Effect of Emulsion Characteristics of a Low-Fat Dairy Spread on Bacterial Growth

Open Access
Publisher Website
Google Scholar
Abstract
The bacteriological keeping" quality of a low-fat dairy spread was investigated and found to be closely related to the size of the serum droplets dispersed in the con- tinuous fat phase. Standard plate and psyehrophilic bacterial counts on 38.8% fat spreads stored at 7.2 C for four weeks increased by about one log cycle. The majority of the serum droplets were in the size range of 3 to 20 microns. In the 30.0% fat spreads, however, where many of the serum droplets exceeded 50 microns~ the standard plate and psyehrophilic bacteria1 counts increased by three to four log eycles over the four-week storage period. During World War II and for some years thereafter, considerable research was conducted by several groups (3, 5, 6, 7) to develop a low-fat dairy spread which would be acceptable to the public. It may or may not have been coincidence that most of the spreads developed were fat-in-water-type emulsions, had little or no resemblance to butter, had a very limited shelf life~ and were not generally accepted. In 1966 the development of a new low-fat dairy spread was reported (2). A typical COlnposi- tion was 35% fat, 17% ealcimn-redueed skim- milk solids, and 48% water. The new spread was a water-in-fat-type emulsion and had a body somewhat like butter. Also, it had very good spreadability at refrigerator tempera- tures, was stable to repeated freezing and thawing, and had a flavor similar to butter. Contrary to expectations for a product which had a pI-I of about 6.5, which was not sterile, and which contained high percentages of pro- tein and water, the preliminalT report (2) indicated the spread had exceptionally good shelf life at refrigerator temperatures. There- fore, the pro'pose of the present investigation was to confirm the shelf-life finding and to discover the reason for it. Experimental Procedures

This publication has 1 reference indexed in Scilit: