Rosnah Shamsudin

Sugar content in watermelon juice based on dielectric properties at 10.45GHz

Determination of sugar content in 10 matured red seedless watermelons by measuring the dielectric properties is described in this paper. The determination is made based on the comparison of watermelon juice and water with sugar mixture. The dielectric properties of both the extracted watermelon juice and water with sugar mixture are measured over the frequency range from 200 MHz to 20 GHz and permittivity data at frequency 10.45 GHz is highlighted using an open-ended coaxial-line probe and network analyzer. Measurements are made at room temperature ± 27 °C; 70–80% RH. The sugar content was the most significant factor affecting the maturity of watermelon. Dielectric properties of watermelon juice and water with sugar mixture were measured and the dielectric properties of both liquids were compared. In this study, data obtained suggests that dielectric properties shows strong relation with sugar content. The dielectric constant is inversely proportional with increment of sugar content. From the dielectric properties measured, the sugar content in the watermelon is predicted. In additional, the standard sugar content measurement, HPLC method is also measured and result of the study is reported in this paper. Dielectric measurement of watermelon juice and water with sugar mixture are presented graphically to show their relationships.

UVC dosage effects on the physico-chemical properties of lime ( Citrus aurantifolia ) juice

Lime juice is in high demand due to a sour taste. Commercial thermal pasteurization extends juice shelf-life; however, fruit juice subjected to thermal pasteurization tends to change color and lose vitamin content. Lime juice was irradiated with ultraviolet-C (UVC) at dosages of 22.76, 30.19, and 44.24 mJ/cm2 to investigate effects on the physicochemical properties of lime juice. pH values of lime juice did not change while total soluble solids, turbidity, titratable acidity, sweetness, and color values of lime juice did change after UV treatments. Changes in quality index indicators were prominent at the highest UV dosage of 44.24 mJ/cm2. A low UVC dosage was effective for treatment of lime juice with minimal changes in juice properties.

Effects of post-drying methods on pomelo fruit peels

Changes in physicochemical properties of moisture, ash, and fat contents, and color, due to freeze and oven post-drying treatments on flavedo, albedo, and lamella pomelo fruit peels were investigated. Physicochemical properties influence consumer acceptability and only a few studies are known. Pomelo peels were subjected to freeze drying and conventional drying at 60°C. Fresh pomelo peel was used as a control. Post-drying treatment changes in moisture, ash, and fat contents were observed, compared to controls. Minimal color changes were observed for freeze drying, compared with oven drying for flavedo, albedo, and lamella. Useful information for evaluation of drying treatments that can be used on pomelo peels is provided.

Formulation and process optimizations of nano-cosmeceuticals containing purified swiftlet nest

The good effects of swiftlet nest (SN) on the skin have been widely investigated. However, the importance of the SN in the area of nano-cosmeceutical research is still limited as it is commonly consumed, rather than being applied to the skin. Formulation and optimization processes are two important issues in the manufacturing of cosmetics. In this work, Response surface methodology (RSM) was utilized to investigate the influence of the nano-cosmeceuticals composition; purified SN (1–5% w/w), and Tween 80 (3–6% w/w) as well as the preparation method; time of homogenization (10–30 min), on the physicochemical properties of nano-cosmeceuticals. The response variables were particle size and zeta potential which were very important characteristics in nano-cosmeceuticals. Formulation and optimization of three independent variables were carried out to obtain an optimum nano-cosmeceuticals with the lowest particle size and high stability formulation. The optimized nano-emulsion containing purified SN with particle size of 136.35 nm and zeta potential of −40.2 mV was successfully formulated. This was obtained experimentally and was closer to the predicted values of 136.22 nm and −40.07 mV, respectively. The optimized formulation remained stable for three months after the centrifugation test as well as storage at different temperatures of 4 °C, 25 °C and 45 °C.

Effective moisture diffusivity and activation energy of rambutan seed under different drying methods to promote storage stability

The effects of two drying methods, oven and microwave drying on the effective moisture diffusivity and activation energy of rambutan seed were studied. Effective moisture diffusivity and activation energy are the main indicators used for moisture movement within the material. Hence, it is beneficial to determine an appropriate drying method to attain a final moisture content of rambutan seed that potentially could be used as secondary sources in the industry. An appropriate final moisture content will provide better storage stability that can extend the lifespan of the rambutan seed. The rambutan seeds were dried with two drying methods (oven and microwave) at two level of the process variables (oven temperature; 40°C and 60°C and microwave power; 250W and 1000W) at constant initial moisture contents. The result showed that a higher value of effective moisture diffusivity and less activation energy were observed in microwave drying compared to oven drying. This finding portrays microwave drying expedites the moisture removal to achieve the required final moisture content and the most appropriate drying method for longer storage stability for rambutan seed. With respect to the process variables; higher oven temperatures and lower microwave powers also exhibit similar trends. Hopefully, this study would provide a baseline data to determine an appropriate drying method for longer storage period for turning waste to by-products.

The application of microwave drying process for rambutan (Nephelium lappaceum L.) seed

ABSTRACT This study aims to investigate the drying characteristics of rambutan seed in a microwave oven. The experiments were conducted at three power levels of 250, 600 and 1000 W and three drying times of 8, 9 and 10 h with three replications. Changes in these operational variables were conducted to highlight their effects on the drying characteristics observed through their drying profiles and final moisture contents. To estimate the drying behaviour, three thin layer equations were used to fit experimental data. Results showed that the drying time and final moisture content were decreased with an increase in the microwave power. Page model was selected as the best mathematical model to describe the drying process. Moisture diffusivity obtained varied from 4.10 × 10−9 to 9.64 × 10−9 m2 s−1 and the activation energy varied between 22.10 to 110.59 g.W−1 at different powers and drying times.