Food and bioproduct processing

The Food and Bioproduct cluster was established in 1998 by the Faculty of Engineering to enhance research and pursue innovations in food and bioproduct processing. The cluster draws on the expertise within the Faculty of Engineering, and collaborators from the Faculty of Science and the Faculty of Medical and Health Science.

The focus of the group is on various aspects of food processing and biotechnology, specifically the engineering and development of value-added food products and new, cost-effective food processing technologies. The work carried out is strongly focused on the interaction of processing routes with product performance. Rigorous engineering approaches are taken and, where appropriate, detailed mathematical modelling of the processes is also carried out.

We are an internationally-recognised team who represent New Zealand in the International Association of Engineering and Food (IAEF). We also have established a strong working relationship with local food processing industries and with national and international food research centres.

Innovative non-thermal and thermal processing of food

We are heavily involved in developing new technologies related to thermal and non-thermal processing of foods. Non-thermal processing of food includes pulsed electric field (PEF), high pressure processing (HPP) and UV treatment. We have built the first PEF unit in the southern hemisphere, and patented a new Pressure Assisted Thermal Sterilisation Technology. Innovative thermal processing of foods such as microwave and ohmic heating are also being investigated as efficient and rapid heating methods. A new cooking technology has been patented based on ohmic cooking of frozen food such as meat patties, which has attracted attention from the Research Center of McDonalds in Chicago. Ohmic cooking of meat patties reduces health hazards, cooking time and energy consumption.

We are on the international forefront of research into High Pressure Processing technology. The Department of Chemical and Materials Engineering has a 0.3L HPP machine used in a number of projects. The Foundation for Research Science and Technology funded a postdoctoral fellow whose work received international recognition and placed our team at the leading edge in this area worldwide. This lead to a strong relationship with the New Zealand Institute for Plant and Food Research (PFR) resulting in funding of a PhD student working on HPP of Green Mussels and co-funding for a larger capacity, 2L HPP machine costing $450,000 (to be installed in 2010). Internationally we have established strong relationships with major international research centres working on HPP including the National Centre for Safety and Technology in Chicago and the National Food Research Institute of Japan, (which provided funding for a PhD student to visit and work in their laboratories for six months).

We are also at the forefront of the application of computational fluid dynamics (CFD) to thermal processing of food such as thermal sterilisation of food in cans and pouches. CFD work has been extended beyond conventional thermal processing to cover non-traditional and innovative processing technologies for solid and liquid food under high pressure conditions.

Food safety and shelf stability are key performance parameters for processed food products. Members of the team have wide experience in using microbial indicators and studying microbial inactivation to assess the impact of processing conditions and storage time. Forth coming projects include studying the effects of new food preservation technologies on food safety and shelf-life, and design of proper pasteurisation processes for specific foods using innovative food processing technologies.

Food microstructure

The team has a particular strength in examining food structure and mechanical performance in the context of innovative process and product development. Worldwide there is an increasing awareness of the relevance of food microstructure and the group is gaining a significant national and international reputation in this area. Food structure, and its relationship to food properties, is the focus of numerous projects underway in this group.

Current projects cover a range of foods and are addressing several fundamental and applied aspects of food structure. These include a large scale collaboration with PFR and Massey University investigating the influence of food structure on mastication, and the changes in structure and rheology that occur up to the point of swallowing, including the role of water and saliva . The structural aspects of food relevant to quality, nutrition and sensory perception cover a range of length scales, from mm down to nm, and the group is developing techniques to assess and quantify structural components, including in situ microscopy methods and statistical tools.

The correlation between structure, rheology and properties of food materials, and how these aspects are influenced by both traditional and non-traditional processing routes are being investigated. Current projects with Fonterra and PFR are supporting PhD students in this area. Uniquely for NZ team members in this area are working with some of the countries top chefs to develop new textures and innovative food products in the field of molecular gastronomy.

The work of the cluster in this area is strongly supported by the Research Centre for Surface and Materials Science (RCSMS), which is able to provide advanced materials characterisation tools that are not available elsewhere in the country.

Pharmaceutical processing

A collaborative project with the School of Pharmacy has designed a supercritical carbon dioxide anti-solvent (SAS) particle processing system and used it to produce micronised particles of carbamazepine, a poorly soluble drug. It was possible to fully characterise the drug solid, before and after treatment, using a number of the specialised materials analysis tools in the Department of C&M Engineering and RCSMS. The work, which was conducted by an ME student was continued by a PhD student in the School of Pharmacy.

Refrigeration and food transportation

During storage and transportation of temperature sensitive products, significant temperature variations may occur due to events such as door opening of the cold storage facility. The objective of this is work is to investigate how Phase Change Materials (PCM) panels placed into a domestic fridge-freezer can aid in maintaining regular temperatures in the presence of heat loads such as door openings, defrosting and regular power loss. Results so far indicate that the addition of PCM panels helps to limit peak temperatures reached during defrosting and also maintains more regular temperatures during door openings. The use of PCM panels reduces ice growth in ice cream and minimises moisture drip loss in frozen meats during storage.

Fouling mitigation and surface engineering

Surface engineering is being investigated by members of the team for applications in selective adhesion or rejection of certain species.

One major area of focus is to design surface chemistry and structure to reduce the adhesion strength of protein and mineral foulants on surfaces. With a knowledge of the chemical interactions that occur between the substrate material and the foulant, we can design or select coatings which minimise these adhesive interactions. The work includes an important type of fouling in the dairy industry, which is microbial fouling. In addition, research is underway investigating the controlled use of gas-liquid multiphase flows to enhance cleaning rate and removal of fouled species in food processing plants and milking machines. This technique is commonly referred to as 'air rumbling', but it has been shown that the method can been optimised by targeting particular multiphase flow regimes.

A second major area of focus is in the removal of proteins from wine (fining) using activated surfaces. At present the largest fining agent used in white wine processing is bentonite, of which the active component, montmorillonite, comprises a lamellar structure with exchangeable cations in the hydrated interlamellar layers. The aim of this programme is to duplicate the cation exchange using immobilised fining surfaces incorporated into process equipment.

Simulation and control

The team incorporates world-class expertise in simulation and control. Current projects underway includes developing control measurement strategies for milk dryer viscosity. Stickiness of processed milk powder results in clumping, which in turn increases production energy. The viscosity of milk is a key parameter that affects stickiness of sprayed milk powders. Therefore it is a key physical property to be controlled for optimised milk powder production. However, no group has developed a measurement technique robust enough for dairy industry application. Novel ideas for milk viscosity measurement have been generated.

Another project is examining tomography for process control of food processing. Tomography is a sophisticated multi dimensional sensor technology that has found application in medicine (e.g. CAT scans) and chemical analysis (e.g. NMR). It is our hypothesis that Electrical Resistance Tomography (ERT) can provide both a measurement of fluid density/viscosity as well as the fouling of the heat transfer surfaces in milk production. A New Zealand PhD student is aiding with this project. The project is also partially supported by Fonterra.

Environmental impact is highly topical and relevant and the team is also examining exergy and eco-efficiency of chemical and food/bio processes. An eco-efficient process is one that is both highly ecologically friendly and economically viable. Cutting edge thermodynamic based measures have been developed by this group for the quantification of the eco-efficiency of oil and gas processes in Canada. This project involves both the further theoretical and practical development of eco-efficiency process indicators for processes other than upstream oil and gas operations i.e. processes that are relevant to New Zealand, specifically biological and food processes. Read more about our work in simulation and control on the I²C² webpage.

We have established strong collaborative links with local companies, including:

• Fonterra
• Heinz Watties Australasia
• Flo-Dry Engineering
• Hort Research
• Crop & Food
• AgriGenesis Bioscience Ltd
• Keam Holden Associate Ltd
• Kiwi Fruit Company/Argon
• Sanford Ltd
• Fast food chains such as McDonalds
• Small companies like the Juice Factory in Auckland

We also work together with international food institutes, universities and companies, including the National Centre for Food Science and Safety in Chicago, Food Science Australia, the Department of Food Science & Technology at Ohio State University and a number of international companies.

• Professor Mohammed Farid (primary contact): Innovative non-thermal and thermal processing of food, pharmaceutical processing, refrigeration and food transport
• Dr Filipa Silva: Innovative non-thermal and thermal processing of food, pharmaceutical processing, refrigeration and food transport
• Professor John Chen: Pharmaceutical processing, simulation and control
• Professor Bryony James: Fouling mitigation and surface engineering, food microstructure
• Associate Professor Mark Jones: Fouling mitigation and surface engineering
• Professor Brent Young: Simulation and control

Researchers around the University

• Professor Laurie Melton, Chemical Sciences
• Associate Professor Siew-Young Quek, Chemical Sciences
• Professor Conrad Perera, Chemical Sciences
• Christina Buchanan, Molecular Medicine and Pathology