Showing papers by "Chung Lim Law published in 2017"

Effect of ambient conditions on drying of herbs in solar greenhouse dryer with integrated heat pump

Abstract: An even span solar greenhouse dryer was built and applied to dry Java tea (Orthosiphon aristatus) and Sabah snake grass (Clinacanthus nutans Lindau). Findings showed that the solar greenhouse dryer performs satisfactorily during clear weather except at nighttime and rainy day due to product rehydration which is heavily influenced by high relative humidity from ambient air. Integrating of heat pump into the solar greenhouse dryer has successfully reduced the room relative humidity by 10–15%. Also, heat pump has mitigated the product rehydration issue by maintaining room relative humidity at maximum of 65% throughout the drying period. The drying rate of Java tea was improved three to fourfold, i.e., from 0.004–0.008 to 0.018–0.025 g H2O/g DM min, whereas 10% of drying time was saved for both Java tea leaf and Sabah snake grass leaf with the assistance of heat pump system. Meanwhile, the supply of dry air from the heat pump system with a magnitude of 0.25–0.50 m/s helps in enhancing the drying rate ...

Drying characteristics of Orthosiphon stamineus Benth by solar-assisted heat pump drying

Abstract: Processing methods of Misai Kucing still remain crude and lack technological advancements. In terms of drying, very few studies have attempted to apply advanced drying technology to improve Misai Kucing quality and drying time. This paper presents first attempt to improve Misai Kucing drying kinetics and product quality through solar-assisted heat pump drying and comparison was made against solar drying. Experimental results showed that solar-dried samples had the greatest total color change and loss of two bioactive ingredients as compared to solar-assisted heat pump-dried samples due to its longer time process, higher drying temperature, and chlorophyll degradation. By comparing the statistical values, it showed that the Page model had the best goodness of fit at all tested dried samples by both drying methods.

Effects of drying on the production of polyphenol-rich cocoa beans

Abstract: The current study emphasizes on the effects of four drying methods, namely, oven drying, adsorption drying, freeze-drying, and vacuum drying on the total polyphenol content and antioxidant activity...

Performance and kinetic evaluation of an integrated anaerobic-aerobic bioreactor in the treatment of palm oil mill effluent.

Abstract: This work presents the evaluation of biokinetic coefficients for a novel integrated anaerobic–aerobic bioreactor (IAAB) at different organic loading rates (OLRs) (10.5–22.5 g COD/L per day) treating palm oil mill effluent. The overall efficiencies of the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were more than 99% for OLR up to 19.5 g COD/L day with biogas production containing 48–64% of methane. The effluent quality remained stable (BOD < 80 mg/L) and satisfied with the discharge limit. Stover–Kincannon model was the most appropriate model to estimate the performance of anaerobic compartment of IAAB, while Monod model was best suited for describing the aerobic compartment.Abbreviations: BOD: biochemical oxygen demand; COD: chemical oxygen demand; DO: dissolved oxygen; GLSS: gas–liquid–solid separator; MLSS: mixed liquor suspended solid; MLVSS: mixed liquor volatile suspended solid; POME: palm oil mill effluent; RAS: returned activated sludge; SBR: sequencing batch reactor; ...

A comparative quality study and energy saving on intermittent heat pump drying of Malaysian edible bird’s nest

Abstract: This paper aims to study the influence of temperature and relative humidity (RH) during intermittent heat pump drying at 28.6–40.6°C, 16.2–26.7% RH, α = 0.2–1.0, and the comparison was made against fan drying (27°C, 39.7% RH, α = 1.00). It was observed that the effects of temperature and RH on drying rate were significant when moisture content was high. Experimental results showed that intermittent heat pump drying at 28.6°C, 26.7% RH, α = 0.2 of edible bird’s nest greatly reduced effective drying time by 84.2% and color change compared to fan drying, and retained the good energy efficiency.

Kinetic retention of sialic acid and antioxidants in Malaysian edible bird’s nest during low-temperature drying

Abstract: Drying is one of the essential processing steps for dried edible bird’s nest; however, sialic acid and antioxidant can be highly thermosensitive and unstable. Therefore, aim of this study was to determine the degradation kinetics of sialic acid and antioxidants during low-temperature drying at 25–40°C as compared to conventional hot air-drying at 70°C. These compounds’ degradation exhibited first-order kinetics. Sialic acid and antioxidant retentions were 83.9 and 96.6%, respectively, at 25°C, and 78.7 and 91.5% at 40°C, respectively, by low-temperature drying; while, 42.5 and 38.7%, respectively, at 70°C by conventional hot air-drying. Finally, empirical models were significantly fitted to predict sialic acid and antioxidant retention as edible bird’s nest reached a certain level of drying, which may be useful from the processing standpoint and validate the usage of low-temperature drying as a process tool for retention of sialic acid and antioxidant in edible bird’s nest.

Intermittent and nonstationary drying technologies: Principles and applications (Advances in Drying Science and Technology)

Abstract: The first comprehensive book on intermittent drying, Intermittent and Nonstationary Drying Technologies: Principles and Applications demonstrates the benefits of this process and covers key issues, including technologies, effect of operating parameters, mathematical modelling, energy-efficiency, and product quality. It discusses such topics as periodic drying, conventional and intermittent food drying processes and food quality, relationship among intermittency of drying, microstructural changes, and food quality, microwave assisted pulsed fluidized and spouted bed drying, and cellular level water distribution. Aimed at food engineers, chemical product engineers, pharmaceutical engineers and technologists, plant design engineers, and researchers and students in these areas, this useful reference helps readers.

Study on retention of metabolites composition in misai kucing (orthosiphon stamineus) by heat pump assisted solar drying

Abstract: In this research, the effects of different drying methods on the two biomarker compounds concentrations, such as sinensetin (SEN) and rosmarinic acid (RA) of Orthosiphon staminues Benth leaves, flowers, stems and mix were investigated. SEN and RA retention among the dehydrated samples were maximum 83.07% in leaves and 92.54% in flowers, respectively by heat pump assisted solar drying method. For heat pump assisted solar dried samples, there are no significant differences (p > .05) in the retention of SEN and RA as compared to fresh samples. However, there are significant differences (p < 0.05) in SEN and RA retention in solar dried leaves, flowers, stems and mix as compared to fresh samples. Besides, an optimization study was performed to evaluate the optimal drying conditions for obtaining high SEN yields from Misai Kucing's leaves, flowers, stems and mixes with high RA contents within the drying parameters.

Retention of sialic acid content in Malaysian edible bird's nest by heat pump drying

Abstract: This paper presents the results of an experimental attempt to improve the drying kinetics for the retention of colour and sialic acid in edible bird’s nest through heat pump drying. Kinetics of hot air drying and heat pump drying were studied by performing various drying trials on edible bird’s nest. Isothermal drying trials were conducted in hot air drying and heat pump drying at a temperature range of 40 °C-90 °C and 28.6 °C-40.6 °C, respectively. Intermittent drying trials were carried out in heat pump drying with two different modes, which are periodic air flow supply and step-up air temperature. Experimental results showed that heat pump drying with low temperature dehumidified air not only enhanced the drying kinetics but also produced a stable final product of edible bird’s nest. Heat pump-dried edible bird’s samples retained a high concentration of sialic acid when an appropriate drying mode was selected.