Document J3NqBzQV1GD3J7n1xnDV24Ze2

352 CHAPTER 31 1962 Guide And Data Boot removed from the product at the rate at which the moisture cornea to the surface of the casing. Any attempt to speed the drying rate results in over drying the surface of the sausage, resulting in a condition known as cose hardening. This condi tion is identified by a dark ring inside the casing, close to the surface of tire sausage which precludes any further attempt to remove moisture from the interior of the sausage. On the other hand, if sausage is dried at too slow a rate, excessive mold occurs on the surface of the casing leading to an un satisfactoryappearanceon the rAdng with some types of mold. It is recommended that the sausage dry room be located where the adjoining spaces do not have a widely diverging temperature difference. For example, locating the dry room above a low temperature cooler causes condensation on the floor of the dry room and leads to mold on the lower rows of sausage. Insulation of variable thickness on all sides of the dry room is desirable to avoid changing conditions due to fluctuations from the adjoining spaces. The height of the sausage dry room to obtain the best results should not exceed 12 to 14 ft to the top stick in order to avoid stratification and to maintain within close limits the required temperature and humidity conditions necessary for this type of installation. It is recognised that there are higher dry rooms operating with satisfactory results. Sausage racks on which the sausage sticks are suspended in the dry room are of wood or steel uprights and rails. Rails of 1' in. galvanized pipe centered through wood uprights are suggested for ease of cleaning. The rails for supporting the ' sausage sticks may be installed with the distance from the. floor to the top of the first rail 3 ft, the distance between rails1 2 ft, with a distance between the top rail and the ceiling of the room not less than i ft. The centering of the rails is, of course, dependent on the length of the sausage stick used by the in dividual sausage manufacturer. Where pipe or wood rails are used the centers should not exceed the length of the sausage stick less 4 in. . Sausage sticks in general are spaced on 6 in. centers on the racks, with the sausages of the variety known as salami, 4 to 5 lb green weight, spaced on 6 in. centers on the sausage sticks. This spacing avoids contact between the sausage which would otherwise cause mold and allows sufficient space for air circulation and uniform evaporation of moisture, from the product. The equipment for producing the required room conditions consist in general of a spray type dehumid&ex o? spray type unit cooler in which the air is cooled by passing through a liquid spray circulated over refrigerating coils inside the con ditioning equipment. In some installations water or salt (NaCl) brine is cooled by ` refrigeration in a separate cooling system, from which it is pumped to the dehumidifier sprays and returned for further cooling. There is also available equipment employing a hygroscopic liquid which is Bprayed in the dehumidifier through which the air is circulated. The moisture condensed from the air in the hygroscopic liquid is evaporated from this liquid ina regenera tor. Treatment of the dehumidifier liquid is advisable to main tain a pH which will minimise corrosion. In accordance with seasonal requirements, this air then passes through a heating coil for reheating the air to the proper temperature prior to introduction to the dry room. A blower type fan of suitable characteristics to overcome resistance, through the conditioning equipment and duct system provides the means for maintaining the proper air circulation requirements. In this type of installation it is very important that the means for introducing and returning the air be given caref^ consideration. The air supply duet system should be located at the floor of the dry room, arranged to introduce the proper air volume in a horizontal direction, close to the floor to e&cb individual row of sausage racks with a total length of blow not to exceed 30 ft. The air return duct system should be located at the ceiling of the dry room and should include branch ducts extending centrally the full length of the sausage racks, over alternate rows of racks. The branch ducts should contain uniformly spaced return air openings located in top of same for returning the air to the conditioning equipment so that the air circula tion throughout the dry room will be uniformly distributed in a vertical direction through the sausage. The branch ducts should be located so that a space of approximately 2 in. is maintained between the ceiling and the top of the branch duct. Excessive air circulation is to be avoided. Roam Dimension*: Fig. 8 40 ft 2 in. X 33 ft 6 in. X 11 ft 6 in. Floor space -- 1350 sq ft Volume = 15,600 cu ft ^ Outdoor wall area--080 sq ft Partition wall area--770 sq ft Ranging Capacity: No. of racks--12 Length of racks--27 ft No. of rails high--5 Spacing of sticks--2 per ft of rail No. of pieces of sausage per stick--7 Average weight per sausage--4 lb 12X27 X 5 X 2 X 7 X 4 - 90,720 lb'of product Say 90,000 lb green weight hanging capacity Loading per day--1500 lb Outdoor Conditions Assumed (Summer):. 95 F db; 75 F wb; 39% rh; 37.8 H; 66 F dp; 96 gr per lb Dry Room Conditions Desired: 55 F db; 50 F wb; 70% rh; 20.2 H; 46 F dp; 46 gr per lb Sensible Heat Calculations Walls (2 in. insul.)--980 X (95 - 55) X 0.10 Partition (4 in. insul.)--770 X (95 -- 55) X 0.067 Floor A Ceiling--2700.X (55 - 55) X 0.10 Infiltration--0.5 X 15,600 X (95 - 55) X 0.243 X 0.075 lights 600 watts X 3.415 Motors 5 hp X 2546 Product 1500 X 0.8 sp bt X (95 - 55)/24 3920 Btuh 2060 Btuh none 5700 Btuh 2050 Btuh 12,730 Btuh 2000 Btuh Total Sensible Heat -- 28,460 Btuh Latent Heat Calculations Product 90,000 X 0-30 X 1000/(60 X 24) - 18,720 Btuh 18,720 X 7000/(60 X 1000) - 2184 gr/min Infiltration 0.5 X 15,600 X 0.075 X (37.8 - 20.2) = 10,300 (10,300 - 5700) X 7000/(60 X 1000) - 537 gr/min Total grains of moisture -- 272. gr/min Assume 12 air changes per hour empty room volume 15,600 X (12/60) X 0.075 - 234 lb air per nan (2721/234) - 113 gr per lb of air to be absorbed. 46 -- 11.2 -- 34.8 gr per lb in supply air. (39 F dp) 39 F dp, 90% rh, 413 F db, 403 F wb, 153 H, gr per lb. Sensible heat gab 28,460/(234 X 0343 X 60) - 83 F Meat, and Fresh Fish 353 db.-latent heat product only = 18,720/(234 X 0-243 X 60) ,, 5.5 F deg. Temperature drop due to evaporative cooling. 8.7 F -- 53 F * 3.2 F deg net temperature rise b room. 55 F db -- 33 F -- 51.8 F db supply air at 39 F dp (343 gr). Refrigerating Load - 234 X (203 - 153) X 60 - 68,800 Btuh tUheal Load = 234 X (17.0 -- 153) X 00 => 32,300 Stub Bam Load = 234 X (20.2 - 17.6) X 60 - 36,500 Btuh LARD CHILLING iln federally 'inspected plants the USDA Meat Inspection Division designates the types of pork fats which, when ren dered, are classified as lard. Other pork fata, when rendered, are designated as rendered pork fats. The rendering process requires considerable heat and the subsequent temperature of the lard at which refrigeration is to be applied may be as high as 120 F. The following data for refrigeration require ments may be used for either type of product. Therequirements of the Meat Inspection Division are good sanitation through all phases of handling. The use of copper or copperbearing alloys where they come, in contact with lard should be avoided because minute traces of copper lower ffie stability of lardSpecific gravity of lard varies from about 0.99 at 0 F to 088 at IGO F. Specific gravity at 70 F is about 0.93. Heat of solidification of lard is approximately 48 Btu per lb. Melting begins at --35 to --40 F and ends at 110 to 115 F. The point of half fusion is in the neighborhood of 40 F. Specific heat of lard b the completely solid form varies from 0.28 Btu per F per lb at --110 F to 0.34 at --40 F. Specific heat in the liquid state varies from 0.50 at 110 F to 0.52 at 212 F. Refrigeration is employed in the production of lard so that the. final product will have smooth texture and firm con sistency. The finest possible crystal structure is desired. Calculation for chilling 1000 lb of lard per hr are: Initial temperature Final temperature Heat of solidification Specific heat 120 F 80 F 48 Btu per lb 0.50 Btu per (U>)(Fdeg) Temp at which melting ends -- % solidifies- final temp tkin at finalTM--------------------------- -- X1001 temperature Temp at which'- melting ends--texop at which melting 115-80 X100 115 --(--40) . =(35/1557(100)-22.6% latent heat of solidification: (22.6/100) X 48 - 10.8 Btu per lb Sensible heat removed 0.50 X (120 - 80) - 20 Btu per lb Total heat removed; (20 4- 10.8) X 1000 - 30,800 Btu per hr 30,800/12,000 -- 2.57 tons net refrigeration Assuming 16 percent toss, due to radiation and other causes tn process, the remand refrigerationfor application to chill 1000 lb lard per hr would be 1.16X2J7--S.86 tons. Filtered lard at 120 F can be chilled and plasticised in a compact internal swept surface chilling unit. This is the mod ern method and the one generally used. Units are available using either ammonia or halogenated hydrocarbons. A re frigerating capacity should be provided equivalent to about three tons per 1000 lb of lard hkndled per hour for the prod uct only and additional refrigeration provided for the require ments of heat equivalent to the work done by the internal swept surface chilling equipment. In the operation of this type of chilling equipment, it is essential to maintain the refrigerant free of oil and other im purities so that the heat transfer surface will not have a film of oil on it to act as insulation and cut down the capacity of the unit. Some installations of such equipment are provided with oil traps connected to the liquid refrigerant leg on the floor below to provide drainage space to accumulate the oil drained from the refrigerant space of the unit. The safety requirements for this type of chilling equipment are quite amply described in the latest revision of the Amer ican Standard Safety Code for Mechanical Refrigeration B9. It must be kept in mind that such units are pressure vessels and as such require safety valves properly installed and properly maintained. The recommended storage temperature for packaged re fined lard is 31 to 33 F. The storage temperature required for prime steam lard in metal containers is 40 F or below. These conditions are recommended for up to a 6 month storage period. If lard is to be kept in storage for a year or more, 0 F is recommended. HIDE CURING Hides represent one of the greatest values of any of the cattle by-products. Great care is taken in all of the operations involved, from the purchase of live cattle to the delivery of the cured hides. The hide is subject to decomposition from bac terial action immediately after the organs of the animal stop functioning. Experience has shown that the best method of stopping this bacterial action is through prompt handling to curing. Curing, as defined by Dr. De Beukelaer of the Amercan Meat Institute Foundation, is the transformation which places the hide in a condition to resist bacterial decomposi tion. This is accomplished by the replacement of natural mois ture in the hide with concentrated brine. Some moisture is lost in this operation. Hie reduction in the weight of the hide in curing is mainly based on this moisture loss and is commonly referred to as shrink. Blood solids removed from tile surface of the hide are also a contributing factor in hide shrinkage. Hide *hnnk may vary between 12 and 18 percent. Normal expectancy is as follows: Native Bull Native Steer 16 to 18% 13 to 18% light Cow Calf A Kip 14 to 17% 12 to 15% The weight of a hide from an ft.mma.1 will vary throughout the year. For example, the hair on the hide is usually short during the late summer and fall, then grows longer during the winter. For a yearly average, it will be satisfactory to assume the green hide is approximately to lYi percent of the live animal weight. Hides from fattened steers .will be in the lower bracket, while the hide will be of higher percentage with lean cattle. Moisture in hides of the same weight will vary because of - conditions on the killing floor, but more noticeably, the mois ture content of green hides will vary considerably from that of cured hides. For this reason, it is desirable to calculate the specific heat for each condition. Siebel's formula for specific heat above freezing should be used: a 4- 0.26 s ------ ---- = 0.008a + 0.20, 100 in which s is the specific beat above freezing of a substance containing o percent of water, 6 percent of solids and 0.2 is the assumed specific heat of the solid matter. (green) - 0.008 X 69 + 0.20 - 0.752 (cured) - 0.008 X 46 +- 0.20 0.568