Rungsinee Sothornvit

Plasticizer effect on mechanical properties of β-lactoglobulin films

Abstract The mechanical properties (elastic modulus, EM; tensile strength, TS and % elongation, %E) of β-lactoglobulin (β-Lg) films plasticized with different plasticizers were determined. Six plasticizer types were studied over a range of concentrations. Propylene-glycol-plasticized β-Lg films were the most brittle, with mechanical properties independent of plasticizer content. Films with other plasticizers studied (glycerol, Gly; sorbitol, Sor; polyethylene glycol, PEG 200 and PEG 400 and sucrose, Suc) exhibited negative exponential dependence on plasticizer concentration for EM and TS, while they exhibited linear dependence on plasticizer concentration for %E. The EM and TS data for each plasticizer were fitted with an exponential model, while %E data were fitted with a linear model to quantify the plasticizer effect. The EM0, TS0 and %E0 of β-Lg films without plasticizer determined from the fitted equations were 1500, 37.28 MPa and 0, respectively. The kEM,kTS and kE values determined from the fitted EM, TS and %E data, respectively, reflect the efficiency of plasticizers. The kEM,kTS and kE values indicate that plasticizer efficiency generally decreased in the order Gly, PEG 200, PEG 400, Sor and Suc, on the bases of mole plasticizer-oxygen-atom/mole β-Lg and mass plasticizer/mass β-Lg. These results reflect the effect of plasticizer composition, size and shape. The kEM,kTS and kE value order was reversed when the basis was changed to mole plasticizer/mole β-Lg. The latter results clearly reflect the effect of plasticizer number of O atoms.

Plasticizers in edible films and coatings

Publisher Summary This chapter summarizes the advantages and disadvantages of plasticizers, plasticizers used, and plasticized-film properties of both polysaccharide- and protein-based films and coatings. Most polysaccharide- and protein-based films and coatings are brittle in nature. To solve this problem, plasticizers are incorporated to enhance the film flexibility and resilience. However, film permeability always increases with increasing plasticizer content. Proper selection of a plasticizer for a given polymer will allow optimization of the film mechanical properties with a minimum increase in film permeability. Common plasticizers for edible films and coatings, include monosaccharides, oligosaccharides, polyols, lipids, and derivatives. Different moisture sorption by various plasticizers contributes to differences in film permeability and mechanical properties. Selection of plasticizers need consideration of the issues of plasticizer compatibility, efficiency, permanence, and economics. The effect of the amount and type of plasticizer on achieving desirable mechanical properties with optimal permeability is of continuing interest to researchers.

PLASTICIZER EFFECT ON THE GLASS TRANSITION TEMPERATURE OF BETA–LACTOGLOBULIN FILMS

The effect of plasticizer on beta–lactoglobulin (.–Lg) film glass transition temperature (Tg) was investigated to elucidate the plasticization mechanism. The Tg of film containing polyethylene glycol 400 (PEG 400) as a plasticizer could not be observed because an ice–melting peak occurred during heating. Films plasticized by propylene glycol (PG), glycerol (Gly), and PEG 200 possessed similar film Tg values, related to the plasticizer water–binding properties. However, sorbitol (Sor) and sucrose (Suc) produced higher film Tg values due to their larger MW and solid–state plasticizer behavior. Lubrication of .–Lg molecules by plasticizer domains external to the .–Lg is suggested as a film plasticization mechanism because no shift in film Tg was observed with increasing plasticizer content. The size, shape, and physical state of plasticizer were the key factors affecting film properties, consistent with previous results on mechanical and oxygen permeability (OP) properties.

Development and characterization of banana flour film incorporated with montmorillonite and banana starch nanoparticles

Banana flour film is an alternative biopolymer material but still needs improvement of its mechanical properties and water vapor permeability. Banana starch nanoparticles (BSNs), prepared using miniemulsion cross-linking, make an interesting reinforcing agent. The properties of plasticized banana flour film (PBF) were characterized incorporated with 5% (w/w) of either montmorillonite; MMT-Na+ (PBF-M) or BSN (PBF-B), including a mixture of nanoparticles at 1:1 for 5% (PBF-MB5) and 10% (PBF-MB10). PBF-MB5 provided better improvement in the film mechanical and water barrier properties compared with PBF-B. Moreover, PBF-MB5 exhibited an intercalated structure as confirmed by the shift peak of pristine MMT-Na+ from 2θ=7.3 to 3.9° and the increase in the d-spacing from 1.21 to 2.26nm in X-ray diffraction. Fourier transform-infrared spectra confirmed the intercalated structure. Therefore, the mixture of BSN and nanoclay at 5% was sufficient to reinforce the biopolymer films as a biomaterial packaging for food and pharmaceutical applications.

Physicochemical and functional properties of protein concentrate from by-product of coconut processing

Coconut cake, a by-product from milk and oil extractions, contains a high amount of protein. Protein extraction from coconut milk cake and coconut oil cake was investigated. The supernatant and precipitate protein powders from both coconut milk and oil cakes were compared based on their physicochemical and functional properties. Glutelin was the predominant protein fraction in both coconut cakes. Protein powders from milk cake presented higher water and oil absorption capacities than those from oil cake. Both protein powders from oil cake exhibited better foaming capacity and a better emulsifying activity index than those from milk cake. Coconut proteins were mostly solubilized in strong acidic and alkaline solutions. Minimum solubility was observed at pH 4, confirming the isoelectric point of coconut protein. Therefore, the coconut residues after extractions might be a potential alternative renewable plant protein source to use asa food ingredient to enhance food nutrition and quality.

Rice stubble as a new biopolymer source to produce carboxymethyl cellulose-blended films

Rice stubble is agricultural waste consisting of cellulose which can be converted to carboxymethyl cellulose from rice stubble (CMCr) as a potential biomaterial. Plasticizer types (glycerol and olive oil) and their contents were investigated to provide flexibility for use as food packaging material. Glycerol content enhanced extensibility, while olive oil content improved the moisture barrier of films. Additionally, CMCr showed potential as a replacement for up to 50% of commercial CMC without any changes in mechanical and permeability properties. A mixture of plasticizers (10% glycerol and 10% olive oil) provided blended film with good water barrier and mechanical properties comparable with 20% individual plasticizer. Principle component (PC) analysis with 2 PCs explained approximately 81% of the total variance, was a useful tool to select a suitable plasticizer ratio for blended film production. Therefore, CMCr can be used to form edible film and coating as a renewable environmentally friendly packaging material.

Microencapsulation of Thai rice grass (O. Sativa cv. Khao Dawk Mali 105) extract incorporated to form bioactive carboxymethyl cellulose edible film

Microencapsulation was investigated to enhance the stability of Thai rice grass extract. Microencapsulated powder (MP) was formed using total solid of extract solution and maltodextrin ratios of 1:4 (MP 1:4) and 1:9 (MP 1:9). The absence of an endothermic peak for both MPs confirmed all extract solutions were coated with maltodextrin. MP 1:9 had a lower total phenolic content (TPC) but was higher in antioxidant capacity than MP 1:4. Moreover, the TPC of the MPs slightly decreased (70.02-93.04%) during storage at 10, 30 and 70°C for 30d. Comparatively, the TPC of the extract solution significantly decreased from 100% down to 20.8%, 11.2% and 8.6% at 10, 30 and 70°C, respectively. Therefore, MP 1:9 incorporated with blended carboxymethyl cellulose film increased the water barrier and the TPC. This film can serve as a bioactive biodegradable packaging material to reduce plastic packaging in the food industry.

Effect of cellulose nanocrystals from sugarcane bagasse on whey protein isolate-based films

Whey protein isolate (WPI) has been utilized as edible film or food packaging material. However, WPI films are hydrophilic due to highly polar amino acids which provide a moderate barrier to water vapor and low mechanical properties. To overcome these drawbacks, cellulose nanocrystals (CNCs) extracted from sugarcane bagasse were incorporated with whey protein. FTIR and TGA were used to confirm the changes in chemical structures and to observe the thermal properties, respectively. The CNCs had sizes of 200-300 nm and diameters of 20-40 nm using TEM and AFM technique, respectively. Different amounts of CNCs (0-8 wt% based on WPI) were added into whey protein solution and formed films. The lightness and transparency of the films tended to decrease with increasing WPI content. The water activity (aw) and water solubility of those films increased, whereas their water contact angle values decreased, implying that the film became more hydrophilic when the cellulose nanocrystal was added. The addition of CNCs increased the tensile strength and Youngs modulus and reduced the water vapor permeability of WPI-based CNC films. However, the CNCs did not change the oxygen permeability of the film. Therefore, the obtained WPI films provided good mechanical performance and may be promising as an alternative product for film packaging.

Modification and characterisation of porcine plasma protein with natural agents as potential cross‐linkers

Summary Modification of porcine plasma protein (PPP) using the natural cross-linkers at different concentrations of rutin (0.6–1% w/w), caffeic acid (1–3% w/w) and genipin (0.15–0.5% w/w) on chemical and thermal properties of PPP was investigated. Among these, rutin was the most significant effective natural agent corresponding to a decrease in the free amino group and sulphydryl group contents including a change in the protein bands’ intensity from SDS-PAGE. However, genipin exhibited greater thermal properties of modified PPP. Moreover, the modification affected the colour of PPP and a change in the FT-IR spectra of the samples. The suitable concentrations of each natural agent were 0.6% rutin, 0.5% genipin and 3% caffeic acid. Therefore, natural cross-linkers such as rutin, caffeic acid and genipin can be considered as alternative cross-linkers to improve the properties of PPP for food processing and biopolymer material applications as they are nontoxic.

Effect of natural waxes and surfactants on mechanical, optical, thermal and water vapor permeability of banana flour composite films

T digestion has long been the main way to harvest anchorage-dependent cells. But trypsin will damage the proteins of extracellular matrix, leading to the degradation of the structure and function of cells. Cultivating cells on thermo-sensitive material, then harvesting cells by lowering temperature, can make the extracellular matrix maintain integrity. In this study, a series of PVDF-g-PNIPAAm thermo-sensitive fiber membranes, M21, M43, M11, and M45 were prepared by electrospinning. Fourier transform infrared spectroscopy and NMR-H spectrum were used to characterize that the PNIPAAm was grafted successfully. The morphology of each fiber membrane was observed by scanning electron microscope, indicating that the grafting percentage of PNIPAAm influenced the spinnability of PVDF. Fourier transform infrared spectroscopy of PVDF and PVDF-g-PNIPAAm fiber membranes showed that electrostatic spinning would not change the structure of thermo-sensitive polymer. PC12 cells were seeded on the surfaces of M21, M43 and M11 for cell experiments. The cell adhesion, proliferation and growth on different fiber membranes were examined. Then the harvested cells on different fiber membranes with temperature reduction were compared with those harvested by trypsin digestion method. The images of cell live/dead fluorescence staining showed that cells in different fiber membranes all had a high viability and the prepared thermo-sensitive fiber membranes had good biocompatibility. The MTT results showed that the nanometer fiber structure was conducive to the proliferation and growth of cells. The cells grown on the surface of M21 were the best and relatively poor on the M11, which indicated that higher grafting ratio is not suitable for the adhesion and growth of cells. Finally the cells cultivated on the three thermo-sensitive fiber membranes after three days were harvested with temperature reduction, showing that high grafting ratio is advantageous to the detachment of cells. Compared with trypsin digestion method, the temperature reduction method has significant advantages.Biomaterials are getting significance in the current research field of gas sensors due to great sensitivity. Performance of biomaterial based gas sensor constructed from gum Arabica and garlic extract in microwave resonant cavity had been investigated. It is shown that extract of garlic clove with multiple medicinal and chemical utility is very helpful in sensing Sulphur Oxide gas. The material under observation undergoes some momentary physical change on exposure to Sulphur Oxide gas. This change can be detected over amplified potentiometric variation through electrical circuitry of microwave resonant cavity. Manipulating this appropriate characteristic a potentiometric gas sensor of faster response and recovery time can be designed. Sensing property of the said material has been studied via microwave attenuation, reflection, and transmission.M materials play an essential role as biomaterials to assist with the repair or replacement of bone tissue that has become diseased or damaged. Plates, screws and pins used to secure serious fractures must be removed by a second surgical procedure after the tissue has healed sufficiently. Repeated surgery increases costs to the health care system and risk to the patient. To overcome these problems biodegradable materials can be used which temporarily support tissue healing and are completely degraded in certain time. Fe-Mn alloys are promising candidates for biodegradable metallic materials because of excellent mechanical properties, which are usually obtained by multi stage forming processes. However, biodegradability rate is usually not sufficient and last too long, degradation is not continuous and sometimes flakes are formed. The main goal of current research is to understand different production processes: casting, hot rolling and annealing; on the corrosion behavior of the biodegradable FeMn17 alloy due to the formation of less-corrosion-resistant deformational martensite. With additions of Mn the mechanical properties increase and the corrosion resistance decreases. The process parameters influenced the biodegradability as well as the mechanical properties. The produced material, cast and hot rolled, has interior stress and that increases the biodegradability, though the annealing process increases the stability of the material and the corrosion resistance.