Applications of nanocellulosic products in food: Manufacturing processes, structural features and multifaceted functionalities

Recent advances in nanocellulose based hydrogels: Preparation strategy, typical properties and food application

Nanocellulose has been favored as one of the most promising sustainable nanomaterials, due to its competitive advantages and superior performances such as hydrophilicity, renewability, biodegradability, biocompatibility, tunable surface features, excellent mechanical strength, and high specific surface area. Based on the above properties of nanocellulose and the advantages of hydrogels such as high water absorption, adsorption, porosity and structural adjustability, nanocellulose based hydrogels integrating the benefits of both have attracted extensive attention as promising materials in various fields. In this review, the main fabrication strategies of nanocellulose based hydrogels are initially discussed in terms of different crosslinking methods. Then, the typical properties of nanocellulose based hydrogels are comprehensively summarized, including porous structure, swelling ability, adsorption, mechanical, self-healing, smart response performances. Especially, relying on these properties, the general application of nanocellulose based hydrogels in food field is also discussed, mainly including food packaging, food detection, nutrient embedding delivery, 3D food printing, and enzyme immobilization. Finally, the safety of nanocellulose based hydrogel is summarized, and the current challenges and future perspectives of nanocellulose based hydrogels are put forward.

Sustainable synthesis pathways: Bacterial nanocellulose from lignocellulosic biomass for circular economy initiatives

The hydrothermal pretreatment process stands out as a pivotal step in breaking down the hemicellulosic fraction of lignocellulosic biomasses, such as sugarcane bagasse and eucalyptus sawdust. This pretreatment step is crucial for preparing these materials for subsequent processes, particularly in food applications. This technique aims to disintegrate plant wall components like cellulose, hemicellulose, and lignin, and facilitating access in later phases such as enzymatic hydrolysis, and ultimately making fermentable sugars available. In this study, sugarcane bagasse and eucalyptus sawdust biomass underwent hydrothermal pretreatment at specific conditions, yielding two key components: dry biomass and hemicellulose liquor. The primary focus was to assess the impact of hydrothermal pretreatment followed by enzymatic hydrolysis, using the Celic Ctec III enzyme cocktail, to obtain fermentable sugars. These sugars were then transformed into membranes via strain Gluconacetobacter xylinus bacterial biosynthesis. Notably, the addition of a nitrogen source significantly boosted production to 14.76 g/ in hydrolyzed sugarcane bagasse, underscoring its vital role in bacterial metabolism. Conversely, in hydrolyzed eucalyptus, nitrogen source inclusion unexpectedly decreased yield, highlighting the intricate interactions in fermentation media and the pivotal influence of nitrogen supplementation. Characterization of membranes obtained in synthetic and hydrolyzed media through techniques such as FEG-SEM, FTIR, and TGA, followed by mass balance assessment, gauged their viability on an industrial scale. This comprehensive study aimed not only to understand the effects of pretreatment and enzymatic hydrolysis but to also evaluate the applicability and sustainability of the process on a large scale, providing crucial insights into its feasibility and efficiency in practical food-related scenarios, utilizing nanocellulose bacterial (BNC) as a key component.

Production of Nanocellulose from Sugarcane Bagasse and Development of Nanocellulose Conjugated with Polylysine for Fumonisin B1 Toxicity Absorption

The present study aimed to extract nanocellulose (NC) from sugarcane bagasse agricultural waste through a chemical method (sulfuric acid hydrolysis and ultrasonication). Subsequently, the nanocellulose product was conjugated with polylysine (NC-PL) and assessed for its efficacy in reducing the toxicity of Fumonisin B1 (FB1), a mycotoxin produced by fungi commonly found in corn, wheat, and other grains. Experimental results confirmed the successful conjugation of NC and PL, as evidenced by FTIR peaks at 1635 and 1625 cm-1 indicating amide I and amide II vibrations in polylysine (PL). SEM analysis revealed a larger size due to PL coating, consistent with DLS results showing the increased size and positive charge (38.0 mV) on the NC-PL surface. Moreover, the effect of FB1 adsorption by NC and NC-PL was evaluated at various concentrations (0-200,000 μg/mL). NC-PL demonstrated the ability to adsorb FB1 at concentrations of 2000, 20,000, and 200,000 μg/mL, with adsorption efficiencies of 94.4-100%. Human hepatocellular carcinoma (HepG2) cells were utilized to assess NC and NC-PL cytotoxic effects. This result is a preliminary step towards standardizing results for future studies on their application as novel FB1 binders in food, food packaging, and functional feeds.

Effects of capsaicin loads on the properties of capsicum leaf protein-based nanocellulose composite films

This study aims to enhance the functionality of conventional protein-based nanocellulose composite films (PNCF) to meet the high demand for natural antimicrobial packaging films. Capsicum leaf protein (CLP) and cellulose nanocrystals (CNCs) extracted from capsicum leaves were used as raw materials. Capsaicin, an essential antibacterial active ingredient in the capsicum plant, was used as an additive. The influence of different capsaicin loads on PNCF physicochemical and material properties was investigated under alkaline conditions. The results show that all film-forming liquids (FFLs) are non-Newtonian fluids with shear thinning behavior. When the capsaicin loading exceeds 20 %, the surface microstructure of PNCF changes from dense lamellar to rod-like. Capsaicin did not alter the PNCF crystal structure, thermal stability or chemical bonding. Capsaicin can be loaded onto the PNCF surface by intermolecular hydrogen bonding reactions with CLP and CNC, preserving capsaicin's biological activity. With increasing capsaicin loads from 0 % to 50 %, the mechanical and hydrophobic properties of PNCF decreased, whereas the diameter of the inhibition zone increased. All PNCFs have UV-blocking properties with potential applications in developing biodegradable food packaging materials. The results of this study provide a theoretical basis for the high-value utilization of capsicum cultivation waste and the preparation of novel PNCF.

Insight into the effect of different nanocellulose types on protein-based bionanocomposite film properties

This paper investigates the effect of five different types of nanocellulose on the properties of protein-based bionanocomposite films (PBBFs) and the mechanism of action. The results show that TEMPO-oxidized nanocellulose (TNC) PBBFs have the smoothest surface structure. This is because some hydroxyl groups in TNC are converted to carboxyl groups, increasing hydrogen bonding and cross-linking with proteins. Bacterial nanocellulose (BNC) PBBFs have the highest crystallinity. Filamentous BNC can form an interlocking network with protein, promoting effective stress transfer in the PBBFs with maximum tensile strength. The PBBFs of lignin nanocellulose (LNC) have superior elasticity due to the presence of lignin, which gives them the greatest creep properties. The PBBFs of cellulose nanocrystals (CNCs) have the largest water contact angle. This is because the small particle size of CNC can be uniformly distributed in the protein matrix. The different types of nanocellulose differ in their microscopic morphology and the number of hydroxyl groups and hydrogen bonding sites on their surfaces. Therefore, there are differences in the spatial distribution and the degree of intermolecular cross-linking of different types of nanocellulose in the protein matrix. This is the main reason for the differences in the material properties of PBBFs.

Leveraging new opportunities and advances in high-pressure homogenization to design non-dairy foods

High-pressure homogenization (HPH) and ultrahigh-pressure homogenization (UHPH) are emerging food processing techniques for stabilizing emulsions and food components under the pressure range from 60 to 400 MPa. Apart from this, they also support increasing nutritional profile, food preservation, and functionality enhancement. Even though the food undergoes the shortest processing operation, the treatment leads to modification of physical, chemical, and techno-functional properties, in addition to the formation of micro-sized particles. This study focuses on recent advances in using HPH/UHPH on plant-based milk sources such as soybeans, almonds, hazelnuts, and peanuts. Overall, this systematic review provides an in-depth analysis of the principles of HPH/UHPH, the mechanism of action, and their applications in other nondairy areas such as fruits and vegetables, meat, fish, and marine species. This work also deciphers the role of HPH/UHPH in modifying food components, their functional quality enhancement, and their provision of oxidative resistance to many foods. HPH is not only perceived as a technique for size reduction and homogenization; however, it does various functions like microbial inactivation, improvement of rheologies like texture and consistency, decreasing of lipid oxidation, and making positive modifications to proteins such as changes to the secondary structure and tertiary structure thereby enhancing the emulsifying properties, hydrophobicity of proteins, and other associated functional properties in many nondairy sources at pressures of 100-300 MPa. Thus, HPH is an emerging technique with a high throughput and commercialization value in food industries.

Multi-functional nanocellulose based nanocomposites for biodegradable food packaging: Hybridization, fabrication, key properties and application

Nowadays, non-degradable plastic packaging materials have caused serious environmental pollution, posing a threat to human health and development. Renewable eco-friendly nanocellulose hybrid (NCs-hybrid) composites as an ideal alternative to petroleum-based plastic food packaging have been extensively reported in recent years. NCs-hybrids include metal, metal oxides, organic frameworks (MOFs), plants, and active compounds. However, no review systematically summarizes the preparation, processing, and multi-functional applications of NCs-hybrid composites. In this review, the design and hybridization of various NCs-hybrids, the processing of multi-scale nanocomposites, and their key properties in food packaging applications were systematically explored for the first time. Moreover, the synergistic effects of various NCs-hybrids on several properties of composites, including mechanical, thermal, UV shielding, waterproofing, barrier, antimicrobial, antioxidant, biodegradation and sensing were reviewed in detailed. Then, the problems and advances in research on renewable NCs-hybrid composites are suggested for biodegradable food packaging applications. Finally, a future packaging material is proposed by using NCs-hybrids as nanofillers and endowing them with various properties, which are denoted as "PACKAGE" and characterized by "Property, Application, Cellulose, Keen, Antipollution, Green, Easy."

Ionic liquid-mediated regeneration of cellulose dramatically improves decrystallization, TEMPO-mediated oxidation and alkyl/alkenyl succinylation

This work demonstrated a successful strategy that simple ionic liquids (ILs) mediated pretreatment could effectively reduce crystallinity of cellulose from 71 % to 46 % (by C₂MIM.Cl) and 53 % (by C₄MIM.Cl). The IL-mediated regeneration of cellulose greatly promoted its reactivity for TEMPO-catalyzed oxidation, which the resulting COO^- density (mmol/g) increased from 2.00 for non-IL-treated cellulose to 3.23 (by C₂MIM.Cl) and 3.42 (C₄MIM.Cl); and degree of oxidation enhanced from 35 % to 59 % and 62 %, respectively. More significantly, the yield of oxidized cellulose increased from 4 % to 45-46 %, by 11-fold. IL-regenerated cellulose can also be directly subjected to alkyl/alkenyl succinylation without TEMPO-mediated oxidation, producing nanoparticles with properties similar to oxidized celluloses (55-74 nm in size, -70-79 mV zeta-potential and 0.23-0.26 PDI); but in a much higher overall yield (87-95 %) than IL-regeneration-coupling-TEMPO-oxidation (34-45 %). Alkyl/alkenyl succinylated TEMPO-oxidized cellulose showed 2-2.5 times higher ABTS* scavenging ability than non-oxidized cellulose; however, alkyl/alkenyl succinylation also resulted in a significant decline in Fe²⁺ chelating property.

Preparation of Cellulose Nanofibers from Corn Stalks by Fenton Reaction: A New Insight into the Mechanism by an Experimental and Theoretical Study

Agricultural biomass wastes are an abundant feedstock for biorefineries. However, most of these wastes are not treated in the right way. Here, corn stalks (CSs) were assigned as the raw material to produce cellulose nanofibers (CNFs) via in situ Fenton oxidation treatment. In order to probe the formation mechanism of an in situ Fenton reactor, the bonding interaction of hydrated Fe²⁺ ions and fiber has been systemically studied based on adsorption experiments, IR spectroscopy, density functional theory (DFT) calculations, and Raman spectroscopy. The results indicate that the coordination of the hydrated Fe²⁺ ion to the fiber generates a quasi-octahedral-coordinated sphere around the Fe center. The Jahn-Teller distortion effect of the Fe center promotes the Fe-O₂H₂ bonding interaction via reduction of the energy gap of the d_z² orbital of the Fe center and π_2py/π_2pz orbitals of the H₂O₂ molecule. The oxidation treatment of the pretreated CS by the in situ Fenton process shows the formation of a new carboxyl group on the fiber surface. The scanning electron microscopy image shows that the Fenton-treated fiber was scattered into the nanosized CNFs with a diameter of up to 50 nm. Both experimental and theoretical studies show that the pseudo-first-order kinetic reaction could describe the in situ Fenton kinetics well. Moreover, the proposed catalytic cycle shows that the large thermodynamic barrier is the cleavage of the O-O bond of H₂O₂ to generate the ^•OH radical, and the whole catalytic cycle is found to be spontaneous at room temperature.

Bacterial Cellulose Nanofibril-Based Pickering Emulsions: Recent Trends and Applications in the Food Industry

The Pickering emulsion stabilized by food-grade colloidal particles has developed rapidly in recent decades and attracts extensive attention for potential applications in the food industry. Bacterial cellulose nanofibrils (BCNFs), as green and sustainable colloidal nanoparticles derived from bacterial cellulose, have various advantages for Pickering emulsion stabilization and applications due to their unique properties, such as good amphiphilicity, a nanoscale fibrous network, a high aspect ratio, low toxicity, excellent biocompatibility, and sustainability. This review provides a comprehensive overview of the recent advances in the Pickering emulsion stabilized by BCNF particles, including the classification, preparation method, and physicochemical properties of diverse BCNF-based particles as Pickering stabilizers, as well as surface modifications with other substances to improve their emulsifying performance and functionality. Additionally, this paper highlights the stabilization mechanisms and provides potential food applications of BCNF-based Pickering emulsions, such as nutrient encapsulation and delivery, edible coatings and films, fat substitutes, etc. Furthermore, the safety issues and future challenges for the development and food-related applications of BCNFs-based Pickering emulsions are also outlined. This work will provide new insights and more ideas on the development and application of nanofibril-based Pickering emulsions for researchers.

Fabrication of Superhydrophobic/Superoleophilic Bamboo Cellulose Foam for Oil/Water Separation

Water is an indispensable strategic resource for biological and social development. The problem of oily wastewater pollution originating from oil spillages, industrial discharge and domestic oil pollution has become an extremely serious international challenge. At present, numerous superwetting materials have been applied to effectively separate oil and water. However, most of these materials are difficult to scale and their large-scale application is limited by cost and environmental protection. Herein, a simple, environmentally friendly strategy including sol-gel, freeze-drying and surface hydrophobic modification is presented to fabricate a bamboo cellulose foam with special wetting characteristics. The bamboo cellulose foam is superhydrophobic, with a water contact angle of 160°, and it has the superoleophilic property of instantaneous oil absorption. Owing to the synergistic effect of the three-dimensional network structure of the superhydrophobic bamboo cellulose foam and its hydrophobic composition, it has an excellent oil-absorption performance of 11.5 g/g~37.5 g/g for various types of oil, as well as good recyclability, with an oil (1,2-dichloroethane) absorption capacity of up to 31.5 g/g after 10 cycles. In addition, the prepared cellulose-based foam exhibits an outstanding performance in terms of acid and alkali corrosion resistance. Importantly, owing to bamboo cellulose being a biodegradable, low-cost, natural polymer material that can be easily modified, superhydrophobic/superoleophilic bamboo cellulose foam has great application potential in the field of oily wastewater treatment.

A Review of Performance Prediction Based on Machine Learning in Materials Science

With increasing demand in many areas, materials are constantly evolving. However, they still have numerous practical constraints. The rational design and discovery of new materials can create a huge technological and social impact. However, such rational design and discovery require a holistic, multi-stage design process, including the design of the material composition, material structure, material properties as well as process design and engineering. Such a complex exploration using traditional scientific methods is not only blind but also a huge waste of time and resources. Machine learning (ML), which is used across data to find correlations in material properties and understand the chemical properties of materials, is being considered a new way to explore the materials field. This paper reviews some of the major recent advances and applications of ML in the field of properties prediction of materials and discusses the key challenges and opportunities in this cross-cutting area.

Overview of potential adverse health effects of oral exposure to nanocellulose

Nanocellulose is an emerging material for which several food-related applications are foreseen, for example, novel food, functional food, food additive or in food contact materials. Nanocellulose materials can display a range of possible shapes (fibers, crystals), sizes and surface modifications. For food-related applications in the EU, information on the safety of substances must be assessed. The present review summarizes the current knowledge on (possible) adverse health effects of nanocellulose upon oral exposure, keeping EU regulatory aspects in mind. The overview indicates that toxicity data, especially from in vivo studies, are limited and outcomes are not unambiguous. The hazard assessment is further complicated by: the diversity in morphologies and surface modifications, lack of standard reference materials, limited knowledge about intestinal fate and absorption, analytical difficulties in biological matrices, dispersion issues, the possible presence of impurities and interferences within biological assays. Two subchronic in vivo toxicity studies show no indications of toxicity for two specific nanocellulose materials, even at high doses. However, these studies may have missed certain early or nano-specific toxic effects, such as inflammation potential, for which other, subacute studies provide some indications. Most in vitro studies show no cytotoxicity; however, several indicate that effects on oxidative stress and inflammatory responses depend on differences in size or surface treatments. Further, too few studies assessed genotoxicity of nanocelluloses. Therefore, immunotoxicity, oxidative stress and genotoxicity require further attention, as do absorption and effects on nutrient uptake. Recommendations for future research facilitating the safety assessment and safe-by-design of nanocellulose in food-related applications are provided.

Feasibility of bionanocomposite films fabricated using capsicum leaf protein and cellulose nanofibers

In this study, the feasibility of fabricating protein-based bionanocomposite films (PBBFs) was analysed by applying capsicum leaf protein (CLP) and cellulose nanofiber (CNF) as raw materials. The effects of different amounts of CNF (solid content 2%) on physicochemical and material properties of PBBFs were investigated. The results showed nanoscale CNFs exhibited good interfacial compatibility with CLP. The hydroxyl groups on the CNF surface promoted the association of hydrogen bonds between CLP, glycerol and CNF, which improved the crystal structure and thermal stability of PBBFs. Concurrently, the mechanical properties and hydrophobicity of PBBFs are also enhanced. PBBFs with 60% CNF content have maximum flexibility and hydrophobicity. All PBBFs exhibited ultraviolet barrier performance, indicating that PBBFs had potential application prospects in the development of degradable food packaging materials. The results of the present study can provide a theoretical basis for the efficient utilisation of capsicum planting waste while improving the ecosystem.