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.

Effect of kaolin impregnated with calico plant extract on properties of starch films.

Starch film has poor tensile properties and poor water resistance. We aimed to improve these properties by adding kaolin impregnated with calico plant extract (CP-Kaolin). UV-Vis spectrophotometry showed that the calico plant extract (CPE) contained 4867.52 mg/L of total phenolic compounds and betacyanins were the predominant constituents. CP-Kaolin was characterized by Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. FTIR analysis showed that betacyanins were adsorbed on kaolin via hydrogen bonding. Zeta potential analysis confirmed the adsorption of betacyanins on kaolin. The intercalation of betacyanins between kaolin platelets was observed by XRD. SEM revealed that CP-Kaolin was well dispersed and embedded within the starch matrix. It was found that the addition of 10 wt% of CP-Kaolin increased the water resistance, tensile strength and thermal stability of starch film. Moreover, starch film containing 10 wt% of CP-Kaolin was sensitive to the change in pH of the fish during storage. Therefore, the addition of CP-Kaolin improved the properties of starch film and starch film composite with CP-Kaolin could be applied as a smart packaging in the food industry.

Characterization of starch film incorporating Hom Nil rice extract for food packaging purposes.

Poor water resistance, mechanical properties and stability limit the food packaging applications of starch films. Since the properties of starch films are improved by incorporating phenolic compounds and anthocyanins from natural plant extracts, Hom Nil rice (HN) extract was incorporated into cassava starch solution to produce a starch-based packaging film. We evaluated the extraction condition to optimize the total phenolic and anthocyanin contents of the HN extract. The optimal ratio of ethanol solution:Hom Nil rice powder was 5:1 v/w% and the optimal extraction time was 60 min. The influence of HN extract on the viscosity of the film solution and the properties of the obtained films were investigated. The results showed that the HN extract increased the viscosity of the starch solution. A film containing 8 wt% of HN extract produced the highest water contact angle and tensile strength, and hindered the retrogradation process. Therefore, cassava starch film modified with the proposed HN extract has the potential to be used as a food packaging material.

Thermoplastic starch composite with oil palm mesocarp fiber waste and its application as biodegradable seeding pot.

Thermoplastic starch (TPS) composites with oil palm mesocarp fiber waste were prepared using compression molding. Oil palm mesocarp fiber (PC) was reduced to powder (MPC) by dry grinding in a planetary ball mill at various speeds and grinding times. It was found that fiber powder with the smallest particle size (33 µm) was obtained at a rotation speed of 200 rpm after milling for 90 min. A TPS composite with 50 wt% of MPC showed the highest tensile strength, thermal stability, and water resistance. A biodegradable seeding pot was produced from this TPS composite that was slowly degraded by microorganisms in the soil without releasing pollutants. The pot could support certain commercially and domestically grown plants for the duration of their growth period and showed potential as an innovative product that could replace existing non-biodegradable products.

Exopolymeric substance from Bacillus velezensis P1 as an antifungal additive in chitosan coating to prolong the shelf life of mangoes.

Bacillus velezensis P1 inhibits various phytopathogenic fungi. Its exopolymeric substance (EPS) was active against Colletotrichum sp. at a minimum inhibitory concentration (MIC) of 6.25 mg/ml. EPS was added to chitosan from squid pen to produce an antifungal film coating. The addition of EPS at its MIC had no effect on the color of the chitosan film. Two components showed good compatibility and the tensile strength of the film was higher than that of neat chitosan film. Mangoes were treated with six different coatings, including the two films. Fruits coated with the films showed the lowest weight loss and prolonged shelf life of mangoes to three times the shelf life of controls (water and 2 % citric acid, w/v) and completely inhibited fungal infection. Film coatings of chitosan, alone or combined with the EPS from B. velezensis P1, showed potential to prolong the shelf life of ripe mangoes and decrease postharvest losses.

Film coating based on native starch and cationic starch blend improved postharvest quality of mangoes.

This work focused on the preparation and characterization of films and coatings based on native cassava starch cationic cassava starch and a blend of the two. The films and coatings are intended for application as coating materials for mango fruits. Due to the good miscibility between native cassava starch and cationic cassava starch, the starch blend film was more hydrophobic than films produced from unblended native cassava starch and unblended cationic cassava starch. In addition, after storage for 10 days, the mangoes coated with the starch blend film had lost the least weight and exhibited only slight changes in physical appearance. Therefore, the coating of native and cationic cassava starch blend is a promising alternative coating that presents no hazard to consumer health or the environment.

Mechanical and barrier properties of starch blend films enhanced with kaolin for application in food packaging.

Starch blend films of native cassava starch and medium distarch phosphate cassava starch (crosslinked cassava starch) were prepared by solution casting. The effects of kaolin content on the water resistance and mechanical properties of the starch blend films were investigated. The addition of 10 wt% kaolin to the starch blend film lowered water vapor permeability to 3.51 × 10-5 g m day-1 m-2 Pa-1, water solubility to 31.60% and raised tensile strength to 2.99 MPa. At this loading of kaolin, the structural integrity of the starch blend film was maintained during immersion in water and thermal stability was enhanced. Scanning electron microscopy revealed kaolin to be well dispersed and embedded within the starch matrix. In summary, the starch blend film composite with 10 wt% kaolin had interesting properties as a material to replace non-biodegradable synthetic plastics for packaging, particularly sachets for food products.

Structure-properties relationships in alkaline treated rice husk reinforced thermoplastic cassava starch biocomposites.

The study focuses on structure-properties relationships in thermoplastic cassava starch (TPS) based biocomposites comprising 5-20 wt% of untreated and treated rice husk (RH). Alkaline treatment with 11% w/v NaOH removed the hemicellulose layer of RH as confirmed by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and resulted in a larger population of -OH groups exposing on the fibril surface. Consequently, the filler-matrix interactions between treated RH and TPS were enhanced, although Brunauer-Emmett-Teller (BET) surface area analysis indicated that the surface area of treated RH was not increased. Interestingly, the biocomposites contained 20 wt% treated RH showed substantially improved tensile strength by a factor of 220% compared to the neat TPS. The biocomposite at 15 wt% treated RH showed high water absorption. TPS with all treated RH contents showed high biodegradation rate, while the thermal stability of the TPS/treated RH biocomposites was slightly decreased. These novel composites showed promising properties for applications as absorbents.

Novel composite foam made from starch and water hyacinth with beeswax coating for food packaging applications.

A novel composite foam was prepared from native cassava starch and water hyacinth (WH) by baking in a hot mold. The effects of WH powder content (0, 3, 5, 7 or 10 wt%, dry starch basis) on the properties of the starch foam were investigated. A starch foam formulation with 5 wt% WH powder exhibited the highest flexural stress at maximum load (3.42 MPa), the highest flexural strain (extension) at maximum load (3.52%), the highest modulus (232.00 MPa), the lowest moisture content (6.77%) and the most uniform cell size distribution (0.44 ± 0.09 mm). Moreover, mechanical properties of starch foam with 5 wt% WH powder were better than the same properties of some commercial foams. After being coated with beeswax, the starch foams retained their shape after immersion in distilled water and their water solubility was significantly reduced. Results indicated that a starch foam/5 wt% WH composite with beeswax coating was a biodegradable foam that could possibly replace commercial non-degradable foam.

Comparison of the effects of calcified green macroalga (Halimeda macroloba Decaisne) and commercial CaCO3 on the properties of composite starch foam trays.

The calcified green macroalga, Halimeda macroloba, is a source of bio-based calcium carbonate which can be used as a filler in starch foam tray. In the first part of this study, the composition and structure of calcium carbonate of this species were investigated using Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) and Scanning election microscopy (SEM). The morphology of the macroalgal powder particles was rod-like and organic materials (e.g. polysaccharide) and calcium carbonate (aragonite form) were present. The second part of the study investigated the effects of calcium carbonate from H. macroloba on the properties of starch foam tray and compared them with the properties of starch foam tray filled with commercial CaCO3. Interestingly, the composites starch foam trays with macroalgal powder had better impact strength than starch/commercial CaCO3 composite foam trays. Moreover, the macroalgal powder affected the thermal properties of the starch foam tray equally as well as commercial CaCO3. However, the macroalgal powder caused more significant changes in the color parameters and the whiteness values of starch foam tray than commercial CaCO3.

Preparation and characterization of thermoplastic starch composites with fly ash modified by planetary ball milling.

Thermoplastic starch (TPS) composites were prepared containing different amounts of unmodified (UFA) or modified fly ash (MFA) powder. The modification of the fly ash was carried out by dry grinding UFA in a planetary ball mill at various speeds and grinding times. The particle size of the fly ash was determined with a laser particle size analyzer and a scanning electron microscope (SEM). It was found that the particle size of the UFA decreased from 59.60 µm to 13.17 µm after grinding for 1 h at 400 rpm. Both UFA and MFA powder were incorporated in a thermoplastic starch. The mechanical properties, water resistance, degradation under simulated weathering conditions and thermal properties of the TPS and the composites were characterized. The maximum tensile strength (7.78 MPa) was obtained in a composite with 2.50% of MFA. This value is about 9 times higher than the tensile strength of the TPS and 2 times higher than that of a TPS/UFA composite with 15.00% UFA. In addition, composites with MFA showed improved water resistance and delayed degradation compared to the TPS and the composites with UFA. The presence of UFA or MFA had a slight effect on the thermal stability of the samples. However, fly ash promoted the final phase of the thermal decomposition of starch indicating a possible catalytic activity.

Transforming fish scale waste into an efficient filler for starch foam.

In this work modified fish scale waste (FS) was used as a filler in order to improve the properties of starch foam prepared by a baking process. The FS was modified under two calcination conditions: at 500 °C for 5 h and at 700 °C for 3 h. The FS powder calcined at 700 °C for 3 h (FS700-3) had higher Ca content and lower protein content and was the filler chosen for experimental study of the effects of its addition on the properties of the starch foam. The addition of FS700-3 to the starch foam produced a more expanded structure due to FS700-3 efficiently supported the growth of existing cells during nucleation and bubble growth. Moreover, the flexural stress at maximum load of the starch foam increased from 1.03 MPa to 1.54 MPa after adding FS700-3 at 10 wt% because of the good adhesion between the two components.

Properties of baked foams from citric acid modified cassava starch and native cassava starch blends.

Starch foams from native cassava starch (NS) and citric acid modified cassava starch (CNS) were prepared using baking processes with blend ratios of 80/20, 60/40, 50/50, 40/60 and 20/80. The density, thickness, morphology, thermal stability and water absorption of the NS, CNS and blended starch foams were determined. The ratio of the two starch components had a significant influence on the density and thickness of the blended starch foams. All blended starch foams showed good water resistance. Moreover, the morphology of the blended starch foam with the NS/CNS ratio of 50/50 showed a more ordered distribution of cell sizes with thicker cell walls than for the NS and CNS foams. The thermal stability of the blended starch foams was somewhat lower than the stability of the NS foam but not to the extent that it affected any potential practical applications.

Biodegradation of thermoplastic starch/eggshell powder composites.

Thermoplastic starch (TPS) was prepared using compression molding and chicken eggshell was used as a filler. The effect of the eggshell powder (EP) on the properties of TPS was compared with the effect of commercial calcium carbonate (CC). The organic compound on the surface of the eggshell powder acted as a coupling agent that resulted in a strong adhesion between the eggshell powder and the TPS matrix, as confirmed by SEM micrographs. The biodegradation was determined by the soil burial test. The TPS/EP composites were more rapidly degraded than the TPS/CC composites. In addition, the eggshell powder improved the water resistance and thermal stability of the TPS.

Interactions of Kraft lignin and wheat gluten during biomaterial processing: evidence for the role of phenolic groups.

The chemical interactions between Kraft lignin and wheat gluten under processing conditions were investigated by determining the extent of the protein network formation. To clarify the role of different chemical functions found in lignin, the effect of Kraft lignin was compared with that of an esterified lignin, in which hydroxyl groups had been suppressed by esterification, and with a series of simple aromatics and phenolic structures with different functionalities (conjugated double bonds, hydroxyl, carboxylic acid, and aldehyde). The protein solubility was determined by using the Kjeldahl method. The role of the hydroxyl function was assessed by the significantly lower effect of esterified lignin. The importance of the phenolic radical scavenging structure is evidenced by the effect of guaiacol, which results in a behavior similar to that of the Kraft lignin. In addition, the significant effect of conjugated double bonds on gluten reactivity, through nucleophilic addition, was demonstrated.

Preparation of cassava starch grafted with polystyrene by suspension polymerization.

Cassava starch grafted with polystyrene (PS-g-starch) copolymer was synthesized via free-radical polymerization of styrene by using suspension polymerization technique. Potassium persulfate (PPS) was used as an initiator and water was used as a medium. The graft copolymer was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction and scanning electron microscopy. The sub-micron spherical beads of PS were observed on the surface of starch granules. SEM micrographs showed porous patches of PS adhering on the starch granules after Soxhlet extraction. FTIR spectra also indicated the presence of PS-g-starch copolymer. XRD analysis exhibited insignificant changes in crystalline structure and degree of crystallinity. The effects of starch:styrene weight ratio, amount of PPS, reaction time and reaction temperature on the percentage of grafting - G (%), were investigated. G (%) increased with increasing starch content. Other variables showed their own individual optimal values. The optimum condition yielding 31.47% of G (%) was derived when the component ratio was 1:3 and reaction temperature and time were 50°C and 2h, respectively. Graft copolymerization did not change granular shape and crystallinity of starch. This study demonstrated the capability of polymerization of styrene monomer on the granular starch without emulsifier and the synthesis of graft copolymer without gelatinization of starch.