Gras Group

“Our work is multi-disciplinary and staff and students have training in the fields of chemical engineering, chemistry, biochemistry and food science. Our research spans fundamental problems through to applied research that aims to translate research findings to a range of industries.” – Associate Professor Sally Gras.

Biography

Professor Sally Gras is Director of the ARC Dairy Innovation Hub which brings together three of Australia’s leading dairy research groups – The University of Melbourne, The University of Queensland and Dairy Innovation Australia Ltd. (DIAL) – in a five-year research program co-funded by the Australian Research Council. The research program addresses some of the major challenges identified as constraints to business growth and productivity in the dairy manufacturing sector.
Prof Gras is Leader of the Food and Agribusiness research theme within the University’s Melbourne School of Engineering where she also teaches Biochemical and Pharmaceutical Engineering within the Department of Chemical Engineering. 

Sally is Associate Director of the Bio21 Molecular Science and Biotechnology Institute where she leads a multi-disciplinary research group. Sally trained as a Chemical Engineer and Molecular Biologist and received her PhD in protein biophysics from Cambridge University, U.K.

Research

Research in the Gras laboratory is focused on five main themes:  dairy science and engineering; biotransformations and pharmaceutical production; functional foods and gut health; protein aggregation and materials; and waste water and environmental microbiology.

The ARC Dairy Innovation Hub undertakes Dairy Science and Engineering research.  The group conduct work in the microstructure theme of the Hub and have developed advanced microscopy tools which provide insights into every stage of Cheddar manufacture as it occurs in Australia, improving our understanding of how process parameters alter cheese structure and properties. Manufacturers have used this research to assess the effect of process or equipment upgrades on their product and to reverse engineer desired properties. These techniques have also been applied to study the properties of buffalo milk and milk products, which has helped smaller manufacturers to improve their processes.

New routes for the production of pharmaceutical drugs are also being explored using enzymes rather than chemical synthesis. Such technology may assist the pharmaceutical industry and improve environmental sustainability.

The Gras laboratory has worked collaboratively with a number of teams and industry partners to examine functional food products, including oligosaccharides produced enzymatically from the lactose found in milk. Other collaborations have examined the science of gut health and the effects of food products on the gut.

Studies of protein aggregation and protein based materials are of interest to the laboratory, which is exploring how fibril-like nanostructures made from synthetic precursors can be used to make new materials for biotechnology and nanotechnology applications.  

Current Research Activities

• Dairy science and engineering
• Biotransformations and pharmaceutical engineering
• Nano and Biomolecular Engineering
• Nanostructured Materials
• Tailored Biomaterials and Emulsions
• Nano-diagnostics, nano-toxicology, nano-therapeutics
• Fermentation processes and scale-up    

Dairy science and engineering –Professor Sally Gras
Milk is a complex mixture of protein, fats and sugars, with significant structural order, from the native milk fat globule membrane to casein micelles. Further microstructural features are generated during the production of dairy products such as homogenised milk, yoghurt and cheese. These nano and microstructures determine the functional properties of these ingredients and foods; they also impact on the subsequent digestion process.

Our interest is in applying microscopic tools to better understand the nano and micro structures that naturally occur in milk and dairy products. We have coupled microscopy and proteomics to probe the milk fat globule membrane in situ on the surface of fat globules and to assess changes that occur during processing. We are also interested in how structure is generated during the production of dairy products, such as cheese. Small scale processes have been developed in our laboratory (e.g. for yoghurt, cream cheese and cheddar cheese) that effectively model larger production processes, allowing higher throughput screening of the key process parameters that determine structure and impact on the physico-chemical properties such as rheology, texture and meltability. Confocal and cryo scanning electron microscopies are used to provide new insights into these processes, including the quantitative comparison of structural features. 

A greater understanding of these dairy structures will assist manufacturers to optimise yield; the ability to predict and tailor textures, or reverse engineer desirable properties, is also of interest to food manufacturers. We work with Australian manufacturers to understand how formulation and large scale processing impacts on the structure of dairy foods; we also work to translate our findings to manufacturing scale. 

This research forms a theme within The ARC Dairy Innovation Hub, sponsored by the Australian Research Council and Australian dairy manufacturing industry, which aims to promote innovation and assist manufacturers to address scientific and engineering challenges.  

Health
Biotransformations and drug production –Professor Sally Gras
We are interested in the use of enzymes and biotransformations as an environmentally friendly route to produce pharmaceutical drugs. We have an active interest in the pharmaceutical industry and several projects in this area.

Protein aggregation and materials –Professor Sally Gras
We are interested in exploring how fibril-like nanostructures made from synthetic precursors can be used to make new materials for biotechnology and nanotechnology applications. This includes the production of hybrid materials that involve DNA origami and studies of the natural fibrillar aggregates made by bacteria. 

The Gras laboratory is also interested in the development of new materials for a range of applications. These include advanced polymeric materials that deliver anti-inflammatory peptides for tissue engineering or drugs for the treatment of cancer. Other new materials include self-assembling peptide systems and grafted peptide layers that can control interfacial properties and nanoparticle aggregation. Several projects involve the synthesis of peptides by FMOC chemistry, these peptides then form the building blocks used to make new materials.

We have also designed de novo peptide sequences that self-assemble to form fibrous structures known as amyloid fibrils. These protein fibers were first found associated with protein misfolding diseases but are now known to occur more widely and can be found on a variety of surfaces, such as the outside of bacterial cells. The material properties of these fibrils and their positive functions in nature suggest these self-assembling structures can be developed as new materials. We are examining fibrils formed by soil bacteria and hope to uncover why these fibrils are different to those formed in disease.

Waste water and environmental microbiology –Professor Sally Gras
We are applying bioengineering skills to a range of environmental problems, such as foaming in wastewater treatment. Foaming causes significant operational problems during wastewater treatment and poses a risk to human health and the environment. We are exploring a new low cost approach using naturally occurring bacteriophage to reduce the number of microbes responsible for foaming.

Techniques

• Microscopy techniques (Confocal, TEM, SEM, cryo-SEM, AFM, S-FTIR). Dairy protein, fat and oligosaccharide analysis, texture and rheological analyses of curd, cheese and other dairy products.   
• Small scale production of dairy products (e.g. yoghurt and cheese). 
• Bacterial and cells are cultured for enzyme production and biotransformation; the group also has capacity for mammalian culture for cell adhesion, migration and cytotoxicity studies. 
• The group has large scale (>5L) fermentation capacity for bacterial and mammalian expression systems. Peptide synthesis, protein characterisation techniques (FTIR, CD, fibre X-ray diffraction) and metabolite and drug analysis by LC, UPLC and HPLC.cations.  

Group Members

Postdoctoral Fellows

Dr Linda De Melis, Research Manager

PhD Students

Luke Richards, PhD student
Bhanu Devnani, PhD student
Wilhelm Burger, PhD student
Anita Pax, PhD student submitted 2018