Effectiveness of Zataria multiflora Boiss essential oil and grape seed extract impregnated chitosan film on ready-to-eat mortadella-type sausages during refrigerated storage

BACKGROUND: The effectiveness of chitosan films containing Zataria multiflora Boiss essential oil (ZEO) (5 and 10 g kg^?1) and grape seed extract (GSE) (10 g kg^?1) on lipid oxidation and microbial (lactic acid bacteria, aerobic mesophiles and inoculated Listeria monocytogenes) characteristics of mortadella sausage at 4 °C for 21 days was evaluated. The release of total phenolics (TPs) into sausage was also assessed. RESULTS: All films exhibited antibacterial activity against L. monocytogenes on agar culture media. Chitosan films containing ZEO were the most effective on the growth of bacteria. The growth of L. monocytogenes was significantly inhibited by ZEO‐GSE containing films especially during storage of the sausages for 6 days. Aerobic mesophiles and lactic acid bacteria were the most sensitive and resistant groups to films by 0.1–1.1 and 0.1–0.7 log cycles reduction, respectively. Sausages wrapped by 10 g kg^?1 GSE + 10 g kg^?1 ZEO films had the lowest degrees of lipid oxidation, which was 23% lower than the control. The TPs of ZEO films decreased to zero after 6 days, whereas TPs of GSE films followed a slight decrease during the storage. CONCLUSION: Antimicrobial/antioxidant chitosan film could be developed by incorporating GSE and ZEO for extending the shelf life of mortadella sausage. Copyright © 2011 Society of Chemical Industry     

Physical properties of a barley protein/nano‐clay composite film containing grapefruit seed extract and antimicrobial benefits for packaging of Agaricus bisporus

Barley protein (BP) was extracted from barley flour, and a BP film was prepared. To improve the physical properties of the BP film, nano‐clay was incorporated. Among the films prepared, the composite film containing 4% BP/1% Cloisite Na⁺ had the best physical property. The composite film containing grapefruit seed extract (GSE) was prepared and used as a packaging film for the button mushroom. Packing of the mushroom with this film inhibited microbial growth during storage. After 7 days of storage, packaging of mushrooms with the film containing 0.7% GSE reduced the populations of total aerobic bacteria and yeast and moulds by 0.95 and 0.58 log CFU/g, respectively, compared with the control. These results suggest that the BP/Cloisite Na⁺ film containing GSE can be used as an environment‐friendly packaging for maintaining mushroom quality during storage.     

The antimicrobial,mechanical, physical and structural properties of chitosan–gallic acid films

Chitosan films incorporated with various concentrations of gallic acid were prepared and investigated for antimicrobial, mechanical, physical and structural properties. Four bacterial strains that commonly contaminate food products were chosen as target bacteria to evaluate the antimicrobial activity of the prepared gallic acid–chitosan films. The incorporation of gallic acid significantly increased the antimicrobial activities of the films against Escherichia coli, Salmonella typhimurium, Listeria innocua and Bacillus subtilis. Chitosan films incorporated with 1.5 g/100 g gallic acid showed the strongest antimicrobial activity. It was also found that tensile strength (TS) of chitosan film was significantly increased when incorporating 0.5 g/100 g gallic acid. Inclusion of 0.5 g/100 g gallic acid also significantly decreased water vapor permeability (WVP) and oxygen permeability (OP). Microstructure of the films was investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) and it was found that gallic acid was dispersed homogenously into the chitosan matrix.     

Physical properties and antioxidant activity of an active film from chitosan incorporated with green tea extract

An active film from chitosan incorporated with aqueous green tea extract (GTE) was developed. The effects of GTE concentrations including 2, 5, 10 and 20% (w/v) of green tea in the film-forming solution on the film properties were determined by measuring physical properties, total polyphenolic content and antioxidant activity of the active films. Fourier Transform Infrared (FTIR) spectrometry was carried out to observe the potential modifications of the chitosan films when incorporated with GTE. The results suggested that incorporation of GTE into chitosan films improved mechanical and water vapor barrier properties and enhanced polyphenolic content and antioxidant activity of the films. Changes in the FTIR spectra of the chitosan films were observed when GTE was incorporated, suggesting some interactions occurred between chitosan and the polyphenols from GTE. This study showed the benefits of incorporation of GTE into chitosan films and the potential for using the developed film as an active packaging.     

Development and characterisation of functional cocoa (Theobroma cacao L.)-based edible films

The aim of this study was to develop functional edible films containing cocoa (Theobroma cacao L.) powder extract using alginate, pectin and chitosan in combination with proteins (whey protein isolate, soya and hemp protein). The films were examined for their physico-chemical (dry matter content, colour, thickness), mechanical (elongation at break (EAB)), bioactive (the content of total polyphenols (TPC), flavan-3-ols (F3olC), antioxidant capacity (AC)) and sensory properties. The plain alginate film exhibited the highest EAB (29.1%). The highest TPC and F3olC were determined in plain alginate (29 mg GAE/g and 2.75 mg (+)-catechin/g) and pectin (29 mg GAE/g and 2.25 mg (+)-catechin/g) films. The addition of proteins resulted in prolonged release of polyphenols and enhanced functional properties; however, the formation of protein–polyphenol complexes caused slight alterations in the bioactive composition of the films. The obtained results indicate a high potential of the developed films as functional, biodegradable form of active food packaging.     

Effects of plasticizers and nano-clay content on the physical properties of chicken feather protein composite films

To prepare chicken feather protein (CFP)/nano-clay composite films and to evaluate the effects of various plasticizers and nano-clay concentrations on the mechanical properties of the films, CFP composite films with various concentrations of Cloisite Na⁺ were prepared, and their physical properties such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were investigated. Optimal CFP films were formed with 5 g of CFP, 0.5 g of glycerol, and 1.5 g of sorbitol in 100 mL of film-forming solution; the TS, E, and WVP of the film were 4.74 MPa, 10.08%, and 3.11 × 10⁻⁹ g m/m² s Pa, respectively. After the nano-clay was incorporated into the CFP film-forming solution, scanning electron microscopy and X-ray diffraction studies were conducted to examine the structural characteristics of the CFP/nano-clay composite films. The incorporation of nano-clay improved the physical properties of the CFP films. The TS of the CFP/nano-clay composite film containing 7% Cloisite Na⁺ increased by 1.21 MPa, and the WVP of the composite film decreased by 1.15 × 10⁻⁹ g m/m² s Pa compared to the CFP film. Therefore, these results suggest that CFP composite films can be prepared with improved mechanical property by the addition of nano-clay and used as a food packaging material in the food industry.     

Physical and antimicrobial properties of Gelidium corneum/nano-clay composite film containing grapefruit seed extract or thymol

To improve the physical properties of Gelidium corneum (GC) film, Cloisite Na⁺ and 30B were incorporated into the preparation of the film. X-ray diffraction patterns of the films indicated that a degree of exfoliation and intercalation are formed depending on the type of nano-clays and its concentration and the film structure affects the physical properties of the GC/nano-composite films. Tensile strength (TS) of the GC film was increased by the addition of nano-clays. GC film had a TS of 19.59 MPa for the control, while the GC film having 3% Cloisite Na⁺ or 30B had TS of 27.37 and 26.40 MPa, respectively. Elongation at break and water vapor permeability were also improved by the addition of 3% nano-clays. The physical properties of the film were not improved by the addition of GSE or thymol, but the additions did inhibit the growth of Escherichia coli O157:H7 and Listeria monocytogenes. The results suggest that the nano-composite films containing GSE or thymol may extend the shelf life of food.     

Antioxidant activity and physicochemical properties of chitosan films incorporated with Lycium barbarum fruit extract for active food packaging

Active packaging film was developed by incorporating Lycium barbarum fruit extract (LFE) into chitosan. The effects of LFE on physicochemical properties of the chitosan/LFE films were evaluated. When the weight ratio of LFE to chitosan was increased from 0:1 to 1:1, DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) free radical scavenging activity of the chitosan/LFE films increased near ten‐folds and reached up to 35.8%; water vapour permeability of the chitosan/LFE films decreased 43.0% from 5.67 g m mm^?2 day^?1 kPa^?1_, and water solubility decreased from 100% to 24.52% because of interactions between LFE and hydrophilic groups of chitosan confirmed by FTIR. However, the chitosan/LFE films became darker after LFE was incorporated. The pure chitosan film showed better tensile strength (23.19 MPa) and elongation at break (22.29%) than the chitosan/LFE films (15.52 MPa and 9.58% for the one with weight ratio of LFE to chitosan of 0.6:1).     

Antimicrobial and physical properties of edible chitosan films enhanced by lactoperoxidase system

Effects of lactoperoxidase system (LPOS) incorporated directly into chitosan films at different concentrations (0.5, 1 and 1.5%) were studied. Films obtained were tested on the inhibition of phytopathogenic strains such as Xanthomonas campestris pv. Mangifera indica, Colletotrichum gloeosporioides (C. 64, C. 4612 and C. 62) and Lasiodiplodia theobromae ngr 05A. Water vapor permeability and mechanical properties of films with LPOS and/or not iodine were also studied. Antibacterial effect obtained by disc diameter technique indicated that chitosan concentration at 1 and 1.5% (w/w) incorporated with LPOS and/or not iodine inhibited higher X. campestris pv. M. indica than chitosan film alone or at low concentrated of 0.5% incorporated by LPOS. The antimicrobial technique using puncture gave very good information on the antifungal effect and on the variability in susceptibility of strains of fungi. C. gloeosporioides C64 and L. theobromae were inhibited completely by 1 and 1.5% chitosan incorporated by LPOS contained or not iodine, while C. gloeosporioides C4612 was sensitive to the presence of iodine and C62 were resistant strains. The properties of chitosan films were not significantly changed by the incorporation of the enzyme system.     

Effect of carp (Cyprinus carpio) oil incorporation on water vapour permeability,mechanical properties and transparency of chitosan films

The effect of carp oil incorporation on properties of chitosan films was evaluated. Chitosan and carp oil were obtained from shrimp wastes and viscera respectively. Tests were performed with different values of chitosan: oil ratios, agitation rates, homogenisation times and pH. The optimum conditions for stability of the film–forming dispersions were of 20,000 rpm at 10 min, and 10:1 ratio of chitosan:oil. The highest values of tensile strength and elongation percentage (%E) of films were obtained at pH 3.5. The addition of carp oil in the chitosan films (10:1 ratio) showed an increase in the resistance to diffusion of water vapour (1.7 g mm m^?2 day^?1 kPa^?1) in relation to pure chitosan films (4.1 g mm m^?2 day^?1 kPa^?1). However, pure chitosan films showed better mechanical properties (38 MPa and%E 18%) and transparency than films of chitosan:oil (20.4 MPa and 8.8%).     

Effects of drying methods and conditions on antimicrobial activity of edible chitosan films enriched with galangal extract

The aim of this work was to study the effects of drying methods and conditions (i.e., ambient drying, hot air drying at 40 °C, vacuum drying and low-pressure superheated steam drying within the temperature range of 70–90 °C at an absolute pressure of 10 kPa) as well as the concentration of galangal extract on the antimicrobial activity of edible chitosan films against Staphylococcus aureus. Galangal extract was added to the film forming solution as a natural antimicrobial agent in the concentration range of 0.3–0.9 g/100 g. Fourier transform infrared (FTIR) spectra and swelling of the films were also evaluated to investigate interaction between chitosan and the galangal extract. The antimicrobial activity of the films was evaluated by the disc diffusion and viable cell count method, while the morphology of bacteria treated with the antimicrobial films was observed via transmission electron microscopy (TEM). The antimicrobial activity, swelling and functional group interaction of the antimicrobial films were found to be affected by the drying methods and conditions as well as the concentration of the galangal extract. The electron microscopic observations revealed that cell wall and cell membrane of S. aureus treated by the antimicrobial films were significantly damaged.     

Active chitosan–polyvinyl alcohol films with natural extracts

Active films were prepared from chitosan (Ch) and polyvinyl alcohol (PVA) containing aqueous mint extract (ME)/pomegranate peel extract (PE). The effect of these extracts on the physical, mechanical, antimicrobial and antioxidant properties of the films were studied. Increased protection against UV light was observed in the films containing the extracts. Addition of ME/PE improved the tensile strength of the films without affecting their puncture strength. Ch–PVA films incorporated with PE had the highest tensile strength (41.07 ± 0.88 MPa). Permeability characteristics of the films were not altered due to addition of extracts. ME/PE conferred antioxidant properties to Ch–PVA films as determined by DPPH radical scavenging activity. The films also exhibited antibacterial activity against Staphylococcus aureus and Bacillus cereus. PE containing films totally inhibited the growth of B. cereus and reduced the number of S. aureus by 2 log cycles. These results suggest that Ch–PVA film containing ME/PE can be used for development of active food packaging materials.     

Effects of nano‐clay type and content on the physical properties of sesame seed meal protein composite films

Sesame seed meal protein (SSMP)/nano‐clay composite films were prepared, and the physical properties of the films were determined. The SSMP film was prepared with 5 g of SSMP and 2 g of glycerol in 100 mL of film‐forming solution, and the tensile strength (TS), elongation (E) and water vapour permeability (WVP) of the SSMP film were 2.51 MP, 21.84% and 3.23 × 10^?9 g m m^?2s^?1 Pa^?1, respectively. Two types of nano‐clays were incorporated to enhance the physical properties of the SSMP film. The TSs of the SSMP film with 5% Cloisite Na⁺ and 7% Cloisite 10A were 6.32 and 5.76 MPa, respectively, and the WVPs of the SSMP nanocomposite films were 2.04 × 10^?9 g m m^?2s^?1 Pa^?1 compared with the SSMP film without nano‐clay, which was 3.23 × 10^?9 g m m^?2s^?1 Pa^?1. Therefore, these results indicate that the SSMP nanocomposite film can be applied in food packaging.     

Postharvest treatment of nanochitosan-based coating loaded with Zataria multiflora essential oil improves antioxidant activity and extends shelf-life of cucumber

The effects of postharvest treatment with chitosan nanoparticles (CSNPs = T1) and Zataria multiflora essential oil (ZEO) incorporated in (ZEO@CSNPs = T2), on the shelf-life extension and antioxidant activities of whole cucumbers during storage were evaluated. Coated and control cucumbers were stored at 10 ± 1 °C with 90-95% RH for 21 days. Measurements of physicochemical and microbial growth were accomplished every 3 days. After 15 days, the fruit decay in the T2 coating was 2% vs. 12 and 97.7% in the T1 coated and uncoated fruit, respectively. Significant differences were obtained for weight loss, firmness, respiration rate, DPPH-radical scavenging activity, reducing power and microbial counts (P < 0.05) during storage. There were significantly higher levels of DPPH-radical scavenging activity and reducing power in T2-treated cucumbers compared with that in the T1-treated followed by the control fruit. In conclusion the ZEO loaded CSNPs coating could improve the quality of cucumber and protect the bioactive components during storage.Industrial relevanceCucumber as a good source of antioxidants is one of the most popular and widely grown vegetable crops in the world. However, it has a short shelf-life (< 14 days) that is mainly related to firmness loss, discoloration, desiccation and fungal rot. The reduction of losses is a major objective of postharvest technology for cucumbers, which tries to utilize safe and efficacious methods to control contamination and the growth of spoiling fungi.On the other hand, the nano-/micro-encapsulation of EOs allows protection of their sensitive bioactive compounds from unfavorable environmental conditions and enhances their bioactivity during food processing and storage. So, in this study a new edible coating, consisting of Zataria multiflora essential oil (ZEO) incorporated into chitosan nanoparticles (CSNPs), was introduced to extend the shelf-life of cucumber as well as protect the bioactive compounds with antioxidant properties.     

Nanofibre-based bilayer biopolymer films: enhancement of antioxidant activity and potential for food packaging application

This study aimed to enhance the antioxidant property of biopolymer film without the incorporation of external agents. The active bilayer film with improved antioxidant activity has been developed by electrospinning zein, a prolamine of corn as nanofibre (average diameter of 286 nm) on solvent cast chitosan film. Zein nanofibres exhibited a slight increase in antioxidant activity as compared to solvent cast zein film. But, zein nanofibre coating on chitosan films significantly improved its antioxidant activity from 12.41% to 44.17%. The developed bilayer films were evaluated for its ability to prevent browning in minimally processed apple slices and compared with those of chitosan and zein films plasticised with polyethylene glycol. Higher surface to volume ratio and better affinity of zein nanofibres in the bilayer film helped enhance its anti-browning ability. Thus, zein nanofibre-coated chitosan bilayer films can be used as an effective anti-browning packaging material for the packing of minimally processed fruits.     

Antimicrobial properties of grape seed extracts and their effectiveness after incorporation into pea starch films

Chemical analysis and antimicrobial nature of grape seed extracts (GSE) and their Reisling Vitis vinifera L. application as fortificants for edible starch films were investigated. GSE possessed an antioxidant activity of 17.18 ± 1.29 mmol TROLOX equivalents g_extract⁻¹ and total phenolic content of 327.58 ± 7.24 mmol gallic acid equivalents g_extract⁻¹ mainly attributed to their flavonoid and phenolic acid composition determined by high-performance liquid chromatography accomplished to a diode array detector and a electrospray ionisation mass spectrometer in negative mode (HPLC-DAD/ESI-MS). GSE inhibited the growth of Gram-positive food-borne pathogens while Gram-negatives were not inhibited. After GSE were incorporated into pea starch films, thickness of enriched films increased and the puncture and tensile strength decreased compared to control films. Furthermore, migration of phenolic compounds from the films to different food simulants, aqueous, acidic and alcoholic solution was determined according to 89\109\EEC directive. A higher particle migration in acidic simulants was found. Finally, the effect of GSE incorporated pea starch films was tested in vitro with pork loins infected with Brochothrix thermosphacta. GSE films reduced the bacterial growth in 1.3 log colony forming units mL⁻¹ after 4 days incubation at 4 °C.     

Effects of essential oil on the water binding capacity,physico-mechanical properties,antioxidant and antibacterial activity of gelatin films

Gelatin films were prepared from gelatin solutions (10% w/v) containing Zataria multiflora essential oil (ZMO, 2, 4, 6 and 8% w/w of gelatin). Scanning electron microscopy observations indicate that ZMO droplets were well dispersed in the film matrix. Water solubility, water swelling, water uptake, water vapor permeability, tensile strength, elongation at break and Young's modulus for gelatin films were 27 ± 0.8%, 391 ± 11%, 135 ± 5%, 0.22 ± 0.014 g mm/m² kPa h, 4.4 ± 0.4 MPa, 125 ± 7% and 8.8 ± 0.4 MPa, respectively. Incorporation of ZMO into gelatin films caused a significant decrease in swelling and water uptake and increase in solubility and water vapor permeability, a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus of the films, dose-dependently. Gelatin/ZMO showed UV–visible light absorbance/transmission ranging from 280 to 480 nm with maximum absorbance at 420 nm. Gelatin films exhibited very low antioxidant activity while, gelatin/ZMO films exhibited excellent antioxidant properties. The gelatin/ZMO films also exhibited excellent antibacterial properties against both Gram-positive and Gram-negative bacteria. Our results suggested that the gelatin/ZMO films could be used as an active film due to its excellent antioxidant and antimicrobial properties for food packaging applications.     

Composite and bi-layer films based on gelatin and chitosan

The aims of this work were: to develop composite, bi-layer and laminated biodegradable films based on gelatin and chitosan, to determine film barrier and mechanical properties and to characterize their microstructure.Gelatin and chitosan concentrations used were 7.5% and 1% (w/w), respectively. Glycerol (0.75%) was added as plasticizer.Physicochemical properties such as moisture content, transparency and color were analyzed. Composite and bi-layer systems showed a compact structure indicating a good compatibility between components.Water vapor permeability (WVP) was independent of film thickness up to 120 μm for gelatin films and 60 μm for chitosan ones. Both, bi-layer and laminated systems resulted effective alternatives to reduce WVP of composite films (at least 42.5%). Bi-layer systems showed better mechanical properties than laminated ones. The resistance at break increased from 54.3 for composite to 77.2 MPa for bi-layer films, whereas elongation at break values of both composite and bi-layer films were similar (2.2–5.7%).     

Physical properties of a composite film containing sunflower seed meal protein and its application in packaging smoked duck meat

Sunflower seed meal protein (SP) films were prepared using various plasticizers, cross-linking agents, Cloisite Na⁺ or red algae, and their physical properties, such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were determined. The TS, E, and WVP of the SP film containing sucrose and fructose (2:1) as a plasticizer and cinnamaldehyde as a cross-linking agent were 3.05 MPa, 34.42%, and 2.25 × 10⁻⁹ g m/m² s Pa, respectively. The incorporation of Cloisite Na⁺ improved the physical properties of the SP film. The TS of the SP/Cloisite Na⁺ composite film containing 3% Cloisite Na⁺ increased by 2.19 MPa, and the WVP of the composite film decreased by 0.52 × 10⁻⁹ g m/m² s Pa compared to the SP film. The incorporation of red algae also improved the TS of the SP film. The TS of the SP composite film containing 1.2% red algae increased by 3.82 MPa compared to the SP film. In addition, an SP/red algae composite film containing grapefruit seed extract (GSE) was prepared and used in food packaging. After 12 days of storage, the population of Listeria monocytogenes inoculated on smoked duck meats packed with the SP/red algae composite film containing 1.2% GSE decreased by 1.31 log CFU/g compared to the control packaging. Therefore, these results suggest that SP composite films can be prepared by the addition of red algae to the SP film–forming solution and that the SP/red algae composite film containing GSE can be used as an antimicrobial food packaging material.     

Physico-mechanical properties of chitosan films with carvacrol and grape seed extract

The physico-mechanical properties of 3 films composed by carvacrol, grape seed extract (GSE) and chitosan in different proportions were studied. The films, prepared by solvent casting technique with the following compositions of the casting solutions in carvacrol, GSE and chitosan: film-1: 9.6 ppm–684 ppm–1.25% w/v, film-2: 60 ppm–400 ppm–1.2% w/v and film-3: 90 ppm–160 ppm–1.24% w/v and were compared to a control (1.25% w/v chitosan) film. Mechanical, structural, barrier and colour properties of the films were evaluated. Film-3 presented the lowest water vapour and carbon dioxide permeabilities (WVP and CO₂P) and tensile strength (TS) values and the highest oxygen permeability (O₂P), whereas film-1 presented the highest water content and the lowest crystallinity, CO₂P, TS and luminosity. These results suggest that in the range studied, carvacrol and GSE affect the film structure and its mechanical properties due to hydrophilic (GSE) and hydrophobic (carvacrol) compounds. This work will help the development of edible films, based on physico-mechanical properties, contributing to food preservation and shelf-life extension.