Previous articleNext article No AccessNew Biological BooksCheese. Volume 1: Basic Technology. J. G. Davis Cheese. Volume 2: Annotated Bibliography with Subject Index. J. G. Davis Darrell D. DeaneDarrell D. Deane Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 41, Number 2Jun., 1966 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/405051 Views: 1Total views on this site PDF download Crossref reports no articles citing this article.

A description is presented of a bacteriophage capable of lysing a strain of S. thermophilus used in the manufacture of Swiss cheese. The bacteriophage was not completely destroyed by the usual pasteurization conditions. Typical sperm-shaped particles had a head diameter of 90 mμ and an overall length of 360 mμ. This bacteriophage was quite specific and lysed but one of four test strains of S. thermophilus. It did not lyse any of the cultures of S. lactis or S. cremoris tested.

All but one of ten samples of whey or culture from four dairy plants experiencing “slowness” in their lactic cultures or products contained lactic streptococcus bacteriophage. The activity pattern of the bacteria-free whey filtate prepared from each of these nine samples indicated a multiple-strain bacteriophage infection.

The use of S. liquefaciens was unsatisfactory as a means of increasing the rate of flavor development in cheddar cheese made from pasteurized milk.

Use of a Parakote wrapper reduced the weight loss of cheddar cheese during curing to a very small amount, as compared with that found when the cheese was paraffined.

Eighty-one samples were obtained from Swiss cheese factories located in three states, mostly in Ohio. Many of these plants were experiencing some degree of slow acid development. A few of the samples were of milk taken before setting or of the whey culture used in the kettle. The majority of the samples were taken directly from the kettles after the curd had been dipped. The samples were collected in sterile, 6-oz. prescription bottles, some of which contained 1 g. of CaCQ, and then mailed without provisions for refrigeration, to the laboratory. Bacteria-free filtrates were prepared from these samples as follows: The whey samples were filtered first through a filter bed of acid-coagulated milk to remove material which otherwise might clog the ultrafilter. The filter bed was prepared by coagulating 150 ml. of sterile milk with 5.5 ml. of 10-per cent lactic acid solution and filtering the mixture through sterile coarse filter paper.

It is often economically desirable for dairy manufacturing plants to be self-sufficient in supplying the milk ingredients of their products. In the manufacturing of ice cream a concentrated milk is used as a source of added serum solids to improve the body and texture. Since the production of milk fluctuates during the seasons it would be desirable, perhaps, to concentrate the solids of the surplus milk to be used during the period of reduced production. It was in an effort to store these milk solids with a minimum of processing that led to the freezing and storing of condensed sldmmilk by some ice cream manufacturers. In m any instances this practice of condensing the surplus skimmilk, freezing and holding it frozen until used to make the ice cream mix, has been carried out successfully ; yet in other cases it has proved to be unsatisfactory because after the skimmilk had thawed it was found that precipitation of the protein had occurred. Therefore, if it were possible to determine by some chemical or physical test the degree of stability of the protein fraction of the milk supply, the suitability of the milk to being stored frozen in the form of condensed skimmilk could be deternfined. STATEMENT OF PROBLEM The purpose of the investigation was to study the characteristics of a milk supply which appears to be associated with the ability of the protein fraction to remain stable after the skimmilk obtained by c entrifugal separa- tion had been condensed and then stored frozen. The study was conducted by making chemical and physical tests on representative samples of milk taken at specific intervals in the manufacture and storage of the plain con- densed skimmilk. Physical and chemical tests were also used to determine the effect of a change in the characteristics of condensed skimmilk during storage upon an ice cream mix and the resultant ice cream.