Optimization of the Physical,Optical and Mechanical Properties of Composite Edible Films of Gelatin,Whey Protein and Chitosan

The aim of this work was to evaluate the effect of the concentration of gelatin (G) (3–6 g), whey protein (W) (2.5–7.5 g) and chitosan (C) (0.5–2.5 g) on the physical, optical and mechanical properties of composite edible films (CEFs) using the response surface methodology (RSM), as well as optimizing the formulation for the packaging of foods. The results of the study were evaluated via first- and second-order multiple regression analysis to obtain the determination coefficient values with a good fit (R ˃ 0.90) for each of the response variables, except for the values of solubility and b*. The individual linear effect of the independent variables (the concentrations of gelatin, whey protein and chitosan) significantly affected (p ≤ 0.05) the water vapor permeability (WVP), strength and solubility of the edible films. The WVP of the edible films varied from 0.90 to 1.62 × 10⁻¹¹ g.m/Pa.s.m², the resistance to traction varied from 0.47 MPa to 3.03 MPa and the solubility varied from 51.06% to 87%. The optimized values indicated that the CEF prepared with a quantity of 4 g, 5 g and 3 g of gelatin, whey protein and chitosan, respectively, provided the CEF with a smooth, continuous and transparent surface, with L values that resulted in a light-yellow hue, a lower WVP, a maximum strength (resistance to traction) and a lower solubility. The results revealed that the optimized formulation of the CEF of G–W–C allowed a good validation of the prediction model and could be applied, in an effective manner, to the food packaging industry, which could help in mitigating the environmental issues associated with synthetic packaging materials.     

Recent Developments in Chitosan-Based Micro/Nanofibers for Sustainable Food Packaging,Smart Textiles,Cosmeceuticals, and Biomedical Applications

Chitosan has many useful intrinsic properties (e.g., non-toxicity, antibacterial properties, and biodegradability) and can be processed into high-surface-area nanofiber constructs for a broad range of sustainable research and commercial applications. These nanofibers can be further functionalized with bioactive agents. In the food industry, for example, edible films can be formed from chitosan-based composite fibers filled with nanoparticles, exhibiting excellent antioxidant and antimicrobial properties for a variety of products. Processing ‘pure’ chitosan into nanofibers can be challenging due to its cationic nature and high crystallinity; therefore, chitosan is often modified or blended with other materials to improve its processability and tailor its performance to specific needs. Chitosan can be blended with a variety of natural and synthetic polymers and processed into fibers while maintaining many of its intrinsic properties that are important for textile, cosmeceutical, and biomedical applications. The abundance of amine groups in the chemical structure of chitosan allows for facile modification (e.g., into soluble derivatives) and the binding of negatively charged domains. In particular, high-surface-area chitosan nanofibers are effective in binding negatively charged biomolecules. Recent developments of chitosan-based nanofibers with biological activities for various applications in biomedical, food packaging, and textiles are discussed herein.     

Development and Characterization of Functional Starch-Based Films Incorporating Free or Microencapsulated Spent Black Tea Extract

Antioxidant polyphenols in black tea residue are an underused source of bioactive compounds. Microencapsulation can turn them into a valuable functional ingredient for different food applications. This study investigated the potential of using spent black tea extract (SBT) as an active ingredient in food packaging. Free or microencapsulated forms of SBT, using a pectin–sodium caseinate mixture as a wall material, were incorporated in a cassava starch matrix and films developed by casting. The effect of incorporating SBT at different polyphenol contents (0.17% and 0.34%) on the structural, physical, and antioxidant properties of the films, the migration of active compounds into different food simulants and their performance at preventing lipid oxidation were evaluated. The results showed that adding free SBT modified the film structure by forming hydrogen bonds with starch, creating a less elastic film with antioxidant activity (173 and 587 µg(GAE)/g film). Incorporating microencapsulated SBT improved the mechanical properties of active films and preserved their antioxidant activity (276 and 627 µg(GAE)/g film). Encapsulates significantly enhanced the release of antioxidant polyphenols into both aqueous and fatty food simulants. Both types of active film exhibited better barrier properties against UV light and water vapour than the control starch film and delayed lipid oxidation up to 35 d. This study revealed that starch film incorporating microencapsulated SBT can be used as a functional food packaging to protect fatty foods from oxidation.     

Migration Testing of GPPS and HIPS Polymers: Swelling Effect Caused by Food Simulants Compared to Real Foods

Migration kinetic data from general purpose polystyrene (GPPS) and high impact polystyrene (HIPS) were generated for a set of model substances as well as styrene monomer and oligomers at different temperatures (20 °C, 40 °C, 60 °C) using food simulants stipulated in the European Regulation (EU) 10/2011 and real foods like milk, cream and olive oil (20 °C, 40 °C). The extent of polymer swelling was characterized gravimetrically and visual changes of the test specimens after migration contact were recorded. Isooctane and 95% ethanol caused strong swelling and visual changes of HIPS, overestimating real migration into foods especially at high temperatures; GPPS was affected by isooctane only at 60 °C. With 50% ethanol, after 10 days contact at 60 °C or 40 °C both polymers were slightly swollen. Contrary, most of the real foods analyzed caused no detectable swelling or visual changes of the investigated polymers. This study demonstrates that the recommendations provided by EU regulations are not always in agreement with the physicochemical properties of styrenic polymers. The critical point remains the selection of adequate food simulants/testing conditions, since the high overestimation of aggressive media can lead to non-compliance of polystyrene materials even if the migration into real food would be of no concern.     

A review of silver nanoparticles in food packaging technologies: Regulation,methods, properties,migration, and future challenges

The development of antimicrobial food packaging is needed for food preservation and quality maintenance. Silver nanoparticles (AgNPs) have been widely used as an antimicrobial agent in food packaging technologies. However, the risks associated with their potential migration into foods are a major concern. This paper comprehensively reviews the use of AgNPs in food packaging technologies. The application of AgNPs in food packaging technologies has been regulated by the United States Food and Drug Administration and the European Food Safety Authority. The addition of AgNPs into food packaging can improve their barrier, mechanical, and antibacterial properties, as well as maintain the quality of foods. Migration of AgNPs from food packaging into foods is still a concern as it has implications for human health associated with their toxicity properties. A study on the toxicological properties of AgNPs released from food packaging needs to be carried out intensively to ensure their safety before being widely implemented. Moreover, comprehensive economic evaluation to implement AgNPs in food packaging is needed as such a study is missing in the literature.     

Present and Future Role of Chitin and Chitosan in Food

The conversion of processed discarded material into valuable by‐products and alternative specialty materials has been identified as a timely challenge for food research and development associated with numerous applications of chitinous products. Chitin, chitosan, calcareous chitin, and chitosan, N‐acetylated chitosan, N‐methylene phosphonic chitosan (NMPC), and N‐lauryl‐N‐methylene phosphonic chitosan (LMPC) are being studied as a result of their broad range of food applications. These biopolymers offer a wide range of unique applications including formation of biodegradable films, immobilization of enzymes, preservation of foods from microbial deterioration, as additives (clarification and deacidification of fruits and beverages, emulsifier agents, thickening and stabilizing agents, color stabilization), and dietary supplements. This review summarizes some of the most important developments in this field.     

Antimicrobial Food Packaging with Biodegradable Polymers and Bacteriocins

Innovations in food and drink packaging result mainly from the needs and requirements of consumers, which are influenced by changing global trends. Antimicrobial and active packaging are at the forefront of current research and development for food packaging. One of the few natural polymers on the market with antimicrobial properties is biodegradable and biocompatible chitosan. It is formed as a result of chitin deacetylation. Due to these properties, the production of chitosan alone or a composite film based on chitosan is of great interest to scientists and industrialists from various fields. Chitosan films have the potential to be used as a packaging material to maintain the quality and microbiological safety of food. In addition, chitosan is widely used in antimicrobial films against a wide range of pathogenic and food spoilage microbes. Polylactic acid (PLA) is considered one of the most promising and environmentally friendly polymers due to its physical and chemical properties, including renewable, biodegradability, biocompatibility, and is considered safe (GRAS). There is great interest among scientists in the study of PLA as an alternative food packaging film with improved properties to increase its usability for food packaging applications. The aim of this review article is to draw attention to the existing possibilities of using various components in combination with chitosan, PLA, or bacteriocins to improve the properties of packaging in new food packaging technologies. Consequently, they can be a promising solution to improve the quality, delay the spoilage of packaged food, as well as increase the safety and shelf life of food.     

Immobilization of Carboxypeptidase A into Modified Chitosan Matrixes by Covalent Attachment

Carboxypeptidase A (CPA) is a metalloexopeptidase that catalyzes the hydrolysis of the peptide bonds that are adjacent to the C-terminal end of a polypeptide chain. The enzyme preferentially cleaves over C-terminal L-amino acids with aromatic or branched side chains. This is of main importance for food industry because it can be employed for manufacturing functional foods from different protein sources with reduced hydrophobic amino acid content for patients with deficiencies in the absorption or digestion of the corresponding amino acids. In that way, strategies for effective multipoint covalent immobilization of CPA metalloenzyme on chitosan beads have been developed. The study of the ability to produce several chemical modifications on chitosan molecules before, during and after its coagulation to form carrier beads lead in a protective effect of the polymer matrix. The chemical modification of chitosan through the use of an N-alkylation strategy produced the best derivatives. N-alkyl chitosan derivative beads with D-fructose presented values of 0.86 for immobilization yield, 314.6 IU g^?1 bead for initial activity of biocatalyst and were 5675.64-fold more stable than the free enzyme at 55 °C. Results have shown that these derivatives would present a potential technological application in hydrolytic processes due to both their physical properties, such as low swelling capacity, reduced metal chelation ability and bulk mesoporosity, and increased operational stability when compared with soluble enzyme.     

Copper Complexes Stabilized by Chitosans: Peculiarities of the Structure,Redox, and Catalytic Properties

Peculiarities of the structure and physicochemical properties of copper–chitosan complexes prepared by different methods were studied by IR, UV-visible, ESR spectroscopy, and electron microscopy. The catalytic activity of redox copper centers stabilized by the chitosan matrix in the reactions of oxidation of o- and p-dihydroxybenzenes in an aqueous medium was determined. Quantitative ESR measurements provide evidence for the localization of virtually all copper ions introduced in the initial heterogeneous chitosan samples with copper contents below 1.5 wt % in the form of isolated Cu²⁺ ions in square planar coordination. The chitosan matrix was shown to strongly bind copper ions under conditions of redox transformations in the catalytic tests or upon prolonged heating in boiling water. Reoxidation of the samples with H₂O₂ results in quantitative restoration of the initial ESR signal of Cu(II). Heterogenized copper–chitosan samples exhibited high activity and stability in the catalytic oxidation of dihydroxybenzenes into quinones, whereas the homogeneous system was characterized by irreversible poisoning due to formation of copper–hydroquinone complexes. Preparation of the binary composite system with a thin heterogeneous copper–chitosan film supported on a macroporous silica allows one to dramatically enhance the specific catalytic activity and the efficiency of the active component. Such an approach may turn out to be useful in the synthesis of supported chitosan catalyst with a low noble metal content.     

Method Validation for Determination of Thallium by Inductively Coupled Plasma Mass Spectrometry and Monitoring of Various Foods in South Korea

Thallium (Tl) is a rare element and one of the most harmful metals. This study validated an analytical method for determining Tl in foods by inductively coupled plasma mass spectrometry (ICP-MS) based on food matrices and calories. For six representative foods, the method’s correlation coefficient (R²) was above 0.999, and the method limit of detection (MLOD) was 0.0070–0.0498 μg kg⁻¹, with accuracy ranging from 82.06% to 119.81% and precision within 10%. We investigated 304 various foods in the South Korean market, including agricultural, fishery, livestock, and processed foods. Tl above the MLOD level was detected in 148 samples and was less than 10 μg kg⁻¹ in 98% of the samples. Comparing the Tl concentrations among food groups revealed that fisheries and animal products had higher Tl contents than cereals and vegetables. Tl exposure via food intake did not exceed the health guidance level.     

Chitosan‐capped sulfur microparticles grafted on UV‐treated PET surface

Antimicrobial materials with immobilized particles are of considerable interest. Sulfur, as one of the abundant elements on earth, is cheap and environmentally friendly; therefore, sulfur particles (SPs) can be used as an effective, nontoxic and low‐cost alternative to metal particles. SPs were prepared by precipitation method using sodium thiosulfate and hydrochloric acid in the presence of chitosan as a stabilizer. Further, SPs were grafted on polyethylene terephthalate (PET) foil activated by ultraviolet radiation. The changes in surface properties of modified foils were characterized by contact angle measurement, electrokinetic analysis and X‐ray photoelectron spectroscopy (XPS). The contact angle decreased on the UV‐treated sample, owing to the formation of oxidized groups. The presence of nitrogen and sulfur on the polymer surface, revealed by XPS, showed that chitosan‐capped SPs were bound to this surface. The surface morphology of samples and particle sizes were examined by scanning electron microscopy. The size of SPs increased after grafting on surface to a few micrometres. The antibacterial activity of the PET samples was tested against Staphylococcus epidermidis and Escherichia coli bacteria strains. UV‐treated samples grafted with one of the tested chitosan‐capped SPs demonstrated antibacterial effect against both of the bacteria strains. This new nanocomposite has potential to be used in medical applications as an antibacterial agent or in food processing as an antimicrobial food packaging material. Food spoilage caused by microorganisms such as E. coli during distribution and storage has a major impact on food quality and shelf life.     

Electrophoretic deposition of hydroxyapatite–CaSiO3–chitosan composite coatings

Electrophoretic deposition (EPD) method has been developed for the fabrication of hydroxyapatite (HA)–CaSiO₃ (CS)–chitosan composite coatings for biomedical applications. The use of chitosan enabled the co-deposition of HA and CS particles and offered the advantage of room temperature processing of composite materials. The coating composition was varied by the variation of HA and CS concentrations in the chitosan solutions. Cathodic deposits were obtained as HA–CS–chitosan monolayers, HA–chitosan/chitosan multilayers or functionally graded materials (FGM) containing HA–chitosan and CS–chitosan layers of different composition. The thickness of the individual layers was varied in the range of 0.1–20 μm. The deposition yield was studied at different experimental conditions and compared with the results of modeling. It was shown that the moving boundary model for the two component system can explain the non-linear increase in the deposition yield with increasing HA concentration in chitosan solutions. The obtained coatings were studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed that these coatings provided corrosion protection of stainless steel substrates in Ringer's physiological solution. The deposition mechanism and kinetics of deposition have been discussed.     

Polymerase chain reaction techniques for food allergen detection

Food allergies represent an important health problem in industrialized countries. Undeclared allergenic foods as contaminants in food products pose a major risk for sensitized persons. Reliable detection and quantification methods for food allergens are necessary to ensure compliance with food labeling and improve consumer protection. The methods currently used for the detection of potential allergens in foods are to target either the allergen itself or a marker that indicates the presence of the offending food. As markers for the presence of potentially allergenic foods or ingredients, specific proteins or DNA fragments are targeted. In routine food analysis, the enzyme-linked immunosorbent assay (ELISA) and the polymerase chain reaction (PCR) in the form of a real-time PCR or in combination with an ELISA have been used. The availability, the characteristics, and some future aspects of DNA-based methods in the rapid and sensitive detection of potentially allergenic food constituents or contaminations are discussed in this review.     

Radiochemical determination of As,Cr, Mo,Sb and Se in foods

A radiochemical neutron activation analysis procedure was applied to the analysis of foods for As, Cr, Mo, Sb and Se. The elements are retained on an inorganic chromatographic resin of hydrated managanese dioxide while interfering elements are removed. Activities from Br, K, Na and P interferences are reduced by up to six orders of magnitude, and detection limits for food analysis are reduced by factors of 100–2000, compared with those normally found for instrumental neutron activation analysis. Detection limits for the foods analyzed are 0.1–0.3 ng/g for As and Sb and 1–10 ng/g for Cr, Mo and Se. Results are presented for various foods and several National Bureau of Standards Standard Reference Materials.     

Thermal analysis,state transitions and food quality

Thermal properties of food systems are important in understanding relationships between food properties and changes in food quality. Concentrated food systems (low-moisture and frozen foods) are seldom in an equilibrium state and they tend to form amorphous, non-crystalline structures. Several glass transition-related changes in such foods affect stability, e.g., stickiness and caking of powders, crispness of snack foods and breakfast cereals, crystallisation of amorphous sugars, recrystallisation of gelatinised starch, ice formation and recrystallisation in frozen foods and rates of non-enzymatic browning and enzymatic reactions. Relationships between glass transition, water plasticisation and relaxation times can be shown in state diagrams. State diagrams are useful as stability or quality maps and in the control of rates of changes in food processing and storage.This revised version was published online in November 2005 with corrections to the Cover Date.     

Crab-Eating Monkey Acidic Chitinase (CHIA) Efficiently Degrades Chitin and Chitosan under Acidic and High-Temperature Conditions

Chitooligosaccharides, the degradation products of chitin and chitosan, possess anti-bacterial, anti-tumor, and anti-inflammatory activities. The enzymatic production of chitooligosaccharides may increase the interest in their potential biomedical or agricultural usability in terms of the safety and simplicity of the manufacturing process. Crab-eating monkey acidic chitinase (CHIA) is an enzyme with robust activity in various environments. Here, we report the efficient degradation of chitin and chitosan by monkey CHIA under acidic and high-temperature conditions. Monkey CHIA hydrolyzed α-chitin at 50 °C, producing N-acetyl-d-glucosamine (GlcNAc) dimers more efficiently than at 37 °C. Moreover, the degradation rate increased with a longer incubation time (up to 72 h) without the inactivation of the enzyme. Five substrates (α-chitin, colloidal chitin, P-chitin, block-type, and random-type chitosan substrates) were exposed to monkey CHIS at pH 2.0 or pH 5.0 at 50 °C. P-chitin and random-type chitosan appeared to be the best sources of GlcNAc dimers and broad-scale chitooligosaccharides, respectively. In addition, the pattern of the products from the block-type chitosan was different between pH conditions (pH 2.0 and pH 5.0). Thus, monkey CHIA can degrade chitin and chitosan efficiently without inactivation under high-temperature or low pH conditions. Our results show that certain chitooligosaccharides are enriched by using different substrates under different conditions. Therefore, the reaction conditions can be adjusted to obtain desired oligomers. Crab-eating monkey CHIA can potentially become an efficient tool in producing chitooligosaccharide sets for agricultural and biomedical purposes.     

The Effect of pH and Sodium Caseinate on the Aqueous Solubility,Stability, and Crystallinity of Rutin towards Concentrated Colloidally Stable Particles for the Incorporation into Functional Foods

Poor water solubility and low bioavailability of hydrophobic flavonoids such as rutin remain as substantial challenges to their oral delivery via functional foods. In this study, the effect of pH and the addition of a protein (sodium caseinate; NaCas) on the aqueous solubility and stability of rutin was studied, from which an efficient delivery system for the incorporation of rutin into functional food products was developed. The aqueous solubility, chemical stability, crystallinity, and morphology of rutin (0.1–5% w/v) under various pH (1–11) and protein concentrations (0.2–8% w/v) were studied. To manufacture the concentrated colloidally stable rutin–NaCas particles, rutin was dissolved and deprotonated in a NaCas solution at alkaline pH before its subsequent neutralisation at pH 7. The excess water was removed using ultrafiltration to improve the loading capacity. Rutin showed the highest solubility at pH 11, while the addition of NaCas resulted in the improvement of both solubility and chemical stability. Critically, to achieve particles with colloidal stability, the NaCas:rutin ratio (w/w) had to be greater than 2.5 and 40 respectively for the lowest (0.2% w/v) and highest (4 to 8% w/v) concentrations of NaCas. The rutin–NaCas particles in the concentrated formulations were physically stable, with a size in the range of 185 to 230 nm and zeta potential of −36.8 to −38.1 mV, depending on the NaCas:rutin ratio. Encapsulation efficiency and loading capacity of rutin in different systems were 76% to 83% and 2% to 22%, respectively. The concentrated formulation containing 5% w/v NaCas and 2% w/v rutin was chosen as the most efficient delivery system due to the ideal protein:flavonoid ratio (2.5:1), which resulted in the highest loading capacity (22%). Taken together, the findings show that the delivery system developed in this study can be a promising method for the incorporation of a high concentration of hydrophobic flavonoids such as rutin into functional foods.     

Application of Pomegranate by-Products in Muscle Foods: Oxidative Indices,Colour Stability,Shelf Life and Health Benefits

In recent years, considerable importance is given to the use of agrifood wastes as they contain several groups of substances that are useful for development of functional foods. As muscle foods are prone to lipid and protein oxidation and perishable in nature, the industry is in constant search of synthetic free additives that help in retarding the oxidation process, leading to the development of healthier and shelf stable products. The by-products or residues of pomegranate fruit (seeds, pomace, and peel) are reported to contain bioactive compounds, including phenolic and polyphenolic compounds, dietary fibre, complex polysaccharides, minerals, vitamins, etc. Such compounds extracted from the by-products of pomegranate can be used as functional ingredients or food additives to harness the antioxidant, antimicrobial potential, or as substitutes for fat, and protein in various muscle food products. Besides, these natural additives are reported to improve the quality, safety, and extend the shelf life of different types of food products, including meat and fish. Although studies on application of pomegranate by-products on various foods are available, their effect on the physicochemical, oxidative changes, microbial, colour stabilizing, sensory acceptability, and shelf life of muscle foods are not comprehensively discussed previously. In this review, we vividly discuss these issues, and highlight the benefits of pomegranate by-products and their phenolic composition on human health.     

Determination of paraffins in food simulants and packaging materials by liquid chromatography with evaporative mass detection and identification of paraffin type by liquid chromatography/gas chromatography and fourier transform infrared spectroscopy

A liquid chromatographic method with evaporative mass detection (EMD) is described for the determination of paraffins in food contact materials that do not contain polyolefin oligomers, or paraffins migrating from these materials into fatty food simulants or certain simple foods. A normal-phase column operating at maximum column efficiency separates nonparaffinic and paraffinic materials without resolving the latter into individual components, and EMD is used to quantitate the paraffins. An on-line qualitative method that uses liquid chromatography/gas chromatography with flame ionization detection discriminates between paraffin waxes and oils in food contact materials, food simulants, and certain simple foods; a Fourier transform infrared spectrophotometric qualitative method also discriminates between waxes and oils, but is usually restricted to food contact materials that do not contain polyolefins and to migration experiments with organic solvents as fatty food simulants (with some other fatty food simulants, paraffin type must then be identified in the food contact material).     

Discovery and validation of urinary exposure markers for different plant foods by untargeted metabolomics

While metabolomics is increasingly used to investigate the food metabolome and identify new markers of food exposure, limited attention has been given to the validation of such markers. The main objectives of the present study were to (1) discover potential food exposure markers (PEMs) for a range of plant foods in a study setting with a mixed dietary background and (2) validate PEMs found in a previous meal study. Three-day weighed dietary records and 24-h urine samples were collected three times during a 6-month parallel intervention study from 107 subjects randomized to two distinct dietary patterns. An untargeted UPLC-qTOF-MS metabolomics analysis was performed on the urine samples, and all features detected underwent strict data analyses, including an iterative paired t test and sensitivity and specificity analyses for foods. A total of 22 unique PEMs were identified that covered 7 out of 40 investigated food groups (strawberry, cabbages, beetroot, walnut, citrus, green beans and chocolate). The PEMs reflected foods with a distinct composition rather than foods eaten more frequently or in larger amounts. We found that 23 % of the PEMs found in a previous meal study were also valid in the present intervention study. The study demonstrates that it is possible to discover and validate PEMs for several foods and food classes in an intervention study with a mixed dietary background, despite the large variability in such a dataset. Final validation of PEMs for intake of foods should be performed by quantitative analysis.