As consumer fashion today demands ever more new food products, software will play a greater part in food design. Eric Russell reports on the increasing use of computer aided design and finite element analysis.
Food designers are increasingly using the tools of mechanical engineering to produce new food products. In particular, they are calling on computer aided design (CAD), computer aided engineering (CAE), computational fluid dynamics (CFD) and finite element analysis (FEA).
These software tools enable food products to be drawn in 3D colour and analysed using reference data stored in a database. This data includes the mechanical, behavioural and chemical properties of materials plus the relevant rules of physics and engineering.
One free database on the internet is at www.nelfood.com. This is the result of an EU project that has collected reliable and useful data on physical properties of foods. It contains 11031 bibliographic references; 1488 evaluated datasets; 260 physical properties; and knowledge bases on water activity and mass diffusion.
In practice, food processing is not so different from mechanical engineering and other manufacturing processes. Food products have to be mechanically strong, withstand heat and retain their appearance just like any component that is engineered out of metal. Both metals and chemicals are created from a mix of ingredients that can be modelled on a computer just like a set of food ingredients.
It is bad news, for example, if biscuits crack in half when being buttered by the eater; and if the mix is too crumbly, a packet of biscuits will arrive on the supermarket shelf as a bag of crumbs. Texture of food in the mouth is also vital to its enjoyment and this is another mechanical feature that can be modelled.
The benefits of computer modelling are the same as for designing engineering components: a new product can be designed on computer and will not take time out of the production department; the computer model can be more easily amended than a physical sample; the data is retained so future designs can be built on existing concepts rather than starting from blank paper again; and designs can be networked simultaneously to other departments such as marketing and production for their consideration.
Software types
In general, CAD software is used for drawing, CFD for predicting flow and FEA for stress analysis. Flow is important to model, whether it be a food mix flowing into a mould, heat flowing evenly through a product during cooking, heat transfer during cooling, heat distribution in an oven or consistency of a food that is to be spread.
Concentration, Heat and Momentum Ltd (CHAM) has developed an ideal software for food modelling with its Phoenics suite. This includes a virtual reality capability that enables a product to be seen in 3D colour and rotated so it can be seen from all angles.
Fluent is another long established software house. Its CFD software is being used in many food areas. In baking, for example, it is used to analyse convective, conductive, and radiative heating.
The company's software is also being used to analyse starch gelatinisation, protein denaturisation, product cooling and drying, forced and natural convection ovens, French fries in oil vats and the roasting of cocoa and coffee beans.
Post production, Fluent software is widely applied to food storage and packaging; from the manufacture of pots and bottles to bulk storage of food ingredients in silos; to moisture penetration in food packaging.
Food moulds, pudding cups, beer cans, drinks bottles and even tea bags have been successfully modelled using Fluent software. Programs provide information on fill times, entrapped air and bubble formation phenomena and splashing predictions.
Preprocessing is the first step in building and analysing a computerised flow model. This covers building the model or importing a design from a CAD package. Fluent offers three preprocessing tools: GAMBIT, G/Turbo and TGrid. Third-party preprocessing tools can also be used.
After preprocessing, the CFD solver does the calculations and produces the results. Fluent offers three general-purpose solvers: Fluent, Fidap, and Polyflow. Postprocessing is the final step in CFD analysis and involves organisation, interpretation and display of the data and images.
Fluent also provides software packages for specific applications including Airpak for ventilation system design and MixSim is for mixing applications.
One American manufacturer of commercial fryers has used Fidap CFD software to model heat flow of hot oil during cooking. The target was to reduce the amount of oil used in the fryer while improving the uniformity of the cooked product.
Oil temperature has a direct effect on the colour and textural characteristics of finished products and, by maintaining different oil temperatures in separate zones of the fryer, products with different characteristics can be produced simultaneously. It is also important to avoid small products clumping together in lumps.
Oil often moves in a vortex in the fryer and, if such localised movement is violent, it can remove the coating from battered products, for example, reducing their visual attractiveness. One improvement resulted in the installation of a simple perforated plate in the fryer and the net effect of the project was substantial oil savings for the customer.
In Italy, the University of Padova has been using a CFD software solution, STAR-CD from The CD adapco Group, to help transform pasta dough into spaghetti, penne and farfalle.
Pasta, in its pre-shaped state, is a non-Newtonian fluid. This means that, while appearing to be a solid, it is actually a fluid. But it does not strictly conform to the rules traditionally associated with liquids.
The fluid dynamics research group at Padova is aiming to improve the understanding of these flows. It will them be possible to work out how to improve the industrial processes behind pasta. It is in the shaping stages that the high variability of the pasta's molecular properties becomes a vital factor. Using specialised instrumentation, university engineers measured the viscosity of pasta to see how it reacted to changes in both temperature and velocity. Then, CFD analysis was used to make changes in the moulders and extruders to optimise the pressure drop and distribution. A useful reduction in pressure meant a matching reduction in energy consumption, reducing the pasta process cost.
Growing role
Software supplier TranscenData Europe says ready meals are becoming increasingly popular and design software is playing an increasing role in product development. Recent figures show that ready meals are one of the highest growth sectors in the food market.
A variety of social changes continue to drive the market forward, with people's increasingly busy lifestyles being a key factor for ready meal purchases. But there can be difficulties trying to persuade software packages from different vendors to communicate with each other and the company offers a data interoperability solution called CADfix. This addresses the fundamental inconsistencies and inaccuracies that prevent the efficient transfer of solid modelling geometry between different computerised systems such as FEA. Called CADfix CAE, the package is specifically for engineering applications.
It is being used by ProEng Solutions, a specialist in the analysis of food processes involved in microwaving, particularly reheatable meals. Dr Sidi Chouikhi, managing director, says factors be considered when looking at microwavable products include safety, quality, flavour, taste, functionality and texture.
A key problem that food manufacturers face is finding packaging that has consumer appeal while at the same time ensuring that the product reheats effectively. The whole package has to deliver on visual appeal, taste and texture. It also has to be heated evenly although there is little time for the heat to flow through the food.
Dr Chouikhi says that ProEng Solutions specialises in product and process engineering projects for the food industry. Using its experimental facilities and simulation capabilities the company provides its clients with fully proven solutions to food product and process engineering problems. One of its areas of expertise is in microwavable products.
ProEng Solutions uses its experimental facilities to measure temperatures around the product during and after heating using infrared thermal imaging as well as conventional thermocouples. This visually demonstrates what is happening to the food inside the microwave as it is being heated.
ProEng Solutions also uses its resources to alter the microwave properties of foods. This enables it to create solutions that provide differential heating and which produce crisping of such products as pizza bases and spring rolls.
Dr Chouikhi says the company is currently looking at a ready-meal concept which includes sauce and rice on one side and spring rolls on the other. The requirement is to re-heat these two sides simultaneously and to end up with suitably heated sauce and rice and hot and crisp spring rolls.
A number of packaging and material options are being explored using simulations and experiments in an attempt to develop a suitable and commercially viable solution that will allow the meal combination to be microwaved all at once. This will save time and make the product more convenient for the consumer.
