Starch Foams Research Articles

Development of a Starch‐Based Foam System With Oxygen‐Controlled Release

AbstractCalcium peroxide (CP) offers promising applications in the food industry due to its oxygen‐donating properties. However, the rapid release of oxygen by CP needs to be addressed for fruit preservation applications. In this paper, a starch‐based foam is prepared to embed CP to alleviate this problem. Results show that the starch foam extruded at 150 °C and 150 rpm shows a high foaming ratio of 19.28 and displays a high moisture adsorption capacity of 0.21 g water/g solids when stored at 97% relative humidity (RH), which effectively regulates the water accessibility to CP. The initial oxygen release rate of the embedded CP is reduced from 0.19 to 0.07 mmol L−1 h−1, and the release time is prolonged. The wet‐stored foam shows excellent cushioning ability, with a recovery ratio higher than 72%. The starch‐based active foam with a tunable release of oxygen and cushioning properties can be used as active packaging for fresh fruit transportation and preservation.

Impact of citrus pectin on the foaming behavior, structures, and barrier properties of the starch foam blocks

The starch foam displays weak barrier properties under humid storage, which limits its applications in the food industry. In this study, citrus pectin was loaded to strengthen the starch foam. Results showed that the pectin (4 wt% ∼ 8 wt%) effectively modified the cell structures of the starch foam block. This was attributed to the increased viscosity of the starch melt during foaming and the enhanced cell stability during cooling, which was promoted by the formation of entanglements, hydrogen bonds, and ester bonds between pectin and starch, as confirmed by FTIR and DSC. Moreover, the pectin-starch foam displayed improved mechanical properties under wet storage conditions, mainly due to the limited moisture adsorption and water migration. The foam containing 4 wt% of pectin exhibited the highest compression-recovery ratio (76.7 %) and a reduced adsorbed moisture content (19.22 %) under 95 % RH. Overall, citrus pectin could improve the starch foaming process and the foam blocks barrier properties.

Optimization of starch foam extrusion through PVA polymerization, moisture content control, and CMCS incorporation for enhanced antibacterial cushioning packaging

Melt strength and moisture content are critical parameters in starch foam extrusion, as they dictate bubble expansion dynamics, which subsequently determine the foam's properties. Despite continuous advancements in the development and application of starch foams, challenges such as water resistance, mechanical strength, and antibacterial activity remain unresolved. This research investigates the influence of polyvinyl alcohol (PVA) polymerization and moisture content on the properties of extruded foam while also exploring the potential for enhancing antimicrobial functionality by incorporating carboxymethyl chitosan (CMCS) into conventional starch foams. The findings underscore the significance of melt strength and intermolecular entanglements in shaping foam characteristics, confirming that bioactive components effectively improve hydrophobicity, foaming characteristics, and antibacterial capabilities. Moreover, by precisely regulating PVA polymerization and moisture content, it became feasible to optimize foam properties and achieve the desired performance. Specifically, foam with a moisture content of 12 % and a PVA polymerization degree of 1700 exhibited exceptional performance, including the highest foaming ratio of 45.62, the minimal water absorption rate of 6.31 %, and the greatest recovery rate of 88.95 %. Furthermore, increasing CMCS concentrations substantially enhances the antibacterial properties of the foam, demonstrating its potential for application in antibacterial cushioning packaging and emphasizing its versatility and practicality.

Study on hydrophobic modification of starch‐based foam with fumigating and spraying

AbstractTo enhance water resistance of starch‐based foam, based on the porous and irregular surface feature of foam, fumigating hexamethyldisilazane (HMDS) and spraying nano‐SiO2/ethanol solution were utilized to enhance hydrophobic properties of the starch‐based foam. Homemade starch‐molded foams were used for hydrophobic modification studies, the results showed that fumigating HMDS can lead to the formation of “Si‐O‐C” bonds between HMDS and starch. Additionally, it can form more stable “Si‐O‐Si” bonds with nano‐SiO2 in the original composites, which can better adhere to the surface of the starch foam to effectively create a waterproof barrier layer. On the basis of HMDS fumigation modification, hydrophobicity was significantly enhanced by further spraying of nano‐SiO2/ethanol solution. When the mass ratio of nano‐SiO2 to ethanol was 6:100, the combination of HMDS and nano‐SiO2 was optimal, while making the roughness of the foam surface suitable, at which time, the contact angle reached 155°, the maximum value under this system, indicating that the hydrophobicity was optimal. The fumigation and spraying method can evenly and comprehensively act on the surface of the porous and irregular starch‐based foam, which facilitates the waterproof post‐treatment process of the industrial application process and has strong practical significance.Highlights Fumigated with HMDS, the starch foam's exhibit some hydrophobic effect. Fumigation followed by spraying is effective in enhancing the hydrophobicity of starch foams. Both the fumigation method and the spray method are suitable for the post‐treatment of hydrophobic of starch foams.

Biodegradable starch foams reinforced by food-chain side streams

Biodegradable starch foam trays offer an eco-friendly substitute for petroleum-based single-use packaging, notably polystyrene foams. However, they lack flexibility, tensile strength, and water-sensitivity, addressable through lignocellulosic reinforcement. This study aimed to develop biodegradable starch foam trays filled with different food-chain side streams for sustainable alternative packaging. Corncob, soybean straw, cassava peel, araucaria seed hull, yerba mate stalks and yerba mate leaves petiole were collected, dried and ground to <250 μm. The trays were filled with 13 % (w/w) of each food-chain side streams and produced by hot molding. The trays morphology, moisture, water activity (aw), thickness, bulk density, tensile strength, elongation at break, Young's modulus, bending strength, maximum deflection, and sorption isotherms were investigated. Reinforcements slightly increased the foams bulk density, reduced the tensile strength and maximum deflection and while bending strength increased from 0.20 MPa to 1.17–1.80 MPa. The elasticity modulus decreased by adding any filling, that resulted in ductility improvement; however, these packaging have moisture-sensitive material especially for aw higher than 0.52, which drives the use recommendation for dry products storage or shipping/transport. The biodegradable starch foam trays filled with side streams were successfully produced and offer excellent alternative to petroleum-based packaging low-density material with bending strength improved.

Evaluating how citrus fiber affects the cell structure and functions of starch-based foam

This work used a proper content of citrus fiber (10 wt% ∼ 30 wt%, dry starch base) to improve the cell structures and functions of starch foam. The insoluble fiber promoted cell nucleation in the starch melt, whereas the soluble pectin improved the starch matrix's strength by forming ester bonding with starches as confirmed by FTIR results. This effectively modified the starch foaming process and endowed the obtained foams with an increased cell density (from 83.37 to 123.44 cell/cm3×104) and a reduced foam density (from 0.457 to 0.142 g/cm3). The foam containing 20 wt% citrus fiber exhibited the highest expansion ratio of 5.20. Due to the improved structures and the tortuous path effect of cellulose crystals, the prepared foams significantly presented a strengthened compression performance and improved moisture resistance. Meanwhile, the fiber-loaded foams displayed a high free radical-scavenging activity (60.30 % ∼ 85.75 %), showing good antioxidant activity. It is therefore believed that this study could provide a facile and green way for producing starch-based foams with desirable functions.

The effect of agar from the seaweed Gracilaria fisheri on properties of biodegradable starch foam

This work focuses on the potential of agar from the seaweed Gracilaria fisheri to modify the properties of starch foam. The effects of different ratios of glycerol and agar on the properties of starch foams were investigated. All formulations used in this study produced easy-to-handle, smooth, single-use foam trays with no visible cracks. The addition of agar slightly affected the off-white color of the foam but red and yellow color values significantly decreased with increments of agar content. As the agar content was increased, the foam became less dense. A foam produced at a glycerol:agar ratio of 3:7 exhibited the highest values of flexural stress at maximum load (3.23 MPa), modulus (194.46 MPa) and hardness (97.50), and the highest temperature at maximum weight loss (Tmax) (337 °C). Therefore, starch foam modified with agar from Gracilaria fisheri showed suitable physical, mechanical and thermal properties for food packaging, and could possibly be used in the place of expanded polystyrene (EPS) foam.

Biodegradable Foam from Cassava Starch Blended with Water Hyacinth Fiber: Effects of Polyvinyl Alcohol Content

Abstract Our previous investigation revealed that the addition of water hyacinth fiber (WHF) and polyvinyl alcohol (PVA) enhanced the mechanical properties of cassava starch-based foam. However, the effect of PVA concentration on the mechanical properties of starch foam is still unclear. Therefore, this study examined the effects of various concentrations of PVA on the foam’s quality and production process. Four levels of PVA (0, 1, 2, and 3% w/w) were tested on the mixed dough of cassava starch and 15% of WHF. The foam was made by baking the dough on a thermopressing machine at a temperature of 190 °C for 3 min. The quality level of foams was determined by their physical and mechanical (compressibility, water adsorption, density, color appearance, and biodegradability) properties as well as the practicality of the dough preparation and baking processes. As a result, the addition of PVA significantly affects the mechanical properties and ease of making dough. A higher concentration of PVA contributed to a better mixture of the dough, resulting in a smoother mixing process that led to foams with stronger mechanical properties. Nevertheless, the application of 2% and 3% PVA did not make a significant difference in the mechanical and physical properties. Foam with 2% PVA showed 32 N/mm2 of compressibility, 10% water absorptivity, 12% water content, and good biodegradability, with 87% of the material lost during 30 days of burial in the soil.

Evaluation of extruded starch foam for glucose-supplying biomaterials

The survival rate of mesenchymal stem cells (MSC), a crucial factor in tissue engineering, is highly dependent on glucose supply. The purpose of this paper is to study the potential of starch foams as glucose suppliers. It is investigated through in vitro hydrolysis by amyloglucosidase in conditions that respect physiological constraints (37 °C and pH 7.4), including a duration of 21 days, and no stirring. Nine extruded starch foams with amylose contents ranging from 0 to 74 %, with various cell wall thicknesses (50 to 300 μm), and different crystallinities (0–30 %) were hydrolysed. These kinetics were fitted by a model which shows that the maximum rate of hydrolysis varies from 7 to 100 %, and which allows the rate of hydrolysis at 21 days to be calculated precisely. The results reveal the major role of amylose in glucose delivery kinetics, and the secondary roles of crystallinity and cell wall thickness of the foams. Additional hydrolysis of starch films revealed that thickness positively influences the amylose chain reorganisation during hydrolysis, which, in slows down and limits glucose delivery. A simple glucose delivery kinetics analysis procedure is proposed to select samples for testing as MSC glucose suppliers.

Pushing the Boundaries of Starch Foams: Novel Laminar Composites with Paper Reinforcement

Pushing the Boundaries of Starch Foams: Novel Laminar Composites with Paper Reinforcement

Starch Foams and Their Additives: A Brief Review

AbstractShort‐life packaging has been contributing to the increased consumption of polymers. Expanded polystyrene (EPS) is a material that is widely used in disposable packaging, however, its residue occupies a large volume, is difficult to degrade, and its recycling is expensive. That's why the interest in looking for a material of natural and biodegradable origin that can be an alternative to petrochemical‐based polymers. One possibility would be starch, which is a natural and biodegradable polysaccharide and can be extracted from different sources. However, natural starch does not have good properties for commercial application, requiring chemical modifications and/or the incorporation of additives. This article carried out a compilation of current studies that work on the development of packaging, whether film or foams, based on plasticized starch (TPS), and analyzes the influence of the incorporation of additives or treatments carried out in the starch. The blowing agent decreases foam density, cell size, and increases cell density. Incorporation of glycerol in starch foams increases the gelatinization temperature, decreases viscosity and resistance to expansion. The surfactant decreases the density and moisture absorption of the foam, the nucleating agent acted by increasing the mechanical strength and density of the foam, and decreases the absorption of water.

Effect of Silica Content on Cellular Structural and Hygroscopicity of Modified Cassava Starch Foam

AbstractThe growth in polymer production is influenced by the high demand from the packaging sector. Expanded polystyrene (EPS) is one of these materials that is widely used in disposable packaging, however, this generates waste that occupies a large volume and is difficult to degrade. Starch, a naturally occurring and biodegradable polysaccharide, may be an alternative in the search for a renewable source material. However, starch foams have some limitations related to their hygroscopicity. The objective of this study is to analyze the influence of silica content (1%, 2%, and 3%) on the cell structure and surface hygroscopicity of cassava starch foams. The foams containing starch, glycerol, and water are produced by thermo‐compression molding. Results show that, at lower contents, silica acts predominantly as a nucleating agent, generating smaller cells in the foam. At the higher silica content, it plays a more efficient role in reducing the affinity of the starch for water. The formulation with 2% silica shows the highest density (0.232 g cm−3), impact strength (2067 J m−2), and contact angle (84.8°).

Use of annatto dye extraction residue as additive in the cassava starch composite foam tray

AbstractPigment extraction from annatto seed results in large amounts of by‐products (~97%) and residual carotenoid content. In this work, composite foam trays containing 90:10 (10AR), 80:20 (20AR), and 70:30 (30AR) cassava starch: annatto residue (AR) ratios were prepared by thermopressing. The physical–chemical properties, thermal stability, antioxidant activity, and biodegradability of the composite foam trays and cassava starch foam tray (control) were measured and compared. High AR ratio (20AR and 30AR) yielded thicker (2.1–2.3 mm), denser (0.72–0.74 g/cm3), and less porous (32.5–33%) composite foam trays than the control due to incomplete cassava starch gelatinization and the presence of fibers, lipids, and proteins in AR. Thus, the composite foam trays had lower mechanical resistance (0.4–0.8 MPa) and elongation (0.4%–0.7%) than the control (2.9 MPa and 1.5%). However, addition of high AR ratio increased the foam tray resistance to water and yielded colorful foam trays with antioxidant property as measured by DPPH• (0.11 to 0.52 μM TE/100 g) and ABTS•+ (7.86–53.77 μM TE/100 g). Increasing the AR ratio in the composite foam tray delayed the biodegradation time by 17 days as compared to the control, but all the foam trays were more biodegradable than EPS. Therefore, AR has potential use in the production of bioactive composite foam trays.

Pore structure and cushioning properties of wastepaper-pulp-reinforced starch-based foams

Foamed plastics do not readily degrade, but degradable starch foam has uneven pores and poor mechanical properties. To improve the cushioning performance of starch foams, a sustainable starch-based packaging cushioning material is prepared through microwave foaming using waste corrugated paper fibers as the reinforcement material. The effects of different fiber contents on the structure and cushioning properties of starch-based foams are studied, and the possibility of replacing petroleum-based foams is discussed through comparisons with conventional cushioning materials. The results indicate that the pore structure of starch-based foaming materials can be controlled by changing the fiber dosage, and a small or excessive amount of fiber is not conducive to the uniform foaming of starch-based composite foams. When 3 g of wastepaper fiber (17.6% by weight of starch) is added, the average diameter of the starch-based foam pores is small, the pore size distribution is relatively uniform, the minimum buffer coefficient is 4.38 and the mechanical properties are closer to those of expanded polystyrene. A peak acceleration of 942.89 m/s2 is obtained from the packaging parts with starch-based foaming materials after drop testing, which reduces the impact load by nearly 50% compared with that of packaging without a cushioning liner. This has the potential to become a sustainable alternative to petroleum-based packaging foams.

Physical and Mechanical Properties of Starch Foam Reinforced with Pineapple (Ananas comosus) Leaves Powder

Investigation of capability of high potential pineapple (Ananas comosus) leaves powder (PLP) as reinforcing material on the starch-based foam production has not been reported. This study was aimed to characterize the physical and mechanical properties of starch foam formed from the mixture of cassava starch and PLP. The foams were made using a baking process on a thermo-pressing machine at temperature of 170°C and 180°C of the lower and upper mold temperature during 120 seconds. The starch foams were formulated with four different concentrations (0, 5, 10, and 15%) of PLP as reinforcement and tested for their characteristics of mechanical (compressibility) strength, water adsorption, morphological structure, density, color appearance, and biodegradability. Addition of PLP up to 15% improved the physical and mechanical properties of the foams.

Evaluating how avocado residue addition affects the properties of cassava starch-based foam trays

Avocado seed (AS) is an interesting residue for biopackaging because it has high starch content (41 %). We have prepared composite foam trays based on cassava starch containing different AS concentrations (0, 5, 10 and 15 % w/w) by thermopressing. Composite foam trays with AS were colorful because this residue contains phenolic compounds. The composite foam trays 10AS and 15AS were thicker (2.1–2.3 mm) and denser (0.8–0.9 g/cm3), but less porous (25.6–35.2 %) than cassava starch foam (Control). High AS concentrations yielded composite foam tray less puncture resistant (∼40.4 N) and less flexible (0.7–0.9 %), but with tensile strength values (2.1 MPa) almost similar to the Control. The composite foam trays were less hydrophilic and more water resistant than control due to the presence of protein, lipid, and fibers and starch with more amylose content in AS. High AS concentration in composite foam tray decreases the temperature of thermal decomposition peak corresponding to starch. At temperatures >320 °C the foam trays with AS were more resistant to the thermal degradation due to the presence of fibers in AS. High AS concentrations delayed the degradation time of the composite foam trays by 15 days.

Effect of Starch Type and Pre-Treatment on the Properties of Gelatin-Starch Foams Produced by Mechanical Foaming.

Incorporating biopolymers in packaging foams can contribute to a more circular packaging system, utilizing renewable and compostable materials. Gelatin, with its favorable physicochemical properties, allows for producing gelatin foams via mechanical foaming, a well-established and low-investment process. To improve foam properties, starch can be added to the gelatin formulation. However, the variability in the properties of starch powders can impact the polymer blend and, consequently, the properties of the dry foam. This study aimed to investigate the impact of different starch powders from different botanical origins (tapioca and corn) and treatments (native or pregelatinized) on the properties of gelatin-starch foams produced by mechanical foaming. The study successfully produced foams with densities of approximately 45-50 kg/m3 and compression properties comparable to EPS (expanded polystyrene) foams. The starch type and pre-treatment significantly influenced the properties of the foam. Pregelatinized starches exhibited slightly higher densities due to lower foamability caused by higher viscosity. Using starch exhibiting total loss of birefringence led to denser foams with greater compression properties than those with starch with a certain degree of crystallinity remaining. Therefore, selecting the appropriate starch type is crucial when developing starch-based materials to ensure optimal material and processing properties align with application requirements.

Preparation and characterization of biodegradable starch foam composite with treated Khlum fiber for food packaging

AbstractStarch foam is a completely biodegradable material that can replace petroleum‐based foams. However, starch foams are sensitive to water and have poor mechanical properties. Khlum fiber that had been alkali‐treated for 1 h (KF‐1h) showed excellent properties as a reinforcement of starch foam. KF‐1h was added to starch at loadings of 0, 1, 3, 5, and 7 wt%. The starch foam composite reinforced with 1 wt% of KF‐1h presented uniformly distributed cells of uniform size, and produced the highest values for flexural stress at maximum load (3.43 MPa), hardness (92.50), and water contact angle (122°) of the studied foams. The modulus of the starch foam composite increased with increments of KF‐1h content but the density and color of the starch foam and the biodegradation process in soil were only slightly affected. This work also demonstrated a practical application of the proposed starch foam composite as a biodegradable food container.

Research progress on the application of tristate water in preparation of starch‐based foaming materials

AbstractResearch on the preparation of starch‐based degradable foams by adding simple raw materials and using simple processes meets the requirements of modern society and market demand. Water is the most common raw material in daily life, its triple transformation is easy to achieve, and it has an important effect on many aspects of the starch foaming process. This paper presents the research results on the preparation of starch‐based foaming materials using water as an important raw material, summarizing the mechanism of the action of solid–liquid gaseous water in the plasticization, foaming, hydrophobic, and swelling processes. Water vapor fumigation of starch materials uses high temperatures to induce the inversion (or dehydration) of the hydroxyl groups distributed on the surface, reducing the water sensitivity of the starch foam surface. Finally, the development trend is analyzed and foreseen, in order to provide new ideas for the development of low‐cost methods to prepare degradable and environmentally friendly packaging materials.

The Use of New Waste-Based Plasticizer Made from Modified Used Palm Oil for Non-Glutinous Thermoplastic Starch Foam.

A novel waste-based plasticizer derived from modified used palm oil (mUPO) was successfully developed and has been used as a new plasticizer to non-glutinous thermoplastic starch foam to improve their properties. The molecular weight and hydroxyl number of the mUPO was 3150 g/mol and 192.19 mgOH/g, respectively. The effects of mUPO content ranging from 0 to 9 phr were investigated. The results revealed that the optimal mUPO content as an additive was 6 wt%. The addition of mUPO had a direct effect on the mechanical properties and thermal properties. The impact strength increased from 1.30 to 4.55 J/m, while the glass transition temperature (Tg) decreased from 70.83 to 66.50 °C by increasing mUPO from 0 phr to 6 phr in the thermoplastic starch foam. The mUPO, on the other hand, has also the potential to reduce shrinkage from 33.91 to 21.77% and moisture absorption from 5.93 to 1.73% by increasing the content from 0 phr to 6 phr in starch foam. Furthermore, the mUPO helps the forming of the foam structure as measured by SEM, and the mUPO utilization of waste-based material could be a promising green alternative plasticizer for starch components, especially starch foam applications.