Food or edible material: processes – compositions – and products – Processes
Patent
1999-07-12
2000-03-07
Bhat, Nina
Food or edible material: processes, compositions, and products
Processes
426330, 422 33, 422295, 99453, 99467, 99483, A23L 3015, A61L 202
Patent
active
060337176
DESCRIPTION:
BRIEF SUMMARY
The present invention is concerned with a method for preservation, particularly ultra high pressure preservation. The method is used for operation in a continuous mode and is particularly suitable in the food industry.
STATE OF THE ART
Industrially prepared food usually has to be subjected to a preservation treatment in order to prevent spoilage during subsequent storage. Ultra-high pressure (UHP) preservation is a preservation method which only relatively recently has been developed for industrial application, although the lethal effect of ultra-high pressure on micro-organisms has been discovered already in the previous century by B. H. Hite. A review of the state of the art can be found in New Methods of Food Preservation (1995, ed. G. W. Gould). UHP preservation is the subject of many patents: e.g. U.S. Pat. No. 4,873,094, U.S. Pat. No. 5,228,394. NL 102 914 describes conducting a spread-like product through a narrow tube under an initial pressure of 40 atmospheres with a beneficial effect on the consistency of the product. This pressure however, is not high enough to have a significant effect on the viability of micro-organisms in the product.
Substances treated in a homogenizer are exposed also to a very high pressure, but during a very short time (several milliseconds). In such a device the shear forces exerted on the substance during the pressure drop are enormous and often damage the product structure. Moreover the energy needed for passing the product through the homogenizing clearance dissipates quickly in a small volume of the shearing device resulting in a local, unacceptably high temperature rise. Usually this rise is approximately 5.degree. C. per 20 MPa of pressure drop, the rise also depending on the thermal capacity and heat conductivity of the product.
A major disadvantage of known UHP preservation techniques is that UHP preservation is applied only batch-wise. Since 20 most food processing is operated in a continuous mode, an UHP preservation method which could be operated as a continuous process would fulfill a need. Only WO 95/22912 describes UHP equipment with which a semi-continuous process can be carried out. Present equipment for UHP processing is complicated and so expensive that it impedes an economic use and consequently the general employment of UHP preservation.
STATEMENT OF INVENTION
We have found an unexpectedly feasible combination of two seemingly controversial conditions: the one condition being maintenance of a high kinematic pressure in a tube which is relatively narrow and open at the exit end, which kinematic pressure in at least a part of the tube is sufficiently high that a microbiologically contaminated fluid during its flowing through the tube gets decontaminated, the other condition being the realisation of a flow which is high enough to make the process economically feasible.
The invention therefore provides a method for decreasing the viability of micro-organisms and/or the activity of enzymes in a contaminated substance by exerting a high pressure to the substance, characterized in that the substance is conducted in a steady flow through a tube, while the pressure difference between the entrance end and the exit end of the tube is maintained at 100 MPa or more. The present method allows a fully continuous UHP preservation process.
BRIEF DESCRIPTION OF THE FIGURE
FIG. 1 shows a schematic view of the equipment with which the invention can be carried out. c is a tube with a length L and an inner diameter d. a is a storage container connected to the entrance of the tube via a pressure unit b. At d the open orifice of the tube is situated.
DETAILS OF THE INVENTION
The invention essentially is carried out by feeding the substance from the storage container a to the entrance of the tube via a pressure unit b and passing it through the tube to the exit at the right hand side.
The invention can be applied on all types of fluid substances which need a decontamination treatment, provided they have a consistency which allows a sufficiently quick passage throu
REFERENCES:
patent: 5316745 (1994-05-01), Ting et al.
patent: 5840353 (1998-11-01), Woolner
Search Report WO/9743814, Sep. 19, 1997.
Agterof Wim
Lelieveld Hubertus L
Reichelt Thomas
Smelt Johannes P
Bhat Nina
Unilever Patent Holdings
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