κ-Carrageenan films derived from Euchema cottoni containing different types and concentrations of emulsifier were developed. Film formation without the addition of emulsifier was used as a control. The physical, mechanical, optical and microstructural properties of these films were determined. Different types of emulsifiers (Tween 20, Tween 40 and Tween 80) exerted significant effects (P≤0.05) on the thickness, moisture content and opacity of the films. Additionally, Tween 20 and Tween 40 with concentrations from 0.1 to 0.5% (v/v) significantly (P≤0.05) improved the tensile strength of the films, ranging from 7.35 to 13.83MPa. The water vapor permeability of the carrageenan films was significantly (P≤0.05) affected by both factors. Increasing the emulsifier concentration also caused an increment in the number of lipid droplets contributing to a smooth surface. Therefore, this study suggests that different types and concentrations of emulsifiers play essential roles in determining the physical properties of carrageenan films.
This study investigated the effects of different types of plant oil (olive oil, corn oil, soybean oil and sunflower oil) on the physical and mechanical properties of kappa-carrageenan films from Euchema cottoni species. The incorporation of plant oils increased the film thickness significantly (P<0.05). However, the moisture content, solubility and tensile strength of films decreased significantly (P<0.05) as plant oils were added. The incorporation of plant oils also contributed to a plasticizing effect, whereby the values for elongation at break increased significantly (P<0.05), from 22.3% to 108.8%. Higher oil content also led to carrageenan films with lower opacity, which contradicted with previous studies. In conclusion, the plant oils used in this research significantly improved film properties, thus demonstrating the potential of these materials to be used as food packaging films and coatings.
The manufacture and potential application of biodegradable films for food application has gained increased interest as alternatives to conventional food packaging polymers due to the sustainable nature associated with their availability, broad and abundant source range, compostability, environmentally-friendly image, compatibility with foodstuffs and food application, etc. Gelatin is one such material and is a unique and popularly used hydrocolloid by the food industry today due to its inherent characteristics, thereby potentially offering a wide range of further and unique industrial applications. Gelatin from different sources have different physical and chemical properties as they contain different amino acid contents which are responsible for the varying characteristics observed upon utilization in food systems and when being utilized more specifically, in the manufacture of films. Packaging films can be successfully produced from all gelatin sources and the behaviour and characteristics of gelatin-based films can be altered through the incorporation of other food ingredients to produce composite films possessing enhanced physical and mechanical properties. This review will present the current situation with respect to gelatin usage as a packaging source material and the challenges that remain in order to move the manufacture of gelatin-based films nearer to commercial reality.
Fresh-cut fruits are popular due to the convenience provided. However, fresh-cut processes damage fruit tissues and reduce the shelf life of products. Pulsed light (PL) treatment is a decontamination method of foods. PL treatment given repetitively at a certain interval during storage could further extend the shelf life of fresh-cut fruits. Edible coating preserves fresh-cut fruits by providing mechanical strength and reducing respiration and water loss. This study was to evaluate the effects of alginate coating combined with repetitive pulsed light (RPL) on sensory quality and flavour of fresh-cut cantaloupes during storage. Cantaloupes were treated with alginate (1.86%, w/v) and RPL (0.9 J/cm2 at every 48 h up to 26 days) alone or in combination. Flavour analysis of fresh-cut cantaloupes was carried out every 12 days during storage at 4 ± 1 °C while sensory analysis was performed on day 32. Alginate coating and/or RPL retained sugar contents (17.92-20.01 g/kg FW for fructose, 18.77-19.98 g/kg FW for glucose and 23.02-29.41 g/kg FW for sucrose) in fresh-cut cantaloupes during storage. Combination of alginate with RPL reduced accumulation of lactic acid although alginate coating was more effective to minimise changes of other organic acids in fresh-cut cantaloupes. The combined treatment was also more effective than individual treatment in retaining total aroma compound concentration of fresh-cut cantaloupes during storage with the highest relative concentration, i.e. 3.174 on day 36. Overall, the combined alginate coating and RPL was effective to maintain the fresh-like sensory quality of fresh-cut cantaloupes with insignificant overall acceptability compared to the control.
The aim of this study was to investigate the effect of cut type and pulsed light (PL) fluence on microbiological stability and quality of fresh-cut cantaloupes. Fresh-cut cantaloupes with various cut types (cuboid, triangular prism and sphere) were treated with PL technology at 6 J/cm(2). Samples were exposed to PL treatment at fluences of 2.7, 7.8, 11.7 and 15.6 J/cm(2) followed by storage at 4 ± 1 °C for 28 days. Microbiological quality, headspace composition, firmness, colour, pH, titratable acidity, total soluble solids, total phenolic content and ascorbic acid content of fresh-cut cantaloupes were determined. Spherical shape was found to be the most suitable shape for PL treatment of fresh-cut cantaloupes due to its significantly lowest (p ≤ 0.05) microbial counts before and after the PL treatment. No significant (p > 0.05) effect was observed for firmness, colour, total soluble solids and total phenolic content of fresh-cut cantaloupes throughout the storage study. Pulsed light treatment using 7.8 J/cm(2) was the best for extending shelf life of fresh-cut cantaloupes with extension of 8 days longer at 4 ± 1 °C compared to the control while maintaining the ascorbic acid content. In conclusion, PL treatment is a potential technique for extending the shelf life of fresh-cut cantaloupes by inactivating microorganisms without compromising the nutritional value.
This study was to investigate the effects of optimised alginate coating combined with repetitive pulsed light (RPL) on cell wall composition of fresh-cut cantaloupes during chilled storage. Fresh-cut cantaloupes were coated with alginate (1.86%, w/v) followed by RPL treatment (0.9 J cm-2 at every 48 h up to 26 days) during storage of 36 days. Cell wall composition of fresh-cut cantaloupes was determined at every 12 days while microscopic analysis was conducted on day 2 and day 36. Alginate was effective in maintaining high pectin fractions of fresh-cut cantaloupes while RPL showed greater contribution in maintaining hemicellulose fraction. However, the combination of alginate and RPL was the most effective treatment to maintain the overall cell wall fractions that contributed to the cell wall integrity of fresh-cut cantaloupes during storage. The alginate + RPL samples also had the greatest cell turgidity and shape with well-defined cell walls at the end of storage.
The objectives of this study were to develop composite films using various gelatin sources with corn oil (CO) incorporation (55.18%) and to investigate the mechanical and physical properties of these films as potential packaging films. There were increases (p < 0.05) in the tensile strength (TS) and puncture strength (PS) of films when the concentration of gelatin increased. The mechanical properties of these films were also improved when compared with films produced without CO. Conversely, the water barrier properties of composite films decreased (p < 0.05) when the concentration of gelatin in composite films increased. Comparing with pure gelatin films, water and oxygen barrier properties of gelatin films decreased when manufactured with the inclusion of CO.
The physicochemical properties of κ-carrageenan films extracted from Eucheuma cottonii (E. cottonii) incorporated with different concentrations and types of plasticizers were studied. Glycerol, sorbitol, and polyethylene glycol-300 (PEG-300) in the range of 10-60% were used as plasticizers. The results showed that the thickness and moisture content (MC) of films increased significantly (p≤0.05) with the increase in plasticizer concentration. Sorbitol-plasticized films had the lowest values. Sorbitol-plasticized films have better mechanical properties and the lowest water vapor permeability (WVP), solubility and water uptake ratio (WUR) compared with glycerol and PEG-plasticized films (p≤0.05). Fourier transform infrared (FTIR) spectra showed the intermolecular reactions between κ-carrageenan and the plasticizers in the films. Scanning electron microscopy (SEM) observations indicated that sorbitol-plasticized films have a compact structure, even at the highest concentration. The melting temperature (Tm) of films decreased (p≤0.05) with an increase in the plasticizer concentration. Here, the glycerol-plasticized films had the lowest values. X-ray diffraction (XRD) showed broad and narrow peaks of the un-plasticized κ-carrageenan film at 2θ=20.0° and 2θ=8.4°, respectively. The intensity of the broad peak increased and the narrow peak disappeared as the concentration of plasticizers increased. In conclusion, films from E. cottonii successfully produced with sorbitol as the plasticizer exhibited good physical properties as packaging films.
This review article provides a comprehensive overview of recent progress in polylactic acid (PLA) extrusion, emphasizing its applications in food packaging. PLA has witnessed a significant rise in demand, particularly within the food packaging sector. A notable increase in research publications has been observed in recent years, exploring the extrusion of PLA and PLA-based composite films. In comparison to conventional techniques such as solvent casting, extrusion offers advantages in scalability and environmental sustainability, especially for industrial-scale production. The benefits of this method include faster drying times, enhanced flexibility, consistent film thickness, and less structural defects. Extensive research has focused on the effect of various PLA blends on film properties, including flexibility, elongation, and barrier properties against water vapour and gases. Furthermore, the incorporation of compounds such as antioxidants, antimicrobials, and natural pigments has enabled the development of active and intelligent PLA-based packaging. This article summarizes the types of additives employed to enhance the physicochemical properties of extruded PLA and film performance. Additionally, this article explores the diverse applications of extruded PLA in active and intelligent packaging for various food products.