student profile: Mr Songwen Tan


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Thesis work

Thesis title: Spray drying engineered milk sugar and protein powders with high porosity or controlled-release properties for food, pharmaceutical and energy applications

Supervisors: Fariba DEHGHANI , Timothy LANGRISH

Thesis abstract:

Australia is a milk-rich nation with multiple milk and dairy products at relatively low prices locally due to the high annual output, making it reasonable to further engineer the products for more applications rather than just simple foods. Spray drying is an industrial technique to produce particles and powders from feed solutions, slurries or suspensions. It has been widely applied for producing milk powder over many years in Australia. In this thesis, the milk sugar (lactose) and proteins (casein and whey proteins), which are the main milk components, have been used to develop novel materials for food, pharmaceutical and energy applications based on spray-drying technology.

Starting with lactose, where a porous structure has been previously developed and used as drug carrier, a micro-meso-macroporous lactose with a unique shape (flower-like) has been engineered in this work by modifying the operating conditions of spray drying and templating technique. The synthesis of the flower-like lactose involves two steps, namely spray drying (mixing components) followed by ethanol washing (removing the templating agents). Porous flower-like lactose has been produced with a high surface area (24-38 m2/g) and a high pore volume (0.31-0.78 cc/g), and these values, along with other characteristics, vary with different operating conditions and/or using different templating agents. The effects of some typical operating conditions, including temperature, particle size, feed concentration and templating agent, have been studied for producing flower-like lactose and its capacity for drug loading. It has been found that, by altering the interior structure of the flower-like lactose particles, the position of loaded drug molecules can be controlled mainly at the core, the region between core and shell, or the shell, indicated by CRM mapping and FIB etching. By tailoring the pore structure based on the differences, in the diffusion coefficients of the templating agents compared with the diffusion coefficient of lactose, the flower-like lactose particles with a porous-core-solid-shell or solid-core-porous-shell structure have been engineered, giving different dissolution profiles of drugs loaded in the particles.

Casein, isolated from milk, is one of the widely used natural products in the food industry, and has been targeted as the second main material to be engineered for controlled release applications in this thesis. In preparation, casein has been acidified at a pH of 1.0 and washed (neutralized) by water to form a novel shampoo/lotion-like gel. The casein gel can be spray dried with food and drug ingredients and compressed to form casein-gel tablets for the controlled release of these ingredients. Typically, microencapsulation of ascorbic acid (vitamin C), coffee and acetaminophen (for pain relief) by the casein gel has been carried out using spray drying for controlled release. After tableting, the controlled release of the ingredients from the casein gel tablets has been achieved, with the release period lasting from a few minutes to over a few days by changing the operating conditions. To better control the release rate, WPI (soluble in water) has been used along with the casein gel at different ratios as the shell materials in the spray-dried particles for the controlled release. Without thermal enhancement, the time required for releasing 80% of the ingredients from the milk protein tablets follows the order: casein-acetaminophen > casein-coffee > casein-ascorbic acid > casein-WPI-acetaminophen > casein-WPI-coffee > casein-WPI-ascorbic acid > WPI-acetaminophen > WPI-coffee > WPI-ascorbic acid. The heat treatment has been applied to the milk protein tablets, showing that the overall release period may be further extended (over two days).

To develop an energy application for milk products, raw whey powder, as a cheap by-product of the cheese and casein production process from an Australian manufacturer, has been used as the source of porous carbons and engineered for capacitive energy storage. Spray drying has been used to produce uniform composite particles containing whey powder and KOH, in which KOH serves as an activation agent to create uniform pores during carbonization, and the proteins in the whey powders act as N dopants. At the optimal KOH concentration of 13% (w/w), the resulting carbon materials contain 3 ± 1 at.% N, have a large specific surface area of 1320 ± 50 m2/g and deliver a specific capacitance of 139 ± 3 F/g at 2 mV/s. Electrochemical impedance spectroscopy analysis indicates that the carbon material has a good ionic conductivity at the electrode-electrolyte interface and efficient diffusion of electrolyte ions into its bulk. A two-electrode symmetric supercapacitor has been assembled, delivering a specific capacitance of 110 F/g and an energy density of 19.8 Wh/kg at a power density of 149 W/Kg, which is comparable with other carbon-material based supercapacitors.

Selected publications

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Journals

  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2019). Controlled release of caffeine from tablets of spray-dried casein gels. Food Hydrocolloids, 88, 13-20. [More Information]
  • Zhong, C., Tan, S., Langrish, T. (2019). Redness generation via Maillard reactions of whey protein isolate (WPI) and ascorbic acid (vitamin C) in spray-dried powders. Journal of Food Engineering, 244, 11-20. [More Information]
  • Tan, S., Jiang, T., Ebrahimi Ghadi, A., Langrish, T. (2018). Effect of spray-drying temperature on the formation of flower-like lactose for griseofulvin loading. European Journal of Pharmaceutical Sciences, 111, 534-539. [More Information]
  • Chen, X., Wei, L., Wang, Y., Zhai, S., Chen, Z., Tan, S., Zhou, Z., Ng, A., Liao, X., Chen, Y. (2018). Milk powder-derived bifunctional oxygen electrocatalysts for rechargeable Zn-air battery. Energy Storage Materials, 11, 134-143. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2018). Preparation of core-shell microspheres of lactose with flower-like morphology and tailored porosity. Powder Technology, 325, 309-315. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Liu, X., Langrish, T. (2018). Role of templating agents in the spray drying and postcrystallization of lactose for the production of highly porous powders. Drying Technology, 36(15), 1882-1891. [More Information]
  • Tan, S., Chen, X., Zhai, S., Ebrahimi Ghadi, A., Langrish, T., Chen, Y. (2018). Spray drying assisted synthesis of porous carbons from whey powders for capacitive energy storage. Energy, 147, 308-316. [More Information]
  • Tan, S., Chen, X., Cui, C., Hou, Y., Li, W., You, H. (2017). Biodegradation of saline phenolic wastewater in a biological contact oxidation reactor with immobilized cells of Oceanimonas sp. Biotechnology Letters, 39(1), 91-96. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Liu, X., Langrish, T. (2017). Hollow flower-like lactose particles as potential drug carriers: Effect of particle size and feed concentration. Powder Technology, 320, 1-6. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2017). Template-directed flower-like lactose with micro-meso-macroporous structure. Materials and Design, 117, 178-184. [More Information]
  • Tan, S., Li, W. (2016). Behaviour of fouling-related components in an enhanced membrane bioreactor using marine activated sludge. Bioresource Technology, 220, 401-406. [More Information]

2019

  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2019). Controlled release of caffeine from tablets of spray-dried casein gels. Food Hydrocolloids, 88, 13-20. [More Information]
  • Zhong, C., Tan, S., Langrish, T. (2019). Redness generation via Maillard reactions of whey protein isolate (WPI) and ascorbic acid (vitamin C) in spray-dried powders. Journal of Food Engineering, 244, 11-20. [More Information]

2018

  • Tan, S., Jiang, T., Ebrahimi Ghadi, A., Langrish, T. (2018). Effect of spray-drying temperature on the formation of flower-like lactose for griseofulvin loading. European Journal of Pharmaceutical Sciences, 111, 534-539. [More Information]
  • Chen, X., Wei, L., Wang, Y., Zhai, S., Chen, Z., Tan, S., Zhou, Z., Ng, A., Liao, X., Chen, Y. (2018). Milk powder-derived bifunctional oxygen electrocatalysts for rechargeable Zn-air battery. Energy Storage Materials, 11, 134-143. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2018). Preparation of core-shell microspheres of lactose with flower-like morphology and tailored porosity. Powder Technology, 325, 309-315. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Liu, X., Langrish, T. (2018). Role of templating agents in the spray drying and postcrystallization of lactose for the production of highly porous powders. Drying Technology, 36(15), 1882-1891. [More Information]
  • Tan, S., Chen, X., Zhai, S., Ebrahimi Ghadi, A., Langrish, T., Chen, Y. (2018). Spray drying assisted synthesis of porous carbons from whey powders for capacitive energy storage. Energy, 147, 308-316. [More Information]

2017

  • Tan, S., Chen, X., Cui, C., Hou, Y., Li, W., You, H. (2017). Biodegradation of saline phenolic wastewater in a biological contact oxidation reactor with immobilized cells of Oceanimonas sp. Biotechnology Letters, 39(1), 91-96. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Liu, X., Langrish, T. (2017). Hollow flower-like lactose particles as potential drug carriers: Effect of particle size and feed concentration. Powder Technology, 320, 1-6. [More Information]
  • Tan, S., Ebrahimi Ghadi, A., Langrish, T. (2017). Template-directed flower-like lactose with micro-meso-macroporous structure. Materials and Design, 117, 178-184. [More Information]

2016

  • Tan, S., Li, W. (2016). Behaviour of fouling-related components in an enhanced membrane bioreactor using marine activated sludge. Bioresource Technology, 220, 401-406. [More Information]

Note: This profile is for a student at the University of Sydney. Views presented here are not necessarily those of the University.