COMPARATIVE STUDY ON DEGRADATION OF POLYLACTIC ACID/ SYZYGIUM AROMATICUM COMPOSITES AGEING IN OUTDOOR ENVIRONMENT AND SOIL BURIAL

Major environmental problems resulting from non-degradable components of plastic wastes have awakened great attention to bioplastic as an alternative material. Among various bioplastic materials, polylactic acid (PLA) is recognised as a promising material especially as a food packaging material. The development of PLA composites using various fillers has extensively been in focus in order to preserve the high quality, safety, and extended shelf-life of packed food. Among the interesting fillers is Syzygium aromaticum (SA). SA, also known as clove, has biological activities such as antibacterial, antifungal, insecticidal, and antioxidant properties. This work investigated the effects of SA filler on the degradations of virgin PLA (VPLA) and recycled PLA (RPLA). The VPLA/SA composites and RPLA/SA composites were prepared using the solvent casting method. The content of SA filler varied in the range of 0 to 20 wt%. The composites were aged in outdoor environment and soil burial. The results revealed that the degradation rate was increased with the increase of SA filler in both ageing environments. After 10 weeks of ageing in the outdoor environment, the weight loss of VPLA/SA composites and RPLA/SA composites containing 20 wt% of SA were 7.7% and 12.8% respectively. Whereas in soil burial, the weight loss of VPLA/SA composites and RPLA/SA composites with similar SA content were 25.6% and 38.3% respectively. The degradation rate was observed to be more rapid in the soil burial as compared to the outdoor environment. Comparably, RPLA and RPLA/SA composites experienced higher degradation rates than VPLA and VPLA/SA composites. The degradation rate was consistent with scanning electron microscope (SEM) images which observed the formation of holes, cavities, cleavages, and grooves on the surfaces of the samples. Thermogravimetric analysis (TGA) results on aged samples showed that VPLA/SA composites and RPLA/SA composites that had aged in soil burial decomposed at lower temperatures. The shortening of degradation time of the VPLA/SA composites and RPLA/SA composites could increase their potential to be used as food packaging materials. ABSTRAK: Masalah utama terhadap alam sekitar yang disebabkan oleh sisa plastik yang sukar terurai, telah menarik perhatian terhadap bioplastik sebagai bahan alternatif. Di antara pelbagai jenis bahan bioplastik sedia ada, asid polilaktik(PLA) dilihat sebagai bahan yang paling sesuai terutamanya sebagai bahan pembungkusan makanan. Perkembangan di dalam penghasilan komposit asid polilaktik yang ditambah dengan pelbagai bahan pengisi telah menjadi fokus terutamanya bagi tujuan meningkatkan kualiti, kesegaran dan jangka hayat makanan. Salah satu pengisi yang mendapat perhatian adalah Syzygium aromaticum (SA). SA yang juga dikenali sebagai bunga cengkeh mempunyai aktiviti biologi, seperti sifat antibakteria, antijamur, racun serangga dan antioksidan yang tinggi. Didalam kajian ini, siasatan terhadap kesan penambahan SA terhadap penguraian PLA asal (VPLA) dan PLA kitar semula (VPLA). Komposit VPLA/SA dan komposit RPLA/SA disediakan dengan menggunakan kaedah pelarutan pelarut. Kandungan pengisi SA adalah didalam julat 0 – 20% mengikut berat. Komposit tersebut dibiarkan menua didalam persekitaran luaran dan didalam tanah. Keputusan kajian mendapati bahawa kadar penguraian semakin meningkat dengan penambahan peratus berat bahan pengisi SA setelah melalui penuaan didalam kedua-dua persekitaran. Setelah penuaan selama10 minggu di dalam persekiran luaran, pengurang berat komposit VPLA/SA dan komposit RPLA/SA yang mengandungi 20 wt% SA adalah 7.7% dan 12.8%. Manakala bagi penuaan didalam tanah, pengurangan berat komposit VPLA/SA dan komposit RPLA/SA dengan kandungan SA yang sama masing-masing adalah 25.6% dan 38.3%. Kadar penguraian diperhatikan lebih cepat bagi penuan didalam tanah dibandingkan dengan penuaan didalam persekitaran luaran. Disamping itu, RPLA dan komposit RPLA/SA mengalami kadar penguraian yang lebih tinggi berbanding VPLA dan komposit VPLA/SA. Kadar penguraian adalah konsisten dengan imej yang dihasilkan oleh imbasan mikroskop elektron (SEM) dimana dapat dilihat pembentukan lubang, rongga, pembelahan dan alur di permukaan sampel. Hasil analisis termogravimetri (TGA) terhadap sampel yang telah dituakan menunjukkan bahawa komposit VPLA/SA dan komposit RPLA/SA yang melalui penuaan didalam tanah terurai pada suhu yang lebih rendah. Tempoh penguraian komposit VPLA/SA dan komposit RPLA/SA yang lebih pendek ini meningkatkan potensi penggunaannya komposit ini sebagai bahan pembungkusan makanan.

Download Full-text

Development of Polylactic Acid Films with Selenium Microparticles and Its Application for Food Packaging

Coatings ◽

10.3390/coatings10030280 ◽

2020 ◽

Vol 10 (3) ◽

pp. 280

Author(s):

Rui Lu ◽

Dur E. Sameen ◽

Wen Qin ◽

Dingtao Wu ◽

Jianwu Dai ◽

...

Keyword(s):

Antioxidant Activity ◽

Antibacterial Activity ◽

Polylactic Acid ◽

Composite Membrane ◽

Food Packaging ◽

Antioxidant Properties ◽

Water Vapor Permeability ◽

Vapor Permeability ◽

Swelling Capacity ◽

Natural Element

Selenium is a natural element which exists in the human body and plays an important role in metabolism. Along with this, selenium also possesses antibacterial and antioxidant properties. Using selenium microparticles (SeMPs) in food packaging films is exceptional. In this experiment, a solution casting method was used to make film. For this purpose, we used polylactic acid (PLA) as a substrate for the formation of a film membrane while SeMPs were added with certain ratios to attain antibacterial and antioxidant properties. The effects of SeMPs on the PLA film and the value of SeMPs in food packaging film production were investigated. The effects of the SeMPs contents on the features of the film, such as its mechanical property, solubility, swelling capacity, water vapor permeability, antioxidant activity, and the antibacterial activity of the composite membrane against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) strains, were studied. The results manifest that the PLA/SeMPs films showed higher water resistance, UV resistance, antioxidant activity, and antibacterial activity than pure PLA film. When the concentration of SeMPs was 1.5 wt%, the composite membrane showed the best comprehensive performance. Although the tensile strength and elongation at break of the membrane were slightly reduced by the addition of SeMPs, the results show that PLA/SeMPs films are still suitable for food packaging and would be a very promising material for food packaging.

Download Full-text

Accelerated Weathering and Soil Burial Effect on Biodegradability, Colour and Textureof Coir/Pineapple Leaf Fibres/PLA Biocomposites

Polymers ◽

10.3390/polym12020458 ◽

2020 ◽

Vol 12 (2) ◽

pp. 458 ◽

Cited By ~ 5

Author(s):

Ramengmawii Siakeng ◽

Mohammad Jawaid ◽

Mohammad Asim ◽

Suchart Siengchin

Keyword(s):

Environmental Factors ◽

Polylactic Acid ◽

Polymer Matrix ◽

Food Packaging ◽

Radiation Temperature ◽

Morphological Properties ◽

Accelerated Weathering ◽

Light Radiation ◽

Soil Burial ◽

Texture Properties

Accelerated weathering and soil burial tests on biocomposites of various ratios of coir (CF)/pineapple leaf fibres (PALF) with polylactic acid (PLA) were conducted to study the biodegradability, colour, and texture properties as compared with PLA.The biodegradability of a lignocellulosic composite largely depends on its polymer matrix, and the rate of biodegradation depends on many environmental factors such as moisture, light(radiation), temperature and microbes. Biodegradation was evaluated by soil burial and accelerated weathering tests. Changes in physical and morphological properties were observed in the biocomposites after weathering. These results allowed us to conclude that untreated CF/PALF/PLA biocomposites would be a more favourable choice owing to their better biodegradability and are suitable for the suggested biodegradable food packaging applications.

Download Full-text

Degradation of agricultural biodegradable plastics in the soil under laboratory conditions

Soil Research ◽

10.1071/sr15034 ◽

2016 ◽

Vol 54 (2) ◽

pp. 216 ◽

Cited By ~ 15

Author(s):

D. H. Barragán ◽

A. M. Pelacho ◽

Ll. Martin-Closas

Keyword(s):

Weight Loss ◽

Microbial Activity ◽

Polylactic Acid ◽

Thermoplastic Starch ◽

Soil Microbial Activity ◽

Chemical Changes ◽

Soil Burial ◽

Soil Microbial ◽

Laboratory Conditions ◽

Cereal Flour

Mulches, usually consisting of polyethylene films, are used in agriculture to improve production. The main drawback of using polyethylene is its extremely high stability. Removing it from the field is usually not feasible, and so wastes remain accumulating in the field and pollute the environment. As an alternative, five potentially biodegradable plastic films for mulching (maize thermoplastic starch–copolyester, cereal flour–copolyester, polylactic acid–copolyester, polyhydroxybutyrate, and potato thermoplastic starch–copolyester) were tested to evaluate their degradation in an agricultural soil. Polyethylene film was used as control. A soil burial test was carried out during 6 months under laboratory conditions and film weight loss, chemical changes and soil microbial activity were monitored. Weight loss was fastest for the polyhydroxybutyrate film, followed by potato thermoplastic starch–copolyester and cereal flour–copolyester. Maize thermoplastic starch–copolyester and polylactic acid–copolyester required 5–6 months to disintegrate. Concomitant to the weight loss, chemical changes in the films and an increase in soil microbial activity were noticed. From the disintegration and biodegradation results of the biodegradable tested films, it is concluded that these films are an alternative for avoiding the soil pollution drawbacks of the polyethylene mulching films.

Download Full-text

Effect of Rubberwood Content on Biodegradability of Poly(butylene succinate) Biocomposites

International Journal of Polymer Science ◽

10.1155/2015/368341 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Hemhong Anankaphong ◽

Duanghathai Pentrakoon ◽

Jirawut Junkasem

Keyword(s):

Weight Loss ◽

Chemical Structure ◽

Physical Appearance ◽

Outdoor Environment ◽

Percentage Weight Loss ◽

Butylene Succinate ◽

Soil Burial Test ◽

Soil Burial ◽

Percentage Weight ◽

Burial Time

Poly(butylene succinate) (PBS) biocomposites incorporated with rubberwood powder (RWP) were fabricated with various RWP weight fractions (i.e., 0 to 40% wt) by injection moulding process. The soil burial test was employed to examine the biodegradability of such biocomposites under outdoor environment for 60 days. The physical appearance, percentage weight loss, chemical structure, and mechanical properties before and after the soil burial test were determined. Apparent changes in physical appearance of the biocomposites from optical micrographs were detected in terms of surface morphology and colour. The percentage of crystallinity of PBS/RWP biocomposites was studied by the X-ray diffraction (XRD) technique, and the XRD pattern revealed a decrease in percentage of crystallinity due to enhancing RWP weight fractions. This may be attributed to a presence of rubberwood powders providing more disordered molecular chain arrangement of PBS matrix and also an agglomeration of the rubberwood powder content at greater concentration as seen in SEM micrographs. With increasing RWP weight fractions and burial time, the results exhibited a considerable change in chemical structure (essentially ester linkage due to biodegradation mechanism of PBS), relatively greater percentage weight loss, and a substantial decrease in flexural properties. Consequently, the results indicate that incorporating RWP enhances biodegradability of PBS/RWP biocomposites; that is, the biodegradation rate of biocomposites increases with increasing RWP weight fractions and burial time.

Download Full-text

Resorbable Gypsum Coating on Calcium Metaphosphate for Controlled Degradation Rate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.309-311.723 ◽

2006 ◽

Vol 309-311 ◽

pp. 723-726

Author(s):

Chang Kuk You ◽

Timur R. Tadjiev ◽

Hong In Shin ◽

Kyo Han Kim ◽

Eui Kyun Park ◽

...

Keyword(s):

Weight Loss ◽

Surface Morphology ◽

Body Fluid ◽

Calcium Sulfate ◽

Degradation Rate ◽

Coating Materials ◽

Heat Treated ◽

Degradation Rates ◽

Calcium Sulfate Hemihydrate ◽

Degree Of Degradation

Five kinds of gypsums, (1) CaSO4•2H2O (caldium sulfate dihydrate; CSD), (2) CaSO4•1/2H2O (calcium sulfate hemihydrate; CSH), (3) CaSO4 (calcium sulfate anhydrite; CSA), (4) CSH200 (CSH heat-treated at 200°C after self-hardening), and (5) CSH600 (CSH heat-treated at 600°C after self-hardening) were used as candidates for coating materials on calcium metaphosphate (CMP) scaffod to control degradation rate of CMP and to extend degradation limit. The disks of CSD, CSH, CSA, CSH 200, and CSH600 were prepared by self-hardening after mixing with water, where CSH200 and CSH600 were heat-treated at 200°C and 600°C, respectively. In order to control fast resorption rate of gypsum, CMP-CSA composites were prepared with different CSA contents such as 0, 5, 10, 20, 30, 50, and 70 vol% and heat-treated at 900°C for 4 hours. The degradation rates of various gypsums were evaluated in revised simulated body fluid (r-SBF) for 1, 3, 7, and 21 days, respectively. Degradation rate of each specimen was measured in terms of weight loss change with time and degraded surface morphology was examined by SEM. All kinds of gypsums were transformd into CSD after self-hardening with water. Most of gypsums were degraded by 35~60 wt% at 7 days and by 70~99 wt% at 21 days of soaking in SBF. In the group of CMP-CSA composites, the degree of degradation of them was considerably retarded compared to that of five pure gypsums. The surface morphology showed elongated needle-like crystals during the degradation with time.

Download Full-text

Towards a Bioactive Food Packaging: Poly(Lactic Acid) Surface Functionalized by Chitosan Coating Embedding Clove and Argan Oils

Molecules ◽

10.3390/molecules26154500 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4500

Author(s):

Elena Stoleru ◽

Cornelia Vasile ◽

Anamaria Irimia ◽

Mihai Brebu

Keyword(s):

Lactic Acid ◽

Food Packaging ◽

Radical Scavenging Activity ◽

Antioxidant Properties ◽

Radical Scavenging ◽

Poly Lactic Acid ◽

Syzygium Aromaticum ◽

Clove Oil ◽

Bioactive Materials ◽

Escherichia Coli Bacteria

Here we introduce a new method aiming the immobilization of bioactive principles onto polymeric substrates, combining a surface activation and emulsion entrapment approach. Natural products with antimicrobial/antioxidant properties (essential oil from Syzygium aromaticum—clove and vegetal oil from Argania spinosa L—argan) were stabilized in emulsions with chitosan, a natural biodegradable polymer that has antimicrobial activity. The emulsions were laid on poly(lactic acid) (PLA), a synthetic biodegradable plastic from renewable resources, which was previously activated by plasma treatment. Bioactive materials were obtained, with low permeability for oxygen, high radical scavenging activity and strong inhibition of growth for Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli bacteria. Clove oil was better dispersed in a more stable emulsion (no separation after six months) compared with argan oil. This leads to a compact and finely structured coating, with better overall properties. While both clove and argan oils are highly hydrophobic, the coatings showed increased hydrophilicity, especially for argan, due to preferential interactions with different functional groups in chitosan. The PLA films coated with oil-loaded chitosan showed promising results in retarding the food spoilage of meat, and especially cheese. Argan, and in particular, clove oil offered good UV protection, suitable for sterilization purposes. Therefore, using the emulsion stabilization of bioactive principles and immobilization onto plasma activated polymeric surfaces we obtained a bioactive material that combines the physical properties and the biodegradability of PLA with the antibacterial activity of chitosan and the antioxidant function of vegetal oils. This prevents microbial growth and food oxidation and could open new perspectives in the field of food packaging materials.

Download Full-text

UV Protective, Antioxidant, Antibacterial and Compostable Polylactic Acid Composites Containing Pristine and Chemically Modified Lignin Nanoparticles

Molecules ◽

10.3390/molecules26010126 ◽

2020 ◽

Vol 26 (1) ◽

pp. 126

Author(s):

Ema Cavallo ◽

Xiaoyan He ◽

Francesca Luzi ◽

Franco Dominici ◽

Patricia Cerrutti ◽

...

Keyword(s):

Polylactic Acid ◽

Food Packaging ◽

Antioxidant Properties ◽

Antibacterial Properties ◽

Nanocomposite Films ◽

Aesthetic Quality ◽

Chemically Modified ◽

Nanoparticles Dispersion ◽

Dark Color ◽

Modified Lignin

Polylactic acid (PLA) films containing 1 wt % and 3 wt % of lignin nanoparticles (pristine (LNP), chemically modified with citric acid (caLNP) and acetylated (aLNP)) were prepared by extrusion and characterized in terms of their overall performance as food packaging materials. Morphological, mechanical, thermal, UV–Vis barrier, antioxidant and antibacterial properties were assayed; appropriate migration values in food simulants and disintegration in simulated composting conditions were also verified. The results obtained indicated that all lignin nanoparticles succeeded in conferring UV-blocking, antioxidant and antibacterial properties to the PLA films, especially at the higher filler loadings assayed. Chemical modification of the fillers partially reduced the UV protection and the antioxidant properties of the resulting composites, but it induced better nanoparticles dispersion, reduced aggregates size, enhanced ductility and improved aesthetic quality of the films through reduction of the characteristic dark color of lignin. Migration tests and disintegration assays of the nanocomposites in simulated composting conditions indicated that, irrespectively of their formulation, the multifunctional nanocomposite films prepared behaved similarly to neat PLA.

Download Full-text

Nanocomposites for Food Packaging Applications: An Overview

Nanomaterials ◽

10.3390/nano11010010 ◽

2020 ◽

Vol 11 (1) ◽

pp. 10

Author(s):

Jawad Sarfraz ◽

Tina Gulin-Sarfraz ◽

Julie Nilsen-Nygaard ◽

Marit Kvalvåg Pettersen

Keyword(s):

Polymer Nanocomposites ◽

Circular Economy ◽

Food Packaging ◽

Antioxidant Properties ◽

Nanocomposite Materials ◽

Consumer Acceptability ◽

Special Focus ◽

Packaging Materials ◽

Mechanical And Thermal Properties ◽

Low Concentrations

There is a strong drive in industry for packaging solutions that contribute to sustainable development by targeting a circular economy, which pivots around the recyclability of the packaging materials. The aim is to reduce traditional plastic consumption and achieve high recycling efficiency while maintaining the desired barrier and mechanical properties. In this domain, packaging materials in the form of polymer nanocomposites (PNCs) can offer the desired functionalities and can be a potential replacement for complex multilayered polymer structures. There has been an increasing interest in nanocomposites for food packaging applications, with a five-fold rise in the number of published articles during the period 2010–2019. The barrier, mechanical, and thermal properties of the polymers can be significantly improved by incorporating low concentrations of nanofillers. Furthermore, antimicrobial and antioxidant properties can be introduced, which are very relevant for food packaging applications. In this review, we will present an overview of the nanocomposite materials for food packaging applications. We will briefly discuss different nanofillers, methods to incorporate them in the polymer matrix, and surface treatments, with a special focus on the barrier, antimicrobial, and antioxidant properties. On the practical side migration issues, consumer acceptability, recyclability, and toxicity aspects will also be discussed.

Download Full-text

Development and Characterization of Functional Starch-Based Films Incorporating Free or Microencapsulated Spent Black Tea Extract

Molecules ◽

10.3390/molecules26133898 ◽

2021 ◽

Vol 26 (13) ◽

pp. 3898

Author(s):

Surakshi Wimangika Rajapaksha ◽

Naoto Shimizu

Keyword(s):

Antioxidant Activity ◽

Lipid Oxidation ◽

Food Packaging ◽

Uv Light ◽

Antioxidant Properties ◽

Black Tea ◽

Wall Material ◽

Food Simulants ◽

Black Tea Extract ◽

Tea Extract

Antioxidant polyphenols in black tea residue are an underused source of bioactive compounds. Microencapsulation can turn them into a valuable functional ingredient for different food applications. This study investigated the potential of using spent black tea extract (SBT) as an active ingredient in food packaging. Free or microencapsulated forms of SBT, using a pectin–sodium caseinate mixture as a wall material, were incorporated in a cassava starch matrix and films developed by casting. The effect of incorporating SBT at different polyphenol contents (0.17% and 0.34%) on the structural, physical, and antioxidant properties of the films, the migration of active compounds into different food simulants and their performance at preventing lipid oxidation were evaluated. The results showed that adding free SBT modified the film structure by forming hydrogen bonds with starch, creating a less elastic film with antioxidant activity (173 and 587 µg(GAE)/g film). Incorporating microencapsulated SBT improved the mechanical properties of active films and preserved their antioxidant activity (276 and 627 µg(GAE)/g film). Encapsulates significantly enhanced the release of antioxidant polyphenols into both aqueous and fatty food simulants. Both types of active film exhibited better barrier properties against UV light and water vapour than the control starch film and delayed lipid oxidation up to 35 d. This study revealed that starch film incorporating microencapsulated SBT can be used as a functional food packaging to protect fatty foods from oxidation.

Download Full-text

Bioactive Alkaloids from Genus Aspergillus: Mechanistic Interpretation of Their Antimicrobial and Potential SARS-CoV-2 Inhibitory Activity Using Molecular Modelling

International Journal of Molecular Sciences ◽

10.3390/ijms22041866 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1866

Author(s):

Fadia S. Youssef ◽

Elham Alshammari ◽

Mohamed L. Ashour

Keyword(s):

Active Sites ◽

Biological Activities ◽

Antioxidant Properties ◽

Marine Organisms ◽

Topoisomerase Iv ◽

Angiotensin Converting Enzyme 2 ◽

Nucleotidyl Transferase ◽

In Silico Studies ◽

Best Fitting ◽

Inhibitory Potential

Genus Aspergillus represents a widely spread genus of fungi that is highly popular for possessing potent medicinal potential comprising mainly antimicrobial, cytotoxic and antioxidant properties. They are highly attributed to its richness by alkaloids, terpenes, steroids and polyketons. This review aimed to comprehensively explore the diverse alkaloids isolated and identified from different species of genus Aspergillus that were found to be associated with different marine organisms regarding their chemistry and biology. Around 174 alkaloid metabolites were reported, 66 of which showed important biological activities with respect to the tested biological activities mainly comprising antiviral, antibacterial, antifungal, cytotoxic, antioxidant and antifouling activities. Besides, in silico studies on different microbial proteins comprising DNA-gyrase, topoisomerase IV, dihydrofolate reductase, transcriptional regulator TcaR (protein), and aminoglycoside nucleotidyl transferase were done for sixteen alkaloids that showed anti-infective potential for better mechanistic interpretation of their probable mode of action. The inhibitory potential of compounds vs. Angiotensin-Converting Enzyme 2 (ACE2) as an important therapeutic target combating COVID-19 infection and its complication was also examined using molecular docking. Fumigatoside E showed the best fitting within the active sites of all the examined proteins. Thus, Aspergillus species isolated from marine organisms could afford bioactive entities combating infectious diseases.

Download Full-text