TECHNOLOGY
New Cottage Cheese Process Uses HCI Direct addition of acid would replace batch fermentation
FILLING. Cottage cheese containers may soon be whizzing down filling line holding cheese made by new direct acidification process. In the process, food-grade hydrochloric acid coagulates skim milk, gives more uniform curd
The age-old batch fermentation method for producing cottage cheese may soon be replaced by a modern, continuous direct acidification process. The new process, originated at the University of Wisconsin and assigned to the Wisconsin Alumni Research Foundation (WARF), uses the direct addition of food-grade hydrochloric acid to coagulate skim milk in produc tion of cottage cheese. The result is a better, more uniform curd. Dean Foods Co. is now using the new process at its Rockford, 111., plant to produce limited quantities of cot tage cheese. Test marketing of the product will likely begin soon in Illi nois and possibly Wisconsin. Equipment for the process was de signed and installed at the Dean plant by the Creamery Products division of St. Regis Paper Co. under an agree ment with WARF. In all likelihood the next two years will see several more of these installations in commer
cial production, Creamery Products division director of research D. C. Roahen told a meeting of the Ameri can Cottage Cheese Institute, held at University Park, Pa. Today, more than 800 million lb. of cottage cheese are produced annually. Most of it is made by a batch fermen tation procedure. Cultures of acidproducing bacteria are added to skim milk. The bacteria convert the lac tose in the milk to lactic acid. The acid lowers the ρ Η of the milk to the isoelectric point (an acid value at which the protein of the milk precipi tates). This results in the formation of a cheese curd. This process has several serious drawbacks. The starter culture often behaves erratically, affecting product uniformity. Considerable time—usu ally 10 to 12 hr.—is needed to form and cook the curd. Finally, equip ment is needed to store the milk dur ing curd formation. According to Mr.
Roahen, the direct acidification process overcomes these problems. The new process was developed at Wisconsin by Dr. C. A. Ernstrom, now at Utah State University. Milk for the process must be fortified and the acidification carried out below room temperature. The skim milk is usually fortified by adding nonfat, dry milk solids to give a total solids content of 14 to 16%. The fortified milk is pasteurized and cooled to 40° F. Then food-grade hydrochloric acid is metered into the milk to lower p H to the isoelectric point. This is accomplished by adding concentrated acid— at a rate of about 3.8 liters per 1000 lb. of milk—while continuously agitating the milk. Curd Former. Next, the acidified mixture is pumped through a certical unit called the curd former, where it is heated to 110° F. The curd former installed in the Dean plant is a heat exchanger consisting of more than 1000 tubes—each 5 / 1 G in. in diameter and 42 in. long—mounted within a jacket containing steam under vacuum. The cold mix enters the bottom of the tubes, starts to coagulate as it moves up the heated tubes, and emerges as coagulated curd at the top where it is cut to size. The big advantage of the process is that it gives a uniform curd that has longer shelf life, Mr. Roahen says. Other advantages are that the process is carried out in a closed system, preventing contamination of the curd. Total time for the process is less than 45 min.; and there are savings in labor and floor space, although complete cost data for the process aren't available yet. Dean has been evaluating the process since early this year. Capacity of the system that Dean is testing is 2000 lb. of curd per hour. Still to be resolved is the labeling problem. Curd made by the new process doesn't meet the Federal Standard of Identity for cottage cheese. There are also state standards to be considered. Dean has asked the Food and Drug Administration for a temporary permit to allow the company to market the product in interstate commerce on a limited, test-marketing basis. Dean has authority to market the cottage cheese in Illinois. Recently, the Wisconsin legislature passed a bill which alters that state's standard of identity for cottage cheese to include the new process.
New Iodine Complex Lubricant Gets Its Properties from Lamellar Metal Diiodides Formation of lamellar metal diiodides provides the lubricating properties of General Electric's new iodine complex lubricant for hard-to-lubricate metals (C&EN, Nov. 22, page 3 5 ) . GE's Robert S. Owens and Dr. Richard W. Roberts, coinventors of the lubricant, have found that the iodine complex lowers the coefficient of friction for any metal that forms a lamellar diiodide. In fact, the GE scientists say, the new lubricant decreases the coefficients of friction of titanium and stainless steel by as much as 75 %, compared with conventional lubricating oils. The complex is formed by adding iodine to an aromatic hydrocarbon, such as n-butylbenzene. Highly electronegative iodine draws electrons from the hydrocarbon to form a charged transfer complex. A hydrophobic hydrocarbon as the complexing agent serves to protect the metal diiodides from hydrolysis by atmospheric water. Mr. Owens and Dr. Roberts say that the nature of the complexing agent is not important. The only qualifications are that it be relatively inexpensive and high boiling. They say that they have tried bromine and chlorine, but have found that iodine works best. The mechanism of this new approach to lubricating titanium and stainless steel as well as lead, cobalt, nickel, and other metals, Dr. Roberts says, involves the generation of diiodides in situ at the wearing interface between two sliding surfaces. Usually these metals are covered with an oxide film that makes them relatively unreactive toward iodine. However, during a sliding process, he says, the oxide films break when irregularities on the surfaces weld together and are then torn apart. This exposes perfectly clean metal surfaces with no oxides. These clean surfaces are highly reactive. The iodine in the complex reacts with the fresh metal to form a thin film only a few molecules thick. The film contains lamellar diiodides with a crystal structure similar to that of graphite—a layer-like crystal with planes of very low shear strength. The friction and wear of the metal are thus reduced. Dr. Arthur M. Bueche, vice presi-
ENGINE. Dr. Richard W. Roberts (right) and Robert S. Owens, inventors of GE's new lubricant, examine a gasoline engine made with parts of titanium, stainless steel, and other metals and used to demonstrate the lubricant
dent in charge of GE's research and development center, in Schenectady, N.Y., points out that the difficulty of working titanium and stainless steel has seriously hampered their use in many desirable applications. The discovery of successful lubricants for stainless steel and titanium can be expected to spur the use of these two metals. The new lubricant, he says, will have its initial impact on the metal working fields, where newer and tougher alloys of titanium, stainless steel, nickel, and other metals are increasingly finding applications in such uses as jet aircraft, nuclear reactor components, and heat exchangers. GE doesn't plan to make the lubricants for sale, Dr. Bueche says. However, the company would be willing to license its find to a producer of lubrication additives. NOV.
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