Edible Moisture Barriers: How to Assess of their Potential and Limits in Food Products Shelf-Life Extension?

Antimicrobial screening of pecan shell extract and efficacy of pecan shell extract-pullulan coating against Listeria monocytogenes, Salmonella enterica, and Staphylococcus aureus on blueberries

Pecan shell is considered an agricultural waste; however, it contains various bioactive compounds with potential inhibitory effect against microorganisms. This study evaluated the antimicrobial efficacy of pecan shell extract (PSE) in vitro using disc-diffusion method and in vivo on blueberries as an antimicrobial coating using pullulan. For in vitro study, 5 and 10 % of aqueous (A-PSE) or ethanol pecan shell extract (E-PSE) incorporated into pullulan film were tested against different bacterial and fungal strains. Pullulan film disc was used as control. The diameter of growth inhibition (mm) around discs was measured. For in vivo study, PSE-P (5 % w/v aqueous pecan shell extract+5 % w/v pullulan), P (5 % w/v pullulan) or control (water) were spray coated on blueberries inoculated (∼5 log CFU/g) with Listeria monocytogenes, Salmonella enterica or Staphylococcus aureus; and stored at 4 °C, 50 ± 10 % RH for 15 days. The effect of antimicrobial coating against pathogens and its impact on quality during storage were determined. A-PSE and E-PSE films were more effective against Gram-positive bacteria and showed no antifungal effect at tested concentrations when evaluated in vitro. Immediately after coating on blueberries, PSE-P significantly reduced Listeria monocytogenes by 2 log CFU/g and lowered survival until day 5 than control or P. Native aerobic microbial population was reduced (P < 0.05) by 0.7 log CFU/g immediately after coating. PSE-P coating or storage time had no significant effect (P > 0.05) on the survival of S. enterica, S. aureus and native fungal population. PSE-P maintained the firmness of blueberry with no significant effect on its color, TSS, and pH during 15 days storage. PSE-P significantly reduced (P < 0.05) the spoilage rate by 21 % than control (28.5 %) and P (37 %); and minimized (P < 0.05) weight loss during storage. Pecan shell extracts show promise as a potential antimicrobial compound whose application on various food products or packaging material could be further explored.

Development of sodium alginate-pectin biodegradable active food packaging film containing cinnamic acid

Plastics are still the most popular food packaging material, and many of them end up in the environment for a long period. Besides, due to packaging material's inability to inhibit microbial growth, beef often contains microorganisms that affect its aroma, colour, and texture. Cinnamic acid is categorized as generally recognised as safe and is permitted for use in food, however, the development of biodegradable food packaging film with cinnamic acid has never been conducted before. Thus, this present study was aimed to develop a biodegradable active packaging material for fresh beef using sodium alginate and pectin. The film was successfully developed with solution casting method. The films' thickness, colour, moisture level, dissolution, water vapour permeability, bending strength, and elongation at break were comparable to those of polyethylene plastic film in terms of these attributes. The developed film also showed the degradability in soil of 43.26% in a duration of 15 days. Fourier Transform Infrared (FTIR) spectra showed that cinnamic acid was successfully incorporated with the film. The developed film showed significant inhibitory activity on all test foodborne bacteria. On Hohenstein Challenge Test, a 51.28-70.45% reduction on bacterial growth was also observed. The antibacterial efficacy of the established film by using fresh beef as food model. The meats wrapped with the film showed significant reduction in bacterial load throughout the experimental period by 84.09%. The colour of the beef also showed significant different between control film and edible film during 5 days test. Beef with control film turned into dark brownish and beef with cinnamic acid turn into light brownish. In conclusion, sodium alginate and pectin film with cinnamic acid showed good biodegradability and antibacterial activity. Further studies can be conducted to investigate the scalability and commercial viability of this environmental-friendly food packaging materials.

Recent advancements, trends, fundamental challenges and opportunities in spray deposited cellulose nanofibril films for packaging applications

Plastic packaging is causing a serious environmental concern owing to its difficulty in degrading and micro-particulates' emissions. Developing biodegradable films has gained research attention to overcome ecological and health issues associated with plastic based packaging. One alternative substitute for petroleum-based plastic is nanocellulose based films, having distinguishing characteristics such as biodegradability, renewability, and non-toxicity. Nanocellulose is classified into three major types, i.e., cellulose nanofibril, cellulose nanocrystals, and bacterial nanocellulose. However, the scope of this review is limited to cellulose nanofibril (CNF) because this is the only one of major types that could be turned into film at a competitive cost with petroleum derived polymers. This paper provides a concise insight on the current trends and production methods of CNF. Additionally, the methods for transforming CNF into films are also discussed in this review. However, the focus of this review is the CNF films produced via spray deposition, their properties and applications, and fundamental challenges associated with their commercialization. Spray deposition or spray coating is an ideal candidate as a large-scale production technique of CNF films due to its remarkable features such as rapidity, flexibility, and continuity. Spray deposited CNF films exhibit excellent mechanical properties and oxygen barrier performance, while, possessing limited moisture barrier performance. The possible pathways to improve the moisture barrier performance and optical properties of these films are also discussed in this review. The existing publications on spray deposited CNF films are also highlighted from the literature. Finally, the current status of industrial production of these films and opportunities for academics and industries are also presented, indicating that fibre production capacity needs to be enhanced.

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.

Application of Dynamic Temperature-Humidity Chamber for Measuring Moisture Sorption Isotherms of Biomaterials as Compared to the Conventional Isopiestic Method

Measurement of water activity and moisture sorption isotherms of foods and biomaterials are important to determine the state of water. In this work, a dynamic temperature-humidity (DTH) controlled chamber was used to measure water sorption isotherm and compared with the conventional isopiestic method. Temperature and relative humidity of DTH chamber can be controlled in the range of -15 to 100°C and 0 to 98%, respectively; thus, measurement of water activity at any point can be measured within the above ranges. The DTH chamber method showed high reproducibility as compared with the conventional isopiestic method when measured isotherms of cellulose, lignin, and hemicellulase were compared at 30°C. Finally, isotherm data of cellulose, lignin, and hemicellulase were generated in the temperature range of 10-90°C using DTH chamber, and these were modelled by BET and GAB equations. The model parameters were correlated with the temperature.

The effects of pectin and wax on the characteristics of oil-in-water (O/W) emulsions

The study was aimed to investigate characteristics of emulsion containing pectin, wax, maltodextrin, and carotenoid enriched flaxseed oil by means of stability, rheology, particle size, and low-resolution of time domain nuclear magnetic resonance (NMR) relaxometry measurements. Emulsions were prepared with different carotenoid enriched-flaxseed oil concentrations (6%, 9%, 12%, and 15% w/w) and ratios of maltodextrin/(pectin+wax) (3:1, 6:1, 9:1, and 12:1 g/g). Percentage separation of 12% oil 12:1 ratio of maltodextrin/(pectin+wax) (g/g), 15% oil 9:1, and 12:1 ratios of maltodextrin/(pectin+wax) (g/g) of emulsions was determined as 2.0 ± 0.5%, 4.0 ± 0.5%, and 8.0 ± 0.5%, respectively. No separation was observed in other emulsions. The rheological behavior of emulsions was best described by the power law model. When the concentration of pectin+wax in the emulsion decreased, the n values of the emulsions were close to 1, indicating that the fluid behavior approaches Newtonian behavior. Moreover, the emulsion viscosity was observed to increase when pectin and wax concentrations in the emulsion increased. The increase in pectin and wax concentration in emulsions with oil contents of 6% and 9% resulted in a reduction in the average particle size. However, if the oil concentration in the emulsions was 12% or more, the increase in the ratio of maltodextrin/(pectin+wax) (g/g) led to a decrease in the average particle size. NMR transverse relaxation times (T₂ ) of emulsions were measured and results showed that T₂ values for almost all formulations decreased when the ratio of maltodextrin/(pectin+wax) reduced. PRACTICAL APPLICATION: Study results demonstrated that the combination of pectin and wax together with maltodextrin as a filling material could be an alternative way to improve emulsion stability. Findings of this study provided useful guidance for the future studies about the potential use of pectin, wax, and maltodextrin as wall material in encapsulation of oils or in producing edible films.

Comparison of physicochemical and mechanical properties of edible films made from navy bean and corn starches

BACKGROUND

Recently, there has been a great interest in developing new applications of edible dry beans (Phaseolus vulgaris L.). The utilization of starch, comprising the major component of dry bean seeds, for the preparation of edible films has just emerged.

RESULTS

In the present study, we chose navy bean as a model dry bean source, isolated its starch component, prepared edible films with different formulations (35 and 40 g L^-1 ), and compared these with the films made using isolated and commercial corn starches. Sunflower oil at 10 g L^-1 was dispersed into film-forming solution to design composite films. The water vapor barrier property, mechanical properties and microstructure of starch films from navy bean and corn were studied to evaluate their potential for use in food packaging. All of the films had smooth and uniform surface and were transparent.

CONCLUSION

Navy bean starch film showed physicochemical and mechanical properties comparable to corn starch films, and the addition of sunflower oil could further improve the water vapor barrier and mechanical properties of films. The findings obtained in the present study demonstrate the potential of using navy bean starch to prepare edible films. © 2020 Society of Chemical Industry.

Preparation and characterization of ethyl cellulose film modified with capsaicin

Pure ethyl cellulose film cannot extend the shelf life of food, and adding capsaicin as an antibacterial agent can inhibit the activity of microorganisms on the surface of the film. The main purpose of this work is to study the properties and specific performance of the film formed by adding capsaicin to ethyl cellulose system. Importantly, the transparent, soft, and stretchable ethyl cellulose-capsaicin composite membrane (EC-Cap) is generally easy to produce and is environmentally friendly. It is the first successful preparation by a casting method. It is worth noting that the FTIR analysis of the film shows that there may be an interaction between the phenolic hydroxyl group in Cap and the hydroxyl group in EC, which means that Cap has successfully participated in the film formation system. Therefore, the cap-containing film not only exhibits a low water absorption, when the cap is appropriate, the elongation at break of the film reaches a maximum of 61.34 % ± 1.37 %. Compared with pure EC membrane, EC-Cap membrane has greater antibacterial activity than pure EC membrane. The practical application of EC-Cap films in the protection of bell peppers has shown positive results, which makes it possible to apply these films to food packaging.

Effect of Tea Polyphenols on Curdlan/Chitosan Blending Film Properties and Its Application to Chilled Meat Preservation

Incorporating phenolic acids into polysaccharide films improves their physical properties, in turn improving their potential commercial applicability as a preservation material for different foods. This study aimed to develop films from curdlan and tea polyphenols, and determine the effect of their contents on the water vapor permeability (WVP) and mechanical properties (tensile strength and elongation at break) of the films. Different ratios of tea polyphenols were incorporated into the curdlan-based films to improve their properties. The results obtained showed that the tensile strength and elongation at break of films were likely to be significantly decreased by adding tea polyphenols, especially at a content of 0.6%, which resulted in a 50% decrease. Meanwhile, the WVP and moisture content of the films was also decreased. However, a low WVP can prevent moisture loss from food. Other film properties, such as antioxidant efficiency, were also investigated. The results showed that the antioxidant potential of the film can be improved by tea polyphenols. The composite films were also applied to the preservation of chilled meat, which resulted in the shelf life being extended by about 3–5 days. Some properties, such as water resistance and DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging capacity of the composite film, were improved.

Shelf life extension of fresh fruit and vegetables by chitosan treatment

Among alternatives that are currently under investigation to replace the use of synthetic fungicides to control postharvest diseases in fresh produce and to extend their shelf life, chitosan application has shown promising disease control, at both preharvest and postharvest stages. Chitosan shows a dual mode of action, on the pathogen and on the plant, as it reduces the growth of decay-causing fungi and foodborne pathogens and induces resistance responses in the host tissues. Chitosan coating forms a semipermeable film on the surface of fruit and vegetables, thereby delaying the rate of respiration, decreasing weight loss, maintaining the overall quality, and prolonging the shelf life. Moreover, the coating can provide a substrate for incorporation of other functional food additives, such as minerals, vitamins, or other drugs or nutraceutical compounds that can be used to enhance the beneficial properties of fresh commodities, or in some cases the antimicrobial activity of chitosan. Chitosan coating has been approved as GRAS substance by USFDA, and its application is safe for the consumer and the environment. This review summarizes the most relevant and recent knowledge in the application of chitosan in postharvest disease control and maintenance of overall fruit and vegetable quality during postharvest storage.

Chitosan films and coatings containing essential oils: The antioxidant and antimicrobial activity, and application in food systems

Chitosan edible films and coatings have shown great promise for their application in food preservation and also are promising systems to be used as essential oil (EO) carriers. This review reports the most recent and relevant studies concerning chitosan films and coatings containing EOs. The effect of EO incorporation on the antioxidant, antibacterial and antifungal activities of chitosan films and coatings in vitro and in vivo, as well as their applications in food systems have been discussed. In general, incorporation of EOs significantly increased the antioxidant, antibacterial and antifungal efficacy of chitosan films and coatings in vitro. EO-incorporated films and coatings also showed greater effectiveness against postharvest fungi and foodborne bacteria in food systems than pure films and coatings. The application of chitosan films and coatings containing EOs usually led to an extension of the shelf-life and reduction of lipid peroxidation of fish and meat products over pure chitosan films and coatings. In addition, chitosan coatings incorporated with EOs were more effective in maintaining fruit and vegetable quality, and controlling their postharvest decay during storage and shelf life than pure chitosan coatings.

Preparation of Modified Films with Protein from Grouper Fish

A protein concentrate (PC) was obtained from Grouper fish skin and it was used to prepare films with different amounts of sorbitol and glycerol as plasticizers. The best performing films regarding resistance were then modified with various concentrations of CaCl₂, CaSO₄ (calcium salts), and glucono-δ-lactone (GDL) with the purpose of improving their mechanical and barrier properties. These films were characterized by determining their mechanical properties and permeability to water vapor and oxygen. Formulations with 5% (w/v) protein and 75% sorbitol and 4% (w/v) protein with a mixture of 15% glycerol and 15% sorbitol produced adequate films. Calcium salts and GDL increased the tensile fracture stress but reduced the fracture strain and decreased water vapor permeability compared with control films. The films prepared represent an attractive alternative for being used as food packaging materials.

Drop Printing of Pharmaceuticals: Effect of Molecular Weight on PEG Coated-Naproxen/PEG3350 Solid Dispersions

Solid dispersions have been used to enhance the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). However, the solid state phase, compositional uniformity, and scale-up problems are issues that need to be addressed. To allow for highly controllable products, the Drop Printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two/three dimensional structures. In this study, DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG3350) solid dispersions with PEG coatings of different molecular weights (MW). A comparison of moisture-accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy (SEM), second harmonic generation (SHG) microscopy, and differential scanning calorimetry (DSC) analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis (TGA) was employed to measure the water content within each sample. The results suggest that the moisture-accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API.

Dynamics of moisture diffusivity in solid triacylglycerol matrices

The effects of lipid formulation in combination with two crystallization conditions, shearing and non-shearing, on the mechanism of water diffusivity were investigated. Five formulations of lipid which varied in fatty acid compositions, solid fat particles, and emulsifier levels were assessed at 5, 20, and 30°C. Polarized light microscopy was used to study microstructural properties of the samples under dynamic and static conditions; and their moisture permeability was examined using gravimetric technique (ASTM E-96). All formulations and crystallization techniques were confirmed to have a large impact on the crystallization properties and dynamics of moisture migration. Dynamic crystallized samples showed altered structures with different patterns of crystalline clusters. Different values of water diffusivity suggested that shearing affected moisture diffusivity of the samples differently. This effect of shearing was more pronounced in the presence of lecithin. A higher migration rate was observed in sheared samples that contained higher amount of long chain saturated fatty acids.

Characterization of multilayered and composite edible films from chitosan and beeswax

Chitosan-based edible films were prepared and subjected to cross-linking reactions using sodium tripolyphosphate and/or to beeswax coating on both films interfaces. In addition, chitosan–beeswax emulsion-based films were produced. The goal of these modifications of the chitosan films was the improvement of their barrier to water vapor and to decrease their affinity to liquid water maintaining or improving the mechanical and optical properties of the original chitosan films. The cross-linking with tripolyphosphate decreased both the water vapor permeability and the water absorption capacity to about 55% and 50% of that of the original chitosan films, respectively. However, there was an increase in the films stiffness, revealed by the increased Young modulus from 42 kPa up to 336 kPa. The multilayered wax–chitosan–wax films exhibited a similar improvement of the barrier properties to water vapor, with the advantage of maintaining the mechanical properties of the original chitosan films. However, these wax-coated films showed a higher water absorption capacity, which is believed to be a consequence of water entry into small pores between the film and the wax layers. Regarding the film samples subjected to cross-linking and further coating with beeswax, a similar behavior as the uncoated cross-linked films was observed. The emulsion-based composite films were characterized by a substantial decrease of the water vapor permeability (40%), along with a decrease in their stiffness. Regarding the optical properties, all films presented a yellowish color with similar values of lightness, chroma, and hue.