The recent approval by the FDA of a microwave sterilisation technology for the production of mashed potatoes opens up a new food safety process for ready-to-eat foods that looks set to save time, improve color and texture and cut refrigeration costs for processors and distributors. The FDA approval of the process is the culmination of a ten-years collaborative effort, involving academia, industry and even the US army. The collaboration was headed by Professor Juming Tang of Washington State University, who has no hesitation in declaring that the new process has the potential to radically change the pre-packaged, low-acid food industry. FEI spoke to Prof. Tang about the development.
Q. Why is this microwave sterilisation process revolutionary?
Single-mode 915 MHz sterilization technology is fundamentally different from conventional retorting methods. The former is volumetric heating whereas the latter is surface heating (by steam or pressurized hot water). Our technology can cut the heating time in conventional thermal processing by 70 to 80 per cent in single serving size meals while achieving the same level of pathogen control. This allows food companies to produce very high quality food products. Essentially, microwave sterilization is a thermal process that delivers thermal energy to foods under pressure to inactivate bacteria harmful to humans. The microwave sterilisation process takes eight minutes, conventional canned foods can spend up to two hours in an industrial pressure cooker.
Q. What did the development of the process entail?
All new technologies to produce low acid shelf-stable foods in the US require FDA acceptance to ensure the processed foods are free from pathogenic bacteria. On the road to regulatory acceptance, steps for the microwave sterilization consortium involved detecting cold spots in the food packages, temperature measurements and the verification of ‘desired microbiological lethality’ in the food products. We have overcome most of the scientific challenges. Designing economically viable industrial systems is one of the remaining challenges, while gaining a better understanding of product formulations to take advantage of the new technology is another challenge.
Q. What are the applications?
The technology is applicable for all types of ready-to eat meals and we are currently preparing the next FDA filing, this time for salmon fillets. In-package microwave sterilized products, such as pasta dishes, pasta sauces and rice dishes are currently available in Europe (for example, TOP’s Foods).
Q. What are the benefits and potential for food manufacturers ?
Like any new technology, cost reduction is not going to happen immediately for the early users. But the price of system and operational costs will come down with market acceptance and with design improvement. US manufacturers have several types of microwave heating systems for food tempering, de-freezing and baking, as well as pasteurisation and drying of semi-liquid products. None of this equipment is designed for high temperature microwave sterilization. The commercial potential of the process is very large. We have received inquiries about this technology worldwide and are in the process of developing the first commercial system. We are working currently to scale up the system so that it could handle 50 to 150 meals/min. We expect that the first commercial unit will reach the market in one and half years.
Q. What about from the product point of view?
The short exposure to high temperature means that there is much less thermal degradation of the product while the efficacy of the sterilisation process means that shelf-life can be extended. (Shelf life for the sweet potato puree that recently received FDA approval is three years).
Q. Who were involved in the collaborative development efforts?
The consortium involved academia, industry and the US army. Industry participants included Kraft Foods, Hormel Foods, Rexam Containers and the Seafood Products Association, with all members of the consortium sharing the same motivation and the desire to produce high quality shelf-stable food for the US military and the general market.
Q. How do you see the technology in five or ten years’ time?
We foresee that this type of technology will dramatically change the industry, much like cell phones and computer software have done over the past 10 years. Processes like ours will ensure food safety, while retaining product quality, and reducing labor costs and energy use.
Further details about the technology are available at www.microwaveheating.wsu.edu.
