageenan-konjac gum mixture.

CONCLUSIONS

This research provides useful information for the formation of κ-carrageenan-konjac gum gel and its application in milk pudding. © 2020 Society of Chemical Industry.

Assessment of possibilities of strawberry jam reformulation

The prevalence of excessive weight gain, obesity, and associated diseases are permanently increasing. Therefore, the interest in food products with a composition suitable for people with the aforementioned health problems is also on the rise. The changes in food composition, nowadays often called reformulation, are mainly focused on reducing the amount of salt, sugar, or fat. Strawberry spreads with different sugar (10 – 40%) and strawberry (20 – 50%) content were prepared and the influence of strawberry jam composition on gel stiffness, colour, and sensory parameters was studied. This study aimed to determine the sensorial and technological limits (sugar and strawberry content) of strawberry jam reformulation. Carrageenan was chosen as a suitable gelling agent for the preparation of these reformulated strawberry products. strawberry spreads. The applicable concentration of carrageenan for the ideal stiffness of strawberry spreads was 2%. The results of the maximum compression force show a statistically significant increase of gel stiffness with increasing addition of strawberry puree, the effect of sugar content was also statistically significant (p = 0.05). This study showed that strawberry spreads with low strawberry and/or sugar content are sensorially acceptable.