A METHOD AND APPARATUS FOR ASCERTAINING THE NET WEIGHT OF A FROZEN, ICE-COATED PRODUCT

Abstract: The method implies that the liquid used to melt the ice-coating of the product in question has a density that is adjusted to the density of said product, with and without ice-coating resp., that the product with ice-coating will float on the surface of the liquid, but without ice-coating will sink into the liquid. Furthermore the circumstance that a given product is sinking into the liquid, as indication that the ice-coating has just melted, is used as starting point for the further treatment of the product. Thus a measuring method is established which contrary to prior art methods is entirely independent of any operator and therefore better suited to provide uniform neutral measurements. The indicated process also renders a high degree of automatization of the measuring procedure feasible.

Description: A method and apparatus for ascertaining the net weight of a frozen, ice-coated product The invention relates to a method for ascertai¬ ning the net weight of a frozen, ice-coated product, said method implying that a charge of the product is placed in a liguid and remains here until the ice-coating has melted, whereupon the product is separated from the liquid and its net weight is deter¬ mined. The purpose of the ice-coating of frozen pro¬ ducts is to prevent the desiccation of such a product during storage in a frozen condition. The ice-coating itself is performed by giving the frozen product, im¬ mediately after the freezing, a thin film of water which freezes to ice and so to speak encapsulates the product and thus protects it from desiccation. When later the net weight of the product per se is to be ascertained, f.i. in connection with a random sampling, it is of course necessary to pay attention to this ice-coating. A simple method would consist in thawing the product and without further ado drain off all the re¬ sulting liquid. However this method is not expedient concerning products which typically are ice-coated, such as shrimps and other small shellfishes, because such products con- tain great quantities of natural fluids and juices which for reasons of taste and consistency must be re¬ tained in the commodity and consequently are to be included in the net weight. This is not possible when using the thawing described above where the natural fluids are drained off together with the icing water, because it is not feasible to decide when only the ice- coating, and not the product itself, has been thawed. In order to remedy this problem an internatio¬ nally acknowledged thawing procedure has been developed, which as said above implies that the frozen, ice-coated product is placed in a lukewarm liquid until the ice- coating has just been thawed. The procedure functions per se irreproachably, but is no more exact than the precision with which it is ascertained when the mel¬ ting of the ice-coating has just occurred. In actual life this is ascertained according to the standard (FAO/WHO CAC/RS 92-1976) by a manual or visual control of the product. Both of these forms of control depend very much on the operator and are for 10 that reason not fully satisfactory. Consequently there is a need for a more neutral and reliable method to ascertain the correct degree of thawing of an ice-coated product. Such an improved procedure is provided by the '■■ -' method according to the invention, which differs from prior art methods by the use of a liquid, whose den- 3 ' sity (g/cm ) is thus adjusted to the density of the product in question, with and without ice-coating resp. , that the product with ice-coating will float on the 20 surface of the liquid, but without ice-coating will sink into the liquid, and that the circumstance, that a given product is sinking into the liquid bath, as indication that the ice-coating has just melted, is used as star¬ ting point for further treatment of the product. 25 T e circumstance, that the product physically changes its location in a suitably chosen or compounded liquid, renders it possible to get an unambiguous and neutral recording of the time when the relevant degree of thawing of said product has just been achieved. ° In a preferred further development of the method according to the invention this fact is used for a continuous and automatic separation of the individual products from the liquid bath concurrently with their sinking into it. This separation is performed preferably 5 with a continuously operating conveyor, pre- ferably a conveyor belt following such a path in rela¬ tion to the surface of the liquid, that products sink¬ ing into the liquid bath are caught by the conveyor and conducted from the liquid bath to a suitable col¬ lecting device, e.g. a sieve. The invention also relates to an apparatus for caryying out the preferred method, said apparatus com¬ prising an upwards open vessel having a conveyor, preferably a conveyor belt, so arranged in relation to the surface of the liquid during operations and also to the inner shape of the vessel, that products sinking into the liquid bath are caught by the conveyor and conducted out of the liquid bath to a suitable external collecting device, e.g. a sieve, combined with a weig ¬ ing machine, the vessel further having means to ensure that products floating on the surface of the liquid bath are not caught by the conveyor. The invention will now be explained in detail with reference to the drawing showing a somewhat sche- atical perspective view of an apparatus to carry out the method according to the invention. The apparatus shown in the drawing comprises an open vessel 1 having an approxi atively V-shape and parallel side walls 2 and 3. The vessel 1 is supported by a stand 4, and a conveyor belt 5 is arranged therein parallel to one of the end walls, and extends down to the bottom of the vessel and right onto the side walls. The vessel 1 contains a certain quantity of liquid 6, f.i. fresh water or salt water. The free surface of the liquid has been divided into two parts 9 and 10 by means of a transverse partition plate 7 extending between the side walls 2 and 3 of the vessel. The partition plate 7 extends a short distance under the surface of the liquid. The apparatus also comprises a weighing machine 12, with a stand 14 supporting both a vibration table 15, and a sieve 16. The weighing machine shown is elec¬ tronic and switched onto a computer terminal 17 for the *-* registration and calculation of the desired data. Nothing however prevents the use of a conventional mechanical balance. The apparatus functions in this wayr A certain approximatively measured charge of the product in quest- •0 ion, f.i. readied frozen and ice-coated shrimps, are placed on the vibration table 15, which advantageously is provided with refrigerating facilities. The opera¬ tion of the vibration table 15 will cause the shrimps to move past its edge 19 and fall individually into the •5 area 9 of the liquid bath 6 in the vessel 1. Due to the ice-coating the shrimps will float on the surface of the liquid, and owing to the presence of the plate 7 they cannot enter the area 10 of the liquid and get into contact with the conveyor belt 5 before the 20 ice-coating has melted. Concurrently with the melting of their ice-coating the shrimps will leave the surface of the liquid and sink into the liquid bath. Here they will be caught by the conveyor belt 5 and transported under the plate 7 5 and out of the liquid bath 10. The shrimps will leave the conveyor belt 5 at its upper end 20 and fall onto the sieve 16. When all shrimps have been transferred to the sieve 16, their net weight can be ascertained immedi- 30 ately. The assembly shown furthermore renders it pos¬ sible to determine the weight of the removed ice-coating, because the weighing machine 12 may also be used to ascertain the original weight of the shrimps with ice-coating after they have been placed on the vibra- 5 tion table 15. On the background of the above it will be under¬ stood that the method described is neutral, automatic and quite independent of any operator and therefore each time will result in uniform measurements. The method according to the invention can also be applied in other less automatized contexts with the same good results. Thus an operator may watch the shrimps in the liquid bath, and when they all have sunk to the bottom, which can be ascertained unambiguously, he may start the further treatment of the shrimps, i.e. their sepa¬ ration from the liquid. This operation can f.i. be per¬ formed by means of a sieve, which during the thawing surrounds the shrimps in the liquid bath, and is then lifted out of the liquid to remove the shrimps there¬ from. As an alternative the liquid can be drained out of the vessel in such a way that the shrimps are re¬ tained by a suitable filter. The liquid used must be compatible with the pro¬ duct in question and have, as said, a suitable density. As examples of usable liquids fresh water and salt water having different concentrations of salt can be mentioned, as well as both fresh and salt water with different additives. Finally it is to be noted that if the conveyor 5 and its surface are suitably sloping and shaped it is under certain conditions possible to omit the partition plate 7.

Claims: P A T E N T C L A I M S 1. A method for ascertaining the net weight of a frozen, ice-coated product, said method implying that a charge of the product is placed in a liquid (6) and remains here until the ice-coating has melted, whereupon the product is separated from the liquid and its net weight determined, characterized in that a li- 3 quid is used whose density (g/cm ) has been thus ad¬ justed to the density of said product, with and without ice-coating resp. , that the product with ice-coating will float on the surface of the liquid, but without ice-coating will sink into the liquid, and the circumstance that a given product is submer¬ ged in the liquid, as indication that the ice-coating has just melted, is used as starting point for fur- ther treatment of the product. 2. A method according to claim 1, characterized in that the individual products continuously and auto¬ matically are separated from the liquid bath concur¬ rently with their sinking into it. 3. A method according to claim 2, characterized in that the products are separated from the liquid bath (6) by means of a continuously operating conveyor (5), preferably a conveyor belt, following such a path in relation to the surface of the liquid (9, 10), that products sinking into the liquid bath are caught by the conveyor, taken out of the liquid bath and to a suitable collecting device, e.g. a sieve (16). 4. A method according to claim 1, characterized in that the products are only separated from the liquid bath, when all, or practically all products are submer¬ ged in the liquid bath. 5. A method according to claim 4, characterized in that the separation of the products from the liquid bath is performed by the lifting of a netlike collec¬ ting device, e.g. a sieve, out of the liquid bath, said sieve demarcating during the melting phase the part of the liquid bath used. 6. A method according to claim 4, characterized in that the separation of the products from the liquid bath is achieved through removal of the liquid through a filter catching the product. 7. An apparatus to apply the method according to claims 2 or 3, characterized in that said apparatus comprising an upwards open vessel ( 1 ) having a conveyor (5), preferably a conveyor belt, arranged in such a manner in relation to the surface of the liquid during operations (9, 10) and also the inner shape of the ves¬ sel, that products sinking into the liquid bath are caught by the conveyor and conducted out of the liquid bath to a suitable external collecting device, e.g. a sieve ( 16 ) , that the external collecting device (16) is com¬ bined with a weighing machine (12) and that the vessel (1) has means (7) to ensure that products floating on the surface of the liquid bath (9, 10), are not caught by the conveyor (5).

Inventors: HERMANSEN PER, HERMANSEN, PER
Applicants: MATCON RADGIVENDE ING FIRMA, MATCON, RAADGIVENDE INGENIOERFIRMA A/S
Application year: 1989
Main classification: A23B4
IPC codes: A23G9, B03B5, G01G17, G01G23, G01N9, G01N33