Short-Chain Fatty Acid Starch Stabilized Pickering Emulsions : Design, Properties and Applications

Pickering emulsions are emulsions stabilized by solid particles. Particles with optimal dual wettability toward both of the oil and water phases, can be adsorbed onto the interface, thereby providing the stability of the emulsions. Starch granules have attracted attention due to their positive characteristics, such as being widely available, inexpensive, biodegradable, and non-allergenic. Due to a relatively low degree of hydrophobicity, chemical modification of starch can improve starch hydrophobicity by esterification with a short-chain fatty acid (SCFA) group. The aim of this thesis was to perform SCFA starch modification by means of esterification of rice and quinoa starches with different SCFA groups and levels of modification. The physicochemical and functional properties of SCFA starches were investigated. As one of the future applications, the emulsifying capacity of SCFA starches was evaluated and in vitro digestion was carried out. Until recently, there have been no studies evaluating the effect of different types of SCFA starches and the levels of modification to the physicochemical properties, emulsification and digestibility. The rationale behind the selection of different types of SCFA starches at different levels of modification and the application of these to stabilize Pickering emulsions were discussed. The esterification of starch with short-chain fatty acids group was successfully quantified by direct stoichiometry, FTIR and 1H-NMR. SCFA starches have shown a different properties compared to their native forms. Native and SCFA-rice starches have a larger particle size compared to native and SCFA-quinoa starches. Both types of starches displayed a polyhedral shape. Upon modification, no changes in particle size were observed. SCFA starches exhibited a reduction in protein and amylose content. SCFA starches demonstrated low gelatinization and pasting temperature. The highest level of resistant starch was observed in the starches with the highest level of modification. Principle component analysis revealed that the physicochemical and functional properties of SCFA starches are highly influenced by the level of modification. SCFA starches were able to perform as a stabilizer in Pickering-type emulsions. The emulsifying capacity was improved by increasing SCFA chain length and levels of modifications. SCFA-quinoa starch Pickering emulsions were observed to have smaller droplet sizes, higher emulsification index, better Turbiscan stability index, and more stable droplet sizes that remained below 50 µm during 50 days of storage. This indicated that Pickering emulsions stabilized by SCFA-quinoa starches were more stable than SCFA-rice starches. In vitro digestion of SCFA starch Pickering emulsions showed that increasing SCFA chain length and modification level reduced the extent of starch hydrolysis. The results of this PhD project implied that increasing the chain length and modification level improved the overall hydrophobicity of the granules and hence improves the emulsification capacity and stability. Improved hydrophobicity resulted in a higher adsorption degree (less free starch) and a denser layer of particles at the interface. Hence, this dense layer protects the oil droplets and prevents the enzyme from getting access to the oil droplets. However, particle coverage was not complete due to the large sizes of the particles. There were therefore still small gaps between starch particles, resulting in lipolysis not being completely arrested. In future research, formulation of SCFA starch Pickering emulsions can be used to investigate the capacity of these emulsions to serve as a carrier for controlled release and targeted delivery of bioactive compounds to a specific location of the gastrointestinal tract, such as the distal locations of the small intestine or the colon

Physico-chemical properties of palm stearin, soybean oil and their binary blends / Nabilah Abdul Hadi

The objective of this study was to determine the changes in physicochemical properties of palm stearin (PS) and soybean oil (SBO) blends at different mixing ratios in order to identify the suitable blend ratio of PS and SBO for certain food applications. Palm stearin was blended with SBO at different ratios of 70:30, 50:50 and 30:70 PS:SBO. The physicochemical properties of PS, SBO and PS:SBO binary blends were determined based on the major fatty acid composition, triacylglycerol profile, iodine value (IV), solid fat content (SFC), slip melting point (SMP) and hardness index (HI). Results indicated that the addition of SBO into PS caused the changes amount in fatty acid composition (FAC) of PS which cause decreased in the palmitic acid but increased in the linoleic acid. These results was supported with triacylglycerols (TAG) profile where the major TAG for PS which was 2-oleo-dipalmitin (POP) was decreased upon dilution with SBO, and increased the triunsaturated acid namely trilinolein (LLL). Blending PS and SBO resulted the IV increased significantly (p<0.05) with the increasing amount SBO thus decreased the SFC, SMP, and HI for all of the blends. Based on SFC, the blend 50:50 PS:SBO have a product stability and resistance to oiling out, with good melting point below body temperature which might be suitable for product such as margarine that must be melted in the mouth with minimum waxiness in order to have a good oral-mel

Physicochemical Properties and Stability of Emulsions Containing Carotenoid-Rich Pumpkin Extract, Whey Protein Concentrate and Carboxymethylcellulose

A response surface methodology with a central composite design was employed to investigate the effects of Carotenoid-Rich Pumpkin Extract (CE), Whey Protein Concentrate (WPC), and Carboxymethyl Cellulose (CMC) on the physicochemical properties and stability of emulsions. The WPC-CMC synergism resulted in the formation of a thick layer around the droplets, thus improving the emulsion system. The optimum levels of CE, WPC, and CMC were determined to be 6.00, 2.00, and 0.87%, respectively, to provide the desired emulsion with a pH of 4.18, a carotenoid degradation stability index of 0.88, a peroxide formation stability index of 0.77, and an apparent viscosity of 0.61 Pa.s

Optimization of mixing parameters on techno-functional properties of fenugreek gum-soy protein isolate dispersion

Fenugreek (Trigonella foenum-graecum L.) gum (FG) has been identified as a hydrocolloid, with promising emulsifying and stabilizing properties. In an emulsion-based food system, these properties dramatically increased when FG was mixed with soy protein isolate (SPI). Nevertheless, it is highly dependent on mixing parameters such as FG:SPI ratio, pH, and temperature, and it is currently not well understood. The objective of this study was to determine the effects of FG:SPI ratio (3:1 - 1:1), pH (3 - 9), and temperature (65 - 85 °C) on techno-functional properties (flow properties, emulsifying properties, and turbidity) of the FG-SPI dispersion, to reveal the optimum mixing parameters. A response surface regression modeling demonstrated that the quadratic effect of the FG:SPI ratio had significantly (p<0.05) increased the flow properties of the dispersion. However, the interaction between FG:SPI ratio and temperature or pH gave the opposite effect. The FG:SPI ratio had the most significant (p<0.05) increasing effect on both emulsifying properties and turbidity. Conversely, the emulsifying properties were determined to decrease with the interaction effect of FG:SPI ratio and pH. The optimized mixing parameters were recorded at FG:SPI ratio of 2.6:1, pH of 3.0, and temperature of 70 °C, with apparent viscosity (0.19 Pa.s), emulsion stability (100%), and turbidity (2.91, Abs600) values were within the predicted ranges. The present findings provide an excellent opportunity to advance the use of FG-SPI dispersion in related to emulsion-based food products

Gain Enhancement of a Dual-Band Planar Slot Dipole using AMC Plane for WBAN and WLAN Applications

A dual band slot dipole antenna made from textile is proposed for Wireless Body Area Network and Wireless Local Area Network applications. The proposed antenna is integrated with an artificial magnetic conductor plane to mitigate backward radiation and reduce Specific Absorption Rate when operated on body. The artificial magnetic conductor plane is formed using a 3 x 3 array of unit cells, each consisting of a square patch integrated with diamond-shaped slot. The proposed antenna (denoted as Antenna B) is compared against another similar antenna (Antenna A) in free space and on-body, in flat condition (on chest) and under two bending axes (x- and y-axes) on the upper arm. Results indicate that Antenna B provided wider upper bandwidth to 766 MHz (in flat condition) and up to 875 MHz when bent. Besides that, higher gain of up to 5 dB with improved front-to-back ratio are also observed

The construction of the Malaysian Educators Selection Inventory (MEdSI): a large scale assessment initiative / Joharry Othman...[et al.]

of a nation’s human resource is undeniable. In Malaysia, teaching has always been perceived as a financially secure and relatively easy job by many, resulting in mass application for entry into teacher education programmes. Many of those who aspire and opto to go into the teaching profession however do so regardless of their personal interests, potential, and values. Pursuing a program that does not fit a person’s personality and interest – despite initially having good academic credentials and excellent co-curricular involvement in school – may result in unsatisfactory academic performance, frustration, change of program and even withdrawal at college level. Hence, in the quest for selecting suitable teacher trainee candidates, a psychometrically sound instrument known as the Malaysian Educators Selection Inventory (MEdSI) was developed as a screening measure to filter the large number of teacher hopefuls. This paper specifically describes the theoretical basis and the constructs of the instrument developed

Pendekatan P-P FIT dalam proses pemilihan calon guru di Institusi Pengajian Tinggi Awam Malaysia

Pemilihan bidang kerjaya khususnya dalam bidang pendidikan menjadi semakin kompleks ketika ini ekoran terdapatnya kebolehan manusia yang pelbagai dan keperluan pelajar yang begitu kritikal selaras dengan ciri pembangunan dan pembentukan insan yang berdaya saing. Pemilihan kerjaya sesuai merupakan salah satu permasalahan terbesar remaja di Malaysia. Masalah ini meliputi masalah dalam membuat keputusan sama ada ingin menceburkan diri dalam kerjaya keguruan ataupun tidak. Amalan pemilihan sedia ada calon untuk kemasukan ke program keguruan di Institusi Pengajian Tinggi Awam (IPTA) adalah berdasarkan pencapaian akademik, ko-kurikulum dan pilihan pelajar. Walaupun pencapaian akademik dan ko-kurikulum pelajar memenuhi syarat, namun pilihan yang dibuat oleh pelajar berkemungkinan tidak tepat dengan personaliti, minat, nilai, dan potensi sebenar diri mereka. Keadaan ini boleh membawa kepada pencapaian yang tidak memuaskan dalam pengajian, kekecewaan, pertukaran program dan penarikan diri daripada program pengajian berkenaan. Ketidakselarasan antara aspek personaliti dan minat merupakan pembaziran modal insan yang berpotensi. Keadaan ini juga merugikan universiti yang telah banyak menghabiskan masa untuk melatih pelajar. Sehubungan itu ujian Malaysian Educators Selection Inventory (MEdSI) yang dibangunkan berasaskan Personality-Programme Fit (P-P Fit) diharapkan dapat mengatasi permasalahan ini

Review on volumetric energy density: inluence on morphology and mechanical properties of Ti6Al4V manufactured via laser powder bed fusion

Various laser powder bed fusion (LPBF) process parameters must be considered as they can independently affect the properties of end-product. However, many studies simply examine one or two LPBF process parameters. Laser power, scan speed, scan spacing, and layer height are the four primary LPBF process parameters that contribute to volumetric energy density (VED) used in LPBF. VED is often used as an optimization metric for LPBF process parameters, because it takes all four major parameters into consideration. Thus, this paper focuses on the effect of VED on the morphology and properties of part, and also discusses on the interrelationship between all four parameters. Common range used for each parameter is 70–400 W for laser power, 70–1800 mm/s for scan speed, 50–140 µm for scan spacing, and 20–50 µm for layer height. It can be seen as the VED increased, the microstructure of as-built titanium alloy Ti6Al4V components exhibited smaller α’ martensite size and larger columnar β grain. High VED can also reduce porosity and defect formation, which will help in increasing part density. The lowest surface roughness reported for LPBF Ti6Al4V is 4.91 µm. Meanwhile, the maximum microhardness obtained is 443 HV and the highest tensile strength achieved is 1400 MPa. The VED used for studies that obtained these results are in the range of 55–65 J/mm3. Thus, it can be concluded that the most suitable VED for LPBF printing of Ti6Al4V is around 55–65 J/mm3

Review on volumetric energy density: Influence on morphology and mechanical properties of Ti6Al4V manufactured via laser powder bed fusion

Various laser powder bed fusion (LPBF) process parameters must be considered as they can independently affect the properties of end-product. However, many studies simply examine one or two LPBF process parameters. Laser power, scan speed, scan spacing, and layer height are the four primary LPBF process parameters that contribute to volumetric energy density (VED) used in LPBF. VED is often used as an optimization metric for LPBF process parameters, because it takes all four major parameters into consideration. Thus, this paper focuses on the effect of VED on the morphology and properties of part, and also discusses on the interrelationship between all four parameters. Common range used for each parameter is 70–400 W for laser power, 70–1800 mm/s for scan speed, 50–140 µm for scan spacing, and 20–50 µm for layer height. It can be seen as the VED increased, the microstructure of as-built titanium alloy Ti6Al4V components exhibited smaller α’ martensite size and larger columnar β grain. High VED can also reduce porosity and defect formation, which will help in increasing part density. The lowest surface roughness reported for LPBF Ti6Al4V is 4.91 µm. Meanwhile, the maximum microhardness obtained is 443 HV and the highest tensile strength achieved is 1400 MPa. The VED used for studies that obtained these results are in the range of 55–65 J/mm3. Thus, it can be concluded that the most suitable VED for LPBF printing of Ti6Al4V is around 55–65 J/mm3