Sunday, July 10, 2011


Pathogenic microorganisms like Salmonella, Listeria and virulent strains of E.coli are causing enormous damage to processed foods in spite of fast advances made by food technology. The recent E.coli poisoning episode in Europe, claiming almost 50 lives and causing health damage to thousands is a classical example of what these organisms can do in harming humans through their foods. Though gamma radiation is considered efficient in destroying these pathogens, this technology has not yet become the industry standard due to consumer apprehension regarding the safety of irradiated foods. It is against such a background one has to appreciate the arrival of High Pressure Processing (HPP) technology which achieves "cold sterilization" without use of chemical preservatives or high temperatures. Introduced commercially in the US during 1990's HPP has come to be established as a reliable technology world over though its high investment cost is a damper to its wide scale use. New Zealand, which has a substantial production base for Avocados is the latest to acquire HPP for extending the life of the fruit from 30 days to more than 60 days that is expected to boost its exports dramatically in the coming years.

"The Kiwi avocado industry has secured a multi-million dollar export deal with Japan thanks to its new food processing technology. The food preserving technology, introduced earlier this year, dramatically extends the shelf life of avocados without the use of any chemicals or other additives. The Ultra High Pressure (UHP) processing technology, which is also known as cold pasteurization, uses pressures of up to 87,000 psi to shock and kill bacteria in food products. Kiwi owned Fressure Foods, a grower-owned company, imported the technology last year, establishing its plant in Pukekohe and creating 40 jobs. Fressure Foods CEO, Vern Dark, says with its ability to extend the shelf-life of avocados and deliver them in a convenient ready to use pack the industry is capable of boosting the country's annual exports by 20 million dollars. "Avocados usually last around 30 days but now we're able to extend this to 60 days. We imagine this extended shelf life will open many new markets. With this technology we are able to add significant value to a commodity product which was too perishable for some of the countries we wanted to export to." One of the first products to receive the UHP treatment is the Fressure Foods Guacamole with significant orders being delivered to Japan and Singapore. Export negotiations are also well advanced in Australia and the products have recently launched in New Zealand supermarkets. Dark says ultra high pressure treatment has driven up total consumption of avocados in the United States, something he is hoping will be repeated here".

It is a fact that the high investment HPP technology is most popular in the US and majority of the 100 plus plants are located in that country. Subjecting products to high hydrostatic pressure causes irreversible denaturation of proteins including bio-active enzymes, fortifies hydrogen bonds, disrupts non-covalent bonds while leaving the covalent bonds unaffected. The texture is maintained while bacteria are made innocuous. It is notable that cold sterilization can be achieved within 3 minutes while traditional thermal processing can take as much as 10-45 minutes. On the limitation side spores are not destroyed unless there is a reduction in the pH of the system while some foods need refrigeration to prevent deterioration due to some enzymes not inactivated during the process. Some of the products commercially being processed by HPP include fish, meat, salad dressings. rice cake, yogurts and Avocado derived guacamole. Considering that food products that cannot be processed at high temperatures need sterilization to ensure consumer safety, HPP is considered the most appropriate technology at present.

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