Dayang Norulfairuz Abang Zaidel

Kinetics of Enzyme-Catalyzed Cross-Linking of Feruloylated Arabinan from Sugar Beet

Ferulic acid (FA) groups esterified to the arabinan side chains of pectic polysaccharides can be oxidatively cross-linked in vitro by horseradish peroxidase (HRP) catalysis in the presence of hydrogen peroxide (H(2)O(2)) to form ferulic acid dehydrodimers (diFAs). The present work investigated whether the kinetics of HRP catalyzed cross-linking of FA esterified to α-(1,5)-linked arabinans are affected by the length of the arabinan chains carrying the feruloyl substitutions. The kinetics of the HRP-catalyzed cross-linking of four sets of arabinan samples from sugar beet pulp, having different molecular weights and hence different degrees of polymerization, were monitored by the disappearance of FA absorbance at 316 nm. MALDI-TOF/TOF-MS analysis confirmed that the sugar beet arabinans were feruloyl-substituted, and HPLC analysis verified that the amounts of diFAs increased when FA levels decreased as a result of the enzymatic oxidation treatment with HRP and H(2)O(2). At equimolar levels of FA (0.0025-0.05 mM) in the arabinan samples, the initial rates of the HRP-catalyzed cross-linking of the longer chain arabinans were slower than those of the shorter chain arabinans. The lower initial rates may be the result of the slower movement of larger molecules coupled with steric phenomena, making the required initial reaction of two FAs on longer chain arabinans slower than on shorter arabinans.

Transparent Branch-Line Coupler Using Micro-Metal Mesh Conductive Film

This letter presents the design of a novel transparent 3 dB Branch-Line Coupler (BLC) using a proprietary self-assembling nano-particle technology based Micro-metal Mesh (MM) conductive film. The transparent MM conductive film has a sheet resistance of 0.7 Ω/sq and a visible-light transmission (VBLT) of 75%, resulting in good conductivity and high transparency, respectively. The proposed transparent BLC is mounted on a 2 mm-thick soda-lime glass substrate of dielectric 5.7 and designed to operate at 2.45 GHz. A layer of MM film on the back of the glass serves as a ground. The transparent BLC delivered measured coupling and transmission values of 3.9 and 4.3 dB, respectively. The transparent BLC can be used as a building block for realizing a transparent Butler Matrix (BM) Beam Forming Network (BFN) for Inter/Intra-Vehicle Wireless Communication (IIVWC) in Intelligent Transport System (ITS). Besides being transparent, the proposed BLC has a measured fractional bandwidth of 38.8% and 0.25 mm profile excluding the glass substrate. These advantages greatly enhance the BLCs potential to be used also as a BM building component that can be mounted onto the glass surfaces of buildings for future 5G indoor wireless communications where beam forming is required.

Microwave-Assisted stabilisation and storage stability study of rice bran oil from different varieties

Rice bran is a by-product from milling process of paddy rice to produce refined rice, however until today, there was limited utilisation of rice bran even though rice bran has the ability and potential to become of the major supplementary sources that function as food agent substance. This is due to the instability of rice bran as it will become unstable due to the hydrolysis and oxidation process. The oxidation process, mainly due to the oil presence in the rice bran, releases substances that is unsuitable for consumption. Immediate extraction of the oil from the rice bran is needed as it will be hydrolysed into free fatty acids (FFA) and glycerol by the activity of lipase enzymes. The stabilisation of rice bran can be done by controlling the lipase activity. This process could indirectly prevent the rice bran from being oxidised. Studies have shown that the lipase enzymes in the rice bran can be inactivated depends on the temperature and duration of heat exposure (stabilisation) as well as the moisture content. In this study, the effect of microwave-assisted stabilisation of rice bran was investigated on the quality of rice bran oil (RBO) extracted. Different varieties of rice bran were used in this study which was from lowland, upland and Bario. Extraction of the rice bran was performed using soxtherm extractor and quality of RBO was determined by analysing its properties in terms of crude RBO yield, moisture content and free fatty acid content. Storage stability of the rice bran was evaluated until 40 d. The results demonstrated that the Bario rice bran showed decrease of oil yield from 0 - 40 d with a difference of 48.9 %, followed by the lowland rice bran by 48.7 %. The upland rice bran oil gives the higher different percentage of 64.2 % during the storage. An increase of moisture content was observed during the storage for all stabilised and unstabilised rice brans. Free fatty acid contents show increase amount in almost all types of rice bran range from 2.5 to 11.9 %.

Extraction and characterisation of pectin from dragon fruit (hylocereus polyrhizus) peels

Pectins are complex carbohydrate molecules that are used in numerous food applications as a gelling agent, thickener, stabiliser, and emulsifier. Dragon fruit (Hylocereus polyrhizus) is one of the tropical fruits that belong to the cactus family, Cactaceae. Since the peels of dragon fruit are often discarded as waste, it would be an advantage to convert it into a value-added product such as pectin. The objective of this study was to investigate the extraction of pectin from dragon fruit peels under different extraction time using hot water extraction method. The dragon fruit peels were extracted using distilled water at 80 °C with different extraction time of 20, 40, 60 and 80 min. The extracted pectin was characterised by its yield, moisture and ash content, degree of esterification and antioxidant activity. Determination of moisture and ash content was conducted using AOAC standard method. The determination of the degree of esterification of pectin was performed using Fourier Transform Infrared Spectroscopy (FTIR). DPPH assay was used to determine the antioxidant activity of the pectin extract. Based on the result, the yield of pectin decreases (20.34 to 16.20 %) with the increase of extraction time, moisture contents were between 4 to 6 % while ash contents were between 7 to 10 %. Pectin from dragon fruit peels was determined as low methoxyl pectin and has high percentage of antioxidant activity with low value of inhibition concentration (IC50) (0.0063 to 0.0080 mg/mL). 60 min extraction sample exhibits the highest antioxidant activity (81.91 % at 40 µg/mL), followed by 80 min extraction (81.68 % at 40 µg/mL), 40 min extraction (81.38 % at 40 µg/mL) and 20 min extraction (81.31 % at 40 µg/mL).

Effect of extraction conditions on pectin yield extracted from sweet potato peels residues using hydrochloric acid

Pectins are complex polysaccharides obtained from higher plants which are structurally composed mainly of α-1, 4-linked-D-galacturonic acid (Gal A). Pectin has a good property of gelling, thickening and emulsification thus it is used widely in food and beverage industry. The applications of pectin in food industry are developing thus the demand of pectin is also increasing. Sweet potato residue is a potential local source of pectin. The peels of sweet potato are usually discarded prior to the consumption of the fruit. In Malaysia, starch industries and small local business are generating a lot of residual waste from sweet potato. Converting the waste into a value-Added product such as pectin would bring great advantage in term of environmental concern and profit. Effects of extraction conditions such as extraction temperature (60 - 100 °C), extraction time (60 - 180 min) and solution pH (1 - 3) on the extraction yield of pectin (%) from sweet potato residues were investigated in this study. The extracting solvent used was hydrochloric acid. The highest yield was 2.59 % which was obtained at extraction temperature 90 °C, extraction time 60 min and solution pH 1.5. All three extraction conditions showed significant effect on the yield of pectin (%).

Effect of impeller design on the rate of reaction of hydrolysis in batch reactor

Lactose is a disaccharide found mostly in milk product. Lactose can cause digestive problem that commonly known as lactose intolerant. Manufacturer pre-treated the milk to produce lactose-free milk. This study aims to investigate the effect of impeller design on the rate of reaction of lactose hydrolysis in batch reactor by utilising immobilised enzyme. Lactose hydrolysis reactions were carried out by adding s-galactosidase (enzyme) into the milk. Alginate was utilised to immobilise the enzyme in order to reuse, enhanced stability and rapid separation of enzymes from the reaction mixture. In this reaction glucose was produced; hence increase sweetness of the milk. Replacing conventional enzymatic processes with immobilised (support) enzyme provides many advantages such as increase the enzyme activity, selectivity, stability and easy recovery from the reaction medium for their reuse. The rate of product formation with different variable such as agitation speed (150 rpm, 250 rpm and 300 rpm) and type of impeller (pitch blade turbine, Rushton turbine, marine propeller and pitch paddle) were investigated. It was found that the highest product formation was with marine propeller at speed 150 rpm with production rate 8.2 mg/L.min, followed by Rushton turbine at speed 250 rpm and pitch blade turbine at speed 300 rpm with production rate 6.2 mg/L.min and 5.4 mg/L.min. Pitch blade shown average of production rate around 3.4 - 4.6 mg/L.min.

Effects of Ingredients Ratio on Physicochemical Properties of Convective-microwave Nutritious Dried Rice Meal

During emergency situation, such as natural disasters or war, diseases outbreak can occur due to lack of nutrition. Due to this issue, a wholesome dried rice meal (DRM) was conceptualised as emergency, quick, nutritious, functional and comforting food for natural disaster and war victims, particularly during the critical period of post-disaster or war period. The DRM was designed so that it can be consumed as dried cracker or semi-solid porridge. The objective of this study was to evaluate the effect of rice (100 g and 200 g), minced chicken meat (30 g and 40 g) and mixed vegetables (25 g and 35 g) ratio on the energy content, vitamin C, and expansion ratio of convective-microwave DRM. The convective-microwave drying method was chosen for DRM preparation to obtain the final product with specific puffing condition which enhances rehydration process and also to shorten the total production time of DRM. The experiments were conducted using factorial design. The experimental results showed that the highest DRM energy content of 1.60 kCal could be achieved by cooking 200 g rice with 40 g minced chicken meat and 25 g mixed vegetables. The DRM with highest vitamin C content of 0.018 g was achieved using 100 g, 30 g minced chicken meat and 25 g mixed vegetables. The DRM with the highest expansion ratio of 1.13 was achieved using 100 g rice, 30 g minced chicken meat and 25 g mixed vegetables. Empirical models for predicting energy contents, vitamin C and expansion ratio of the DRM were also obtained.

Physicochemical Properties and Storage Stability of Margarine Containing Anthocyanins from Roselle Calyces

Addition of encapsulated anthocyanins in margarine formulation improves the stability of margarine. In this study, investigation on the storage and stability characteristics of water-in-oil emulsion, i.e. margarine, containing encapsulated or non-encapsulated anthocyanins from Roselle was carried out. Encapsulation of anthocyanins was performed using microwave-Assisted technique to study the dispersion and stability of anthocyanins in the margarine. Margarines were formulated with three different oil-To-Aqueous ratios (88:12, 86:14 and 84:16). The blend formulation was compared with commercial margarine and the stability of the margarine was determined by using chemical, physical and texture stability analysis and. Margarine containing non-encapsulated anthocyanin showed improved stability compared with encapsulated anthocyanin.

Thermotolerance study of bagasse-Alginate encapsulant using effective thermal conductivity model for sustainable probiotic feed

A great potential in the synthesis of heat resistant microcapsules for probiotic was developed via the synthesis of heterogeneous material. In the study of heterogeneous material, effective thermal conductivity is widely used in measuring the thermal behaviour of the material and is regarded as a key thermophysical property. Production of heterogeneous material could be created via filler incorporation. Incorporation of filler in the microcapsule matrix could enhance the thermotolerance characteristic of the microcapsule. The encapsulation wall concentration also could contribute to the value of effective thermal conductivity of the heterogeneous material. This research is aimed to model fitting the series model of effective thermal conductivity using data collected from immobilised Lactobacillus rhamnosus NRRL 442 in alginate microcapsule (NaA) with incorporated sugarcane bagasse (SB). Different alginate concentration of 1 %, 2 % and 3 % and NaA : SB ratio of 1 : 0, 1 : 1 and 1 : 1.5 were used in synthesising the microcapsules. The microcapsules were produced using the extrusion method. The lowest effective thermal conductivity was obtained from the same microcapsule preparation using 3 % of alginate concentration and at a NaA : SB concentration ratio of 1 : 1.5. The microcapsules prepared using 1 % of alginate concentration and a NaA : SB concentration ratio of 1:0 showed the highest effective thermal conductivity. The regression values (R2) for all alginate concentrations (1 %, 2 % and 3 %) were found to be 0.9997, 1.0000, and 0.9973. The regression models of the effective thermal conductivity in all alginate concentrations versus filler (SB) concentration were plotted. High coefficient of determination was obtained and showed strong correlation between effective thermal conductivity and SB concentration for different alginate concentration. This study could be beneficial in the production of products that necessitate heat treatment thermo tolerance especially in pelleted probiotic feed.

Efficiency and thermal stability of encapsulated anthocyanins from red dragon fruit (Hylocereus polyrhizus (Weber) Britton & Rose) using microwave-assisted technique

Anthocyanins are one of the commonly used natural colorants for beverages, confectionary, fruit preparation and ice cream. Strong antioxidant activity of these anthocyanins has attracted great interest to the food industry. The instability of anthocyanins through the factors such as light, pH, temperature and oxygen has given problem during processing and storage of these compounds. One of the approaches to overcome this problem is by encapsulating the material using wall material. This study was conducted to investigate the efficiency of encapsulation of anthocyanins from red dragon fruit (Hylocereus polyrhizus (Weber) Britton & Rose) using microwave-assisted technique with different drying times and thermal stability of the encapsulated anthocyanins. Encapsulated anthocyanins were produced in form of powder using maltodextrin as the wall material. The encapsulation drying time were varied from 1 min to 3 min with fixed power, 330W. The encapsulated anthocyanins were analyzed in effect of thermal heating (60°C and 80°C). The results indicated that, at different encapsulation drying time, 2 min capsule showed the highest yield of encapsulation where 3 min capsule showed the highest encapsulation efficiency followed by 2 min capsule with 4% differences. From this study the encapsulation at 2 min drying time showed the most feasible encapsulation process. Thermal study at 60°C and 80°C showed that anthocyanins degraded faster at higher temperature, 80°C for all capsule types.