Acid-free preparation and characterization of kelp (Laminaria japonica) nanocelluloses and their application in Pickering emulsions

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

Effects of Laminaria japonica polysaccharide and coumaric acid on pasting, rheological, retrogradation and structural properties of corn starch

The aim of this study was to investigate the effects of Laminaria japonica polysaccharide (LJP) and coumaric acid (CA) on pasting, rheological, retrogradation and structural properties of corn starch (CS). Rapid viscosity analysis (RVA) revealed that LJP significantly increased the peak viscosity, trough viscosity, final viscosity, and setback viscosity of CS gel (p < 0.05) in a concentration-dependent manner. The addition of LJP and CA simultaneously caused the pasting of CS to need a greater temperature (from 75.53 °C to 78.75 °C), suggesting that LJP and CA made CS pasting more difficult. Dynamic viscoelasticity measurements found that all gels exhibited typical characteristics of weak gel. When compared to CS gel, 4 % LJP increased the viscosity and fluidity of gel and the simultaneous addition of LJP and CA reduced the elasticity. The steady shear results showed that the all gels were pseudoplastic fluids with shear-thinning behavior. In the meanwhile, the addition of LJP and CA enhanced the pseudoplasticity of CS-LJP-CA gel and improved its shear thinning. Furthermore, thermodynamic results showed that 8 % LJP promoted the retrogradation of CS gel and 2.0 % CA delayed the retrogradation of CS gel. Notably, on the 7th day of retrogradation, 2.0 % CA significantly decreased the retrogradation rate of CS-LJP by 19.31 % as compared to CS + 8 % LJP. Microstructure observation revealed that LJP made the honeycomb network structure of CS gel partially collapsed, and the surface of CS-LJP gel developed venation. Nevertheless, the structure of CS-LJP gel was clearly enhanced by adding CA. FT-IR spectra demonstrated that the addition of LJP or CA to CS did not result in the formation of a new distinctive peak in the system, suggesting the absence of a new group. Moreover, LF-NMR findings showed that LJP and CA strengthened the gel structure of CS and enhanced its capacity to retain water. This study not only provided a new insight into using LJP and CA to regulate the gel properties of CS, but also provided scientific strategy for developing starchy foods.

Pickering emulsions stabilized by cellulose nanocrystals extracted from hazelnut shells: Production and stability under different harsh conditions

Cellulose nanocrystals (CNCs) are biodegradable particles that have emerged as promising stabilizers for Pickering emulsions. This study investigated the effectiveness of CNCs in forming the Pickering emulsion from hazelnut shells (HS), an agricultural waste. Following the alkaline and bleaching treatments applied to HS, CNCs were obtained from treated hazelnut shell with acid hydrolysis. The physicochemical characteristics of CNCs were investigated using dynamic light scattering, XRD, FTIR, SEM, and TEM. A high crystalline (69.6 %) CNCs with a spherical shape were obtained. Contact angle and interfacial tension tests were conducted and showed that CNCs had amphiphilic nature. Pickering emulsions were investigated for their size, zeta potential, and stability under varying CNC concentrations. The results showed that when CNCs concentration increased from 0.5 to 2.0 wt%, droplet diameter decreased approximately 1.8 times and zeta potential increased. Creaming was not observed during 28 days of storage in a concentration of 2.0 wt% CNCs. The CNC stabilized emulsions exhibited high stability within a range of pH, temperatures, and salt concentrations. This study demonstrated that CNCs extracted from HS as environmentally friendly and cost-effective materials, could serve as a new stabilizer for Pickering emulsions especially for high temperature and low pH sensitive products such as mayonnaise.

Chitin nanofibers prepared by enzymatic hydrolysis: Characterization and application for Pickering emulsions

Chitin nanofibers (ChNFs) have a wide range of applications in numerous fields owing to their exceptional material properties and biological functionality. This research focused on producing ChNFs with diameters of 20-70 nm using chitinase and ultrasound from crayfish shells. The impact of enzymatic duration on ChNF yield and performance was investigated. Results revealed ChNFs forming a high aspect ratio network structure. Chitinase hydrolysis enhanced ChNF dispersion and yield while improving crystallinity and thermal stability without significantly altering their chemical structure. Enzymatically modified ChNF suspensions also exhibited stable rheological properties. Moreover, ChNFs showed good emulsification and emulsion stability in Pickering emulsion. The mechanism may be the effective adsorption of ChNFs at the oil-water interface, and the formation of a ChNF network in the continuous phase that prevents droplet coalescence. This study highlights that the potential of chitinase and ultrasound for the production of ChNFs and the utilization of crayfish shell waste.

Pomelo peel derived nanocellulose as Pickering stabilizers: Fabrication of Pickering emulsions and their potential as sustained-release delivery systems for lycopene

Two kinds of nanocellulose (cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were synthesized from pomelo peels via a facile approach of TEMPO oxidation and sulfuric acid treatment respectively. The FTIR results illustrated that hemicelluloses and lignin were completely removed from the pomelo peel cellulose substrate. The obtained CNFs and CNCs possessed a uniform morphology and nanoscale particle size. The stability of CNF-based Pickering emulsions was higher than that of emulsions stabilized with CNCs, due to the formation of gel structure induced by the CNFs' longer fibrils. Increased oil fractions enhanced the viscoelasticity of CNF-based Pickering emulsions. The in vitro digestion results suggested that increased oil fractions decreased the lipolysis degree, as a result of the larger droplet size and higher viscoelasticity of emulsion. The release of lycopene showed a trend similar to that of FFA release, suggesting that higher oil fractions were beneficial for controlling lycopene release during gastrointestinal digestion.

Low temperature-resistant superhydrophobic and elastic cellulose aerogels derived from seaweed solid waste as efficient oil traps for oil/water separation

Aerogel has excellent application potential in adsorption, heat preservation, and other areas due to its typical advantages of low density and high porosity. However, there are several issues with the use of aerogel in oil/water separation, including weak mechanical qualities and challenges in eliminating organic contaminants at low temperature. Inspired by cellulose Iα, which has excellent performance at low temperature, this study used cellulose Iα nanofibers extracted from seaweed solid waste as the skeleton, through covalent cross-linked with ethylene imine polymer (PEI) and hydrophobic modification of 1, 4-phenyl diisocyanate (MDI), supplemented by freeze-drying technology to form three-dimensional sheet, and successfully obtained cellulose aerogels derived from seaweed solid waste (SWCA). The compression test shows that the maximum compressive stress of SWCA is 61 kPa, and the initial performance still maintains 82% after 40 cryogenic compression cycles. In addition, the contact angles of water and oil on the surface of the SWCA were 153° and 0°, respectively, and the stable hydrophobic time in simulated seawater is more than 3 h. By combining the elasticity and superhydrophobicity/superoleophilicity, the SWCA with an oil absorption capacity of up to 11-30 times its mass, might be utilized repeatedly for the separation of an oil/water mixture.

Review of Functional Aspects of Nanocellulose-Based Pickering Emulsifier for Non-Toxic Application and Its Colloid Stabilization Mechanism

In the past few years, the research on particle-stabilized emulsion (Pickering emulsion) has mainly focused on the usage of inorganic particles with well-defined shapes, narrow size distributions, and chemical tunability of the surfaces such as silica, alumina, and clay. However, the presence of incompatibility of some inorganic particles that are non-safe to humans and the ecosystem and their poor sustainability has led to a shift towards the development of materials of biological origin. For this reason, nano-dimensional cellulose (nanocellulose) derived from natural plants is suitable for use as a Pickering material for liquid interface stabilization for various non-toxic product formulations (e.g., the food and beverage, cosmetic, personal care, hygiene, pharmaceutical, and biomedical fields). However, the current understanding of nanocellulose-stabilized Pickering emulsion still lacks consistency in terms of the structural, self-assembly, and physio-chemical properties of nanocellulose towards the stabilization between liquid and oil interfaces. Thus, this review aims to provide a comprehensive study of the behavior of nanocellulose-based particles and their ability as a Pickering functionality to stabilize emulsion droplets. Extensive discussion on the characteristics of nanocelluloses, morphology, and preparation methods that can potentially be applied as Pickering emulsifiers in a different range of emulsions is provided. Nanocellulose's surface modification for the purpose of altering its characteristics and provoking multifunctional roles for high-grade non-toxic applications is discussed. Subsequently, the water-oil stabilization mechanism and the criteria for effective emulsion stabilization are summarized in this review. Lastly, we discuss the toxicity profile and risk assessment guidelines for the whole life cycle of nanocellulose from the fresh feedstock to the end-life of the product.

Survivability of probiotics encapsulated in kelp nanocellulose/alginate microcapsules on microfluidic device

Probiotics are living microorganisms that can produce health benefits to the host only when they are ingested in sufficient quantities and reach the intestines active state. However, the external environment that probiotics face for a long time before administration and the low pH environment in the stomach after administration can greatly reduce their activity. In this work, we proposed a simple microfluidic encapsulation strategy to efficiently prepare the probiotics-loaded nanocellulose/alginate delivery system, which can improve the storage stability and gastrointestinal survival rate of probiotics. The microcapsules were found to be monodisperse, and the average particle size was<500 μm by observing the microstructure and macroscopic morphology. The kelp nanocellulose was cross-linked in the microcapsule and formed a dense surface with alginate. Through the simulated gastrointestinal digestion experiment, it was found that the survival of probiotics in microcapsules containing 0.5 % and 1.5 % kelp nanocellulose decreased by 1.77 log CFU/g and 1.65 log CFU/g respectively, which was significantly lower than that of nanocellulose-free microcapsules (3.70 log CFU/g). And all the treated groups could release probiotics above 7 log CFU/g after digesting intestinal juice for 6 h. Furthermore, through the storage experiment, it was found that the microcapsules with 1.5 % kelp nanocellulose could still release 8.07 log CFU/g probiotics after four weeks. The results provide a new strategy for probiotics processing and extensive high-value utilization of marine natural products.

Preparation and Evaluation of Undaria pinnatifida Nanocellulose in Fabricating Pickering Emulsions for Protection of Astaxanthin

Pickering emulsions stabilized from natural sources are often used to load unstable bio-active ingredients, such as astaxanthin (AXT), to improve their functionality. In this study, AXT-loaded Pickering emulsions were successfully prepared by 2,2,6,6-tetramethy-1-piperidine oxide (TEMPO)-oxidized cellulose nanofibers (TOCNFs) from Undaria pinnatifida. The morphology analysis showed that TOCNFs had a high aspect ratio and dispersibility, which could effectively prevent the aggregation of oil droplets. The stable emulsion was obtained after exploring the influence of different factors (ultrasonic intensity, TOCNFs concentration, pH, and ionic strength). As expected, AXT-loaded Pickering emulsions showed good stability at 50 °C and 14 days of storage. The results of simulated in vitro digestion showed that the emulsions exhibited higher release of free fatty acids (FFAs) and bioaccessibility of AXT than those in sunflower oil. Hence, our work brought new insights into the preparation of Pickering emulsions and their applications in protection and sustained, controlled release of AXT.

Isolation, structural characterization and bioactivities of polysaccharides from Laminaria japonica: A review

Laminaria japonica is a familiar marine plant and is often used as food due to its abundant carbohydrates, vitamins and minerals. As one of the main types of active substances in L. japonica, polysaccharides are widely used in the food and chemical industries and in medicine and healthcare due to their health benefits, such as immunoregulatory, antioxidant, and antidiabetic effects. However, there has been no systematic summary of the isolation, structural characterization and bioactivities of L. japonica polysaccharides (LJPs). Therefore, the present review includes a survey of extraction and purification methods for these bioactive molecules, along with a dissertation on the structural characterization of the carbohydrate components. Moreover, an overview of the most recent results related to LJP biological activities is provided. This review provides a useful reference for further research, production, and application of LJPs in functional foods and therapeutic agents.

Recent Developments in the Formulation and Use of Polymers and Particles of Plant-based Origin for Emulsion Stabilizations

The main scope of this Review was the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, it was discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro- and macro-structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies as well as their challenge and future perspectives were described.

Recycling of Brewer's Spent Grain as a Biosorbent by Nitro-Oxidation for Uranyl Ion Removal from Wastewater

Developing biosorbents derived from agro-industrial biomass is considered as an economic and sustainable method for dealing with uranium-contaminated wastewater. The present study explores the feasibility of oxidizing a representative protein-rich biomass, brewer's spent grain (BSG), to an effective and reusable uranyl ion adsorbent to reduce the cost and waste generation during water treatment. The unique composition of BSG favors the oxidation process and yields in a high carboxyl group content (1.3 mmol/g) of the biosorbent. This makes BSG a cheap, sustainable, and suitable raw material independent from pre-treatment. The oxidized brewer's spent grain (OBSG) presents a high adsorption capacity of U(VI) of 297.3 mg/g (c 0(U) = 900 mg/L, pH = 4.7) and fast adsorption kinetics (1 h) compared with other biosorbents reported in the literature. Infrared spectra (Fourier transform infrared), 13C solid-state nuclear magnetic resonance spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis were employed to characterize the biosorbents and reveal the adsorption mechanisms. The desorption and reusability of OBSG were tested for five cycles, resulting in a remaining adsorption of U(VI) of 100.3 mg/g and a desorption ratio of 89%. This study offers a viable and sustainable approach to convert agro-industrial waste into effective and reusable biosorbents for uranium removal from wastewater.

Pickering emulsion stabilized by cellulosic fibers: Morphological properties-interfacial stabilization-rheological behavior relationships

This work aimed to study the stabilization mechanism induced by different morphologies of cellulosic fiber in O/W emulsion. Three types of cellulosic fibers were named squashed cellulose, incompletely nanofibrillated cellulose, and completely nanofibrillated cellulose, respectively. Squashed cellulose acted as barriers between the droplets to stabilize emulsion via depletion flocculation, whereas incompletely nanofibrillated and completely nanofibrillated cellulose formed covering layer via interfacial adsorption and connected adjacent droplets to create the droplet-fiber network structure via bridging flocculation. Differently, completely nanofibrillated cellulose formed the denser covering layer leading to a more stability of droplet. Importantly, it had the higher capacity of bridging flocculation, which can tightly connect the adjacent droplets to form a stronger droplet-fiber 3D network structure. Consequently, in rheological analysis including creep compliance, and dynamic modulus, the corresponding emulsions showed excellent anti-deformation ability and dynamic stability. This study provides practical guidance on the productions of foodstuff and cosmetic.

Interest of Pickering Emulsions for Sustainable Micro/Nanocellulose in Food and Cosmetic Applications

In the present review, natural and non-toxic particles made of micro/nanocellulose were specifically targeted as stabilizers of emulsions located at dispersed and continuous phases interfaces (called Pickering Emulsions, PEs). PEs are biphasic systems stabilized by solid particles with a recent interest in food and cosmetic domains. PEs have been more and more studied in the last ten years due to their advantages compared to conventional emulsions with surfactants. PEs have already been stabilized with various types of particles and particularly cellulose. Even if some studies showed that PEs were more stable when cellulose was chemically modified, numerous other recent studies showed that unmodified micro/nanocellulose is also promising biomaterial to stabilize PEs. Micro/nanocelluloses can be extracted by various green processes from numerous agricultural wastes and co-products, as banana peels, corncob, ginkgo seed shells, lime residues, mangosteen rind, oil palm empty fruit bunches, pistachio shells, as well as wheat straw. Main green processes used to treat cellulose are grinding, high pressure homogenization, microfluidization, enzymatic hydrolysis, subcritical water, extrusion, electron beam irradiation, cryocrushing, microwaves or sonication. PEs formulated with cellulose clearly participate to a global sustainable development but, additional studies will be necessary to better understand PEs stability and improve properties.