Design of Polymeric Films for Antioxidant Active Food Packaging.

Antioxidant active food packaging can extend the shelf life of foods by retarding the rate of oxidation reactions of food components. Although significant advances in the design and development of polymeric packaging films loaded with antioxidants have been achieved over the last several decades, few of these films have successfully been translated from the laboratory to commercial applications. This article presents a snapshot of the latest advances in the design and applications of polymeric films for antioxidant active food packaging. It is hoped that this article will offer insights into the optimisation of the performance of polymeric films for food packaging purposes and will facilitate the translation of those polymeric films from the laboratory to commercial applications in the food industry.

Facile Mechanochemical Approach To Synthesizing Edible Food Preservation Coatings Based On Alginate/Ascorbic Acid-Layered Double Hydroxide Bio-Nanohybrids.

A bionanohybrid based on ascorbic acid-intercalated layered double hydroxides (LDHs) was synthesized using a facile and novel mechanochemical grinding technique, and its efficacy as an edible food coating is reported. Ascorbic acid-intercalated Mg-Al-LDHs (AA-LDHs) are synthesized using a green water-assisted grinding approach. The successful synthesis of the mechanochemically ground AA-LDHs was confirmed by the shifts observed in the basal peaks of the LDHs based on a powder X-ray diffraction, changes in the positions of vibrational frequencies of ascorbic acid based on Fourier Transform Infrared Spectroscopy, and significant changes in the intensity and peak positions of the core-shell bands based on X-ray photoelectron spectroscopy. The resulting nanohybrid further demonstrates thermal stability in thermogravimetric and derivative thermogravimetric analysis. Transmission electron microscopy images of the mechanochemically synthesized AA-LDHs reveal a plate-like morphology, which is a characteristic of the hydrotalcite-like structure. In a novel application, an edible coating was prepared by blending the AA-LDHs into a biocompatible alginate matrix, and the coating was developed on freshly plucked strawberries using the dip-coating method. In order to evaluate the efficacy of the coating, the total phenolic content, pH, microbial growth, weight loss, titratable acidity, and ascorbic acid content were monitored in the coated and uncoated fruits for a period of 18 days. The results reveal that the shelf life of strawberries increases from 9 days to 15 days for the nanohybrid coated fruits, suggesting the potential food preservation applications of the nanohybrid.

Facile synthesis and characterizations of antibacterial and antioxidant of chitosan monoterpene nanoparticles and their applications in preserving minced meat.

Chitosan nanoparticles loaded monoterpenes (ChMNPs) were prepared for preservation of minced meat from oxidative changes and growth of microorganisms. Four monoterpenes (limonene, linalool, menthol and thymol) were used to synthesis of four different types of ChMNPs. The physicochemical characteristics of nanoparticles were analyzed using Scanning electron microscopy (SEM) and Zeta potential. SEM showed that the nanoparticles were nearly uniformly shape and size and the zeta potential values ranged between 0.0346 and -0.1690 mV. In vitro antimicrobial activity of Ch, monoterpenes (M) and ChMNPs against Gram (-) bacteria Escherichia coli (ATCC 8739) and Salmonella typhimurium (ATCC 1402) was analyzed using serial dilution test. E. coli was more susceptible than S. typhimurium to these products. ChMNPs exhibited good in vivo antimicrobial and antioxidant property for the minced meat samples during refrigerated storage. Verification of testing hypothesis was performed by assessing a DPPH radical scavenging activity, peroxide value and E. coli reduction of experimental nanoparticles. Significant effects of ChMNPs were observed at 1000 and 2500 mg/kg on the total number of E. coli in meat samples during storage time. The results indicate that ChMNPs can be used to preserve food as antimicrobial agents and to extend shelf life.

Hydrogen Peroxide Oxygenation of Furan-2-carbaldehyde via an Easy, Green Method.

Derivatives of 2(5 H)-furanone (γ-crotonolactone) are important intermediate synthetic products with a wide range of biological effects that have become widely used in the pharmaceutical industry, medicine, and veterinary medicine, in particular in the prevention and treatment of fish diseases. However, the environmental issue of obtaining these compounds while reducing the negative impact on the surrounding environment remains relevant. This article describes for the first time a method of γ-crotonolactone synthesis that is based on the concept of green chemistry. Synthesis is carried out under mild conditions using nontoxic reagents by furfural oxidation. For the first time, a mixture of hydrogen peroxide and acetic acid was used for the oxidation of furfural in a ratio of 1:0.05. A mixture of organic acids (succinic, maleic, fumaric, formic, and cinnamic acids), obtained as a byproduct in the synthesis of γ-crotonolactone, can be used as a highly effective, ecofriendly organic fertilizer or in a preparation with a stimulating effect.

Synthesis and mechanical properties of quaternary salts of chitosan-based films for food application.

A novel method is described to synthesize quaternary salts of chitosan with dimethylsulfate and subsequently cast films. In an attempt to improve both mechanical and hydrophobic characteristics, the chitosan was previously modified by N-alkylation, introducing 4, 8 and 12 carbons moieties into the polymeric chain. Analysis by FTIR and solid-state CP-MAS (13)C NMR spectroscopy confirmed the success of both alkylation and quaternization processes. The average degree of quaternization of these N-methylated derivatives was calculated to be 35%. DMA measurements indicated that chitosan and its derivative films are typically brittle materials, exhibiting similar non-linear viscoelastic behaviors. The films of unmodified chitosan have a very small strain (approximately 2.8%), though they were the most resistant films (Young's modulus=2283 MPa; tensile strength >44.0 MPa). In general, the alkyl-chitosan derivatives appear to be more plastic than chitosan films but less resistant, e.g., for butyl chitosan: maximum strain=13.1%; tensile strength=13.4 MPa and Young's modulus=171 MPa. Conversely the quaternization reaction increased the hardness of the parent sample, viz. for quaternary salt of dodecyl chitosan: maximum strain=2.6%; tensile strength=38.3 MPa and Young's modulus=1792 MPa.

Chitosan grafted monomethyl fumaric acid as a potential food preservative.

The present study aims at in vitro antibacterial and antioxidant activity evaluation of chitosan modified with monomethyl fumaric acid (MFA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as mediator. Three different kinds of chitosan derivatives Ch-Ds-1,Ch-Ds-2 and Ch-Ds-3 were synthesized by feeding different concentration of MFA. The chemical structures of resulting materials were characterized by (1)H NMR, (13)C NMR, HR-XRD, FT-IR and TNBS assay. The results showed that Ch-Ds-1, Ch-Ds-2 and Ch-Ds-3 were successfully synthesized. The % amino groups of chitosan modified by MFA were evaluated by TNBS assay and ranging from 1.82±0.05% to 7.88±0.04%. All the chitosan derivatives are readily soluble in water and swelled by dimethyl sulfoxide (DMSO), toluene and dimethyl formamide (DMF). The antioxidant activity for all the chitosan derivatives have been significantly improved (P<0.05) compared to the chitosan. Upon antibacterial activity at pH 4.0, all the chitosan derivatives showed significant (P<0.05) antibacterial activity against Gram positive Staphylococcus aureus, Listeria monocytogenes strains and Gram negative Escherichia coli and Salmonella enteritidis strains compared to chitosan. In conclusion, MFA modified chitosan has shown enhanced activities along with solubility, and could be used as a novel food preservative and packaging material for long time food safety and security.

3D-QSAR, synthesis, and antimicrobial activity of 1-alkylpyridinium compounds as potential agents to improve food safety.

Cetylpyridinium chloride (CPC), an alkylpyridinium compound has been recently approved by the US Food and Drug Administration to reduce bacterial contamination in poultry. Although CPC is very effective and has a very good safety record, its relatively high lipophilicity may limit its use in high fat containing foods such as beef. In this study we present the CoMFA analysis (3D-QSAR) of the antimicrobial activity of 60 N-alkylpyridinium compounds against different bacteria. CoMFA contours showed that the activity is highly influenced by the steric factor. Based in these contours we designed new candidates, which were synthesized and characterized by spectroscopic data. MIC activity over Gram positive and Gram negative microorganisms validated the 3D-QSAR study.

Synthesis and studies on antioxidants: ethoxyquin (EQ) and its derivatives.

In our study ethoxyquin (EQ) and its two complexes with flavonoids were obtained from ethoxyquin (1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline, EQ) and quercetin (EQ-Q, 1:1) or rutin (EQ-R, 1:1). Cytotoxicity of the tested compounds was studied using the trypan blue exclusion method and the properties of the studied compounds were also analyzed with the TUNEL method evaluating their ability to induce apoptosis. It was shown that EQ induced apoptosis in cultured human lymphocytes, especially at 0.25 and 0.5 mM concentrations. The same effects were also observed after the incubation of lymphocytes with EQ-Q and EQ-R, but the numbers of apoptotic cells observed were lower than for EQ.

Antimicrobial films produced from chitosan.

Antimicrobial films were prepared by dissolving chitosan into hydrochloric, formic, acetic, lactic and citric acid solutions. Below 40 degrees C, the counter ions could be classified into two groups based on their effect on zero-shear-rate viscosity in 2% solutions of organic acids. Chloride and citrate produced solutions with much lower viscosities than formate, acetate and lactate. At higher temperatures, these differences vanished, and the activation energies of viscous flow were all similar between 40 and 60 degrees C. Films prepared from these solutions were evaluated in tension for Young's modulus, stress and elongation at yield and break points. Films made from hydrochloric, formic and acetic acids were hard and brittle, whereas those from lactic and citric acids were soft and could be stretched. Good correlation was found between Young's modulus and volume of the counter ion. Film properties are essentially governed by the volume of the counter ion and not by the interactions between this counter ion and the macromolecule. Results suggest that acetate has the maximum molecular volume above which the film strength decreases very rapidly.

Industrial production of L-ascorbic Acid (vitamin C) and D-isoascorbic acid.

L-ascorbic acid (vitamin C) was first isolated in 1928 and subsequently identified as the long-sought antiscorbutic factor. Industrially produced L-ascorbic acid is widely used in the feed, food, and pharmaceutical sector as nutritional supplement and preservative, making use of its antioxidative properties. Until recently, the Reichstein-Grüssner process, designed in 1933, was the main industrial route. Here, D-sorbitol is converted to L-ascorbic acid via 2-keto-L-gulonic acid (2KGA) as key intermediate, using a bio-oxidation with Gluconobacter oxydans and several chemical steps. Today, industrial production processes use additional bio-oxidation steps with Ketogulonicigenium vulgare as biocatalyst to convert D-sorbitol to the intermediate 2KGA without chemical steps. The enzymes involved are characterized by a broad substrate range, but remarkable regiospecificity. This puzzling specificity pattern can be understood from the preferences of these enyzmes for certain of the many isomeric structures which the carbohydrate substrates adopt in aqueous solution. Recently, novel enzymes were identified that generate L-ascorbic acid directly via oxidation of L-sorbosone, an intermediate of the bio-oxidation of D-sorbitol to 2KGA. This opens the possibility for a direct route from D-sorbitol to L-ascorbic acid, obviating the need for chemical rearrangement of 2KGA. Similar concepts for industrial processes apply for the production of D-isoascorbic acid, the C5 epimer of L-ascorbic acid. D-isoascorbic acid has the same conformation at C5 as D-glucose and can be derived more directly than L-ascorbic acid from this common carbohydrate feed stock.

A novel formulation of thiamine dilaurylsulphate and its preservative effect on apple juice and sterilised milk.

Thiamine dilaurylsulphate (TLS), synthesised by a new method, was developed for a formulation with a wide antimicrobial spectrum and evaluated in apple juice and milk. The result of a disc diffusion method showed that TLS, which was synthesised from sodium lauryl sulphate and thiamine hydrochloride, had strong growth-inhibitory effects on Gram-positive bacteria, yeasts, and moulds, but had weak inhibitory effects on Gram-negative bacteria such as Escherichia coli. Moreover, the TLS antibacterial spectrum could be broadened to all microbes by formulation with organic acids, such as gluconic acid or acetic acid, since organic acids have synergistic effects on TLS bacteriostasis. Compared to TLS, the formulation had a better preservation in milk (pH 6.64) by viable microbial counting, although the antibacterial effect of the formulation with TLS showed no significant difference in apple juice (pH 3.98). Therefore, the TLS formulation has wide application and better potential, as a preservative, to enhance food safety.

Food and feed enzymes.

Humans have benefited from the unique catalytic properties of enzymes, in particular for food production, for thousands of years. Prominent examples include the production of fermented alcoholic beverages, such as beer and wine, as well as bakery and dairy products. The chapter reviews the historic background of the development of modern enzyme technology and provides an overview of the industrial food and feed enzymes currently available on the world market. The chapter highlights enzyme applications for the improvement of resource efficiency, the biopreservation of food, and the treatment of food intolerances. Further topics address the improvement of food safety and food quality.

Identification and releasing characteristics of high-amylose corn starch-cinnamaldehyde inclusion complex prepared using ultrasound treatment.

In this study, the high-amylose corn starch-cinnamaldehyde inclusion complex was prepared by an ultrasound treatment and its releasing characteristic was investigated. The results showed that the ultrasound treatment (35°C, 10min and 250W) generated a higher encapsulation rate of 40.2% than the conventional treatment (encapsulation rate, 5.7%). Data obtained from Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA) indicated that cinnamaldehyde was successfully encapsulated by high-amylose corn starch and the encapsulation significantly increased the dissociation temperature of cinnamaldehyde by around 70°C. Compared to the physical mixture of high-amylose corn starch and cinnamaldehyde, the formed inclusion complex had good retention ability and reduced the releasing rate of cinnamaldehyde from 57.5% to 28.4% in the first week. These results suggest that cinnamaldehyde could be encapsulated by high-amylose corn starch with an ultrasound treatment for presenting the releasing behavior in food preservation.

Novel chemical synthesis of ginkgolic acid (13:0) and evaluation of its tyrosinase inhibitory activity.

A novel efficient synthesis of ginkgolic acid (13:0) from abundant 2,6-dihydroxybenzoic acid was successfully developed through a state-of-the-art palladium-catalyzed cross-coupling reaction and catalytic hydrogenation with an overall yield of 34% in five steps. The identity of the synthesized ginkgolic acid (13:0) was confirmed by nuclear magnetic resonance, mass spectrometry, infrared, and high-performance liquid chromatography. The reaction sequence of this method can be readily extended to the synthesis of other ginkgolic acids. The synthesized ginkgolic acid (13:0) exhibited promising anti-tyrosinase activity (IC50 = 2.8 mg/mL) that was not correlated to antioxidant activity as probed by 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ferric reducing ability of plasma, and oxygen radical absorbance capacity assays. The synthetic strategy developed in this work will significantly facilitate biological studies of ginkgolic acids that have great potential applications in food and pharmaceuticals.

Antioxidant and antimicrobial activity of xylan-chitooligomer-zinc complex.

In this study, a ternary complex based on natural polysaccharides was explored as a novel food preservative. Chitooligomer was obtained by enzyme hydrolysis of chitosan with immobilised neutral protease, and the degree of polymerisation (DP) was mainly from 2 to 5. Chitooligomer-zinc complex (CGZC) was first produced and then co-heated with xylan to prepare xylan-chitooligomer-zinc complex (XCGZC). XCGZC showed higher antioxidant and antibacterial activity than chitooligomer, chitooligomer-zinc and xylan-chitooligomer. The IC(50) of XCGZC was 5.37 mg/mL, which was equal to the antioxidant ability of 3.28 mg/mL BHT. The diameter of the inhibition zone for XCGZC against Escherichia coli and Staphylococcus aureus was 17.2 ± 0.4 and 30.3 ± 0.6mm vs. control of 6.0mm. Besides, XCGZC had excellent antibacterial activity against Bacillus subtilis, Salmonella typhimurium, Bacillus megaterium. Therefore, XCGZC can be used as a novel promising preservative with antibacterial and antioxidant properties in the food industry.

Production of spherical granule from viscous red ginseng extracts for improving product fluency and preservation and its physicochemical properties.

Viscose red ginseng extracts dried and coated using fluidized bed coater may broaden their application in food processing industry and increasing the consumer acceptance. The operating conditions of fluidized bed coater were optimized for obtaining high yield and uniform spherical granule. The physicochemical properties and sensory characteristics among the concentrates, the fluidized bed dried core particle and the spherical granules of red ginseng extract were compared. The preservative properties of these materials were also analyzed. The predicted maximum yield of spherical granule was 85.42%, at a feeding rate (FR) of 111.04 mL/min, an atomization air pressure (AP) 275.30 kPa, and a product temperature (PT) of 68.53 degrees C. Most of ginsenosides, which were known as functional material, did not show significant changes after granulation, while the flowability and water solubility increased. Also, for a 10-mo storage at 30 degrees C, the spherical granule was the most stable among the materials considered. It can be concluded that the application of fluidized bed coater can be used for making the food product of viscous extracts more valuable.

[Synthesis of new mandelic acid derivatives with preservative action. Synthesis and acute toxicity study]. / Sinteza unor noi derivati ai acidului mandelic cu actiune conservanta. Sinteza si studiul toxicitatii acute.

Starting from the antiseptic action of DL mandelic acid, there were synthesized a series of esters of the mandelic acid, esters which could have preservative action. This study present the synthesis, structure validation and the acute toxicity study, for the new synthesized compounds. The esters were obtained by acylating 4-hydroxybenzoic acid propyl, ethyl, methyl esters and salicylic acid with the DL mandelic chloride (that was protected initially by the hydroxylic group). The structure of the synthesized compounds was confirmed by quantitative elemental analysis and RMN 1H spectral measurements. The acute toxicity was determined for two of the esters, who proved to had a preservative action (previously studied) and indicated that these esters have a small toxicity.

Incorporation of nisin in micro-particles of calcium alginate.

Nisin was successfully incorporated into a matrix of calcium alginate and ground into micro-particles smaller than 150 microns. Formation of micro-particles and incorporation of nisin was verified by scanning electron microscopy and by the reduction in the inactivation of nisin activity with proteolytic enzymes. Incorporation efficiency was 87-93% and the nisin in the alginate-incorporated form was 100% active against an indicator culture of Lactobacillus curvatus both in MRS broth and reconstituted skim milk.

Controlled release of water-soluble polymeric complexes of sorbic acid with antifungal activities.

We synthesized six water-soluble polymeric complexes of sorbic acid with polyvinylpyrrolidone of different molecular weight (mol wt). As shown by infrared absorption spectrum analysis, the complexes were formed by hydrogen bonding. The complexes (SC1, with mol wt=10 kDa, SC2 with mol wt=25 kDa, SC3 with mol wt=30 kDa, SC4 with mol wt=40 kDa, SC5 with mol wt=90 kDa, and SC6 with mol wt=360 kDa) were characterized as low mol wt (SC1, SC2, and SC3) and high mol wt (SC4, SC5, and SC6). The antifungal potencies of the complexes were tested by the macrodilution susceptibility method against environmental and clinically important fungi. Sorbic acid as well as the complexes exhibited minimum inhibitory concentrations (MICs) lower than potassium sorbate against all the strains tested. MICs of SC1, SC2, and SC3 were shown to be 2- to 4-fold lower for yeast and 1.5- to 3-fold lower than those of sorbic acid for moulds, respectively. The MICs of SC4 and SC5 against both of the Candida species tested ranged from 500 to 800 microg/ml, whereas for SC6 and sorbic acid they were about 1 mg/ml. The potencies of the high mol wt complexes against moulds were decreased by increasing the mol wt. For both of the moulds tested, the MICs of SC4 were slightly lower than those of sorbate. The MICs of sorbic acid and SC5 were equal to 300 microg/ml and 500 microg/ml respectively for Aspergillus parasiticus and for Penicillum viridicatum. The susceptibility to SC6 of all of the hyphomycetes tested was higher than that to sorbic acid. The low mol wt complexes and the sorbic acid exhibited minimal fungicidal concentrations (MFCs) 2 and 3 times higher respectively than the MICs. Sorbic acid and SC3 at a concentration of 2.5 mg/ml in an in vitro time kill curve study of Candida tropicalis were shown to be fungistatic, whereas SC1 and SC2 were fungicidal at the same concentrations. For Aspergillus parasiticus sorbic acid at 2.5 mg/ml was fungistatic for a 24-h period, whereas SC1, SC2, and SC3 were fungicidal.