Traditional methods of food preservation such as: fermentation,
chemical processing by adding salt or sugar, drying, freezing, high
temperature treatment, had been known since the origin of humankind
and the development of civilization brought only their further
improvement. Development of science in the 20th century introduced two
totally new and not known before methods of food preservation:
* irradiation of food - applying ionized radiation, which still
arouses questions, doubts and reservation of consumers
* and method of high pressure processing of food.
Fruit derived products are traditionally produced by thermal
processing which inhibits microbial spoilage and reduces enzymatic
activity being present in fruit. Although ensuring safety and shelf
life of fruit products, thermal pasteurisation dramatically affects
many quality factors of fresh fruits, particularly texture, colour,
aroma and vitamin content. The magical motto of present day of food
market is not only safety but also freshness of food.
High pressure treatment reduces microbial counts and enzyme activity
and affects product functionality, these provide good potential basis
for development of new processes for products preservation and
modification.
The pioneering research in this field was done by Hite and his group
in 1899 in the United States. The scientists demonstrated that peaches
and pears treated with pressures up to 410 MPa for 30 minutes in room
temperature did not spoil during the subsequent five years of storage.
The first commercial products made in 1989-1995 using high pressure
treatment have been almost all plant or plant containing products. In
1990 in Japan were introduced into market UHP - apple, strawberry and
kiwi jams and also UHP juices from various citrus fruits. But still
there are many scientific and practical problems concerning
fundamental and applied research and pilot and industrial production
of fruit products.
The main problem for UHP processing of fruit products there is
inactivation of native enzymes present in fruit.
In High Pressure Research Center pressure processing was carried out
using the high pressure food processor for fresh strawberries,
raspberries cherry, apricot, pears, apples and fruit juices or
fruit-vegetable pulps.
Quality analysis of the products was performed including
physicochemical parameters. Anthocyanins and flavonoids level,
activity of enzymes and sensorial evaluation was investigated.
This lecture reviews some of the results obtained from High Pressure
Research Center of Polish Academy of Sciences research project on the
application of high pressure technology to selected fruit products.
REFERENCES
1. Cano P.M., Hermandez A., De Ancos B. Combined high-pressure /
temperature treatments for quality improvement of fruit-derived
products. In: Processing Foods, Oliveira F.A.R., Oliveira J.C.,
Hendrix M.E., Knorr D., Gorris L.G.M. (Eds.), CRC Press Boca
Raton, London, New York, Washington D.C., p. 301
2. Fonberg-Broczek M., Arabas J., Kostrzewa E., Reps A., Szczawinski
J., Szczepek J., Windyga B., Porowski S. High-pressure treatment
of fruit, meat and cheese products - equipment, methods and
results. In: Processing Foods, Oliveira F.A.R., Oliveira J.C.,
Hendrix M.E., Knorr D., Gorris L.G.M. (Eds.), CRC Press Boca
Raton, London, New York, Washington D.C., p. 281
3. Knorr D.(1995) High pressure effects of plant derived foods. In:
High Pressure Processing of Foods, Ernshaw, D.E. and Hasting,
A.P.H. (Eds), Nottingham University Press, Nottingham, U.K. p. 123
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