Fabrication of Carboxymethyl Cellulose/Agar-Based Functional Films Hybridized with Alizarin and Grapefruit Seed Extract

Tuning thermoresponsive properties of carboxymethyl cellulose (CMC)-agarose composite bioinks to fabricate complex 3D constructs for regenerative medicine

3D bioprinting has emerged as a viable tool to fabricate 3D tissue constructs with high precision using various bioinks which offer instantaneous gelation, shape fidelity, and cytocompatibility. Among various bioinks, cellulose is the most abundantly available natural polymer & widely used as bioink for 3D bioprinting applications. To mitigate the demanding crosslinking needs of cellulose, it is frequently chemically modified or blended with other polymers to develop stable hydrogels. In this study, we have developed a thermoresponsive, composite bioink using carboxymethyl cellulose (CMC) and agarose in different ratios (9:1, 8:2, 7:3, 6:4, and 5:5). Among the tested combinations, the 5:5 ratio showed better gel formation at 37 °C and were further characterized for physicochemical properties. Cytocompatibility was assessed by in vitro extract cytotoxicity assay (ISO 10993-5) using skin fibroblasts cells. CMC-agarose (5:5) bioink was successfully used to fabricate complex 3D structures through extrusion bioprinting and maintained over 80 % cell viability over seven days. Finally, in vivo studies using rat full-thickness wounds showed the potential of CMC-agarose bulk and bioprinted gels in promoting skin regeneration. These results indicate the cytocompatibility and suitability of CMC-agarose bioinks for tissue engineering and 3D bioprinting applications.

Development of seaweed-derived polysaccharide/cellulose nanocrystal-based antifogging labels loaded with alizarin for monitoring aquatic products' freshness

Intelligent freshness indicator labels have attracted great interest for their massive potential in monitoring the freshness of aquatic products over the years. However, there is still a challenge where fogging on the labels during dramatic temperature changes affects the reading of freshness. At the same time, the freshness indicator labels need high mechanical strength to resist collision damage during transportation and storage. Herein, an antifogging freshness indicator label was developed based on seaweed extracts and alizarin. Firstly, soluble polysaccharides and insoluble components were extracted from Gelidium amansii, and cellulose nanocrystal (CNC) was further prepared from the insoluble components by sulfuric acid hydrolysis. Subsequently, a polysaccharide-based film was fabricated using soluble polysaccharides as the matrix materials and CNC as the reinforcement agent. Antifogging experiments showed that the hydrophilic composite films presented good antifogging performance. After loading with alizarin, the composite indicator label exhibited both antifogging and freshness-indicating properties for the salmon sample. The work provided a new idea for developing freshness indicator labels suitable for low-temperature transportation and storage.

Recent Advances in Functional Cellulose-based Films with Antimicrobial and Antioxidant Properties for Food Packaging

The packaging of food plays a crucial role in food preservation worldwide. However, traditional packaging systems are passive layers with weak efficiency in protecting the food quality. Therefore, packaged foods are gradually spoiled due to the oxidation and growth of microorganisms. Additionally, most of the commercial packaging films are made of petroleum-based materials which raise environmental concerns. Accordingly, the development of eco-friendly natural-derived active packaging systems has increased the attention of scientists. Cellulose as the most abundant polysaccharide on earth with high biocompatibility, no toxicity, and high biodegradability has extensively been applied for the fabrication of packaging films. However, neat cellulose-based films lack antioxidant and antimicrobial activities. Therefore, neat cellulose-based films are passive films with weak food preservation performance. Active films have been developed by incorporating antioxidants and antimicrobial agents into the films. In this review, we have explored the latest research on the fabrication of antimicrobial/antioxidant cellulose-based active packaging films by incorporating natural extracts, natural polyphenols, nanoparticles, and microparticles into the cellulose-based film formulations. We categorized these types of packaging films into two main groups: (i) blend films which are obtained by mixing solutions of cellulose with other soluble antimicrobial/antioxidant agents such as natural extracts and polyphenols; and (ii) composite films which are fabricated by dispersing antimicrobial/antioxidant nano- or microfillers into the cellulose solution. The effect of these additives on the antioxidant and antimicrobial properties of the films has been explained. Additionally, the changes in the other properties of the films such as hydrophilicity, water evaporation rate, and mechanical properties have also been briefly addressed.

pH-responsive double-layer film based on chitosan/curcumin-β-cyclodextrin complex/cinnamaldehyde and zein/alizarin for pork freshness monitoring and maintaining

A pH-responsive double-layer film comprising chitosan (CS), zein (Z), curcumin-β-cyclodextrin complex (Cur- β-CD), alizarin (AL) and cinnamaldehyde (CIN) was developed to detect spoilage and prolong the shelf life of pork. The outer Z/AL is the colorimetric responsive and highly protective outer layer, while the CS/Cur- β-CD/CIN is the fluorescence responsive and functional layer. The CS/Cur- β-CD/CIN-Z/AL film demonstrated excellent barrier properties against oxygen (8.48 × 10-13 g (m s Pa)-1) and water (2.42 × 10-11 g (m s Pa)-1) primarily due to the polar interactions in the Z structure and its hydrophobic nature. The addition of AL and Cur provided the CS/Cur- β-CD/CIN-Z/AL film with pH colorimetric and fluorescence response capabilities, respectively. Furthermore, the inclusion of Cur- β-CD, CIN and AL significantly enhanced the film's antioxidant and antibacterial properties, with radical scavenging rates of 79.29 % (DPPH) and 89.84 % (ABTS), as well as antibacterial efficiencies of 96.2 % (S. aureus) and 85.78 % (E. coli). To test the effectiveness of the double-layer film, a freshness monitoring and maintenance experiment was conducted on pork stored at 4 °C for 8 days. Various parameters of pork, including surface color, pH value, total volatile bases nitrogen (TVB-N), total viable counts (TVC), thiobarbituric acid reactive substance (TBARS), hardness and springiness, were measured, along with the color and fluorescence intensity (FL) of the film. The shelf life of the pork was extended by at least 2 days compared to the control group, and the pork was considered inedible if ΔE ≥ 12 or FL intensity ≤ 2160. Overall, this food packaging film shows promise in simultaneously monitoring and maintaining the freshness of pork.

Comprehensive Review on Fruit Seeds: Nutritional, Phytochemical, Nanotechnology, Toxicity, Food Biochemistry, and Biotechnology Perspective

Fruit seeds are leftovers from a variety of culinary sectors. They are generally unutilized and contribute greatly to global disposals. These seeds not only possess various nutritional attributes but also have many heath-beneficial properties. One way to make use of these seeds is to extract their bioactive components and create fortified food items. Nowadays, researchers are highly interested in creating innovative functional meals and food components from these unconventional resources. The main objective of this manuscript was to determine the usefulness of seed powder from 70 highly consumed fruits, including Apple, Apricot, Avocado, Banana, Blackberry, Blackcurrant, Blueberry, Cherry, Common plum, Cranberry, Gooseberry, Jackfruit, Jamun, Kiwi, Lemon, Mahua, Mango, Melon, Olive, Orange, and many more have been presented. The nutritional attributes, phytochemical composition, health advantages, nanotechnology applications, and toxicity of these fruit seeds have been fully depicted. This study also goes into in-depth detailing on creating useful food items out of these seeds, such as bakery goods, milk products, cereal-based goods, and meat products. It also identifies enzymes purified from these seeds along with their biochemical applications and any research openings in this area.

Recent advances on natural colorants-based intelligent colorimetric food freshness indicators: fabrication, multifunctional applications and optimization strategies

With the increasing concerns of food safety and public health, tremendous efforts have been concentrated on the development of effective, reliable, nondestructive methods to evaluate the freshness level of different kinds of food. Natural colorants-based intelligent colorimetric indicators which are typically constructed with natural colorants and polymer matrices has been regarded as an innovative approach to notify the customers and retailers of the food quality during the storage and transportation procedure in real-time. This review briefly elucidates the mechanism of natural colorants used for intelligent colorimetric indicators and fabrication methodologies of natural colorants-based food freshness indicators. Subsequently, their multifunctional applications in intelligent food packaging systems like antioxidant packaging, antimicrobial packaging, biodegradable packaging, UV-blocking packaging and inkless packaging are well introduced. This paper also summarizes several optimizing strategies for the practical application of this advanced technology from different perspectives. Strategies like adopting a hydrophobic matrix, constructing double-layer film and encapsulation have been developed to improve the stability of the indicators. Co-pigmentation, metal ion complexation, pigment-mixing and using substrates with high surface area are proved to be effective to enhance the sensitivity of the indicators. Approaches include multi-index evaluation, machine learning and smartphone-assisted evaluation have been proven to improve the accuracy of the intelligent food freshness indicators. Finally, future research opportunities and challenges are proposed. Based on the fundamental understanding of natural colorants-based intelligent colorimetric food freshness indicators, and the latest research and findings from literature, this review article will help to develop better, lower cost and more reliable food freshness evaluation technique for modern food industry.

pH-sensitive smart indicators based on cellulose and different natural pigments for tracing kimchi ripening stages

Five natural pigments including water-soluble [butterfly pea (BP), red cabbage (RC), and aronia (AR)] and alcohol-soluble [shikonin (SK) and alizarin (ALZ)] were extracted, characterized, and loaded onto cellulose for preparing pH-sensitive indicators. The indicators were tested their color response efficiency, gas sensitivity, response to lactic acid, color release, and antioxidant activity. Cellulose-water soluble indicators showed more obvious color changes than alcohol-soluble indicators in lactic acid solution and pH solutions (1-13). All cellulose-pigment indicators exhibited prominent sensitivity to ammonia compared to acidic vapor. Antioxidant activity and release behavior of the indicators were influenced by pigment type and simulants. Kimchi packaging test was carried out using original and alkalized indicators. The alkalized indicators were more effective in showing visible color changes during kimchi storage than the original indicators, and cellulose-ALZ displayed the most distinct color change from violet (fresh kimchi, pH 5.6, acidity 0.45 %) to gray (optimum fermented kimchi, pH 4.7, acidity 0.72 %), and to yellow (over fermented kimchi, pH 3.8, acidity 1.38 %) which followed by BP, AR, RC, SK respectively. The findings of the study suggest that the alkalization method could be used to show noticeable color changes in a narrow pH range for application with acidic foods.

Performance-enhanced regenerated cellulose film by adding grape seed extract

Eco-friendly packaging material with intelligent colorimetric performance has been a requirement for food safety and quality. This work focused on a food packaging material from regenerated cellulose films that added the grape seed extract (GSE) and polyethylene glycol 200 (PEG). FTIR and SEM techniques were employed to prove the compatibility of GSE with cellulose matrix. The composite film showed an enhanced elongation at break (16.61 %) and tensile strength (33.09 MPa). The addition of PEG and GSE also improved the water contact angle of regenerated-cellulose film from 53.8° to 83.8°. Moreover, the composite films exhibited UV-blocking properties while maintaining adequate transparency. The GSE induced the regenerated films with a macroscopic change in color under different pH conditions. Furthermore, the loading of GSE slowed down the decomposition of strawberries and delayed the self-biodegradation compared with the control for more than 3 days and 18 days. The present study showed a regenerated cellulose film with acceptable mechanical and hydrophilia properties, pH-responsiveness, anti-decomposition, and delayed biodegradation performances, indicating a potential color sensor in food packaging.

Recent advancements in natural colorants and their application as coloring in food and in intelligent food packaging

Colorants are widely employed in the food industry as an essential ingredient in many products since color is one of the most valued attributes by consumers. Furthermore, the utilization of colorants is currently being extended to the food packaging technologies. The objective of this review was to compile recent information about the main families of natural coloring compounds, and to describe their real implications in food coloring. In addition, their technological use in different food systems (namely, bakery products, beverages, meat and meat products, and dairy products) and their utilization in intelligent packaging to monitor the freshness of foodstuffs with the aim of extending food shelf life and improving food properties was discussed. The potential of using natural colorant in different food to improve their color has been demonstrated, although color stability is still a challenging task. More interestingly, the application of intelligent colorimetric indicators to exhibit color changes with variations in pH can enable real-time monitoring of food quality.

Gelatin/poly(vinyl alcohol)-based functional films integrated with spent coffee ground-derived carbon dots and grapefruit seed extract for active packaging application

Nanoparticles are attractive, functional additives with great potential to be applied in biomaterial and food packaging. However, these particles are not soluble in water, thus limiting their widespread application. Here, we report a facile fabrication of carbon dots (CDs) using the spent coffee ground as the carbon source through a hydrothermal method. The CD was added to the gelatin/poly(vinyl alcohol) (Gel/PVA) film and grapefruit seed extract (GSE) to prepare multifunctional packaging films. The functional films' physiochemical and functional properties and packaging application were investigated. The composite film showed good UV protection properties with a slight decrease in transparency. The composite film containing CD/GSE showed strong antioxidant activity, scavenging >38 % DPPH and 100 % ABTS radicals. The film also exhibited significant antibacterial activity against the foodborne pathogens Listeria monocytogenes and Escherichia coli, completely eradicating the growth of these bacteria within 9 h of exposure. The CD/GSE-incorporated Gel/PVA films were used for pork packaging. The films were able to enhance the pork shelf life by reducing the L. monocytogenes bacterial growth in meat by 2 Log CFU/mL lower than the control wrapping film. The multifunctional Gel/PVA films are expected to be used for the active packaging of meat products.

Novel ammonia-responsive carboxymethyl cellulose/Co-MOF multifunctional films for real-time visual monitoring of seafood freshness

Nowadays, ammonia-responsive biopolymer-based intelligent active films are of great interest for their huge potential in maintaining and monitoring the freshness of seafood. However, it is still a challenge to create biopolymer-based intelligent active films with favorable color stability, antibacterial and visual freshness indication functions. Herein, cobalt-based metal-organic framework (Co-MOF) nanosheets with ammonia-sensitive and antibacterial functions were successfully synthesized and then embedded into carboxymethyl cellulose (CMC) matrix to develop high performance and multifunctional CMC-based intelligent active films. The influence of Co-MOF addition on the structure, physical and functional characters of CMC film was comprehensively studied. The results showed that the Co-MOF nanofillers were homogeneously embedded within the CMC matrix, bringing about remarkable promotion on tensile strength (from 45.3 to 62.2 MPa), toughness (from 0.7 to 2.3 MJ/m³), water barrier and UV-blocking performance of CMC film. Notably, the obtained CMC/Co-MOF nanocomposite films also presented excellent long-term color stability, antibacterial activity (with the bacteriostatic efficiency of 99.6 % and 99.3 % against Escherichia coli and Staphylococcus aureus), and ammonia-sensitive discoloration performance. Finally, the CMC/Co-MOF nanocomposite films were successfully applied for real-time visual monitoring of shrimp freshness. The above results demonstrate that the CMC/Co-MOF nanocomposite films possess huge potential applications in intelligent active packaging.

Alizarin: Prospects and sustainability for food safety and quality monitoring applications

Active and intelligent food packaging has emerged to ensure food safety, quality, or spoilage monitoring and extend the shelf life of food. The development of intelligent packaging has accelerated significantly in recent years with a focus on monitoring changes in the quality of packaged products in real-time throughout the food supply chain. As one of the popular natural colorants, alizarin has attracted much consideration due to its excellent functional properties and quality to color change under varying pH. Alizarin is an efficient and cost-effective biomaterial with numerous biological features such as antioxidant, antibacterial, non-cytotoxic, and antitumor. This review focuses on an in-depth summary and prospects for alizarin as a natural and safe colorant that has the potential to be incorporated into intelligent packaging to track the freshness of packaged foodstuffs. The use of alizarin as an intelligent packaging agent shows huge potential for the application of food packaging and brings it one step closer to real-time monitoring of food quality throughout the supply chain. Finally, various limitations and future requirements are discussed to underscore the importance of developing alizarin-based intelligent functional food packaging systems.

Grapefruit Seed Extract-Added Functional Films and Coating for Active Packaging Applications: A Review

Recently, consumers have been increasingly inclined towards natural antimicrobials and antioxidants in food processing and packaging. Several bioactive compounds have originated from natural sources, and among them, grapefruit seed extract (GSE) is widely accepted and generally safe to use in food. GSE is a very commonly used antimicrobial in food; lately, it has also been found very effective as a coating material or in edible packaging films. A lot of recent work reports the use of GSE in food packaging applications to ensure food quality and safety; therefore, this work intended to provide an up-to-date review of GSE-based packaging. This review discusses GSE, its extraction methods, and their use in manufacturing food packaging film/coatings. Various physical and functional properties of GSE-added film were also discussed. This review also provides the food preservation application of GSE-incorporated film and coating. Lastly, the opportunities, challenges, and perspectives in the GSE-added packaging film/coating are also debated.

Hemigraphis alternata Leaf Extract Incorporated Agar/Pectin-Based Bio-Engineered Wound Dressing Materials for Effective Skin Cancer Wound Care Therapy

The rapidly expanding area of regenerative medicine may soon enter a new phase owing to developments in biomaterials and their application in generating new tissues. Chemicals and synthetic drugs are currently the subject of heated debate due to their effects on human health and the environment. Therefore, scientists seek out new products and procedures that are harmless to both the environment and human health concerns. Bio-based materials provide excellent functional qualities with a variety of applications. This study resulted in the development of a film with antimicrobial, hydrophilic, and anti-cancer properties, which is most beneficial in the medical sectors. In this study, we developed a blended biodegradable film containing agar and pectin (AP), with excellent surface functional properties framed through a casting technique. Additionally, the property can be changed by the addition of extract of hemigraphis alternata (HA) extract. The incorporation of extract in AP (APH) can be used for anti-cancer wound care therapy. The fabricated film is biodegradable, biocompatible, and non-toxic. This material is entirely based on a green methodology, and it was prepared in a concise manner without the use of any hazardous solvents. Based on the overall nature of biopolymer, the prepared material is a promising alternative to our society.

Biodegradable Active Packaging Material Containing Grape Seed Ethanol Extract and Corn Starch/κ-Carrageenan Composite Film

An active film composed of corn starch/κ-carrageenan and ethanolic grape seed extract (0, 1, 3, and 5 wt% of GSE on corn starch basis) were successfully prepared using the solvent casting technique. The effects of the different concentrations of ethanolic grape seed extract (GSE) on the physicochemical properties, antioxidant properties, and antibacterial properties of CS/κC films were analyzed. The results showed that the addition of GSE inhibited the recrystallization of starch in the composite film. The glass transition temperature of composite film is 121.65 °C. With the addition of GSE, the surface roughness of the composite film increased, and the cross-section displayed a stratification phenomenon. Meanwhile, when GSE was added to the composite film, the tensile strength of the composite film decreased (3.50 ± 0.27 MPa), the elongation at break increased (36.87 ± 2.08%), and the WVP increased (1.58 ± 0.03 g mm/m2·d· kPa). With the increase of the concentration of GSE in the composite film, the a* value and b* value of the composite film increase, the L* value decreases, and the opacity increases. The lipid oxidation test proved that the composite films containing 1% GSE has a significant inhibitory effect on the oxidation of lard (p < 0.05). The above results indicate that the GSE can be used as a food-grade packaging material and has a good application prospect in the food industry.

Shikonin Functionalized Packaging Film for Monitoring the Freshness of Shrimp

A shikonin embedded smart and active food packaging film was produced using a binary mixture of gelatin and cellulose nanofiber (CNF). Shikonin is an alcohol-soluble natural pigment extracted from Lithospermum erythrorhizon root. The fabricated film showed good pH-responsive color changes and volatile gas sensing properties. Moreover, the film exhibited excellent antioxidant and antibacterial activity against foodborne pathogens. The shikonin incorporated gelatin/CNF-based film showed excellent UV-light barrier properties (>95%) and high tensile strength (>80 MPa), which is useful for food packaging. The hydrodynamic properties of the film were also slightly changed in the presence of shikonin, but the thermal stability and water vapor permeability remained unaffected. Thus, the inclusion of shikonin in the gelatin/CNF-based film improves not only the physical properties but also the functional properties. The film’s color indicator properties also clearly show shrimp’s freshness and spoilage during storage for 48 h. The shikonin-based functional film is expected to be a promising tool for multi-purpose smart and active food packaging applications.

Recent Advances in pH-Responsive Freshness Indicators Using Natural Food Colorants to Monitor Food Freshness

Recently, due to the enhancement in consumer awareness of food safety, considerable attention has been paid to intelligent packaging that displays the quality status of food through color changes. Natural food colorants show useful functionalities (antibacterial and antioxidant activities) and obvious color changes due to their structural changes in different acid and alkali environments, which could be applied to detect these acid and alkali environments, especially in the preparation of intelligent packaging. This review introduces the latest research on the progress of pH-responsive freshness indicators based on natural food colorants and biodegradable polymers for monitoring packaged food quality. Additionally, the current methods of detecting food freshness, the preparation methods for pH-responsive freshness indicators, and their applications for detecting the freshness of perishable food are highlighted. Subsequently, this review addresses the challenges and prospects of pH-responsive freshness indicators in food packaging, to assist in promoting their commercial application.

Genipin-Crosslinked Gelatin/Chitosan-Based Functional Films Incorporated with Rosemary Essential Oil and Quercetin

Functional food packaging films were prepared using a binary mixture of chitosan and gelatin through crosslinking with genipin and hybridization with rosemary essential oil and quercetin. The mixture of chitosan and gelatin produced the compatible film, and the added fillers also showed good compatibility. The physical properties of the chitosan/gelatin film were not greatly affected by crosslinking with genipin, and the functionality of the composite film was increased by the addition of rosemary essential oil and quercetin. The bioactive additives did not significantly affect the hydrophobicity and water vapor barrier properties of the chitosan/gelatin film but significantly changed the color, while the mechanical and thermal properties were slightly affected. The addition of these functional fillers significantly improved the UV protection, antioxidant, and antibacterial properties of the chitosan/gelatin film. Therefore, the novel chitosan/gelatin film with genipin crosslinking and the integration of rosemary essential oil and quercetin is considered to have high potential for applications in active food packaging.

Smart Biopolymer-Based Nanocomposite Materials Containing pH-Sensing Colorimetric Indicators for Food Freshness Monitoring

Nanocomposite biopolymer materials containing colorimetric pH-responsive indicators were prepared from gelatin and chitosan nanofibers. Plant-based extracts from barberry and saffron, which both contained anthocyanins, were used as pH indicators. Incorporation of the anthocyanins into the biopolymer films increased their mechanical, water-barrier, and light-screening properties. Infrared spectroscopy and scanning electron microscopy analysis indicated that a uniform biopolymer matrix was formed, with the anthocyanins distributed evenly throughout them. The anthocyanins in the composite films changed color in response to alterations in pH or ammonia gas levels, which was used to monitor changes in the freshness of packaged fish during storage. The anthocyanins also exhibited antioxidant and antimicrobial activity, which meant that they could also be used to slow down the degradation of the fish. Thus, natural anthocyanins could be used as both freshness indicators and preservatives in biopolymer-based nanocomposite packaging materials. These novel materials may therefore be useful alternatives to synthetic plastics for some food packaging applications, thereby improving the environmental friendliness and sustainability of the food supply.

Mechanical and Physicochemical Properties of Composite Biopolymer Films Based on Carboxymethyl Cellulose from Young Palmyra Palm Fruit Husk and Rice Flour

Carboxymethyl cellulose from young Palmyra palm fruit husk (CMCy) film has low water barrier properties, which can limit its application. Thus, the combination of CMCy with other polysaccharides, such as rice flour (RF), may solve this problem. The aim of this study is to prepare the CMCy/RF composite films in different proportions (CMCy100, CMCy75/RF25, CMCy50/RF50, CMCy25/RF75, and RF100) and investigate their mechanical and physicochemical properties. The film strength (33.36−12.99 MPa) and flexibility (9.81−3.95%) of the CMCy/RF composite films decreased significantly (p < 0.05) with an increase in the RF proportion. Blending the RF with CMCy could improve the water vapor permeability (9.25−6.18 × 10−8 g m m−2 s−1 Pa−1) and film solubility (82.70−21.64%) of the CMCy/RF composite films. Furthermore, an increased lightness with a coincidental decreased yellowness of the CMCy/RF composite films was pronounced when the RF proportion increased (p < 0.05). However, the addition of RF in different proportions did not influence the film thickness and transparency. Based on SEM micrographs, all film samples had a relatively coarser surface. FTIR spectra showed that some interactions between CMCy and RF blended films had occurred. According to these findings, the CMCy50/RF50 composite film was found to be the best formulation because it has good mechanical and physicochemical properties.

Fabrication of highly transparent and multifunctional polyvinyl alcohol/starch based nanocomposite films using zinc oxide nanoparticles as compatibilizers

This work explored biodegradable polyvinyl alcohol/starch (PVA/ST) film compatibilized by rod-like ZnO nanofillers as multifunctional food packaging materials. The influence of rod-like ZnO nanofillers on the microstructural, UV-shielding, antibacterial, mechanical, thermal, together with water barrier performances of PVA/ST composite films was fully studied. Results revealed that rod-like ZnO nanofillers could be uniformly distributed into the PVA/ST matrix, playing the role of compatibilizers to provide compact and dense nanocomposite films. The resulting nanocomposite films presented greatly improved mechanical and water vapor barrier properties as compared to virgin PVA/ST film. Moreover, the well distributed ZnO endowed PVA/ST film with excellent antimicrobial activity against both E. coli and S. aureus, together with outstanding UV-shielding capability meanwhile retaining highly optical transparency (approximately 90%). The developed PVA/ST/ZnO films were tested for packaging fresh-cut carrot slices to prevent microbial infection and prolong their shelf life. These results indicated that the developed highly transparent and multifunctional PVA/ST/ZnO nanocomposite films possess broad application prospects in active food packaging field.

Nutrients and bioactives in citrus fruits: Different citrus varieties, fruit parts, and growth stages

Citrus fruits are consumed in large quantities worldwide due to their attractive aromas and taste, as well as their high nutritional values and various health-promoting effects, which are due to their abundance of nutrients and bioactives. In addition to water, carbohydrates, vitamins, minerals, and dietary fibers are important nutrients in citrus, providing them with high nutritional values. Citrus fruits are also rich in various bioactives such as flavonoids, essential oils, carotenoids, limonoids, and synephrines, which protect from various ailments, including cancer and inflammatory, digestive, and cardiovascular diseases. The composition and content of nutrients and bioactives differ significantly among citrus varieties, fruit parts, and growth stages. To better understand the nutrient and bioactive profiles of citrus fruits and provide guidance for the utilization of high-value citrus resources, this review systematically summarizes the nutrients and bioactives in citrus fruit, including their contents, structural characteristics, and potential health benefits. We also explore the composition variation in different citrus varieties, fruits parts, and growth stages, as well as their health-promoting effects and applications.

Preparation of pectin/agar-based functional films integrated with zinc sulfide nano petals for active packaging applications

Here we report on the robust synthesis of zinc sulfide nanoparticles (ZnSNP) using a simple one-pot reaction. The prepared ZnSNP was characterized and confirmed to be a petal-shaped nanoparticle. The ZnSNP was added to fabricate the pectin/agar-based functional composite film. The integration of ZnSNP has greatly improved the physical properties of the film, such as mechanical and UV protection properties, without significantly changing the transparency of the film. The addition of the nanofillers did not affect the film's hydrophobicity, water vapor barrier, and thermal properties. Moreover, the composite film showed intense antibacterial activity against foodborne pathogenic bacteria, E. coli and L. monocytogenes. The functional bio-nanocomposite films based on pectin/agar have high potential in active packaging applications.