Thermoplastic starch (TPS) bioplastic, the green solution for single-use petroleum plastic food packaging - A review

A comprehensive review on starch-based sustainable edible films loaded with bioactive components for food packaging

Biopolymers like starch, a renewable and widely available resource, are increasingly being used to fabricate the films for eco-friendly packaging solutions. Starch-based edible films offer significant advantages for food packaging, including biodegradability and the ability to extend shelf life. However, they also present challenges such as moisture sensitivity and limited barrier properties compared to synthetic materials. These limitations can be mitigated by incorporating bioactive components, such as antimicrobial agents or antioxidants, which enhance the film's resistance to moisture and improve its barrier properties, making it a more viable option for food packaging. This review explores the emerging field of starch-based sustainable edible films enhanced with bioactive components for food packaging applications. It delves into fabrication techniques, structural properties, and functional attributes, highlighting the potential of these innovative films to reduce environmental impact and preserve food quality. Key topics discussed include sustainability issues, processing methods, performance characteristics, and potential applications in the food industry. The review provides a comprehensive overview of current research and developments in starch-based edible films, presenting them as promising alternatives to conventional food packaging that can help reduce plastic waste and environmental impact.

Carbon Recycling of High Value Bioplastics: A Route to a Zero-Waste Future

Today, 98% of all plastics are fossil-based and non-biodegradable, and globally, only 9% are recycled. Microplastic and nanoplastic pollution is just beginning to be understood. As the global demand for sustainable alternatives to conventional plastics continues to rise, biobased and biodegradable plastics have emerged as a promising solution. This review article delves into the pivotal concept of carbon recycling as a pathway towards achieving a zero-waste future through the production and utilization of high-value bioplastics. The review comprehensively explores the current state of bioplastics (biobased and/or biodegradable materials), emphasizing the importance of carbon-neutral and circular approaches in their lifecycle. Today, bioplastics are chiefly used in low-value applications, such as packaging and single-use items. This article sheds light on value-added applications, like longer-lasting components and products, and demanding properties, for which bioplastics are increasingly being deployed. Based on the waste hierarchy paradigm-reduce, reuse, recycle-different use cases and end-of-life scenarios for materials will be described, including technological options for recycling, from mechanical to chemical methods. A special emphasis on common bioplastics-TPS, PLA, PHAs-as well as a discussion of composites, is provided. While it is acknowledged that the current plastics (waste) crisis stems largely from mismanagement, it needs to be stated that a radical solution must come from the core material side, including the intrinsic properties of the polymers and their formulations. The manner in which the cascaded use of bioplastics, labeling, legislation, recycling technologies, and consumer awareness can contribute to a zero-waste future for plastics is the core topics of this article.

Acetylated nanocellulose reinforced hydroxypropyl starch acetate realizing polypropylene replacement for green packaging application

The use of natural starch as a replacement for petroleum-based packaging materials is limited due to its poor processability, weak mechanical properties, and strong moisture sensitivity. To address these limitations, this study adopts molecular design of hydroxypropylation and acetylation to sequentially modify natural starch, and material design of introducing acetylated cellulose nanofibers (ACNF) into the starch matrix to reinforce the material. Hydroxypropylation decreased the interaction force between the starch molecular chains, thereby reducing the glass transition temperature. Subsequent acetylation introduced hydrophobic acetyl groups that disrupted intermolecular hydrogen bonds, enhancing the mobility of the starch molecular chain, and endowed the hydroxypropyl starch acetate (HPSA) with excellent thermoplastic processability (melt index of 7.12 g/10 min) without the need for plasticizers and notable water resistance (water absorption rate of 3.0 %). The introduction of ACNF generated a strong interaction between HPSA chains, promoting the derived ACNF-HPSA to exhibit excellent mechanical strength, such as high impact strength of 2.1 kJ/m2, tensile strength of 22.89 MPa, elasticity modulus of 813.22 MPa, flexural strength of 24.18 MPa and flexural modulus of 1367.88 MPa. Its overall performance even surpassed that of polypropylene (PP) plastic, making it a potential alternative material for PP-based packaging materials.

Recent advances in reinforced bioplastics for food packaging - A critical review

Recently, diversifying the material, method, and application in food packaging has been massively developed to find more environment-friendly materials. However, the mechanical and barrier properties of the bioplastics are major hurdles to expansion in commercial realization. The compositional variation with the inclusion of different fillers could resolve the lacking performance of the bioplastic. This review summarizes the various reinforcement fillers and their effect on bioplastic development. In this review, we first discussed the status of bioplastics and their definition, advantages, and limitations regarding their performance in the food packaging application. Further, the overview of different fillers and development methods has been discussed thoroughly. The application of reinforced bioplastic for food packaging and its effect on food quality and shelf life are highlighted. The environmental issues, health concerns, and future perspectives of the reinforced bioplastic are also discussed at the end of the manuscript. Adding different fillers into the bioplastic improves physical, mechanical, barrier, and active properties, which render the required protective functions to replace conventional plastic for food packaging applications. Various fillers, such as natural and chemically synthesized, could be incorporated into the bioplastic, and their overall properties improve significantly for the food packaging application.

Comparison of anaerobic digestion of starch- and petro-based bioplastic under hydrogen-rich conditions

To identify an economically viable waste management system for bioplastics, thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) were anaerobically digested under hydrogen (H2)/carbon dioxide (CO2) and nitrogen (N2) gas-purged conditions to compare methane (CH4) production and biodegradation. Regardless of the type of bioplastics, CH4 production was consistently higher with H2/CO2 than with N2. The highest amount of CH4 was produced at 307.74 mL CH4/g volatile solids when TPS digested with H2/CO2. A stepwise increased in CH4 yield was observed, with a nominal initial increment followed by accelerated methanogenesis conversion as H2 was depleted. This may be attributed to a substantial shift in the microbial structure from hydrogenotrophic methanogen (Methanobacteriales and Methanomicrobiales) to heterotrophs (Spirochaetia). In contrast, no significant change was observed with PBAT, regardless of the type of purged gas. TPS was broken down into numerous derivatives, including volatile fatty acids. TPS produced more byproducts with H2/CO2 (i.e., 430) than with N2 (i.e., 320). In contrast, differential scanning calorimetry analysis on PBAT revealed an increase in crystallinity from 10.20 % to 12.31 % and 11.36 % in the H2/CO2- and N2-purged conditions, respectively, after 65 days of testing. PBAT surface modifications were characterized via Fourier transform infrared spectroscopy and scanning electron microscopy. The results suggest that the addition of H2/CO2 can enhance the CH4 yield and increase the breakdown rate of TPS more than that of PBAT. This study provides novel insights into the CH4 production potential of two bioplastics with different biodegradabilities in H2/CO2-mediated anaerobic digestion systems.

Effect of different proportions of glycerol and D-mannitol as plasticizer on the properties of extruded corn starch

In this study, thermoplastic starch (TPS) was prepared by melt extrusion process, in which glycerol and/or D-mannitol were used as plasticizers, and the effect of different glycerol/D-mannitol ratios (4:0, 3:1, 2:2, 1:3, and 0:4) on the physicochemical properties of the extruded starch samples was investigated. The short-range molecular order, crystallization, gelatinization, thermal stability, and thermal properties of the TPS samples were analyzed through attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), rapid visco analysis (RVA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results showed that the crystallinity and short-range molecular order of the TPS samples increased with increasing glycerol content. Conversely, the water absorption index (WAI) and water solubility index (WSI) of the TPS samples decreased with increasing glycerol content. In addition, the TPS samples with higher glycerol content exhibited higher gel and thermal stabilities. This study provides a theoretical basis for starch extrusion and plasticization in the preparation of TPS-based materials with specific properties.

Influence of Glycerol and SISAL Microfiber Contents on the Thermal and Tensile Properties of Thermoplastic Starch Composites

The increasing use of petroleum plastics has caused environmental damage due to the degradation time of these materials. An alternative to petroleum plastics could be thermoplastic starch (TPS). However, thermoplastic starch does not exhibit satisfactory tensile properties. The mechanical properties of thermoplastic starch can be improved by adding sisal microfibers. Thus, the objective of this study was to evaluate the influence of different levels of glycerol and sisal microfibers on the thermal and tensile properties of thermoplastic corn starch composites. The microfibers were obtained via mechanical treatment followed by chemical treatment (alkaline treatment and bleaching). The films were obtained by the casting method using commercial corn starch and glycerol as a plasticizing agent, reinforced with sisal microfibers. Fourier transform infrared spectroscopy (FTIR) results revealed that the addition of microfibers did not change the chemical structure of the TPS matrix. The films from the samples with 18% glycerol and 10% microfibers had the highest value for the maximum tension, equal to 4.78 MPa. The thermal decomposition profile of TPS was not altered by the addition of microfibers. Our findings demonstrated the profound influence of glycerol and microfiber contents on the tensile properties of thermoplastic starch composites.