Review of surface treatment methods for polyamide films for potential application as smart packaging materials: surface structure, antimicrobial and spectral properties

Background: Antimicrobial packaging is currently one of the emerging technologies being pursued to extend the shelf-life of food products. Polyamides (PA) are widely used in food packaging, principally in laminate constructions, where they are used alone or combined with other materials. PA can be surface-treated using UV, plasma and corona treatments to create active film surfaces for various industrial applications. Scope and Approach: The object of this article was to review different surface treatment methods for the potential manufacture of smart packaging materials including antimicrobial application in particular and to review the necessary spectral characteristics deemed necessary to achieve this. Key Findings and Conclusions: XPS and AFM methods are useful tools in the identification of film surface analysis. For UV treatment, different light sources, including lasers, can be applied to create antimicrobially-active packaging materials. UV-treated PA films possess antimicrobial properties and offer potential for industrial and medical packaging applications, however, the application of such packaging materials to foods needs some special consideration. Different plasma treatment methodologies can be used for modification of PA surfaces, followed by attachment of antimicrobial coatings which are very limited in literature. Surface studies have shown that plasma-treated PA surfaces possess spectral properties similar to those for UV-treated samples. Corona treatment, like UV and plasma treatments, induce the modification of functional groups on PA film surfaces. Corona treatment has the capacity to activate polymeric surfaces for adhesion of a variety of functional coatings and should be explored further in terms of creating special antimicrobial coatings

Incorporation of commercially-derived antimicrobials into gelatin-based films and assessment of their antimicrobial activity and impact on physical film properties

Four antimicrobials, namely; Articoat DLP 02 (AR), Artemix Consa 152/NL (AX), Auranta FV (AFV) and sodium octanoate (SO) were examined for their effectiveness, both before and after heat treatments, against bacterial strains Bacillus cereus, Pseudomonas fluorescens, Escherichia coli, Staphylococcus aureus and the microflora obtained from commercial beef steaks. Minimum inhibitory concentrations (MIC) using AR, AX, AFV and SO against these microbes were then obtained using the 96-well plate method. SO was the most effective against all bacterial strains, demonstrating the lowest MIC compared to the other antimicrobials. These antimicrobials were then successively incorporated into beef-derived gelatine films and these films were subsequently tested for structural, mechanical and barrier properties. Significantly (p < 0.05) enhanced water vapour barrier properties were determined only for antimicrobial films containing AX or SO when compared to control films. On the basis of FTIR spectra, significant changes in the structure of SO-containing films were determined when compared with control gelatin films. It was shown that active antimicrobial agents could potentially serve as commercial antimicrobial coatings for application onto conventional plastic-based food packaging

The impact of sugar particle size manipulation on the physical and sensory properties

peer-reviewedThe overall objective of this research was to assess the effect of sugar particle size manipulation on the physical and sensory properties of chocolate brownies. A control sugar (commercially available, 200-5181 μm) and four of its sieved sugar separates (mesh size of 710, 500, 355 and 212 μm) were determined by grinding and sieving. The particle diameter and diameter distributions of the control sugar and each sugar fraction were measured. As a result, five sugar treatments were determined for chocolate brownie formulations; Control (C200-5181 μm), Large-particle replacement (LPR924-1877 μm), Medium-particle replacement (MPR627-1214 μm), Small-particle replacement (SPR459-972 μm) and a known MIX sample. Samples were tested using sensory (hedonic & intensity), instrumental (texture and colour) and compositional analyses (moisture and fat). Brownie samples containing the smallest sugar fraction (SPR459-972 μm) were perceived as significantly sweeter than any other sample (p < 0.05). Brownies containing this fraction were also the softest and moistest samples (p < 0.05). Texture liking was significantly associated with the LPR924-1877 μm brownie (p < 0.05). Darkness of brownie samples increased (p < 0.05) as sugar particle size decreased. Therefore, sugar particle size alteration affects the physical and sensory properties of chocolate brownies and could be used as a viable approach to reduce sugar in confectionery-type products

Development and assessment of duplex and triplex laminated edible films using whey protein isolate, gelatin and sodium alginate

The objective of this study was to assess the ability of producing laminated edible films manufactured using the following proteins; gelatin (G), whey protein isolate (WPI), and polysaccharide; sodium alginate (SA), and to evaluate their physical properties. Additionally, films’ preparation employing these ingredients was optimized through the addition of corn oil (O), Overall, 8-types of laminated films (G-SA, G-WPI, SA-WPI, SA-G-WPI, GO-SAO, GO-WPIO, SAO-WPIO, SAO-GO-WPIO were developed in this study. The properties of the prepared films were characterized through the measurement of; tensile strength (TS), elongation at break point (EB), puncture resistance (PR), tear strength (TT), water vapour permeability (WVP) and oxygen permeability (OP). The microstructure of cross-sections of laminated films was investigated by scanning electron microscopy (SEM). Mechanical properties of films were dramatically enhanced through the addition of film layers. GO-SAO laminate showed the best barrier properties to water vapour (22.6 ± 4.04 g mm/kPa d m2) and oxygen (18.2 ± 8.70 cm3 mm/kPa d m2). SAO-GO-WPIO laminate film was the strongest of all laminated films tested, having the highest TS of 55.77 MPa, PR of 41.36 N and TT of 27.32 N. SA-G-WPI film possessed the highest elasticity with an EB value of 17.4%

Thiacalix[4] arenes with terminal thiol groups at the lower rim: Synthesis and structure

Methods were developed for the synthesis of ω-mercaptoalkoxy derivatives of thiacalix[4]-arenes in the 1,3-alternate conformation containing different numbers (2-5) of methylene spacers at the lower rim. The hydrazinolysis of the corresponding thioacetates is the most efficient method for the synthesis of these compounds. © 2009 Springer Science+Business Media, Inc

Surface Attachment of Active Antimicrobial Coatings Onto Conventional Plastic Based Laminates and Performance Assessment of These Materials on the Storage Life of Vacuum Packaged Beef Sub-Primals

Two antimicrobial coatings, namely Sodium octanoate and Auranta FV (a commercial antimicrobial composed of bioflavonoids, citric, malic, lactic, and caprylic acids) were used. These two antimicrobials were surface coated onto the inner polyethylene layer of cold plasma treated polyamide films using beef gelatin as a carrier and coating polymer. This packaging material was then used to vacuum pack beef sub-primal cuts and stored at 4 °C. A control was prepared using the non-coated commercial laminate and the same vacuum packaged sub-primal beef cuts. During storage, microbial and quality assessments were carried out. Sodium octanoate treated packages significantly (p \u3c 0.05) reduced microbial counts for all bacteria tested with an increase of 7 and 14 days, respectively compared to control samples. No significant effect on pH was observed with any treatment. The results suggested that these food grade antimicrobials have the potential to be used in antimicrobial active packaging applications for beef products

Surface attachment of active antimicrobial coatings onto conventional plastic-based laminates and performance assessment of these materials on the storage life of vacuum packaged beef sub-primals

Two antimicrobial coatings, namely Sodium octanoate and Auranta FV (a commercial antimicrobial composed of bioflavonoids, citric, malic, lactic, and caprylic acids) were used. These two antimicrobials were surface coated onto the inner polyethylene layer of cold plasma treated polyamide films using beef gelatin as a carrier and coating polymer. This packaging material was then used to vacuum pack beef sub-primal cuts and stored at 4 °C. A control was prepared using the non-coated commercial laminate and the same vacuum packaged sub-primal beef cuts. During storage, microbial and quality assessments were carried out. Sodium octanoate treated packages significantly (p < 0.05) reduced microbial counts for all bacteria tested with an increase of 7 and 14 days, respectively compared to control samples. No significant effect on pH was observed with any treatment. The results suggested that these food grade antimicrobials have the potential to be used in antimicrobial active packaging applications for beef products

A new type of polytopic coordination compound: The synthesis and NMR studies of the first hybrid thiacalix[4]arenoclathrochelates

Nucleophilic substitution of the reactive chlorine atoms of iron(II) dichloroclathrochelate with thiol-terminated thiacalix[4]arene nucleophiles in the 1,3-alternate conformation afforded the first hybrid calixarenoclathrochelates with both ring-closed and ring-opened structures. The 1:1, 1:2 and 1:3 condensations of tetra-O-substituted thiacalix[4]arenes with thiol-terminated spacer substituents at the lower rim of the macrocyclic platform were performed. These thiol-terminated calixarene precursors were obtained from their O-ω-bromoalkyl precursors in the 1,3-alternate conformation, which are the products of alkylation of the parent thiacalix[4]arene with a series of homological α,ω-dibromoalkanes. The complexes obtained were characterized using elemental analysis, MALDI-TOF and ESI mass spectrometry, IR, 1H, 19F, 11B and 13C{1H} NMR spectra; their molecular structures in solution were thoroughly studied by one- and two-dimensional NMR spectroscopy as well as by molecular mechanics calculations. The formation of the thiacalix[4]arenoclathrochelates depends on the length of their ribbed spacer substituents in the chelate α-dioximate fragments of the cage frameworks; those with four bridging methylene groups seem to be optimal for the synthesis of the ring-closed hybrid molecules with two metal-encapsulating macrobicycles. © 2012 Elsevier Ltd. All rights reserved

The impact of sugar particles size and natural substitutes for the replacement of sucrose and fat in chocolate brownies: Sensory and physicochemical analysis

As fat contributes important textural properties such as lubricity and tenderness to cakes, it is plausible to focus on ways to increase the perception of these properties with the aim of creating the illusion of a higher fat. The utilisation of small sugar particles has been shown to increase the moist and soft texture of Chocolate Brownies. The present study assessed three different sugar particle sizes in their ability to create the illusion of fat content and therefore their ability to permit fat replacement (FR) in this product. The unground commercial sugar (200-5181 µm) was used as the control (UC) and two of its sieved sugar separates, Large (L924-1877 µm) and Small (S459-972 µm) were investigated. For each, fat was replaced using pureed black beans. The most accepted sample was used for sucrose replacement (SR) using inulin and Rebaudioside A. (Reb A.). Samples containing the smallest sugar fraction with 25% FR were most significantly associated overall acceptability (OA) (p<0.01). The application of small sugar particles did not significantly negatively affect OA or liking of samples at a level of 75% FR compared to the other two sugar fractions. The utilisation of small sugar particles (459-972 µm) in the preparation of baked goods could aid baking & industry professionals in reducing the fat content of cake-like products

The Application of Pureed Butter Beans and a Combination of Inulin and Rebaudioside A for the Replacement of Fat and Sucrose in Sponge Cake: Sensory and Physicochemical Analysis

peer reviewedDetermining minimum levels of fat and sucrose needed for the sensory acceptance of sponge cake while increasing the nutritional quality was the main objective of this study. Sponge cakes with 0, 25, 50 and 75% sucrose replacement (SR) using a combination of inulin and Rebaudioside A (Reb A) were prepared. Sensory acceptance testing (SAT) was carried out on samples. Following experimental results, four more samples were prepared where fat was replaced sequentially (0, 25, 50 and 75%) in sucrose-replaced sponge cakes using pureed butter beans (Pbb) as a replacer. Fat-replaced samples were investigated using sensory (hedonic and intensity) and physicochemical analysis. Texture liking and overall acceptability (OA) were the only hedonic sensory parameters significantly affected after a 50% SR in sponge cake (p < 0.05). A 25% SR had no significant impact on any hedonic sensory properties and samples were just as accepted as the control sucrose sample. A 30% SR was chosen for further experiments. After a 50% fat replacement (FR), no significant differences were found between 30% sucrose-replaced sponge cake samples in relation to all sensory (hedonic and intensity) parameters investigated. Flavour and aroma intensity attributes such as buttery and sweet and, subsequently, liking and OA of samples were negatively affected after a 75% FR (p < 0.05). Instrumental texture properties (hardness and chewiness (N)) did not discriminate between samples with increasing levels of FR using Pbb. Moisture content increased significantly with FR (p < 0.05). A simultaneous reduction in fat (42%) and sucrose was achieved (28%) in sponge cake samples without negatively affecting OA. Optimised samples contained significantly more dietary fibre (p < 0.05).Food Institutional Research Measur