US2346880A

US2346880A - Gelatin preparation

Info

Publication number: US2346880A
Application number: US391461A
Authority: US
Inventors: Walter M Urbain
Original assignee: Ind Patents Corp
Current assignee: Industrial Patents Corp
Priority date: 1941-05-02
Filing date: 1941-05-02
Publication date: 1944-04-18
Anticipated expiration: 1961-04-18

Description

p i 8, 1944. w. M. URBAIN 2,346,880

GELATIN PREPARATION Filed May 2, 1941 A TORNEY Patented Apr. 18, 1944 GELATIN PREPARATION Walter M. Urbain, Chicago, 111-, assignor to Industrial Patents Corporation, Chicago, 111., a corporation of Delaware Application May 2, 1941, Serial No. 391,461

16 Claims.

This invention relates to the preparation of dry protein material in a substantial sterile condition, and more particularly it is directed to a method and apparatus for preparing gelatin suitable for edible purposes substantially free from bacteria and molds.

Gelatin is commonly prepared by a method. involving hot aqueous extraction from a suitable source material such as hides or bones which have had albuminous and mucinous matter removed therefrom, concentration of the aqueous gelatin extract in evaporators, spreading of the concentrated gelatin solution as a thin film upon a moving belt, chilling the concentrated gelatin on the belt until it sets up into a jelly, removing the wet gelatin film from the moving belt, and drying it on a suitable support. As is clearly evident, the product, especially when employed in food preparations, should be substantially free of bacteria. Every precaution is therefore employed by the manufacturers to prevent containination of the gelatin product with bacteria or mold. However, it has been found that even when operating under very closely controlled, sanitary conditions throughout the process, the final product will often be infected with bacteria. This unfortunate result seems to occur more frequently in the summer than in the winter. A detailed study has shown that the chilled gelatin jelly is generally free from bacteria but that the dried film is usually contaminated.

It has now been found that the source of contamination is the presence of bacteria on the supports for the chilled gelatin film during the drying period. Even though these supporting frames or screens are kept in a clean condition it has been found that they are the origin of the contamination. If the frames are free of bacteria there seems to be no substantial development of bacteria in the gelatin film during the hot drying period. The drying step is particularly conducive to bacteria development because of the increased temperature for substantial periods of time, but it has been found that in normal operation unless the gelatin is infected by the frames or supports during this period there is no substantial increase in bacteria count. However, the screens which are re-used for supporting fresh sheets to be dried are found to develop bacteria rather readily.

In spite of the fact that attempts are made to keep the frames clean, they retain small particles of gelatin which, because of the nature of the frame or screen surfaces, are not always removed in the cleaning process. The gelatin particles, lumps or films serve as fuel of infection for subsequent sheets of jelly. Because of the longer period that these contaminated particles of gelatin are in the Warm air drying chamber they develop an exceptionally high bacteria count. These infected areas in contact with the gelatin sheet undergoing drying infect the sheet. The drying period then amounts to an incubation which develops the infection, resulting in a high count gelatin. In the summertime the usual high humidity necessarily increases the drying time and consequently increases the incubation period.

Wet methods of cleaning and sterilizing the upporting screens are not desirable because the wood framework of the screens onrepeated wetting and drying will harden and sometimes twist out of shape. Furthermore, the process is long, and the labor costs are very high. Dry methods of disinfecting the screens likewise cause'drying out and breaking of Wood frames, and as in the wet method take considerable time. Chemical methods have the added-disadvantage of the possibility of contamination of the edible gelatin to be dried while supported on t e frames. Because of the infection througliout the gelatin particles or films contaminating the screen, simple surface-sterilizing methods cannot be used alone.

It has now been found possible to prepare gelatin substantially free from bacteria conveniently by the standard procedures. The present process comprises, in general, the irradiation of the supporting frames with ultra-violet radiation of sufilcient intensity to materially disinfect the frames including the gelatin contaminant thereon just prior to placing on said frame the gelatin jelly sheet to be dried in the air drying chamber. Until this invention, it has been generally accepted that ultra-violet radiation could only be used for air and surface sterilization or for sterilization of thin films of water or the few other substances which similarly readily transmit ultraviolet light. On the contrary, it has now been determined that it is possible to sterilize substantia1 thicknesses of gelatin particles infected with bacteria not only at the surface but substantially throughout it in a very short time of exposure and at a relatively low cost. Considering the relatively great thickness of the gelatin films orparticle's which .adhere to the screens or frames git is'surprising that the substantialsterilization-of the frames and adherent gelatin particles canbe effected by the present process sincethe absorption of ultra-Violet rays is yery great by even thin layers of material and increases rapidly with inthat the ultra-violet light from a 3.5 ampere mercury vapor lamp at a distance of centimeters had only a superficial actionon gelatin gel and that it did not proceed deeper after a certain minimum duration of exposure because of the opacity of gelatin to rays of short wave length.

In addition, Steenbock, United States Patent No.

1,871,135, discloses that with the ordinary mercury vapor lamp irradiation of various materials, among which is gelatin, antirachitic activation is effected but not sterilization. However, substan tially complete sterilization has been effected in a' fraction of a minute by the present method. This is startling since sterilization of other organic compounds by earlier ultra-violet procedures either was efi'ected in very thin films, or wasaccomplished with thicker particlesjsu'ch as lumpy sugar which could not be sterilized in fifty minutes by direct radiation, only after two minutes of treatment by shakingto expose fresh surfaces.

(J, Ind. and Eng. Chem, vol. 31, p. 1168, 1939.)

It has been discovered that it is essential that the effective ultra-violet radiation be of suflicient intensity that the rays penetrating through substantial layers of material are still of sufficient intensity, e. g., about microwatts per square millimeter, to cause a rapid abiatic action. This is obtained by a highintensity source of ultraviolet radiation in excess of 25 microwatts per square millimeter (at the surface) by an amount governed by the thickness and the coflicient of absorption of the gelatin or other protein contaminant on the creen. For example, with average conditions of operation the surface intensity of 50 to 100 microwatts per square millimeter of active radiation has been found satisfactory although less may prove operative depending on the type and intensity of contamination and time of treatment. The period of treatment preferably should be sufficiently long to yield substantial tancy for radiation of wave lengths shorter than 2,800 Angstroms. Therefore, believing that sterilization could not be eifected, earlier workers erations. Some of the inoculated gelatin coated screens were irradiated with a three hundred and sixty watt Uviarc lamp at a distance of about eight inches for different irradiation periods. Following the irradiation a sterile 10% aqueous gelatin jelly was laid on the screens and after incubation at room temperature for 24 hours this gelatin was dried in a wind tunnel and stripped oflthe screens aseptically. The bacterial count of this gelatin from the different frames was observed and the results are given in the following Prior either would not have attempted to sterilize the gelatin by this means or would have used the usuallow intensity ultra violet sources to accomplish the result of'questionable value; namely, simple surface'sterilization.

The ability of high intensity radiation to penetrate gelatin is demonstrated by the following experiment. A number of gelatin drying screens employed in conjunction witha K. & L. gelatin casting machine were dipped in a10% aqueous gelatin solution which had a high'bacteria count. The gelatin adhering to the screens was permitted to dry. To the coated screens was then applied a gelatin jelly prepared from the high count solution, after which the screens were. again dried. These pieces of 'jelly were about one-fourth inch thick and oneinchin' diameterbefore drying, and shrank toa thickness of about one-sixteenth inch after drying; Particles. this ..size are about as w seny a eeted;.e qlieerri et rl n- It is apparent from these results that the dried gelatin from the highly contaminated screens which had been irradiated by the high intensity ultra-violet rays had a much lower and more satisfactory bacterial count. The conclusion is therefore drawn that the radiation from the high intensity Uviarc lamp was of suflicient intensity that in the short time periods listed sufficient penetration was obtained to substantially sterilize the contaminated gelatin present in relatively thick pieces. The 360 watt fused quartz mercury arc lamp or Uviarc lamp employed in the above experiment has an arc length of about six inches maximum, a rating of 54 watts per arc inch, and develops 284 microwatts of ultra-violet energy per square millimeter at 10 centimeters. It has an over-all length of 10 inches and a diameter of inch maximum. The radiation characteristics of the lamp are as follows:

This data indicates that the lamp is ahigh intensity lamp and is not to be confused with the low intensity germicidal or Sterilamps commonly employed for surface sterilization.

Although good results are obtained by using the lamps alone, it has been found advantageous to employ reflectors for the lamps notonly in back of the lamps but on the other side of'the screens in order to throw back as much of the ultra-violet light as possible, thus increasing the efficiencies of the lamps about 50%, and alsopro- -te cting the workers in the surrounding; area.

The metal employed affects the efiiciency of reflection, the order of preference being roughly: stainless steel, stellite, nickel plate, polished aluminum, polished tin and Duralumin. i

In commercial operation the location for the installation of the ultra-violet lamps depends on the'following considerations: I

1. The lamps must effectively irradiate all the surfaces of the screens.

2. Sufiicient exposure must be obtained by the correct combination. of the number of lamps, intensity of radiation, and time of exposure.

3.- The interval of time between irradiation and use of the screensshould be as short as possible.

4. The lamp should be mounted so as not to interfere with the continuous operation of the chilling and drying apparatus, e. g., a K. 8: L. machine.

5. Protection must be provided for the operators against the actinic rays and glare, and ozone generated by the lamp. r

The commercial installation represented in Figures I and II of the accompanying drawing represents a satisfactory compliance with the above listed requirements in a & L. apparatus.

Figure I is a side elevation of a modified K. 8: L.

I passes over the large drum 3 the gelatin jelly u sheet is stripped from the belt I by scraper 5. The gelatin jelly sheet 4 is then carried by the endless take-oif belt 6 on a series of pulleys to the rotary cutter l which cuts the jelly sheet into two longitudinal strips. The gelatin strips are then cut transversely by rotary cutter 8 into sheets about five feet long. The high intensity lamps 9 are mounted below the endless belt 6. Mounting them in this position requires the raising of the take-off belt 6 from its usual position to make room for the lamps which are in the enclosing hood IZ. In the large scale apparatus for commercial production employing 1,200 watt lamps, it is usually desirable to place two or three pairs of lamps side by side so that the radiation coversabout three feet of the length and the entire width of the frames or screens I0, moving on the endless open belt or chain I I at a distance of about eight inches under the lamps 9. This develops at least 300 microwatts per square millimeter of active ultra-violet radiation. Four such lamps are generally sufficient to provide adequateexposure when the K & L. chilling belt I is operated at maximum speed, usually about ten feet per minute. A polished stainless steel reflection plate I3 is placed under the screen to reflect a substantial quantity of the ultraviolet light and to increase the efiiciency of the lamps. The screens I0, substantially sterilized by the treatment at this point, move but a short distance before the cut chilled gelatin strips 4 are placed thereon by the take-off belt 6; hence no appreciable time intervenes between the sterilization and use of the screens. The loaded screens are removed from the endless belt as it passes over the gear I4 and are placed on movable supporting racks (not shown) which are removed to a drying chamber through which passes a stream of warm, relatively dry air. Protection for the workers against actinic rays and glare is provided by the hood l2 and suitable shielding. Ozone generated by the lamps is removed by drawing air by means of an exhaust fan (not shownl out of the room past the lamps 9 at a rate of- 2,000 cubic feet a minute through the twelve inch duct l5. "Ihis ventilation also serves to cool the lamps 9, adding to their effective life. The following table shows the effectiveness of the radiation of the screens in commercial production of gelatin satisfactory from a bacterial standpoint.

TABLE III Conveyor Irradiation period per Bacteria of lamps g g fi unit area. per gm.

' sec.

6 16 '30 0 l6 40 6 l6 l0 6 0 10,000, 000 6 0 4, 300,000 6 o 11, 000, 000

I0 10 120 10 10 70 l0 i0 10 0 300, 000 10 0 300. 000 10 0 780, 000

In obtaining the above data artificial drying conditions approximating high humidity or delayed drying operation were made by holding the terlstics:

TABLE IV Electrical data Arc watts 1200 Arc length -inches 12.5 Inside diameter do 0.7 Volts 350 Amperes 4 Radiation characteristics Microwatts Wavelength,

per sq. cm. Angstroms at 1 meter It develops about 1,420 microwatts per square millimeter of active ultra-violet radiation at ten centimeters. The above characteristics including power consumption and ultra-violet radiation output demonstrate that this is a high intensity source of ultra-violet. This lamp may be effectively employed at distances of two feet from the irradiated surface.

A satisfactory lam-p should have sufiicient radiation of low wavelength below the limit of about 3,600 Angstrorns. The shortest rays have the most lethal action and .it is preferred to employ lamps emanating a substantial radiation having. wavelengths less than 2,800 Angstroms; The 1,200 watt lamps not only has 17% of its radiation in th highly active range, but its high overall .powerproduce an exceptionally high quantity of total short wave radiation. In other words, there is a great quantity of high intensity radiation that is well above the minimum threshold intensity of ultra-violet radiation to effect lethal action, usually of the order of 25 microwatts per square millimeter. Above this value the lethal action depends on the time and to a great extent on the intensity of ultra-violet radiation, which two values fix the total quantity of radiation. Although about 5,000 microwatt seconds per squaremillimeter radiation is extremely effective with the above-discussed lamp under ordinary conditions of operation,increased intensity of active ultra-violet radiation may reduce this volume, and vice versa. The intensityof .the 1,200 watt lamp is so exceptionally high that not only short times of exposure are possible, but even in those short times more than simple surface sterilization is obtained.

The present operation is so eifec'tive'that, even though periodic washingof the screens is given for assuring proper operation,the screens are sterilized without the removal of' the substantial quantities of accumulated gelatin on the screens usually accomplished by such washings.

The ordinary germicidal or sterilamps have an operating wattage of only about ten' to fifteen watts, or about one to one and one-half watts per arc inch, and a highly active ultra-violet intensity of only fifteen to .twenty microwatts per square millimeter at ten centimeters. The 1,200 watt lamp develops about seventy to ninetyfive times the ultra-violet light produced by the usually employed lamp. To accomplish the same result with the small commercial low-intensity lamps as with the large high-intensity lamp is not only impractical, but probably impossible because of the problem of getting sufiicient lamps in a position to irradiate simultaneously the same surface with about the same energy consumption.

The above procedure for treating the screens is substantially dilferent than the direct irradiation of dry gelatin, gelatin solutions or gelatin jelly, since it elfects the production of substantially sterile gelatin without physical modification or deterioration which results from treating gelatin directly with ultra-violet radiation. Treatment of gelatin in various forms with certain ultra-violetradiation will affect the viscosity, solubility, swelling, whipping properties, taste, odor and various other properties, depending on the form during treatment as well as the duration and intensity of treatment.

As many widely different modifications and embodiments of the invention hereinbefore set forth may be made without departing from the spirit and scope thereof, only such limitations should be imposed as are indicated in the following claims.

I claim: I

,1. In the process of drying films of gelatin jelly, the. steps which comprise irradiating the drying frame with high intensity ultra-violet radiation of an intensity greater than twenty-five microwatts per square millimeter for a time suflicient to substantially sterilize the frames and any gelatin adhering thereto and prior to any substantial recontamination applying a gelatin film for drying on the sterilized frame so that a sub stantially sterile film'o'f gelatin jelly dried thereon is 'obtained;-

1 '2. In the process of drying films of gelatin jelly, the steps which comprise irradiating the drying support with ultra-violet radiation of an plying gelatin to the sterilized support for drying.

3. In the process of drying films of gelatin jelly, the step which comprises irradiating the drying support immediately prior to placing the gelatine to be dried thereon with the rays from at least one twelve hundred watt, high intensity, ultra-violet, fused quartz, mercury arc lamp at a distance of not more than two feet from the frame for a period sufficient to sterilize the support and any gelatin adhering thereto.

4. In the process of drying films of gelatin jelly, the steps which comprise irradiating the drying support with ultra-violet radiation of an intensity of not less than fifty microwatts per square millimeter for a sufficient period to substantially sterilize the support and any gelatin adhering thereto and promptly thereafter applying to the sterilized support the gelatin for drying.

5. In the proces of drying films of gelatin jelly, the step which comprises irradiating the drying support immediately prior to placing the gelatin to be dried thereon with ultra-violet radiation of an intensity of not less than fifty microwatts per square millimeter for a sufiicient period that the total irradiation is five thousand microwatt seconds per square millimeter.

6. In the process of drying films of gelatin jelly, the step which comprise irradiating the drying support with ultra-violet radiation of an intensity of not less than one hundred microwatt per square millimeter for a sufiicient period to substantially sterilize the support and any gelatin adhering thereto and prior to any substantial recontamination applying gelatin to the sterilized support for drying.

7. In the process of drying films of gelatin jelly, the step which comprise irradiating the drying support with ultra-violet radiation of an intensity of not less than three hundred micro- Watts per square millimeter for a sufficient period to substantially sterilize the support and any gelatin adhering thereto and promptly thereafter applying to the sterilized support the gelatin for drying.

8. In the process of drying films of gelatin jelly, the step which comprises irradiating ,the drying support with ultra-violet radiation of an intensity of not less than three hundred microwatts per square millimeter for a period of time that the total irradiation i five thousand microwatt seconds per square millimeter, said irradiation being made just prior to the placing of the gelatin jelly film thereon. 1

9. A process for the manufacture of dried gelatin material of low bacterial content wherein gelatinous material is dried on a drying support normally tending to retain impurities which contaminate the gelatin dried thereon, which comprises treating the support with ultraviolet radiation of sufiicient high intensity to substantially sterilize the surface of the support and any particles of gelatin material retained thereon and immediately thereafter placing the gelatinous material on said support for drying.

' 10. A process for the manufacture of edible gelatin of low bacterial count wherein the gelatin jelly is dried in films on screens normally tending to retain on the surface thereof impurities, including particles of gelatin which contain a high bacterial count, and to contaminate the gelatin films dried thereon, which comprises subjecting the screens to ultra-violet radiation of suiiicient high intensity to substantially sterilize the surface thereof and any particles of gelatin adhering thereto and immediately drying the gelatin films on the sterilized screens.

11. In an apparatus for treating gelatin, the combination of a source of ultra-violet radiation, a reflector, means for conveying gelatin screens between the source of radiation and the reflector, and means for depositing films of gelatin on the screens immediately after passing between said source of radiation and said reflector.

12. In an apparatus for treating gelatin, the combination of a conveyor means for gelatin screens, a second conveyor means superimposed on said first conveyor means for depositing sheets of a gelatin on said screens, and one or more high intensity ultra-violet lamps for irradiating and sterilizing said screens immediately prior to depositing the gelatin sheets thereon.

13. A process for the manufacture of dried gelatin material of low bacterial content which comprises treating th drying support with ultra violet radiation of sufficient high intensity and for a period of time sufficient to substantially sterilize the surface of the support and any gelatin adhering thereto and prior to any substantion recontamination applying the gelatin to said support for drying.

14. A process for the manufacture of dried gelatin material of low bacterial content which comprises treating the drying support with ultra violet radiation of suflicient high intensity and for a period of time suificient to substantially sterilize the surface of the support and any gelatin adhering thereto and prior to any substantial recontamination drying a film of gelatin on said support.

15. In an apparatus for manufacturing gelatin, the combination of a source of ultra violet radiation, means for subjecting for a predetermined time a support for a gelatin film to rays from said source of radiation and means for depositing said gelatin film on said support promptly after the irradiation thereof.

16. In an apparatus for manufacturing gelatin, the combination of a source of ultra violet radiation, means for exposing for a predetermined time a support for a gelatin film in radiation relation with said ultra violet and means for depositing said gelatin film on said support immediately after irradiation thereof.

WALTER M. URBAIN.