Document 2R0831JkkeBXo2xEawr0NRq0b

372 CHAPTER 32 1962 Guide And Data broken, freeing the fat from globular form. This permits the accumulation of the fat, free of non-fat portions which formerly held it in suspension. Concentration from 80 to 98 percent Fat Content The concentrated oil and serum product at 165 F enters the serum separator which removes the major portion of serum to concentrate the fat to 98.5 to 99 percent. The oil-serum prod uct enters gravity type separator slightly below center. The fat is directed upward while the serum is directed down and is discharged back into the balance tank for 40 percent cream just ahead of the centrifugal separator. This return serum is thus re-separated so that there is no possible fat loss. Pasteurization and Cooling 98 percent Fat The 98.5 percent purity fat is directed to a second section of the plate type heat exchanger in which it is heated to 190 F and is immediately cooled to 110 to 120 F in a third section. It is then directed to a battery of three composition control t-a-nWa to standardize components for the desired butter. Composition Control of the Butter Mix In this step the various components of fat, moisture, salt, and curd are standardized. Also, a controlled portion of un broken fat is introduced. This is accomplished by segregation of a portion of the 80 percent cream in the special balance tank which receives cream from tire heavy cream separator. The desired quantity is metered by a positive pump into the 98.5 percent fat as it enters the plate heat exchanger for heat ing to 190 F and subsequent cooling. The standard Kohman butter test is made on the thoroughly mixed fat and unbroken fat in the composition control tanka. The required quantities of water, salt and color are then added to produce the desired composition. By means of the equipment and procedures available, it is possible to obtain much closer quantitative control than in the produc tion of batch churn butter. The standardized butter mix in the composition control tanks is thoroughly agitated to insure extremely accurate control throughout the entire quantity in the tank. Controlled Crystallization and Solidification of the Butter The thoroughly agitated butter mix is removed from the composition control tanks by means of a small centrifugal pump which supplies a steady pressure to the high pressure pump feeding the chiller at pressures up to 325 lb, thence to the crystallizer and final extruder. The chiller is so designed that the butter mi* is cooled from standardizing temperatures' of 110 F to approximately 40 F at which temperature it passes to the crystallizer. The design also produces intimate working of the product so that there is a definite controlled seeding of butter crystals. The crystallizer provides for the control of the crystallizing structure during growth. In pasting through this machine the temperature of the product is increased 10 to 11 F deg due to heat of crystalliza tion so that the finished product is discharged at approxi mately 50 F. The extruding table is such that the product can either be printed directly by means of a conventional butter printer or it can be boxed with a special boxer into standard 60 lb cubes. MICROBIOLOGY OF BUTTER Cream pasteurized either at 160 to 165 F for 30 min or at 200 F or higher with the continuous method may contain only one-tenth percent or less of the bacteria that were present in the raw cream. Generally all yeasts mid molds are strayed. Enzymes are inactivated. If the equipment with which the pasteurized cream and the butter come in contact has been thoroughly cleaned and sterilized, it would be expected that the finished butter would contain very few bac teria and no yeasts or molds, but microorganisms are picked up by the cream and butter from the wooden churn, the wash water, and wooden packing utensils. If all metal equipment were used and if the water were first pasteurized it should be possible to manufacture butter containing but a few micro, organisms. If a starter is added to cream before ehurning, the butter will contain numerous lactic acid bacteria but organisms do not cause deterioration in butter held under re frigeration. Well-worked butter contains several billion moisture droplets per gram; the majority of the droplets are too rn>fl to supply moisture and nutrients for bacterial growth. Salt inhibits the growth of microorganisms. It is important there fore, to thoroughly work the butter so that the brine droplets arc uniformly distributed in the butter. lipase-producing bacteria, if present in butter, may came a rancid flavor when the temperature of the butter permits their growth. These organisms may be present in the raw cream, but they are killed by pasteurization. They may be added to butter by untreated wash water. The enzyme lipase hydrolyzes fat with the result that rancid-fiavored fatty acids are formed. Other microorganisms may cause decomposition of protein which is present in small amount in butter. They may also be present in raw cream and in contaminated water. If present in butter held even at a fairly low temperature, such as from 40 to 50 F, they may grow and cause a disagreeable putrid flavor in the butter. Control lies in (a) correct pasteurization; (6) thorough cleaning of all equipment including sterilization with hot water, steam or chemicals; (c) the use of pure water; (tf) thorough distribution of the brine in the butter. As yeasts and molds are killed by efficient pasteurization and can be destroyed on the equipment by sterilization with boiling water or chemicals, it is possible to manufacturebutter that is free, or practically free, from these organisms. It b important to see that yeasts and molds are not added to butter from parchment paper, butter printers, the hands of the worker, and the air in the workrooms or refrigerators. STORAGE OF BUTTER For short-time storage a temperature of the refrigerator of 32 to 40 F is satisfactory. For long-time storage a temperature of -- 10 to 0 F should be used. The butter should be pro tected with a covering so that absorption of odors is pre vented, oxidation of the fat on the surface of the butter is minimized, and shrinkage in weight due to evaporation is prevented- Specification for butter containers issued by the Com modity Stabilization Service of the U. S. Department of Agriculture on April 1, 1957 are: (a) Bulk Containers: Bulk butter containers shall be regular slotted corrugated or solid fiberboard containers of not le** ^*n 200 pound bursting strength to contain either 60 or 64 pounds net. The inside surfaces of the contamers, indnrimg the flaps be paraffined with not less than 128 F molting point paraffin sufficient to prevent absorption of moisture by the fiberboard. Containers must have printed on two rides CREAMERY BUTTER--KEEP REFRIGERATED." Bulk butter containers shall be lined with vegetable parchmtnri paper of not less than 27 pounds baric weight per ream (500 sheets 24* X 36*). The parchment liners shall be of sufficient length and width and so placed in the containers, that all surfaces of the butter, shall be completely covered. The liners ih*H be p(W|try and Dairy Products 373 by bring held completely immersed in a salt solution at polling point for 30 minutes. The salt solution shall contain igss than 15 pounds of salt per 100 pounds of water and shall Efthanged not less than once a week.' /W Print Butter: One pound prints shall be Elgin or Western solid prints, and properly wrapped with a single sheet of 30 Sund weight dry waxed vegetable parchment paper or wet 2!ljnrth paper, or with a 20 to 30 pound wet strength paper "13 wnh a blend of polyethylene and micro-crystalline or waxes. Thirty-two prints shall be pocked on their side in P^nOpound bursting strength regular slotted corrugated or solid ruerboajri container. The inride of each shipping container shall Coaxed with a fully refined wax, having a melting point of not wg tvn 128 F to a point approximately one inch beyond the Lgre line. As an alternate to waxing one inch beyond the score- Eos of the containers, the entire inride surfaces and the end flaps which form the inride surface of the containers shall be {nsed. -A* an alternate to waxing inside surfaces the containers - shall be lined with 30 pound bleached kraft paper waxed to 40 oounds b**TM weight, or with its equivalent of parchment paper ~jtfhly waxed. Tnc liners shall be of sufficient length to line ends, sides, and bottom and have a minimum of 2 inch overlap on the toiTSnug-fittiog, dry chipboard pads not less than 20 point shall be inserted inride print boxes, two on the bottom and one on the "(c) No. 10 Cans: Six pounds net of butter shall be packed in can. For domestic shipment, six cans shall be packed in a 200 pound bursting strength regular slotted corrugated or solid fiberboard container." "One pound print and No. 10 can containers for domestic use hall have printed or stenciled on two rides, BUTTER--KEEP REFRIGERATED (less than 2 weeks below 40, more than 2 weeks OF or lower). No lettering on flaps." The specific heat of butter and other dairy products at temperatures varying from 32 to 140 F is given in Table 5. The temperature of the butter when removed from the chum ranges from 56 to 62 F. Assuming a temperature of the packed butter of 60 F the heat that must be removed from 1000 lb in order to reduce the temperature to 32 F is: 1000 X (60 - 32) X 0.52 = 14,456 Btu It is assumed that the average specific heat at the given range of temperature is 0.52. The heat units that are to be re moved from the butter containers and packaging material should be added. In medium size butter printing operations the butter stor age rooms are maintained at 40 F, but in some instances, lower temperatures are desired in order to firm up the butter at a .faster rate for handling in an automatic molding and wrapping machine. A Refrigerant 12 system with an auto matic hot gas defrost system is used for such a storage room. DETERIORATION OF BUTTER DURING STORAGE Ths dcvelopment of an undesirable flavor in butter during storage may be caused by (a) growth of microorganisms; (b) absorption of odors from the atmosphere; (c) fat oxidation; (d) catalytic action by metallic salts; (e) activity of enzymes; (f) low pH (high acid) of salted butter. Normally there will be no growth of microorganisms be low 32 F. If salt-tolerant bacteria are present their growth will be slow below 32 F. Growth of microorganisms does not take place at 0 F or below, but some may survive in the butter held at this temperature. It is important to store butter in a room where the atmosphere is free from odors. Butter will readily ahsorb odors from the atmosphere or from odoriferous ma terials with which it comes into contact. A stale, tallowy flavor is caused in the butter when oxida tion takes place. The chemical change takes place slowly in butter held in cold storage, but is hastened by the presence, of metals or metallic oxides. With the almost 100 percent replacement of tinned copper Table 5 .... Specific Heals of Milk and Milk Derivatives Whey Whole Milk 20% Cream 30% Cream 60% Cream Butter Butter Fat 32 F 0.978 0.940 0.920 0.750 0.723 0.673 . 0.606 0.560 (0.512)* (0.445)* 59.0 F 0.976 0.943 0.938 0.923 0.940 0.983 1.016 1.053 (0.527)* (0.467)* 1044) f 0.974 0.952 0.930 0.899 0.880 0.852 0.787 0.721 0.556 0.500 140.0 F 0.972 0 963 0.918 0.900 0.886 0-860 0.793 0.737 0-580 0.530 * For butts' ood batter tat, values ia psrentbeeis were obtained by ertnpota- taoo, mwt--' asmnptioa that the beat ia about the same m the aotid and liquid states. equipment with stainless steel equipment, a tallowy flavor is not as common as formerly. Factors that favor oxidation are fight, high acid, high pH and metal. Enzymes present in raw cream are inactivated by the pasteurization temperatures and holding times now used. The only enzymes that may cause deterioration of butter are those produced by microorganisms that gain entrance to the pasteurized cream and butter. The chemical changes caused by enzymes present in butter are retarded by a lowering of the storage temperature. A fishy flavor may develop in salted butter, during cold storage. The development of the defect is favored by high acidity (low pH) of the cream at the time of churning andmetalfic salts. With the use of stainless steel equipment and tiie proper control of the pH of the butter this defect now occurs very rarely. For salted butter which is to be stored for several months, even at -- 10 F it is advisable to use good quality cream avoid exposing the milk or cream to strong light, copper, or iron, and to adjust the acidity of the cream churned so that the butter serum will have a pH of 7.0. TOTAL REFRIGERATION LOAD FOR A BUTTER MANUFACTURING PLANT Many dairy plants that manufacture butter are also processing and manufacturing other products such as ice. cream, fluid milk products, and cottage cheese. A common re frigeration system is used. The method of determining the refrigeration load is illustrated by the example below. Example 1: Determine the total refrigeration load for a plant" manufacturing butter from 12,600 lb of 30 percent cream per day. in 3 churning. __ Solution: The refrigeration requirement is obtained in the following steps A to E. A. If the cream ia separated in the plant rather than on the farm, it would have to be pooled down from 90 F separating tem perature to 40 F to 45 F for holding until it is processed. --12,-6--0-0---;X---(--90 --F - 4--0---F---)---X----0--.-8-5- - 3719 lIbt_ I_ce B. After pasteurization, the temperature of the cream is reduced to approximately 100 F with city water, then on down to 40 F with refrigeration. 12,600 X GOO F - 40 F) X 0.85 -------------------------------------------------- - 4463 lb Ice -- 144 C. After churning, the butter wash' water (city water) is usually cooled to 45 F. then used to wash the butter granules. A volume of water equal to the volume of cream churned may be used. ' 12,600 X (60 F - 45 F) X 1.00 _ -------- ----------- i----------------------------- --- 1313 lb Ice 144