Search

Starch-based nanocomposite films containing chitosan nanoparticles (S/CNP films) are biodegradable and promising alternatives for non-biodegradable synthetic plastics. Nonetheless, limited work has been conducted to investigate the biodegradability of the films in soil. Thus, this work is aimed at investigating the biodegradation of starch-based films containing different concentrations of CNP (0, 10, 15, 20, 25% w/w solid starch) via a soil burial test using compost and planting soils. The biodegradability was investigated in terms of weight loss, visual appearance, morphology, and structural changes. It was found that S/CNP films biodegraded slower than neat starch films, and the degradation rate was reduced by 46 and 44% in compost and planting soils, respectively, with the increase in the concentrations of CNP from 10 to 25% w/w incorporated into the films. The degradation rate of films in compost soil after 8 days was found to be higher (0.0617 g/day) than in planting soil (0.0266 g/day). Visual appearance, morphology, and structural change results also supported these findings. The biodegradable S/CNP films can be used to reduce the usage of synthetic plastic.

Carboxymethyl cellulose (CMC) is a food additive that plays an important role in the structure-forming of most food. The current extraction of CMC from wood has created competition with the wood industries. To ensure the sustainability of CMC, the search for alternatives to wood is critical. A study on the extraction of CMC from oil palm empty fruit bunch (OPEFB) stalk fibres (SCMC) was successfully carried out previously by the authors. In this study, the potential application of SCMC on low-fat ice cream properties was investigated. Liquid ice cream mix with SCMC had a higher viscosity (129.4 cP) when compared to the control sample (25.5 cP). However, the viscosity of liquid ice cream mix produced using SCMC was slightly lower than the one produced using the commercial CMC (360 cP). The overrun of the SCMC low-fat ice cream was slightly lower (35.2%) than the one produced using commercial CMC (41.5%). The resistance of SCMC and commercial CMC low-fat ice creams towards melting were about the same (60.28% and 58.75% respectively). The commercial CMC produced slightly harder (38.19 N) ice cream than the one with SCMC (28.88 N). Thus, the low-fat ice cream produced using SCMC is comparable with the low-fat ice cream produced using commercial CMC. This indicates the reliability of the extracted CMC from OPEFB stalk fibres to be applied in food, and thus creates a complete solution for the utilization of palm oil mill by-product to produce a value-added product.

The issue of food safety is a major concern in the oil palm industry as it will affect national income. 3-MCPD and GE are contaminants formed during the refining of palm oil, mainly in the deodorization step. Palm oil was reported to contain one of the highest levels of these contaminants amongst all vegetable oils. Both 3-MCPD and GE are characterized as a possible risk to human health. This review aimed to provide a comprehensive summary of the 3-MCPD and GE precursors and mitigation strategies to minimize the 3-MCPD and GE formation. Therefore, the oil palm industry should address these issues and find ways to comply with food laws, acts, regulations, and standards enforced by local and international authorities.

The aim of this study was to investigate the functional properties of Tilapia’s fish scale gelatin films with various type of plasticizers. Gelatin film solutions using solution casting method with different type of plasticizers; glycerol, sorbitol, glycerol: sorbitol (80:20), and diethylene glycol with concentration of 30% were stirred at 60 °C for one hour and dried at room temperature for 2 days. The determination of film characterizations was included thermal (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), mechanical testing using the Texture Analyzer and chemical properties (Fourier transform infrared spectroscopy (FTIR)). Essentially, all plasticizers show an improvement by able to plasticizing with increasing of elongation at break in between 14 and 50% compared to the gelatin film without plasticizer. Meanwhile, the tensile strength of plasticized gelatin films decreased drastically compared to the unplasticized gelatin film. From the result obtained in TGA analysis, film with sorbitol and dietheylene glycol demonstrated low resistance toward high temperature compared to film with glycerol and glycerol:sorbitol gelatin film. In addition, all the gelatin film with different plasticizers show the value of Tg around 60-70.85 °C except for sorbitol with Tg 79.98 °C due to strong intermolecular chain interaction between the sorbitol and gelatin. FTIR spectrum analysis demonstrated that only gelatin film with glycerol does not have any amide group that related to stretching vibration of carbonyl group along the polypeptide backbone of the plasticized film which later give highest tensile strength. Hence, notable differences of functional properties were found with four different type of plasticizers used in the gelatin film, especially in term of temperature resistance and mechanical properties

Hard ice cream has been mechanically characterized in-situ by using compression stress relaxation tests. However, the main challenge in the study of ice cream mechanics is the need to perform analyses at low temperatures (−20 °C). Therefore, in this study, a customized compression test device was developed, which can be used for experimental analysis at low temperatures (−20 °C) inside a freezer. The viscoelastic behavior of hard ice cream was analyzed using the test device, as observed from the reduction of stress at holding deformation. Viscoelastic modeling was then performed using the finite element method by using user material subroutine. The model agreed to the tests results at small deformation (1 mm deformation), but it required the use of a softening function at large deformation. The findings of this study suggest the non-linear viscoelastic behavior of hard ice cream under low temperatures.

The influence of natural protrusion, also known as silica bodies, was studied in relationship to sliding resistance reinforcement in an oil palm fibre-polyethylene composites. Experimental work on oil palm fibres-LLDPE composites (using fibres with and without protrusions) was conducted, which included x-ray microtomography (µ-CT scan), scanning electron microscopy, and degree of grafting analyses. A finite element micromechanical model was then developed using information from the experimental results to simulate fibre pull-out from the matrix. Microscopic observation after mechanical tests of the composites showed crater marks due to silica bodies in contact with the matrix, whereas fibres were uniformly distributed inside the matrix from the µ-CT scan. Likewise, the degree of grafting analysis showed a positive influence of silica bodies as an additional reinforcement to the composites. These were further supported by the modelling results of fibre pull-out, which showed a clear difference between models with and without silica bodies.

Investigation on viscoelastic behaviour of oil palm fibres was reported through experimental and finite element modelling study. The experimental work through tensile stress relaxation and cyclic tests revealed time-dependent behaviour and damage within the oil palm fibres. From the former test results, stresses of fresh fibres reduced more than the dried ones after 1 second relaxation, whereas increasing damage was observed under larger deformations from the latter test results. Finite element modelling results using Prony series viscoelastic model with damage function only agreed with small deformation test, whereas Parallel Rheological Framework viscoelastic model agreed with large deformation test. The former model can be used for biodegradation study, which does not involve large deformation, whereas the latter model is suitable for biocomposites study under large deformation.

This paper demonstrates the potential use of toy-bricks as the building block of a mechanical tensile testing instrument for the mechanical characterisation of natural fibres. A table-top tensile testing instrument was developed using LEGO parts (Mindstorms EV3 and Technics) and a 2 kg capacity load cell, whereas deformation modes were programmed in an open source programming language. Experimental work was conducted on oil palm fibres under different tensile modes (i.e. constant deformation, triple-twisted-tension and deformation-relaxation modes), which showed anisotropic-viscoelastic behaviour, and microstructural damages due to deformation.

Investigation on the effect of starch interface towards mechanical behaviour of rice grains was reported through mechanical tests (compression and three-point bending) and finite element micromechanics model. The model considered starch kernels within the rice grain (for milled rice) as well as a layer of husk on top (for unmilled rice). The interface between the kernels was modelled using cohesive zone model to simulate interfacial damage. Higher fracture stress was reported at lower moisture content from the three-point bending, and linear elastic behaviour was observed from compression tests of milled rice, which was independent of moisture contents. The force-displacement curves of milled rice are linear, whereas unmilled rice showed initial softening before hardening at approximately 0.1 mm displacement. The representative finite element models showed agreement with compression and bending experiments, suggesting significant influence of starch interface damage towards fracture of milled rice grain.

Ultrasonic treatment (UT) effects on methylcellulose (MC) for the food coating purpose prior to deep‐fat frying process of potato strips were demonstrated. Different concentration of MC (0.5–2.0 wt/vol%) solutions were subjected to UT at 20 W to evaluate the effect of UT treated coatings on rheological behavior of the coated samples and their efficiency in minimizing the oil uptake. Application of UT to methylcellulose (UTMC) clearly showed a phase transition from fluid‐ to gel‐like between 20 and 65°C with the increasing in the oscillatory frequency and temperature ramp test of UTMC showed the sol–gel transition occurrence is lower than non‐UTMC at 20 and 29°C, respectively, within the linear viscoelastic region. When the MC concentrations were varied, the most effective concentration was noticed to occur at 1.0 (wt/vol%) UTMC whereby the relative variation of water retention and oil uptake were reduced to about 49.9 and 31.0%, respectively, as compared to 1.0 wt/vol% non‐UTMC formulation. Experimental results affirm that UTMC coating application can be used successively to improve rheological properties of MC by minimizing oil uptake on fried food. PRACTICAL APPLICATION: Ultrasonic treatment (UT) application to methylcellulose (MC) solutions with varied concentration (0.5–2.0 wt/vol%) clearly showed a phase transition from fluid‐to‐gel like with the increasing in the oscillatory frequency (10⁻¹ to 10² rad/s) and temperature ramp test (65–10°C) at low shear strains compared to non‐UTMC. The gelation of UTMC was faster than non‐UTMC when coated onto the substrate at the ambient conditions thus allowed the transformation of green coating layer to form the gel layer instantaneously. Application of MC was successfully in minimizing oil uptake on fried potato strips whereby the most effective layer was noticed to occur at 1.0 wt/vol% UTMC. Introducing UT to polysaccharide coating, that is, MC benefit the food coating industries by increasing the food coating process efficiency so that the coated layer can be fully utilized to increase the function of the coated substrate.

Physicochemical, morphological, rheological characteristics and finite element modelling of wheat flour, rice flour, starch and gluten were studied in this work. The physicochemical analysis of rice flour exhibited almost similar characteristics to wheat flour without gluten present. Rice flour and rice starch contained higher value of carbohydrate and fibres compared to wheat flour and wheat starch. Likewise, rice flour and rice starch interacted strongly with water and oil due to higher value of water absorption, water solubility and oil absorption indices compared to wheat flour and wheat starch. SEM images showed that rice starch had uniform size, smaller polyhedral shape and were closely intact between granules, whereas wheat starch consisted of large and small granules that were sphere and irregular in shapes. Compression tests conducted on all the doughs showed viscoelastic behaviour and permanent set. Stress-strain curve of rice starch-gluten dough are shown to be higher than wheat starch-gluten dough. Oscillation tests conducted on all doughs showed larger storage than loss modulus, indicating more elastic than viscous behaviour of the doughs. Finally, finite element model using ‘chess’ geometry for starch and gluten was able to simulate deformation of starch-gluten dough.

A large volume of oil palm empty fruit bunch (EFB) is generated as waste feedstock around the globe. This abundant waste containing 0.75% oil on average could be a promising feedstock for biodiesel production if oil recovery could be accomplished in an economically-viable and environmentally-friendly manner. To achieve that, a new method called High Pressure Water Spray (HPWS) system was introduced and performed by spraying pressurized water (500 psi) at 30 °C, 60 °C, and 90 °C and combination of water-steam at 120 °C and 150 °C onto the surface of the oil palm empty fruit bunches (EFB). The results obtained indicated that, the highest oil removal yield of 94.41 ± 0.02 wt% was obtained at 150 °C. Moreover, bioprospection of biodiesel properties based on fatty acid methyl ester (FAME) profile revealed that the biodiesels produced from the fresh crude palm oil and residual oil were comparable and were in accordance with international standards. In addition to that, the HPWS process led to an enhanced quality of the remaining lignocellulosic materials for conversion into other value added bio-products such as ligno-ethanol by decreasing lignin content and increasing cellulose content. In view of environmental impact assessment, the HPWS system showed favorable impacts on all the end-point damage categories especially in resources damage category. Moreover, economic assessment showed that the recovered CPO could be generated at a low price of USD 0.41 vs. USD 0.66 for CPO. Overall, this process could drastically increase the market value of an abundant type of waste in many parts of the world, i.e., EFB leading to the generation of additional wealth for the palm oil industry.

An experimental and numerical study on ram extrusion of bread dough was conducted in order to develop predictive models for the pressures involved, as well as the deformation of the extruded dough. Such studies are needed as high pressures can potentially lead to significant degassing, tearing and shearing of the dough and hence poor bread quality; the latter limits the use of extrusion processes which would otherwise be a cost – effective forming process. A laboratory extrusion rig was designed, with dies of varying angles and exit radii. Rate dependent behaviour was observed from tests conducted at different extrusion speeds, and higher extrusion pressure was reported for dies with smaller exit radius or larger die angle. A simulation of extrusion was performed to predict the extrusion pressure as well as the extrudate swell, as a function of die geometry and extrusion rate. A continuum approach was taken in the constitutive model of dough which is a starch filled system in a protein matrix. A nonlinear viscoelastic model combined for the first time with the Mullins model for filled rubbers is found to capture the continuum behaviour well. A Coulomb friction law combined with a maximum shear stress limit was used to describe the contact definition between the extrusion barrel and the dough. Higher die angles and higher extrusion speeds require higher shear stress limit values for the model and the experiments to agree. A possible reason for this is that the shear stress limit depends on maximum strain as well as strain rate imposed during the extrusion process. Static zones were observed both experimentally and numerically. The onset of the static zones was predicted well but quantifying the geometry of the latter needs further studies.

This work investigates the non-linear mechanical behavior of oil palm mesocarp fibers (OPMF) using tensile tests, microstructure observation, and finite element models. The micrograph images showed the fiber’s surface with partly embedded silica bodies, while the cross section contained cell wall structures. Viscoelastic behavior was observed when the fibers were relaxed over time after being stretched, whereas the stress--strain curves from the cyclic tests indicated permanent set (plastic strain) due to the fibers’ deformation. Finite element models were developed comprising single particles (2D and 3D) and 2D multi-particle geometries representing silica bodies embedded in a matrix representing the fiber. The modeling results suggested that silica bodies do not contribute much to the integrity of OPMF, highlighting the need to have a more complex model that considers cellular structures of the fibers and a constitutive relationship of cellulose, hemicelluloses, and lignin.

Computer numerical control (CNC) software is the “brain” of a machine tool as it controls the machine tool’s movement. The development of open CNC controller systems is one of the most popular topics in the last three decades due to the current CNC remains exclusive and costly. However, there is no open-source system that can use with an open CNC controller. In this developed system, the drilling G-code was analyzed to extract the points before simulating and sending it to any open CNC controller machine. Among the machining processes used most extensively is drilling. The used modules and functions are created by LabVIEW. The results show the system’s extracted points are similar to the draw drilling point in Solid work.

The heterogeneous lignocellulosic contents of oil palm empty fruit bunch (OPEFB) fiber requires the use of chemical or biological pre-treatment for further value-added applications. An effective biological pre-treatment was preferred since it is mild, low energy, substrate specific and will not generate any inhibitory chemicals that interfere enzymatic activities and fermentation process. The biological pre-treatment of OPEFB fibers by local isolate Pycnoporus sanguineus was investigated in this work to improve its biodegradability through laccase production via solid-state fermentation approach. The effects of physical parameters (temperature, inducer concentrations, substrate loading) were explored to obtain maximum laccase production by P. sanguines. Results showed that the use of extractive-free OPEFB fiber at 30 °C supplemented with 4 mM of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 10 g of OPEFB loading yielded laccase production that was 2.1 fold higher compared to raw OPEFB. The changes of chemical and surface structures of raw, chemicals and laccase treated OPEFB were reported from Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TGA) and scanning electron microscopy (SEM) analyses. The simulated techno-economic analysis suggested economic feasibility of a batch bio-refinery for laccase production in an industrial scale feed at a maximum rate of 50 tons OPEFB/batch. From the simulated baseline study, the cost price forecast for laccase production was 14.26 US$/kg owing to the capital (65.87%) and raw materials costs (31.68%). This study reveals the potential of P. sanguineus to be used not only in biorefinery industry but also in biopulping, biobleaching (in textile and paper industries) and degrading phenolic waste (dye, colorant, pesticide waste).

Microcrystalline cellulose (MCC) extracted from empty fruit bunches (EFB), stalk and spikelet were characterised through physicochemical and microstructure analyses. Raw stalk fibres yielded the highest cellulose content (42.43%), followed by EFB (32.33%) and spikelet (18.83%). Likewise, lowest lignin and residual oil content was reported in raw stalk fibres compared to EFB and spikelet. SEM revealed significant changes on fibres' surface morphology throughout the extraction process. FTIR analysis showed that main characteristic peaks of hemicellulose and lignin was absent on the extracted MCC. The crystallinity index for MCC extracted from EFB (82.5%), stalk (82.2%) and spikelet (86.5%) was comparable to commercial MCC (81.9%). Results suggested stalk fibres is more preferable for the production of MCC compared to EFB and spikelet. Further rheological studies showed viscoelastic behaviour with no significant differences between commercial and stalk-based MCC, while modelling work showed ability to simulate complex deformation of the MCC-hydrogel/food mixture during processing/handling stage.

The aims of the study were to observe the dissolution profile of four types of selected fruit powder fast dissolve tablet and apply different dissolution profile comparison methods, in order to select most applicable method. Spray dried powder of pitaya, pineapple, guava and mango were used as raw material. Each type of fruit powder tablet has identical dissolution profile. Dissolution profiles and dissolution rate of fruit powder tablets were different at different dissolution environment. In model-independent and statistical method pairwise comparison was performed and in model dependent method profile comparison was carried out based on best fitting of mathematical model equation. Dissolution Profile comparison methods represented that model independent method use wide range of value for profile comparison and it was direct and easy; model dependent method was indirect and complex and for critically compare the dissolution profile statistical method was the most suitable method.

Understanding the non-linear mechanical behaviour of oil palm mesocarp fibres (OPMF) is important for bio-composite application. The mechanical characterisation of this fibre is challenging due to the microstructure of the fibres consisting of silica bodies on the surface and cellular structures within the cross section. In this work, we proposed a constitutive material model for OPMF by including a stress-softening function into the large strain viscoelastic model. The model shows agreement with loading–unloading and stress relaxation tensile tests. The model was then used for micro-scale finite element modelling of the fibre–silica body–matrix (resin) interface to simulate sliding of a bio-composite material. A multi-particles model was also developed to check the effect of the constitutive model towards the mechanics of a bio-composite system. Modelling results suggested that under the micro-scale level (~50 μm), silica body plays a major role in improving the mechanical behaviour of the bio-co...

The current extraction of carboxymethyl cellulose (CMC) from wood has created competition with wood industries. Interest in alternative sources is critical to ensure the sustainable production of CMC. Therefore, the extraction of CMC from oil palm empty fruit bunch (OPEFB) stalk fibres was evaluated. CMC extracted from OPEFB stalk fibres was characterized for chemical composition as well as by spectroscopic, microscopic, physicochemical, and rheological tests. Highest cellulose content was obtained from raw stalk fibres with the least amount of lignin and residual oil as compared to the empty fruit bunch (EFB) and spikelet. The XRD analysis revealed that the native cellulose was transformed into an amorphous phase, as evidenced from the characteristic peaks that had almost disappeared. Likewise, the FTIR analysis showed that major peaks in the lignin and hemicellulose were absent, which enabled the cellulose to be converted to CMC. Microscopy analysis showed notable changes in the fibres’ morphology throughout the extraction process. In addition, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), physicochemical studies, and rheological tests on extracted CMC showed that there was a significant difference between each phase of the extraction process and this showed that OPEFB stalk fibre was feasible to produce CMC that was comparable to those of commercial CMC.

In this study four types fruit powder were mixed together in a 1:1 ratio and tableting was carried out by direct compaction method. Two types tablet were produced, normal mix fruit powder tablet and fruit powder effervescent tablet. Compressibility of the powder mixtures were observed by using Kawakita and Ludde equation. Normal fruit powder mixture was more compressible rather than fruit powder mixture with effervescent agent. Dissolution test was carried out in the dissolution medium of distilled water and simulated saliva fluid at room temperature and 37.5 °C temperature, respectively. Fruit powder effervescent tablet was dissolved faster in simulated saliva.

Investigating the mechanical behaviour of silica bodies in oil palm empty fruit bunches (OPEFB) is important to improve the process of silica body removal. This study will assist in providing an understanding of the role of OPEFB as a bioresource material for the bioconversion process. The microstructure of silica bodies/protrusions on the OPEFB fibre surface was modelled using the finite element method, based on the information obtained from scanning electron microscopy (SEM). The effects of silica body geometry, possible anisotropy/orthotropy, and debonding between the interface of the silica body and OPEFB fibre were investigated. Agreements were observed between the results using both circular and spiked silica body models with different geometries and volume fractions. In addition, the cohesive debonding modelling results showed that once critical stress was activated, the stress-strain curve deviated from the no-debond model. The results also suggested that the value of cohesive energy should be between 0.5 kN/m and 4 kN/m.

An experimental and numerical study on ram extrusion of bread d ough was conducted. A laboratory ram extrusion rig was designed and manufactured, where dies with di fferent angles and exit radii were employed. Rate dependent behaviour was observed from tests conducted at different extrus ion speeds, and higher extrusion pressure was reported for dies with decreasing exit radius. A finite element simulation o f extrusion was performed using the adaptive meshing technique in Abaqus. Simulations using a frictionless contact b etween the billet and die wall showed that the model underestimates the response at high entry angles. On the other hand, when the coefficient of friction value was set to 0.09 as measured from friction experiments, the dough response was over estimated, i.e. the model extrusion pressure was much higher than the experimentally measured values. When a critical shear stress limit, max W , was used, the accuracy of the model predictions improved. The results showed that higher die angles require higher max W values for the model and the experiments to agree.

Experimental and numerical investigation was conducted to study the micromechanics of oil palm empty fruit bunch fibres containing silica bodies. The finite viscoelastic-plastic material model called Parallel Rheological Network model was proposed, that fitted well with cyclic and stress relaxation tensile tests of the fibres. Representative volume element and microstructure models were developed using finite element method, where the models information was obtained from microscopy and X-ray micro-tomography analyses. Simulation results showed that difference of the fibres model with silica bodies and those without ones is larger under shear than compression and tension. However, in comparison to geometrical effect (i.e. silica bodies), it is suggested that ultrastructure components of the fibres (modelled using finite viscoelastic-plastic model) is responsible for the complex mechanical behaviour of oil palm fibres. This can be due to cellulose, hemicellulose and lignin components and the interface behaviour, as reported on other lignocellulosic materials.

The mechanical behaviour of dough, gluten and starch were studied in an effort to investigate whether bread dough can be treated as a two phase (starch and gluten) composite material. Mechanical loading tests revealed rate dependent behaviour for both the starch and gluten constituents of dough. There is evidence from cryo-Scanning Electron Microscopy (SEM) that damage in the form of debonding between starch and gluten occurs when the sample is stretched. In addition, a reasonable agreement is seen between the Lodge material model and the compression test data only, indicating again that possibly ‘damage’ is essentially debonding which does not occur under compression, unlike tension and shear loading. A composite finite element model was developed using starch as filler and gluten as matrix. The interface between the starch and gluten was modelled as a cohesive contact interaction. When the interaction of starch and gluten is strong, as indicated for the dough with no damage, the stress-strain curve is always higher than the gluten stress-strain curve under both tension and shear loading. In contrast, when damage is activated in the form of debonding, the dough stress-strain curves under tension are seen to cross over the curves for gluten and therefore leading to lower stress values than in gluten. No damage/debonding occurs under compression when a damage function is used which is in good agreement with the experimental data.

The effect of alkali pre-treatment (sodium hydroxide, NaOH) on the microstructural, mechanical, and chemical composition of oil palm stalk fibres (OPSF) is reported for future bioconversion processes. The OPSF was pre-treated with various concentrations of NaOH (5, 10, 20, 30, and 40% w/v). Scanning electron microscopy analysis revealed that 5% w/v alkali concentration caused complete removal of silica bodies and waxy layers, whereas pronounced degradation of the fibres occurred at 40% w/v NaOH concentration. Mechanical test results showed that the maximum elastic modulus of untreated OPSF was 2.5 GPa and the modulus was not sensitive to alkali concentration. Permanent set (plastic strain) and viscoelastic behaviours of OPSF were observed from the loading-unloading and stress relaxation test results, respectively. Agreement was observed between the Prony series viscoelastic model and test results, which provided further evidence of the viscoelastic behaviour of OPSF.

The surface of oil palm empty fruit bunch fibres contains embedded silica bodies or protrusions. The mechanical contribution of the protrusions towards the integrity of the fibres is still not clearly investigated. In this work, 2D and 3D finite element simulations on the surface and cross section of the fibres, respectively, were performed. The information for the models was obtained from scanning electron microscopy analysis and mechanical tests for the silica body characteristics and elastic modulus, respectively. Different silica bodies arrangements and the effect of spiked geometry of the silica bodies was investigated using 2D models. Cohesive zone modelling was introduced to simulate damage or debonding between the interface of silica bodies and fibre. A 3D finite element model was later developed consisting of a silica body (sphere) embedded halfway in the matrix. The numerical results showed that the 2D model was sensitive to critical stress compared to silica bodies spiked geometry, arrangement of silica bodies on the fibre surface, and cohesive energy. On the other hand, the results showed that for 3D models with thicknesses larger than 0.2 mm, the effect of the silica bodies on the elasticity of the fibre was not significant.

The mechanical behavior of dough, gluten, and starch was studied in an effort to investigate whether bread dough can be treated as a two phase (starch and gluten) composite material. Mechanical loading tests revealed rate-dependent behavior for both the starch and the gluten constituents of dough. There is evidence from cryo-scanning electron microscopy that damage in the form of debonding between starch and gluten occurs when the sample is stretched. In addition, the Lodge material model was found to deviate from the tension and shear stress-strain test data by a considerably larger amount than from the compression test data. This could indicate that “damage” is dominant along the gluten-starch interface, causing debonding; the latter occurs less under compression loading, but is more prevalent in tension and shear loading. A single-particle finite element model was developed using starch as a filler contained in a gluten matrix. The interface between starch and gluten was modeled using cohesive zone elements with damage/debonding occurring under opening/tension and sliding/shear modes. The numerical results are compared to experimental stress-strain data obtained at various loading conditions. A comparison of stress-strain curves obtained from 2D and 3D single-particle models and a 2D multiparticle model led to good agreement, indicating that the single-particle model can be used to adequately represent the microstructure of the dough studied here.

The mechanical behaviour of dough and gluten was studied in an effort to investigate whether bread dough can be treated as a two phase (starch and gluten) composite material. The dough and gluten show rate dependent behaviour under tension, compression and shear tests, and non-linear unloading-reloading curves under cyclic compression tests. There is evidence from cryo-Scanning Electron Microscopy (SEM) that damage in the form of debonding between starch and gluten occurs when the sample is stretched. A composite finite element model was developed using starch as filler and gluten as matrix. The interaction between the starch and gluten was modelled as cohesive contact. The finite element analysis predictions agree with trends seen in experimental test data on dough and gluten, further evidence that debonding of starch and gluten is a possible damage mechanism in dough.