Preparation and characterization of lotus root starch based bioactive edible film containing quercetin-encapsulated nanoparticle and its effect on grape preservation

Tough, antibacterial, antioxidant, antifogging and washable chitosan/nanocellulose-based edible coatings for grape preservation

This study focused on extracting nanocellulose from food processing waste to create a multi-functional edible coating for preserving grapes. Nanocellulose, in the form of short rods with diameters ranging from 30 to 130 nm, was extracted from soy hulls. Edible coatings were then prepared through an ion cross-linking method. Results revealed that the film surfaces and cross-sections were smooth, flat and pore-free, with monomers cross-linked through hydrogen bonding, ester bonds and electrostatic interactions. Further, the incorporation of soy-hull nanocellulose (2 g) effectively improved the mechanical strength (elongation = 281.03 % and tensile strength = 114.88 MPa), barrier properties and antifogging and antibacterial properties (95.55 %) of SCT composite films. Moreover, compared with the control, the SCT-3 coating can extend the shelf life of grapes to 10 d at 25 °C. This study offers a new perspective on the high-value use of agricultural by-products and development of edible films.

Starch based films and coatings for food packaging: Interactions with phenolic compounds

Biodegradable starch based films and coatings have been a research focus for food packaging. Phenolic compounds have many benefits for food and health applications. This review summarized the recent advances in the development of starch based films and coatings with added phenolic compounds and extracts. The impact of the added phenolic compounds and extracts on physicochemical, mechanical, barrier, antioxidant and antimicrobial properties of starch films and coatings were described. The starch films and coatings with added phenolics were applied in the packaging of both plant and animal based food products with increased shelf life. For intelligent packaging, anthocyanins were formulated into the starch films and coatings to reflect the degree of food freshness. Composite starch materials with the addition of nanoparticles, proteins and other polysaccharides were also formulated to improve the mechanical and biological functions of the films and coatings. Significant limitations in the studies were noted due to the lack of understanding of the nature of starch-phenolics interactions at the molecular level. Overall, optimal formulations of added phenolic compounds and extracts should be obtained to have targeted mechanical, barrier, and biological properties.

Sustainable nanofiber films based on polylactic acid/modified cellulose nanocrystals containing various types of polyphenols, exhibiting antioxidant activity and high stability

The type of phenolic compounds significantly influences the physicochemical properties and biological activities of packaging materials. This study aimed to investigate the effects of caffeic acid (Caf), esculetin (Esc), or quercetin (Que) on the physicochemical and antioxidant properties of polylactic acid/modified cellulose nanocrystals (PM) nanofiber film. FTIR and XRD analyses confirmed the successful encapsulation of Caf, Esc, and Que. in the PM films. Incorporating these phenolic compounds enhanced PM's water vapor barrier and surface hydrophobicity. Additionally, Esc improved the tensile strength by 26 % without sacrificing the elongation at break of the PM. Notably, the PM/Caf, PM/Esc, and PM/Que. films exhibited high antioxidant capacity and excellent storage stability (stable within 60 days). Finally, three antioxidant packaging films effectively delayed lipid oxidation and protein degradation in pork and maintained meat color. These resluts suggest that the developed PM/Caf, PM/Esc, and PM/Que. films have potential applications in active food packaging.

A bibliometric analysis of hydrogel research in various fields: the trends and evolution of hydrogel application

Hydrogel, a polymer material with a three-dimensional structure, has considerably expanded in research across multiple fields lately. However, the lack of a comprehensive review integrating the research status of hydrogel across diverse fields has hindered the development of hydrogel. This bibliometric analysis reviewed the hydrogel-related research over the past decades, emphasizing the evolution, status, and future directions within a multitude of fields, such as materials science, chemistry, polymer science, engineering, physics, biochemistry molecular biology, pharmacology pharmacy, cell biology, biotechnology applied microbiology, etc. We encapsulated applications and the potential of hydrogel in wound healing, drug delivery, cell encapsulation, bioprinting, tissue engineering, electronic products, environment applications, and disease treatment. This study integrated the current matrix system and characteristics of hydrogels, aiming to offer a cross-field reference for hydrogel researchers and promote the advancement of hydrogel research. Furthermore, we proposed a novel and reproducible bibliometric research paradigm, which can provide a more comprehensive analysis of the trends and trajectory of a research field.

Correlation analysis of starch molecular structure and film properties via rearrangements of glycosidic linkages by 1,4-α-glucan branching enzyme

The functional characteristics of starch films are significantly influenced by the amylose content and the distribution of the amylopectin chain length. This work used 1,4-α-glucan branching enzyme to molecularly reconstruct corn, pea, and cassava starch in order to examine the association. Films made of both natural and enzyme-modified starch were produced using the casting method. The study investigated the variations in starch films properties and explored the relationship between starch molecular structure and film qualities by correlation analysis. The results showed a significant positive connection (r = 0.954) between the tensile strength and amylose content, as well as a positive correlation (r = 0.939) between the A chains and the elongation at break. The average chain length (r = 0.932) and amylose content (r = 0.902) showed a positive correlation with the degradation temperature, whereas the amylose content (r = -0.946) showed an adverse correlation with the transparency. The B3 chain (r = 0.851) and the average chain length (r = 0.839) both exhibited a positive connection with its contact angle. As a result, our study thoroughly assesses how starch structure affects the characteristics of starch films and offers a fundamental modification pathway for the development of new application areas.

Fabrication of corn starch-based composite films functionalized by Rosa roxburghii Tratt fruit pomace via extrusion compression molding for active food packaging

In this study, various levels (0 %-30 % w/w, based on corn starch) of Rosa roxburghii Tratt fruit pomace (RRTP) were used as antioxidant fillers to develop corn starch (CS)-based bioactive films via the extrusion compression molding technique. The results showed that incorporating RRTP into CS could remarkably improve the barrier, mechanical and antioxidant properties of the films compared to pure CS film. In particular, the composite film containing 30 % RRTP had the lowest water vapor permeability and oxygen permeability of 2.94 × 10-10 g·m·m-2·s-1·Pa-1 and 0.87 × 10-14 kg·m·m-2·s-1·Pa-1, respectively, together with the highest tensile strength of 3.41 MPa and the strongest DPPH scavenging activity of 88.59 %. LCMS analysis confirmed that RRTP contained many phenolic compounds, which conferred high antioxidant activity to the composite films. Additionally, FTIR analyses demonstrated the formation of hydrogen bonds between CS and RRTP, along with good compatibility as confirmed by XRD and SEM. More importantly, the mushrooms packaged in the CS/30%RRTP film maintained optimal appearance and freshness after 12 days at 4 °C, demonstrating the promising role as antioxidant active packaging for food, following new trends for functional packaging.

Synthesis of cytocompatible gum Arabic-encapsulated silver nitroprusside nanocomposites for inhibition of bacterial pathogens and food safety applications

Silver nitroprusside (AgN) exhibits significant antibacterial activity; however, its inherent toxicity poses a major concern. This study synthesized AgN with enhanced antibacterial properties while minimizing toxicity. Gum Arabic (GA), a natural polysaccharide widely utilized in food and biomedical applications owing to its exceptional cytocompatibility, was selected for encapsulating AgN to mitigate toxicity while preserving or enhancing its biological activity. The resulting composite material, GA-AgN nanocomposites (NCs), was systematically characterized using various analytical techniques. Transmission electron microscopy analysis revealed that GA-AgN NCs exhibited a rectangular morphology, with an average size of 230.13 ± 62.8 nm. The zeta potential of GA-AgN NCs was measured at -29.3 ± 0.70 mV. Furthermore, GA-AgN NCs demonstrated stability over diverse storage durations, incubation periods, and pH conditions by maintaining its size and surface charge. X-ray diffraction results indicated a reduction in the crystallinity of AgN when incorporated into the amorphous GA matrix, while Fourier-transform infrared spectroscopy analysis confirmed that the functional properties of both AgN and GA were preserved in the NCs. The release of Ag and Fe ions from the NCs was observed to be time- and pH-dependent. Importantly, the incorporation of GA did not compromise the antibacterial or antibiofilm efficacy of AgN against bacterial pathogens. Additionally, GA significantly mitigated the cytotoxic effects of AgN on NIH3T3 cells and red blood cells. Furthermore, GA-AgN NCs effectively extended the shelf-life of Salmonella enterica-infected green grapes. Thus, this study illustrates that GA-fabricated AgN NCs exhibit potential as an antibacterial agent in food preservation applications.

Interactions, structures, and functions of pomegranate peel reinforced starch film

This work aimed to exploit the effects of pomegranate peel (PP) addition (10 %) and homogenization process (0-12,000 rpm) on the film-forming behavior and interactions of starch film to improve its microstructures and properties. Microrheology results showed that the viscosity of the film suspension was reduced by homogenization, and the amylopectin aggregation was restricted by PP particles under film formation. This helped improve the accessibility of starch and PP, increasing the hydrogen bond energy in the composites from 18.12 to 19.35 kJ/mol and promoting the ester bonds as confirmed by the FTIR results. As a result, the starch film reinforced by PP and homogenization showed a uniform and compact microstructure with reduced water activity, increased UV-blocking capacity (from 67.46 % to 90.11 %), enhanced mechanical resistance, and reduced water vapor permeability (from 4.70 to 2.21 × 10-10·g·m-1·s-1·Pa-1). Additionally, the starch film with 10 % PP also presented superior antimicrobial properties and antioxidant activity with rates of over 86 %, providing an effective strawberry preservation function.

Preparation of soybean isolate protein/xanthan gum/agar-Lycium ruthenicum anthocyanins intelligent indicator films and its application in mutton preservation

The preparation of intelligent indicator films containing anthocyanins and their utilization for real-time monitoring of meat freshness represents a prominent research topic of food packaging. In this study, anthocyanins (ALR) were extracted from Lycium ruthenicum (LR) using solvent extraction. Subsequently, these anthocyanins were incorporated into films composed of soybean isolate protein (SPI), xanthan gum (XG) and agar, resulting in SPI/XG/Agar-ALR pH-responsive intelligent indicator films. The physical properties, structural characterization and application in mutton preservation were evaluated to identify the intelligent indicator films with the optimal addition ratio of ALR. The results indicated that the SPI/XG/Agar-5 % films exhibited exceptional performance in terms of thickness, mechanical properties, water vapor transmission rate, oxygen transmission rate and light transmission rate. Scanning electron microscope observations revealed that the SPI/XG/Agar-5 % films possessed a smooth and flat surface, while fourier transform infrared spectroscopy analysis confirmed their excellent compatibility. The DPPH radical scavenging rate of the SPI/XG/Agar-5 % film reached 80.75 ± 0.63 %. When applied to the preservation of mutton, the SPI/XG/Agar-5 % film significantly extended the shelf life and effectively monitored the freshness of the meat. This study not only broadens the application scope of Lycium ruthenicum anthocyanins but also provides a foundation for the development of smart packaging materials.

Effect of Dual-Modified Tapioca Starch/Chitosan/SiO2 Coating Loaded with Clove Essential Oil Nanoemulsion on Postharvest Quality of Green Grapes

As consumer awareness regarding health and nutrition continues to increase, there is a growing demand for fresh, nutritious fruits such as green grapes. However, the short storage life and susceptibility of these fruits to spoilage lead to significant commercial losses. Currently, the plastic wrap method is commonly used to keep green grapes fresh, but this packaging effect is limited and not environmentally friendly. Therefore, there is an urgent need to explore sustainable and effective preservation methods. In this study, a high-pressure microfluidization technique was employed to prepare an essential oil nanoemulsion with a ratio of Tween 80 to clove essential oil of 1:1, and a biopolymer-based film solution was prepared using dual-modified tapioca starch and chitosan loaded with clove essential oil nanoemulsion. The dual-modified tapioca starch/chitosan/SiO2/1.25 wt % clove essential oil (DM/Ceo-1.25) solution coating was successfully applied for the packaging and preservation of fresh green grapes. Compared with the CK and polyethylene wrap (PE) groups, the DM/Ceo-1.25 coating significantly improved the quality of the green grapes, increasing the storage period of the green grapes from 4 to 8 days at room temperature. On the 10th day of storage, the coated grapes retained significantly better quality, with a hardness of 4.01 N, a titratable acidity of 1.625%, an anthocyanin content of 1.013 mg/kg, and a polyphenol content of 21.32 μg/mL. These results indicate that the DM/Ceo-1.25 solution coating developed in this study can be used as a new active material for fruit preservation and provides ideas for the development of safer and more sustainable food packaging.

Valorization of okara by-product for obtaining soluble dietary fibers and their use in biodegradable carboxymethyl cellulose-based film

In the face of mounting environmental concerns and the need for sustainable innovation, the use of agro-industrial wastes as raw materials offers a promising pathway. In this context, this study investigated the okara, a by-product of soy processing, as a novel source of soluble dietary fiber for the enrichment of carboxymethyl cellulose (CMC) biodegradable films based on environmental benefits of waste reduction with the creation of renewable packaging alternatives. Okara soluble dietary fiber (OSDF)-enriched CMC film was compared with films made from traditional and innovative soluble dietary fibers, such as pectin, inulin, and β-glucan. OSDF was obtained through acid hydrolysis at 121 °C, achieving a yield of 5.31 % relative to its initial dry weight. All the produced films exhibited a maximum crystallinity of 5 %, as revealed by X-ray diffraction (XRD), indicative of their largely amorphous structure, while scanning electron microscopy (SEM) ensured their uniformity and flawlessness. The CMC film enriched with okara soluble dietary fiber exhibited key properties, such as thickness, water vapor permeability, and thermal stability, comparable to other soluble fibers studied. These characteristics are essential for effective packaging applications. A notable distinction of the OSDF-enriched film was its capacity to block UV light, offering protection for light-sensitive items. The solubility tests showed that okara and β-glucan contributed to films with a higher solubility percentage. Mechanical testing underscored the influence of fiber on tensile strength, with the film enriched with β-glucan outperforming others at 27.5 MPa. All films showed rapid biodegradation within one week, emphasizing their eco-friendliness and the study alignment with sustainable development objectives in packaging.

Multi-functional reinforced food packaging using delivery carriers: A comprehensive review of preparation, properties, and applications

With the rapid development of globalization, food packaging takes on more responsibility, while guaranteeing product quality and safety. In this context, the health risks associated with chemically synthesized additives and inorganic nanoparticles have opened a new chapter in the reinforcement of food packaging with natural active ingredients. Various delivery carriers have been developed to overcome the limitations of poor stability, uneven dispersion, and low bioavailability of natural active ingredients. The combination of encapsulation technologies can increase the biocompatibility of the active ingredient with the packaging material. Moreover, the protective and slow-release effects of the carrier matrix on the active ingredients are desirable for the reinforcement of food packaging. This review presents the latest advances in the application of delivery systems in food packaging, including the types of delivery systems used in food packaging, reinforced properties of food packaging, and potential applications in the food industry. Previous scientific studies found that active ingredient-loaded delivery carriers increased the effectiveness of food packaging in preventing food spoilage. Furthermore, the integration of active packaging with smart food packaging exhibits the synergistic effects of freshness monitoring and quality preservation. This review also discusses the challenges and trends in reinforcing food packaging with delivery carriers under a synergistic strategy that will provide new ideas and insights for the development and application of innovative food packaging.

Ultrasonic spraying quercetin chitosan nonwovens with antibacterial and deodorizing properties for sanitary napkin

With economic and social development, there is a growing focus on menstrual hygiene, and traditional sanitary napkins are no longer sufficient to meet women's needs. In this study, quercetin (QC) was efficiently and uniformly ultrasonic sprayed on thermally bonded chitosan nonwovens (CS) to prepare a multifunctional surface layer of sanitary napkins (QCX@CS). CS sprayed with 3 layers of QC (QC3@CS) exhibits excellent mechanical properties and high antibacterial rates against Escherichia coli (99.51 %) and Staphylococcus aureus (99.87 %), respectively. Besides, QC3@CS demonstrates strong free radical scavenging abilities, which have great potential to reduce the effects of reactive oxygen species on immune and metabolic functions during menstruation. QC3@CS demonstrates strong deodorizing abilities, with rates of 87.22 % for acetic acid and 90.88 % for ammonia, which could effectively eliminate the unpleasant odor associated with menstruation. Moreover, QC3@CS ensures excellent water absorption, anti-return properties, and cytocompatibility. This study may provide valuable insights into developing functional sanitary napkin materials based on natural extracts.

Sodium alginate/chitosan-based intelligent multifunctional bilayer film for shrimp freshness retention and monitoring

Developing bifunctional innovative food packaging for maintaining and monitoring food freshness is crucial for food safety. Here, we prepared tannic acid cinnamaldehyde nanoemulsions through self-assembly and ionic cross-linking between the natural emulsifiers tannic acid and cinnamaldehyde, and were incorporated into chitosan as a protective outer layer. Sodium alginate anchored with alizarin was employed as the sensing inner layer. A pH-sensitive bilayer film integrating real-time monitoring and maintenance of food fresh food freshness was designed using layer-by-layer assembly (LBL) technology. The prepared bilayer film exhibited 100 % UV protection, >99 % antimicrobial effect, and 94.86 % and 97.91 % clearance rates for DPPH and ABTS free radicals, respectively. In addition, the bilayer film exhibited high biosafety and sensitive, reversible, and rapid response to pH/NH3. Shrimp preservation experiments showed that the smart bilayer film could effectively slow down the growth of microorganisms on the surface of shrimp, extend the freshness period of shrimp, and could monitor the freshness of shrimp in real-time through color changes. In conclusion, the prepared SL-CCT bilayer film has excellent potential for food preservation and freshness monitoring, providing a new perspective for design and development of multifunctional smart food packaging films.

Effects of quercetin- and Lactiplantibacillus plantarum-containing bioactive films on physicochemical properties and microbial safety of grass carp

In this study, the electrospinning technique was used to co-encapsulate Quercetin (Qu) and Lactiplantibacillus plantarum 1-24-LJ in PVA-based nanofibers, and the effect of bioactive films on fish preservation was evaluated at the first time. The findings indicated that both Lpb. plantarum 1-24-LJ and Qu were successfully in the fibers, and co-loaded fibers considerably outperformed single-loaded fiber in terms of bacterial survival and antioxidant activity. Following fish preservation using the loaded fibers, significant reductions were observed in TVB-N, TBARS, and microbial complexity compared to the control group. Additionally, the co-loaded fibers more effectively reduced the counts of H2S-producing bacteria and Pseudomonas. In the future, fibers with both active substances and LAB hold promise as a novel approach for fish preservation.

A comprehensive review on starch-based sustainable edible films loaded with bioactive components for food packaging

Biopolymers like starch, a renewable and widely available resource, are increasingly being used to fabricate the films for eco-friendly packaging solutions. Starch-based edible films offer significant advantages for food packaging, including biodegradability and the ability to extend shelf life. However, they also present challenges such as moisture sensitivity and limited barrier properties compared to synthetic materials. These limitations can be mitigated by incorporating bioactive components, such as antimicrobial agents or antioxidants, which enhance the film's resistance to moisture and improve its barrier properties, making it a more viable option for food packaging. This review explores the emerging field of starch-based sustainable edible films enhanced with bioactive components for food packaging applications. It delves into fabrication techniques, structural properties, and functional attributes, highlighting the potential of these innovative films to reduce environmental impact and preserve food quality. Key topics discussed include sustainability issues, processing methods, performance characteristics, and potential applications in the food industry. The review provides a comprehensive overview of current research and developments in starch-based edible films, presenting them as promising alternatives to conventional food packaging that can help reduce plastic waste and environmental impact.

Preparation and characterization of Iturin A/chitosan microcapsules and their application in post-harvest grape preservation

Iturin A (IA) encapsulated in chitosan (CS) microcapsules (IA/CS) underwent thorough physicochemical characterization using thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM confirmed the smooth, spherical morphology of the IA/CS microcapsules, while FTIR revealed complex intermolecular interactions between IA and CS. TGA demonstrated thermal stability within the 0-100 °C range, while particle size analysis revealed an average diameter of 553.4 nm. To evaluate IA/CS efficacy in post-harvest grape preservation, grapes were treated with sterile water (CK), 10 g/L CS, 0.1 g/L IA/CS, and 0.1 g/L chitosan empty microcapsules (CKM), then stored at 25 °C for 16 days. IA/CS significantly reduced decay and respiration intensity by 52.3 % and 23.8 %, respectively, compared to CK. IA/CS treatment also inhibited abscission rate, weight loss, firmness reduction, total soluble solids consumption, titratable acidity consumption, polyphenol oxidase, and peroxidase activities on par with CS treatment (p > 0.05), but performed better than CK (reductions of 26.9 %, 41.2 %, 25.8 %, 27.2 %, 24.2 %, 19.4 %, and 17.4 %, respectively) and CKM (p < 0.05). Sensory evaluation confirmed that IA/CS effectively suppressed decay, slowed post-harvest metabolic activity, and maintained grape quality. Therefore, IA/CS microcapsules offer a promising method for extending grape shelf life and preserving quality.

The application of starch-based edible film in food preservation: a comprehensive review

Using renewable resources for food packaging not only helps reduce our dependence on fossil fuels but also minimizes the environmental impact associated with traditional plastics. Starch has been a hot topic in the field of current research because of its low cost, wide source and good film forming property. However, a comprehensive review in this field is still lacking. Starch-based films offer a promising alternative for sustainable packaging in the food industry. The present paper covers various aspects such as raw material sources, modification methods, and film formation mechanisms. Understanding the physicochemical properties and potential commercial applications is crucial for bridging the gap between research and practical implementation. Finally, the application of starch-based films in the food industry is discussed in detail. Different modifications of starch can improve the mechanical and barrier properties of the films. The addition of active substances to starch-based films can endow them with more functions. Therefore, these factors should be better investigated and optimized in future studies to improve the physicochemical properties and functionality of starch-based films. In summary, this review provides comprehensive information and the latest research progress of starch-based films in the food industry.

Recoverable and degradable carboxymethyl chitosan polyelectrolyte hydrogel film for ultra stable encapsulation of curcumin

Hydrogels have shown great potential for application in food science due to their diverse functionalities. However, most hydrogels inevitably contain toxic chemical cross-linking agent residues, posing serious food safety concerns. In this paper, a curcumin/sodium alginate/carboxymethyl chitosan hydrogels (CSCH) were prepared by self-assembly of two oppositely charged polysaccharides, carboxymethyl chitosan and sodium alginate, to form a three-dimensional network encapsulating curcumin for extending food shelf life. The network structure of the CSCH film confirmed by FTIR, XRD, and XPS was mainly formed by electrostatic interactions. The chemical stability of CSCH network encapsulated curcumin was 4.2 times greater than that of free curcumin, with excellent gas barrier, antimicrobial, antioxidant, and biosafety properties. It was found that CSCH films reduced dehydration, prevented nutrient loss, inhibited microbial growth, and lowered the respiration rate, which effectively maintained the quality of mango and prolonged its shelf-life up to 11 days. Notably, CSCH films possessed the properties of rapid recycling (10 mins) and biodegradability (53 days). This polysaccharide-based hydrogel film provides a viable strategy for the development of green and sustainable food packaging.

Development and Analysis of Silver Nitroprusside Nanoparticle-Incorporated Sodium Alginate Films for Banana Browning Prevention

Banana (Musa acuminate) has been popular among consumers worldwide due to its rich nutrients and minerals. However, bananas are highly susceptible to the physical and biological factors that lead to postharvest loss during transportation and storage. In this work, novel sodium alginate (SA) films incorporated with silver nitroprusside nanoparticles (AgNNPs) were prepared to extend the shelf life of bananas through antibacterial and antioxidant coating. The results exhibited that AgNNPs were cubical and that their size was <500 nm, with metal composition being Ag and Fe. Additionally, the incorporation of AgNNPs in the SA film was seen in FE-SEM and zeta analysis, with an average size of about 365.6 nm. Furthermore, the functional and crystalline properties of AgNNPs were assessed through FTIR and XRD. Transmittance testing of the SA-AgNNPs films confirmed they have good UV barrier properties. SA-AgNNPs films exhibited excellent high antibacterial activity against foodborne pathogens including L. monocytogenes, S. enterica, and E. coli at the concentration of 500 µg/mL. Moreover, during the storage of bananas, SA-AgNNPs nanocomposite coatings act as a barrier to microbial contamination and slow down the ripening of bananas. As a result, compared with SA-coated and uncoated bananas, SA-AgNNPs-coated bananas exhibited the lowest weight loss and lowest total bacterial colonies, thus greatly extending their shelf life. Particularly when coated with SA-AgNNPs films, total bacterial colonies (TBC) in the banana peel and pulp were as low as 1.13 × 103 and 51 CUF/g on the ninth day of storage, respectively. Our work offers an efficient strategy to improve the quality of bananas during the postharvest period, with extensive applications in fruit preservation and food packing.