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%

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

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

Gelatin films: Study review of barrier properties and implications for future studies employing biopolymer films

Production of conventional packaging materials is now recognised as having had a major impact on world pollution. Edible/Biodegradable/Compostable (EBC) films may offer sustainable alternatives to some conventionally-used packaging materials. One of the largest protein groups available for EBC materials is bovine gelatin. Knowledge and control of gelatin barrier properties is essential if it has any potential of becoming an industrial packaging material. Review of the relevant literature demonstrated that data for gelatin barrier properties generated was generally incomparable owing to a lack of experimental standardisation. Some standard approaches are adopted for further study, particularly, to reach a point where recommendations can be made about industrial use of gelatin as a packaging material. This review investigated barrier properties of bovine-derived gelatin films and factors affecting them for potential future industrial application. Bovine gelatin barrier properties were normalized to the same units and were dependent on film thickness, production methods employed, film composition, relative humidity, plasticizer content and nature, gelatin source and testing methods used. Literature comparison for barrier properties underlined high variability in results. It is suggested, and highly recommended that future studies carried out by researchers investigating EBC films should employ the use of standard units to express water vapor permeability (WVP) and oxygen permeability (OP) values as g x mm (or μm)/m2 d atm (or kPa) and cm3 mm (or μm)/m2 d atm (or kPa), respectively. Further research is necessary to compare results under controlled test conditions

Parameters Affecting the Water Vapour Permeability of Gelatin Films as Evaluated by the Infrared Detecting Method ASTM F1249

The purpose of this study was to assess testing parameters for measurement of water vapour permeability (WVP) properties of bovine gelatin films by ASTM F1249. This method utilises an infrared sensor to determine the WVP of conventional plastic-based films and has been widely applied within the packaging industry, but has had very limited application with hydrophilic compostable/edible packaging materials. These films have low WVP properties with highly variable WVP values (as studied by ASTM E96); consequently, this parameter has to be carefully controlled. Assessment of the module was carried out using bovine gelatin films with different thicknesses of film, and gelatin was chosen as an example of such film types using the following Mocon Permatran testing parameters: 50 or 70% relative humidity (RH), 100 or 150 cm3 nitrogen gas flow rates for the module’s RH-cell (100 cm3 for all other cells). In all cases, WVP increased with an increase in gas flow rate. This method showed that WVP increased with increasing gelatin film thickness, and categorically supports previous—and often unexplained—WVP findings for other hydrophilic, biopolymer films. The current study is a helpful guide to the examination of water barrier properties of hydrophilic edible/biodegradable/compostable packaging materials in research and industry

Microscopy-assisted digital photography as an economical analytical tool for assessment of food particles and their distribution through the use of the ImageJ program

Numerous technologies are available for particle analysis, such as laser diffraction, laser in-line particle size analysis, acoustic attenuation spectroscopy etc. However, in many situations, particle size analysis needs only to be conducted in single-type research, negating the purchase of high cost equipment. Microscopy assisted photography can be used followed by the analysis of the photo in ImageJ program in this case. It has been known seaweeds possess a high nutritional profile and can partially replace some ingredients such as salt. In represented method we describe an analytical tool for food particle size diameter analysis and probability distribution validated using four different seaweed separates (2360 to 355 µm mesh sizes). This method is cheap and consists of an ordinary digital camera (or cell phone camera), any microscope (or cell phone lens) or digital micrometer (for large particles) and open-sourced software â ImageJ. For seaweed sample separates obtained from 212 to 180 µm sieve mesh sizes, only microscopy equipped with a digital camera was employed. This method can be applied for any other industry such as biological samples, pharmaceutical etc., with a particular any range of particles distribution depending on accuracy required and camera lens resolution