Polyphenol-Enriched Protein Oleogels as Potential Delivery Systems of Omega-3 Fatty Acids.

Omega-3 polyunsaturated fatty acids (n-3 FAs) are essential nutrients and are considered effective in improving human health. Recent studies highlight the importance of the combination of n-3 FAs and polyphenols for limiting the oxidation of n-3 FAs and exhibiting synergistic beneficial effects. Herein, we developed a novel formulation technology to prepare oleogels that could be used for the codelivery of n-3 FAs and polyphenols with high loading efficacy and oxidative stability. These oleogels are made from algal oil with polyphenol-enriched whey protein microgel (WPM) particles as gelling agents via simple and scalable ball milling technology. The oxidative status, fatty acid composition, and volatiles of protein oleogels during accelerated storage were systematically assessed by stoichiometry and gas chromatography-mass spectrometry. These results showed that protein oleogels could overcome several challenges associated with the formulation of n-3 oils, including long-term oxidative stability and improved sensory and textural properties. The protein oleogel system could provide an excellent convenience for formulating multiple nutrients and nutraceuticals with integrating health effects, which are expected to be used in the care of highly vulnerable populations, including children, the elderly, and patients.

The novel pickering emulsion gels stabilized by zein hydrolysate-chitin nanocrystals coacervates: Improvement on stability and bioaccessibility for curcumin.

The aim of this paper was to explore the synergistic mechanism of the novel Pickering emulsion gels stabilized by zein hydrolysate (ZH, low DH of 5%)-chitin nanocrystals (CNCs) coacervates, and investigate their improvement on the stability and bioaccessibility of curcumin. Interestingly, the ZH with low DH of 5% exhibited aggregated precipitation at pH 5.0. The ZH was absorbed on the surface of CNCs to form ZH-CNCs coacervates by hydrogen bonding and electrostatic neutralization. Moreover, the novel Pickering emulsion gels stabilized by the appropriate ZH-CNCs coacervates showed better rheologicalproperties, emulsion stability and oxidation resistance. As new carriers for curcumin, they could effectively improve the stability and antioxidantactivity (over 90%). Further, the free fatty acid (FFA) release ratewas reduced to below 3.89% and the corresponding bioaccessibility increased to over 80% in vitro digestion. The novel delivery system was potentially designed in foods and pharmaceuticals for the purposes of enhanced stability, delayed lipolysis, or sustained nutrient release.

Structuring of Edible Liquid Oil into Smart Thermo-Triggered Soft Matters for Controlled Bioactive Delivery.

Growing interest is being dedicated to smart soft matters because of their potential in controlling bioactives upon exposure to an appropriate stimulus. Herein, structuring of edible liquid oil into oleogels and emulgels as smart thermo-triggered soft vehicles for controllable release of diverse nutrients was developed. Edible liquid oil was trapped inside the crystal network structure of phytosterols and monoglycerides resulting in bicomponent solidlike oleogels. Subsequently, both water-in-oleogel (W/O) emulgels and glycerol-in-oleogel (G/O) emulgels were further fabricated by spatial distribution of the stabilizing interfacial crystals around dispersed droplets as well as the network crystals in the continuous phase. Rheological measurements showed that the gel strength of the oleogel-based emulgels depends on the fraction of the aqueous phase and is greater than that of corresponding oleogels due to a filler effect of dispersed aqueous droplets within the crystal network, offering an additional strategy to tune the structure and rheology. Comparatively, introducing glycerol endowed a higher gel strength for the oleogel-based emulgels than water, particularly at increased filler loads. In addition, these soft matters exhibited interesting thermoresponsive nature, which exhibit the flexibility for programmed release of coencapsulated bioactive components upon exposure to an appropriate thermal triggered switchable. The resulted smart thermo-triggered soft matters have emerging opportunities for application in functional active ingredient delivery by on-demand strategies.

One-pot ultrasonic cavitational emulsification of phytosterols oleogel-based flavor emulsions and oil powder stabilized by natural saponin.

Phytosterols oleogel-based flavor emulsions were successfully fabricated for the first time using natural tea saponin as emulsifier and one-pot ultrasonic technique. The effects of ultrasonic time and power, surfactant concentration, and type of flavor oils (e.g., orange, lemon and peppermint) on the emulsion droplet size were investigated. Submicron emulsions with a dispersed phase made by flavor oil (20 wt%) + phytosterol (4 wt%) were stabilized with 3 wt% saponin were obtained by applying an ultrasonic time of 5 min and ultrasonic power of 280 W. The natural tea saponin emulsions exhibited a superior stability and encapsulation efficiency of phytosterol, compared to traditional emulsifiers. Flavor oil-phytosterol enriched powders were prepared by spray-drying and characterized by SEM, XRD and repose angle. The natural saponin encapsulated oil + phytosterol powders had excellent fluidity, redispersion behavior and low phytosterol crystallinity. It was demonstrated that ultrasound is an effective and suitable technique for fabricating fortified flavor emulsions and microcapsules, which may be used for developing functional lipids-based applications in the food, beverage and cosmetic industries.

Salt reduction in bread via enrichment of dietary fiber containing sodium and calcium.

The high intake of sodium and low intake of dietary fiber are two major dietary risk factors for preventable deaths worldwide, highlighting the need and implementations for developing health foods with low-salt/high-dietary fibers. Bread as a staple food contributes about 25% to the daily intake of sodium in many countries, and salt reduction in bread still remains a great technical challenge. In this study, we developed a simple method to reformulate the white bread in terms of reducing salt contents via dietary fiber fortification, while maintaining the taste and texture qualities. Low molecular weight water-extractable arabinoxylans (LMW-WEAX) as a soluble dietary fiber was first hydrated in salt water before dough mixing, leading to an inhomogeneous spatial distribution of sodium in bread and accelerating the release of sodium ions from crumbs, allowing 20% salt reduction in bread without impacting the salt perception. Data from the moisture content, crumb structure, water distribution, dough rheology and bread texture properties suggest that the pre-hydrated incorporation of LMW-WEAX mitigates the detrimental effect of dietary fiber on the dough and bread quality. The modulation of Ca2+ on the permeability of Na+ through the mucus layer and implication in salt enhancement of the bread were investigated. Results show that the pre-hydrated incorporation of WEAX containing Na+ and Ca2+ (1.0%) makes it possible to reduce 30% salt content in breads, which have implications in the large-scale production of low-salt/high-dietary fiber bread.

Structural characterization of pectin-bismuth complexes and their aggregation in acidic conditions.

Bismuth-contained therapies are effective in treating gastric ulcer and eliminating Helicobacter pylori (Hp). Anion polysaccharides ligand could reduce the intake of bismuth, and enhance drug efficacy of bismuth compounds. In this study, pectin-bismuth (PB) was prepared and the changes of PB structure in acidic environment were reported for the first time. The structure of PB was characterized by FT-IR, XRD, and TGA, which suggested that combined with bismuth could alter the crystal structure of pectin. XPS confirmed the ionic binding of Bi3+ with carboxyl groups of pectin. The aggregating of PB with different pH level were also investigated, and the influence of pH on PB structure were observed by SEM. Results showed that PB has much larger volume of flocculation in acidic environment compared with bismuth nitrate. Additionally, apparent shear stress (τa) of PB suspension was evaluated. These results revealed the structural characteristics and acid-induced aggregation of pectin-bismuth, and bismuth could aggregate in acidic solution with the gelation of pectin.

Slowing the Starch Digestion by Structural Modification through Preparing Zein/Pectin Particle Stabilized Water-in-Water Emulsion.

Slowing the digestion of starch is one of the dominant concerns in the food industry. A colloidal structural modification strategy for solving this problem was proposed in this work. Due to thermodynamic incompatibility between two biopolymers, water/water emulsion of waxy corn starch (WCS) droplets dispersed in a continuous aqueous guar gum (GG) was prepared, and zein particles (ZPs), obtained by antisolvent precipitation and pectin modification, were used as stabilizer. As the ratio of zein to pectin in the particles was 1:1, their wetting properties in the two polysaccharides were similar, which made them accumulate at the interface and cover the WCS-rich droplets. The analysis of digestibility curves indicated that a rapid (rate constant k1: 0.145 min-1) and a slow phase ( k2: 0.022 min-1) existed during WCS digestion. However, only one slow phase ( k2: 0.019 min-1) was found in the WCS/GG emulsion, suggesting that this structure was effective in slowing starch digestion.

Hierarchical high internal phase emulsions and transparent oleogels stabilized by quillaja saponin-coated nanodroplets for color performance.

Herein, we report novel high internal phase emulsions and transparent oleogels that exhibit a hierarchical configuration by manipulating the spatial assembly of a natural small molecular-weight quillaja saponin for color performance. Quillaja saponin (QS) is a natural triterpenoid bidesmosidic from the soapbark tree (Quillaja saponaria Molina). Fairly monodispersed QS-coated nanodroplets (∼154 nm) were prepared using the ultrasonic emulsification strategy, and then used as block stabilizers for the fabrication of stable oil-in-water high internal phase emulsions (HIPEs, ϕ = 0.75). The resulting HIPEs can be easily converted into transparent oleogels with a very high oil loading (99.7%) through oven drying (70 °C). The jelly-like oleogels exhibit weak elastic, shear thinning behavior, good thixotropic recovery, and thermostabilization properties, which might be provided by the percolating 3D network of QS fibrils in the oil phase. We spatially tuned the color performance of the HIPEs and subsequent oleogels by locating the compositions of food colorants in different sections of their hierarchal architecture. The design and construction of hierarchical HIPEs and oleogels provide a promising new route for multitask functional delivery applications in various fields including food, cosmetics, and medical applications.

Plant protein-based delivery systems for bioactive ingredients in foods.

The application of food-grade delivery systems for the encapsulation, protection and controlled release of bioactive food ingredients have recently gained increasing interest in the research fields of functional foods and pharmaceutics. Plant proteins (mainly soy proteins, zein and wheat gliadins), which are widely available and environmentally economic compared to animal derived proteins, can be made into various delivery platforms, such as micro- and nanoparticles, fibers, films and hydrogels. In this paper, we review the recent progress in the preparation of food-grade delivery systems based on plant proteins for bioactive ingredients, and highlight some of the challenges and directions that will be the focus of future research. The preparation and application of bifunctional particles, which were able to deliver the bioactives to oil/water interface and stabilize the interface, are also described, providing a novel perspective for the design of plant protein-based delivery system.

Synergistic foaming and surface properties of a weakly interacting mixture of soy glycinin and biosurfactant stevioside.

The adsorption of the mixtures of soy glycinin (11S) with a biosurfactant stevioside (STE) at the air-water interface was studied to understand its relation with foaming properties. A combination of several techniques such as dynamic surface tension, dilatational rheology, fluorescence spectroscopy, and isothermal titration calorimetry (ITC) was used. In the presence of intermediate STE concentrations (0.25-0.5%), the weak binding of STE with 11S in bulk occurred by hydrophobic interactions, which could induce conformational changes of 11S, as evidenced by fluorescence and ITC. Accordingly, the strong synergy in reducing surface tension and the plateau in surface elasticity for mixed 11S-STE layers formed from the weakly interacting mixtures were clearly observed. This effect could be explained by the complexation with STE, which might facilitate the partial dissociation and further unfolding of 11S upon adsorption, thus enhancing the protein-protein and protein-STE interfacial interactions. These surface properties were positively reflected in foams produced by the weakly interacting system, which exhibited good foaming capacity and considerable stability probably due to better response to external stresses. However, at high STE concentrations (1-2%), as a consequence of the interface dominated by STE due to the preferential adsorption of STE molecules, the surface elasticity of layers dramatically decreased, and the resultant foams became less stable.

Complexation of resveratrol with soy protein and its improvement on oxidative stability of corn oil/water emulsions.

This work was to evaluate the potential of soy protein isolate (SPI)-resveratrol (RES) complex as an emulsifier to improve the effectiveness of RES as a natural antioxidant in corn oil-in-water emulsions. The physical properties and oxidative stability of emulsions stabilized by the native SPI-RES and heated SPI-RES complexes were evaluated. The water solubility of RES was enhanced by complexation with SPI, which was mainly driven by hydrophobic interactions. Heat treatment favoured the formation of the SPI-RES complex and endowed it with a higher antioxidant activity. Furthermore, the emulsions stabilized by the SPI-RES complexes showed an increased oxidative stability with reduced lipid hydroperoxides and volatile hexanal. This improving effect could be attributed to the targeted accumulation of RES at the oil-water interface accompanied by the adsorption of SPI, as evidenced by the high interfacial RES concentration. These findings show that the soy protein-polyphenol complex exhibited a good potential to act as an efficient emulsifier to improve the oxidative stability of emulsions.

Chitin microfibers reinforce soy protein gels cross-linked by transglutaminase.

To improve the gel strength, we attempt to introduce the microcomposite concept into the food gel system. A stable positively charged chitin microfibers (CMFs) suspension was fabricated by a facile microfluidizer approach without changing its chemical structure. The obtained CMFs bearing width of about 0.5-5 µm and length of more than 500 µm were then developed in a transglutaminase cross-linked ß-conglycinin (7S) gel. The morphological and rheological characterizations of the 7S-CMF composited gels were done as a function of the protein and CMFs concentrations. Results showed that the presence of the CMFs network improved the gel strength significantly. This effect was CMFs content dependent and was related to the formation of a sponge-like porous microstructure. We inferred that the CMFs provided an initial framework for gel formation and added structural rigidity to the protein gel. The role of protein was to participate in network development as an electrostatic coating and gelation component.

Formation of complex interface and stability of oil-in-water (O/W) emulsion prepared by soy lipophilic protein nanoparticles.

A lipophilic protein nanoparticle (LPP) was fabricated by ultrasonication of the soy lipophilic protein (LP), which contains hydrophobic proteins and phospholipids. This LPP (Rh = 136 ± 0.8 nm, ζ-potential = -20 mV, pH 7.0) had an improved dispersibility and acted as an emulsifier. The oil/water (O/W) emulsion stabilized by this LPP exhibited superior physical stability over long-term storage (8 weeks), during a stress storage test (200 mM NaCl addition and heating at 90 °C), and in the presence of Tween 20 (1.0-4.0 wt %), in contrast to those emulsions stabilized by ß-conglycinin and glycinin. Langmuir-Blodgett method and interface pressure determination revealed that LPP formed rigid and rough granular film at air/water interface. The excellent stability of emulsions stabilized by LPP highlights the synergic effect between hydrophobic proteins and phospholipids. These findings suggest that the complexes of hydrophobic protein aggregates and biosurfactant could form a stable interface which could be developed into a novel strategy to fabricate a stable food emulsion.

Enhanced physical and oxidative stabilities of soy protein-based emulsions by incorporation of a water-soluble stevioside-resveratrol complex.

To strengthen the effectiveness of resveratrol (RES) as a natural antioxidant in food systems, this work attempted to enhance the water solubility of RES by utilizing the solubilizing properties of stevioside (STE) and investigated the effect of STE-solubilized RES (STE-RES) incorporation on the stability of soy protein isolate (SPI)-based emulsions. The physical properties and oxidative stability of SPI emulsions with STE/STE-RES were evaluated. The water solubility of RES increased with the increase of STE concentration up to its critical micelle concentration, suggesting the solubilization of hydrophobic RES in STE self-assembled micelles. STE micelles competitively adsorbed at the oil-water interface with SPI, forming a mixed SPI and STE interfacial layer, thus resulting in a decrease in particle size and evident enhancement in the physical stability of SPI-based emulsions. After the incorporation of STE-RES, SPI emulsions showed an enhanced oxidative stability with reduced lipid hydroperoxides and volatile hexanal. This improvement was believed to be mainly attributed to the targeted migration of RES to the interface during the adsorption of the STE-RES complex, as evidenced by high interfacial accumulation of RES.