A Comparison of Cottage Cheese Yields Using Culture and Direct Acidification

Commercial production of cottage cheese constitutes a significant portion of the total fluid milk utilization in the U.S. Since 1955, yearly per capita consumption of cottage .cheese has steadily increased from 1. 77 kg (3.9 lb) to a high of 2.45 kg (5.4 lb) in 1971 and 1972 (101, 122). A relatively sharp increase in the price of milk solids-not-fat depressed the yearly per capita consumption of cottage cheese to 2. 14 kg (4. 7 lb) in 1974 and 1975 (121). A gradual recovery from this depression was experienced in 1976 with the yearly per capita consumption increasing from 2.10 to 2.18 kg (4.8 lb), which represents 464 million kg (1.02 .billion lb) of cheese (121). Consumption of cottage cheese is not geographically uniform in the U.S. The Northeast, North Central, and Pacific areas of the U.S. account for the greatest volume of creamed cottage cheese (120). The Pacific area accounts for the highest consumption of lowfat cottage cheese, while the Northeast has the highest utilization of dry cottage cheese curd (120). A problem of major concern in the cottage cheese industry today is poor yields. In the 1950’s, yield factors of 1.80 to 1.85 kg of 80% moisture curd per kg milk solids were commonplace (2). During the 1960’s, the yield factor dropped to 1. 70 to 1. 75 for at least two reasons: 1) Larger vats and mechanical agitation had become wide spread, resulting in greater yield losses as curd fines; 2) The composition of the milk supply had changed, resulting in milk lower in solids (2). Of particular interest to cottage cheese manufacture was the decrease in the casein content of milk. Casein comprises 85% of the milk solids found in cottage cheese (64). High or low cottage cheese, yields can be directly attributed to high or low milk casein levels (2, 19, 91). By the 1970\u27s, continued emphasis for greater milk production had selected the Holstein breed to predominate. Holsteins characteristically produce milk lower in solids than do other dairy breeds (2). Milk today (2, 64, 134) is more likely to contain 2. 3% casein rather than the 2. 5% listed in reference books (58, 129). Fortification of low-solids milk with non-fat dry milk (NFDM.) was once a common method used to improve cottage cheese yields (19, 83). However, the trend towards consumption of foods lower in fat and a relative change in the price supports of butter and NFDM resulted in an increase in the price of NFDM. Many manufacturers of cottage cheese determined that fortification of skim milk was no longer economically sound and discontinued the practice (83). Today\u27s cottage cheese manufacturers are having difficulty in obtaining 1. 70 kg curd per kg milk solids (2). Thirty years ago, 36% recovery of milk solids was common, but today few plants can attain 33% recovery of milk sol ids (75). Cottage cheese manufacturers have experienced the predicament of increasing consumer demand in conjunction with declining yields and more costly non-fat milk solids. The combination effectively forced an increase in the price of cottage cheese, resulting in a stagnation of sales increases. A cottage cheese manufacturing process utilizing conventional equipment, but eliminating bacterial cultures entirely, has recently gained Federal identity (42) and commercial acceptance (5, 45). This patented (18) process directly acidifies milk with food grade acids. The end product is reported to be indistinguishable from good quality cultured cottage cheese (4, 5, 44). Benefits attributed to the process are the elimination of problems that can arise with conventional culture processes, decreased production time, and improved product consistency (44, 45). A most notable claim concerns a cottage cheese yield greater than the yield attainable by the conventional culture process (4, 5, 44). This study compared cottage cheese yields from a widely accepted culture procedure versus the direct acidification method described above