Food Packaging Research Articles

Design, New Materials, and Production Challenges of Bioplastics-Based Food Packaging

This paper outlines the current design trends in food packaging, its main environmentally friendly material alternatives, and industrial processing technologies. In this respect, this important product has undergone several evolutions throughout history. Initially acting as a containment device, it has later evolved into a source of information and even a marketing platform for food companies, always with a view to extending shelf life. However, these functionalities are highly dependent on the materials used and their properties. In this respect, plastics have conquered the food packaging market due to their affordability and flexibility. Nevertheless, environmental concerns have arisen due to their impact on the environment, in addition to the introduction of stricter industry regulations and increased consumer environmental awareness. Therefore, this work found that the current design trends in food packaging are toward sustainability, reducing packaging complexity, with easier recycling, and material selection that combines both sustainability and functionality. In the case of bioplastics as a sustainable alternative, there is still room for improvement in their production, with careful consideration of their raw materials. In addition, their technical performance is generally lower, with challenges in barrier properties and processability, which could be addressed with the adoption of Industry 4.0.

Association between phthalate exposure and rash eczema disease: based on NHANES 2005-2006.

Phthalates are commonly found in plastic products, personal care products, and food packaging. In recent years, the relationship between phthalates and skin diseases such as eczema has been gaining attention. As endocrine disruptors, phthalates may increase the risk of eczema by affecting the immune system or skin barrier function. This study used a cross-sectional design based on data from the 2005-2006 National Health and Nutrition Examination Survey to assess the association between phthalate exposure and eczema in adults using generalized linear models, restricted cubic spline plots and weighted quantile sum regression. Eczema diagnosis was determined by participants' self-report of whether they had ever been diagnosed with eczema by doctors. Phthalate exposure was assessed by urinary concentrations of phthalates. A total of 1203 subjects, aged 18years and over, were recruited for the study, comprising 627 males and 576 females. We found that females had significantly higher phthalate exposure concentrations than males. There was a significant positive correlation between monoisononyl phthalate (MiNP) and eczema. Mixture analysis similarly found a positive correlation between phthalates and rash eczema, and MiNP was the main contributor. Further sex-stratified analyses showed that this association occurred predominantly in females, while no significant association was found in the male population. Phthalates may have adverse effects on skin health, particularly in women. Future studies should further investigate the mechanisms of this association and focus on other types of phthalates and their effects on skin health.

Microemulsion gel systems: Formulation, stability studies, biopolymer interactions, and functionality in food product development.

Microemulsion gels (MGs) are nanostructured systems created by the addition of thickening agents/biopolymers to a microemulsion's aqueous or oily phases, offering benefits like improved solubilization, enhanced stability, high encapsulation efficiency, and sustained release with versatile applications in food, pharmaceuticals, and cosmetology. MGs are intricate systems with thermodynamic robustness and controllable rheological characteristics crucial for obtaining high structural integrity and achieving innovative results regarding food product development in diverse areas of food, including colloidal carriers, food packaging, active compound delivery, antimicrobial vectors, and production of biopolymer nanoparticles. Therefore, a comprehensive analysis, hence understanding about MG systems, is needed to identify trends and gaps, helping researchers to identify promising areas for innovation and providing direction for future research. This review offers a comprehensive analysis of MG systems, their characteristics, formulation, formation mechanisms, design approaches, digestion dynamics, and rheological properties. MGs excel in solubilizing hydrophilic and lipophilic bioactives due to their enhanced viscosity and interconnected droplet network within the gel matrix. Despite their advantages, challenges, such as formulation complexity, require further understanding. This article also explores innovative biopolymers, characterization, and extensive applications, while addressing case studies, and emerging trends leveraging the potential of MG systems for enhancing food stability, functionality, and nutritional value.

Recent advances in sustainable biopolymer films incorporating vanillin for enhanced food preservation and packaging

Abstract With advances in food technology and research, the usability and effectiveness of biopolymer blended films are evolving rapidly. Sustainable biopolymer films derived from natural sources such as chitosan, alginate, gelatin, pectin, starch, and protein have attracted great attention due to their biodegradability and environmental benefits. Recent studies have shown that the integration of vanillin into biopolymer films generally offers enhanced mechanical strength, barrier properties, UV protection properties, and bioactive characteristics for efficient protection of food quality and extending shelf life. This review focuses on the newest developments in sustainable biopolymer films integrated with vanillin, with an emphasis on their preparation methods, physical and chemical properties, action mechanisms, antimicrobial activity, antioxidant activity, and potential uses in food preservation and packaging, along with the metrics of publications. Using vanillin in biopolymer films for food packaging is safe and environmentally friendly, and it maintains food quality after it's been harvested, showing a significant advance with exciting prospects for further study. Overall, incorporating vanillin into biopolymer films signifies a promising step forward in creating environmentally friendly and effective solutions for food packaging. Graphical abstract

Enhancing Biodegradable Packaging: The Role of Tea Polyphenols in Soybean Oil Body Emulsion Films

To address the increasingly diverse demands for biodegradable packaging materials, such as for their physical properties and antioxidant properties, this study incorporated tea polyphenols (TPs) into soybean oil body emulsions (SOBs) and added a certain proportion of sodium alginate (SA) and octenyl succinic starch sodium (SSOS) to prepare a biodegradable soybean oil body–tea polyphenol (ST) emulsion film. The study systematically evaluated the effects of different concentrations of TP (0–6 wt.%) on the structure, physicochemical properties, antioxidant activity, and antibacterial activity of ST films. The results showed that the physical properties, such as tensile strength and elongation at break, of the films increased significantly with the addition of TP, and the antioxidant and antibacterial activity also increased with the increase in TP concentration. When TP concentration was 2.5 wt.%, the barrier properties of the film (ST-2.5) significantly improved (p < 0.05), while water content and water solubility decreased. The Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis results showed that the structure of ST films became tighter at this point. The addition of TP also affected the sensory properties of ST films, such as with an increase in the opacity of the film. Compared with the control, the light transmittance of ST-6.0 decreased by 23.68% at a wavelength of 600 nm, indicating a significant reduction in film transparency. Moreover, the biodegradability test showed that ST films have good degradability. Therefore, the ST film, as a functional edible film, has broad application prospects in the food packaging industry.

Characterization of nanosilver antibacterial bacterial cellulose composite membranes coated with montmorillonite and their potential application in food packaging.

Bacterial cellulose (BC) is a natural, renewable polymer material with an ultrafine nanonetwork structure. However, BC has limited applications in food packaging and medical materials because of its lack of antibacterial properties. To expand the applications of BC, a new BC composite membrane was synthesized via an ex situ method. The BC membrane was first immersed in 100 mL of deionized water containing 3 mg of AgNO₃ for 24 h to incorporate silver nanoparticles (AgNPs). The BC-Ag composite was immersed in a 2 wt% montmorillonite (MMT) solution for 24 h to prepare the BC-Ag-MMT composite membrane. The structure and antibacterial properties of the composite were then examined. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful synthesis of the BC-Ag-MMT composite membrane. The results revealed that the addition of AgNPs and MMT resulted in a significant decrease in porosity (13.23 ± 1.12 %), water vapor transmission rate (735.12 ± 12.55 g/(m2·day)), and oxygen permeability (2.28 ± 0.29 g/(s·m2Pa)) while increasing the membrane thickness (0.89 ± 0.08 mm). The incorporation of MMT into BC notably improved the thermal stability of the membrane and further influenced its porosity. The antibacterial activity was evaluated via the inhibition zone method. The BC-Ag-MMT composite membrane exhibited antibacterial activity against Salmonella paratyphi A, Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella enterica. These findings demonstrated that the BC-Ag-MMT composite membrane possesses exceptional physical and chemical properties, mechanical strength, and antibacterial efficacy. The composite membrane holds significant potential for applications in food packaging.

A comprehensive review of gum-based electrospun nanofibers for food packaging: Preparation, developments, and potential applications.

Gums represent an intriguing group of biopolymers utilized in the food industry owing to their exceptional properties. These intricate carbohydrate biomolecules possess the capacity to form gels and mucilage structures by binding with water. Their stabilizing potential, heightened viscosity, emulsifying characteristics, broad compatibility, and cost-effectiveness render them a valuable resource in the realm of food packaging. Electrospun nanofibers (ENFs) derived from gums offer an amplified surface-to-volume ratio in comparison to bulk materials at the macroscopic level, resulting in increased porosity and enhanced mechanical properties. These attributes have the potential to enhance surface functionalities and diversify their range of applications. Despite the limited availability of gum types for the synthesis of ENFs, extensive research has been dedicated to the advancement of gum-based ENFs and the exploration of their applications. This review paper delves into the influence of gum properties on solution spinnability and the prospective applications of gum-based ENFs in active and intelligent food packaging.

Graphene-based nanomaterials applications for agricultural and food sector.

In the past decade, graphene-based nanomaterials (GBNs) have been considerably investigated in agriculture due to their exceptionally enriched physicochemical properties. Productivity in the agricultural sector relies significantly on agrochemicals. However, conventional systems suffer from a lack of application efficiency, resulting in environmental pollution and associated problems. Due to high surface area, easy functionalization, high chemical stability, biocompatibility, and ability to adhere to biological structures, GBNs become a promising candidate for agro-delivery carriers. A comprehensive review on developments of GBNs for pesticide delivery, nutrient delivery, food packaging and preservation, and their impacts on plant growth and development are missing in the literature. To address this, here we presented a detailed review on the material design, agrochemicals loading, release or diffusion kinetics, in-vivo applications, and effects of GBNs on plants. The GBNs found to improve the efficacy of existing agrochemicals and food preservatives, aiming to decrease the overall burden of these substances. The incorporation of GBNs in biocompatible and biodegradable polymers is reported to improve their oxygen barrier and mechanical properties for food packaging applications, targeting to reduce the use of petroleum-derived polymers based current food packaging materials, which leads to serious environmental impacts. In the context of plant nanobionics, GBNs has been found to boost the plant growth at low concentrations. Here, recommendations for future research have been deliberated, drawing reference from the relevant area to gain a deeper understanding of the underlying science, and to develop better delivery and packaging applications approaches. Additionally, discussions on recommendations regarding the safe concentration of GBNs for plant nanobionics are presented to facilitate their secure and effective utilization.

Fabrication, modification, interaction mechanisms, and applications of fish gelatin: A comprehensive review.

Fish gelatin (FG) is an essential natural biopolymer isolated from aquatic sources and has been considered as a feasible substitute for mammalian gelatins. However, its inferior mechanical and gelling properties limit its applications. Consequently, FG has been modified using various methods. This review summarizes the extraction techniques (including traditional acid and alkaline methods, as well as newer technologies such as ultrasonic-assisted and microwave-assisted extraction), modification strategies (mechanical treatments, physical mixing with polysaccharides, utilization of the Hofmeister effect, chemical modifications, etc.), along with their mechanisms of action. Additionally, we discussed the applications of FG and its modified products. Furthermore, this review highlights the safety and prospects for FG and its derivatives. The mechanical properties and biological functions of FGs are enhanced after modification. Thus, modified FG composites exhibit diverse applications in areas such as foaming agents and emulsifiers, food packaging, three-dimensional printing, drug delivery systems and tissue engineering. This paper aims to provide comprehensive information for future research on FG with the intention of broadening its applicability within the industries of food, cosmetics, and pharmaceuticals. Nevertheless, the development of tough gels, aerogels, and stimuli-responsive hydrogels based on FG requires further investigation.

Effect of strengthening agents on properties of dual-modified cassava starch-based degradable films.

Insufficient hydrophobicity and mechanical properties pose significant challenges in the development of starch-based degradable films. This study prepared modified (crosslinked, acetylated, and crosslinked & acetylated) cassava starch films, and different concentrations of strengthening agents (polyvinyl alcohol, sodium alginate, gelatin, and hyaluronic acid) were added to produce modified starch composite films. The physical properties, structure characteristics, and degradability of these films were systematically evaluated. The dual-modified (crosslinked & acetylated) starch film exhibited superior hydrophobic properties (contact angle=90.04°), and the addition of strengthening agents significantly enhanced the tensile strength of the composite films (p<0.05). Fourier transform infrared spectra confirmed that the strengthening agents interacted with starch through hydrogen bonding. Additionally, the hyaluronic acid-starch composite film exhibited the most rapid degradation in soil (53% weight loss after 30days of storage) and achieved the highest comprehensive score for physical properties. This film combined exceptional hydrophobicity and mechanical properties, making it an ideal candidate for food packaging applications. These findings suggest that the hyaluronic acid-starch composite film has broad potential applications in the field of degradable food packaging films.

Enhancing mechanical and thermal properties of bio-composites: Synergistic integration of ZnO nanofillers and nanocrystalline cellulose into durian seed starch matrix.

The increasing demand for sustainable materials necessitates advancements in bio-composites with enhanced properties. This study addresses the limitations of Durio zibethinus Murr (DZM) seed starch bio-composites, particularly their poor mechanical strength and thermal stability. Using solution casting, zinc oxide (ZnO) nanofillers and nanocrystalline cellulose (NCC) were incorporated into the starch matrix. The optimized composite with 0.4g ZnO exhibited a significant improvement in crystallinity (79.40%), tensile strength (0.44MPa), and thermal stability (15.54% residual mass). These findings highlight the potential of the developed bio-nanocomposites for applications in food packaging and medical devices, combining enhanced durability with environmental sustainability.

Pregnant women’s lifestyles and exposure to endocrine-disrupting chemicals: a machine learning approach

Women have ubiquitous exposure to various endocrine disrupting chemicals (EDCs) present in personal care products, food packaging, and processing. Pregnancy is a phase of increased vulnerability to environmental stressors. Therefore, we aimed to identify questionnaire based variables of pregnant women’s lifestyle factors affecting the prenatal concentrations of EDCs: bis-phenol A (BPA), triclosan (TCS), parabens, and phthalates. We also aimed to explore the association between these lifestyle factors and EDC exposure in pregnant women in South Korea. This study is a part of Korean CHildren’s ENvironmental health Study (Ko-CHENS). The following lifestyle factors: usage of personal care products, eating habits, cooking practices, food storage practices, and chemical exposure were evaluated through questionnaire. We examined prenatal EDCs: phenols (BPA), TCS, parabens (MEP, ETP, and PRP), and phthalates (MEHHP, MEOHP, MECPP, MBZP, MCOP, MCPP, MCNP, and MNBP). The random forest and least absolute shrinkage and selection operator regression machine learning models were used to predict the important lifestyle factors affecting the prenatal EDC concentrations in pregnant women. Next, we calculated the lifestyle score and evaluated its association with prenatal EDCs, respectively. Our results show that pregnant women who used makeup [β: 1.01, 95% C.I.: 0.01,2.00] >6 times/week had a significant increase in early-pregnancy (EP) ΣParaben exposure. Using perfume up to 3 times/month was significantly associated with EP TCS exposure (β: 0.05, 95% C.I.: 0.01,0.23). While, using perfume >6 times/week was significantly associated to late-pregnancy (LP) ΣParaben exposure, and consuming cup noodles significantly increased LP ΣDEHP exposure. Linear model analysis showed that the lifestyle score significantly increased the EP (β: 0.24, 95% C.I.: 0.07,0.40) and LP (β:0.10, 95% C.I.: 0.01,0.20) ΣParaben exposure. Therefore, pregnant women’s lifestyle factors, such as using makeup and perfume and eating habits (e.g., cup noodle consumption), were associated with prenatal EDC exposure.

Engineering antibacterial plasma-polymerized polyethylene glycol-ZnO nanocomposite coatings for extending pork sausage shelf life.

Recently, interest in eco-friendly techniques for producing antibacterial food packaging films has surged. Within this context, plasma polymerization is emerging as a promising approach for applying degradable antibacterial coatings on various plastic films. This research therefore employs an atmospheric pressure aerosol-assisted plasma deposition technique to create polyethylene glycol (PEG)-like coatings embedding zinc oxide nanoparticles (ZnO NPs) of varying sizes on polyethylene (PE) substrates. The antimicrobial efficacy of these plasma-polymerized PEG-ZnO coatings against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) is assessed, demonstrating a robust antibacterial effect, particularly when using smaller ZnO NPs (35-45nm). The deposition of uniform, conformal PEG-ZnO nanocomposites with a chemical composition akin to standard PEG polymers has been achieved. In addition, ZnO NPs are homogeneously dispersed within the PEG matrix, up to a concentration of 1wt%. To assess the antibacterial performance in contact with real food, pasteurized pork sausages inoculated with a mixture of L. monocytogenes or LAB strains are wrapped in plasma-coated PE and vacuum-packed. Bacterial growth is monitored during storage at 7°C over time, demonstrating that the developed plasma-polymerized PEG-ZnO nanocomposite effectively inhibits bacterial growth during refrigerated storage, with a more pronounced effect on LAB. The release of Zn from the developed PEG-ZnO nanocomposite into various food simulants also remains below the specific migration limit (5mg kg-1 or L-1 food), confirming coating safety. Overall, plasma-polymerized PEG-ZnO nanocomposite coatings thus show great promise as effective degradable antimicrobial films for food packaging applications.

Orange peel essential oil in rice starch encapsulating material for antimicrobial application against Escherichia coli.

This study investigated the formation of fibers and capsules using rice starch as a wall material to encapsulate orange peel essential oil (OPEO) by electrospinning for antimicrobial applications. Rice starch at a concentration of 20% (w/v) and varying OPEO concentrations (30%, 40%, and 50%, w/w) were used to produce materials. Free OPEO was analyzed for its chemical profile and antimicrobial activity. The electrospun material was characterized for morphology, size distribution, loading capacity, functional groups, thermal properties, and antimicrobial activity against Escherichia coli. Limonene was identified as the main component of OPEO. The free OPEO was effective against E. coli and Salmonella Typhimurium. When different concentrations of OPEO were incorporated into 20% rice starch solutions, a decrease in electrical conductivity was observed, leading to the formation of fibers and capsules instead of just fibers. The loading capacities of the materials were 35%, 29%, and 28% for OPEO concentrations of 30%, 40%, and 50%, respectively. Encapsulation of OPEO resulted in increased thermal stability. The material with 50% OPEO achieved a 6-log reduction in E. coli, showing strong potential for active packaging to reduce food contamination. Future research should explore its practical use in food packaging.

The reaction mechanisms of ethylene oxide and propylene oxide with food Simulants: Based on experiments and computational analysis.

Ethylene oxide (EO) and propylene oxide (PO) are widely used as sterilizing agents in the food industry. However, their residues in food packaging can migrate into food and react with it, affecting the accuracy of residue detection in food. This study aims to explore the reaction mechanisms between EO and PO and aqueous food simulants using both experimental and computational methods. Especially to investigate the effects of temperature, pH and material structure on these reactions. Experimentally, the stability of EO and PO in different types of aqueous food simulants at 20°C, 40°C and 70°C was observed. It was found that at 20°C, EO and PO reacted rapidly in 4% EtOH, which 90% has reacted in 72h, and only 10%-20% reacted in other types of food simulants. All reactions accelerated with increasing temperature. At 70°C, all reactions have been completed except for 50% EtOH, which 80% has reacted in 72h. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that EO and PO can form diols or glycol ethers. Computationally, Density Functional Theory (DFT) and Transition State Theory (TST) was used to calculate the energy barriers of the reaction processes. The results showed that the energy barrier for the reaction of EO and PO with water is about 125kJ/mol. The energy barrier can be reduced by about 40kJ/mol with acid catalysis. Reactivity at the binding sites was analyzed through the Fukui function (FF), average local ionization energy (ALIE), and electrostatic potential (ESP) analysis. According to the results, the f+value at C7 in PO is 0.041 higher than it at C5. The ESP value of EO is 0.15kcal/mol higher than that of PO and the ALIE value of EO is also 0.11eV higher. The experimental results show the impact of temperature, and calculation results highlight the effects of pH and material structure on reaction mechanism. These results can help guide the development of safer packaging materials and provide theoretical support for more accurate detection of residues in food.

Sodium alginate-camellia seed cake protein active packaging film cross-linked by electrostatic interactions for fruit preservation.

The evolution of production and lifestyle patterns has led to an increasing demand for multifunctional packaging materials that exceed the capabilities of traditional single-function options, thus driving continuous innovation in the field. In this study, a novel approach is presented, where camellia seed cake protein, derived from camellia seed oil production by-products, is incorporated into sodium alginate to create biobased active packaging films. The antioxidant and UV-shielding properties of the sodium alginate-camellia seed cake protein films are enhanced by the incorporation of camellia seed cake protein. A closely intertwined structure is created between sodium alginate and camellia seed cake protein through electrostatic interactions, resulting in effective water vapor barrier capabilities. Furthermore, the active packaging films exhibit antimicrobial activity against E. coli and S. aureus, providing significant advantages for fruit preservation. This research is essential in delaying fruit spoilage, extending shelf life, and providing new insights into the development of biobased multifunctional food packaging materials.

Probing the Thermo-oxidative Degradation of Ethylene Vinyl Alcohol (EVOH) by Time-Resolved Rheology and NMR Spectroscopy

EVOH's excellent gas barrier properties have enabled its continued market growth in numerous applications including food packaging, fuel tanks, and construction. However, EVOH's susceptibility to thermo-oxidation limits its ability to be reprocessed. While it is generally known that EVOH degradation leads to cross-linking, detailed degradation rates and mechanisms are not well established. Understanding EVOH degradation has been elusive because readily accessible thermal and spectroscopy methods do not reveal significant changes. Moreover, gel permeation chromatography requires specialized solvents and columns. We report that measuring changes in viscoelasticity with time-resolved rheology (TRR) is a facile way to monitor the temporal dynamics of EVOH degradation. TRR was performed on EVOH grades with ethylene copolymer contents of 27, 32, 48 mol%. As expected, the grade with the highest ethylene content was the most stable. However, with time, all the EVOH grades transitioned from a Carreau-like fluid to a power law fluid and no longer exhibited terminal behavior. Cole-Cole plots also revealed that EVOH relaxation evolved from rapid process into a long, complex process consistent with network formation. The mechanism of degradation was further elucidated by using 13C distortionless enhancement of polarization transfer (DEPT-135) nuclear magnetic resonance spectroscopy. These results showed that degradation occurred by ring-opening of lactone terminal groups that led to cross-linking. This enhanced understanding provides a foundation for developing methods to probe and mitigate EVOH degradation.

Challenges in lignin integration within biopolymer matrices: Toward stable and effective lignin nanoparticles as additives for sustainable food packaging

Challenges in lignin integration within biopolymer matrices: Toward stable and effective lignin nanoparticles as additives for sustainable food packaging

Seeing is believing: How front-of-pack food imagery shapes parents' perceptions of child-oriented snack foods.

Child-oriented snack foods often display front-of-pack images suggesting they are natural or wholesome, yet many of these products are ultra-processed and nutrient poor. This study investigated parent's perceptions in response to common forms of front-of-pack food imagery on child-orientated snacks. An online experiment comprising four between-subjects food image conditions (no image; food photo; food cartoon; cartoon of children gardening) and two within-subjects snack type conditions (fruit; vegetable) was conducted with N=800 Australian adult parents/guardians of children aged 4-10 years. Participants viewed packaged snacks then rated them on visual appeal, perceived healthfulness, suitability for their child, and purchase intentions. For each outcome, 4 (between-subjects) x 2 (within-subjects) mixed ANOVAs were performed, with significant main effects explored using post-hoc pairwise t-tests with Bonferroni adjustment. The extent to which perception metrics predicted purchase intention within each condition was examined using multiple regression analyses. Participants perceived snacks displaying food photographs as healthier compared to all other conditions. When children's snacks displayed food photos, participants perceived the snack as more suitable for their child and showed stronger intentions to purchase the product than when cartoon children were displayed. Participants preferred fruit over vegetable snacks across all metrics, particularly when the picture was photorealistic. Visual appeal was the only perception metric that consistently predicted purchase intention across conditions. Findings provide clear evidence that parent's perceptions and purchase intentions towards children's snack foods are enhanced by pictures displayed on the packaging. Policy to regulate food packaging should require that foods depicted on the packaging accurately reflect product ingredients, particularly where whole foods are represented, and the actual ingredients are highly processed and no longer provide the nutrition of whole foods.

Transparent, mechanically robust and antibacterial food packaging film based on starch/PVA/citric acid/carboxycellulose nanofibers by one-pot green process

Transparent, mechanically robust and antibacterial food packaging film based on starch/PVA/citric acid/carboxycellulose nanofibers by one-pot green process