Refrigeration – Processes – Treating an article
Patent
1991-06-21
1992-10-20
Capossela, Ronald C.
Refrigeration
Processes
Treating an article
62378, 62380, F25D 1306
Patent
active
051560089
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an arrangement for freezing a food product.
For freezing food products, use is often made of freezing equipment in which the product is carried by some type of supporting structure during freezing. Once the freezing is completed, the product should be removed from the supporting structure, which in many cases involves substantial difficulties.
When using e.g. a freezing tunnel with a belt conveyor where the conveyor belt, in the form of a flat conveyor belt, feeds the product through the long freezing tunnel, the product will freeze onto the conveyor belt. It must then be scraped off or broken loose from the supporting structure, leaving remnants of the product frozen fast on the supporting structure. This freezing technique also requires considerable space, and the process cannot be modified or discontinued until the entire product has been transformed into solid ice phase.
When using e.g. a freezer with a foraminated conveyor belt, the product may also freeze on to the belt or receive impressions or be deformed by the belt.
Although it is previously known in the art, by different types of surface treatment, to try to prevent a product from freezing fast on e.g. a steel belt, these attempts have met with but little success.
The difficulties mentioned above, which are especially pronounced for products having soft consistency or a soft or moist surface, can however be overcome by stabilising at least one surface of the product before final freezing, whereby to obtain improved handleability of the product.
The object of the invention is to provide a method and an arrangement bringing about such stabilization in an uncomplicated fashion by freezing at least one surface of the product, without, of course, any risk of the product freezing fast on the belt.
According to the invention, this object is achieved by placing the product on a supporting structure which has previously been given such a low temperature that the product when contacting the supporting structure will not freeze to it, maintaining the product on the supporting structure for a sufficient time to cause at least its surface layer nearest the supporting structure to pass into the frozen state, and removing the product from the supporting structure for final freezing in a separate freezer.
The invention relies on the presumably newly discovered phenomenom that there is no tendency whatever of the product freezing to the conveyor belt when the temperature of the supporting structure becomes sufficiently low. The temperature at which this phenomenom appears depends on the nature of the product and thus varies with the composition of the product to be frozen. Hence, for each product there is a critical temperature below which this phenomenom can be brought about. The value by which the temperature should fall below the critical temperature in actual practice is dependent on the properties of the material of the supporting structure on which freezing should be performed, and on how the temperature decrease of the supporting structure is achieved.
It is thus likely that an increase of the water content of the product above a certain value entails a decrease of the critical temperature. The same probably also applies to a more liquid consistency of the product.
The properties of the material of the supporting structure which are most likely to affect the practical temperature required for avoiding that the product freezes fast on the conveyor belt are the thermal conductivity of the material and its heat capacity. This can probably be explained by the heat transfer process occurring during the time period counting from the moment the product to be subjected to surface-freezing is placed on the supporting structure to the moment the portion of the product surface facing the supporting structure and making direct contact with the supporting structure when placed thereon has passed into the frozen state. During this time period, the temperature in the boundary between the product and the supporting structure
REFERENCES:
patent: 3611745 (1971-10-01), Schlemmer
patent: 3791162 (1974-02-01), Baker
patent: 4205536 (1980-06-01), Kasahara
Eek Lars
Olsson Lennart
Capossela Ronald C.
Frigoscandia Food Process Systems AB
LandOfFree
Method and arrangement for freezing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and arrangement for freezing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and arrangement for freezing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-185605