Changes in the lignocellulosic structure of oil palm empty fruit bunches (OPEFB) during composting treatment using an in-vessel composter was investigated in this work. The composting process was completed within 40 days of treatment, and the final C/N ratio achieved was 13.85. Scanning electron microscopy (SEM) revealed that the structure of OPEFB material was severely degraded, especially during the thermophilic phase where the biodegradation process was most active. Close examination of the physicochemical and thermal analysis using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetric and differential thermal analysis (TG/DTA) showed that the crystallinity size of the OPEFB structure decreased. This result was attributed to the removal of silica bodies from OPEFB materials. Also, the functional groups of cellulose, hemicelluloses, and lignin structures had changed throughout the composting period, and the most extensive degradation of cellulose was detected in the thermophilic phase. It was also found that the exothermic peak of the matured compost reduced most significantly compared to the raw OPEFB. In conclusion, the in-vessel composting system was able to enhance the degradation process of OPEFB materials for producing compost.

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The effect of different aeration rates on the organic matter (OM) degradation during the active phase of oil palm empty fruit bunch (EFB)-rabbit manure co-composting process under constant forced-aeration system has been studied. Four different aeration rates, 0.13 L min(-1) kg(DM)(-1),0.26 L min(-1) kg(DM)(-1),0.49 L min(-1) kg(DM)(-1) and 0.74 L min(-1) kg(DM)(-1) were applied. 0.26 L min(-1) kg(DM)(-1) provided enough oxygen level (10%) for the rest of composting period, showing 40.5% of OM reduction that is better than other aeration rates. A dynamic mathematical model describing OM degradation, based on the ratio between OM content and initial OM content with correction functions of moisture content, free air space, oxygen and temperature has been proposed.

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 (1mm 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.

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 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.

Jackfruit frozen confection has been mechanically characterised in situ by using compression tests. There are no available studies on the mechanical behaviour of jackfruit frozen confection.   The aim of this study is to identify the mechanical properties of jackfruit frozen confections formulated with different concentrations of jackfruit puree. In this study, the experimental analyses are conducted using a compression test device made from LEGO Mindstorms EV3. The portable device is placed inside a freezer to enable the measurements to be done in low temperatures (-20oC). This is to overcome the limitation of an actual texture analyser which can only be operated at room temperature. The mechanical properties of jackfruit frozen confections at different jackfruit puree concentrations (10%, 20% and 30%) are obtained using the tester and analysed. The tests conducted are uniaxial compression, stress relaxation test and multi-step stress relaxation test. It has been observed that frozen confection with 20% jackfruit puree concentration (JF20) is able to withstand a higher force of compression (27.79kPa) compared to the ones with 10% (JF10) and 30% (JF30) concentrations, at 21.15kPa and 10.48kPa, respectively. For stress relaxation test, JF30 has the highest increasing stress for a strain of 0.05 to 0.2 but it decreases at a strain of 0.3 to 0.4. The results of the multi-step relaxation test on JF30 show agreement with the other two tests where the stress decays starting from the 3rd step until the 5th step of the test. This study provides information on the behaviour of jackfruit frozen confection when subjected to compression and stress that imitates the movement during consumption.

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