Document Type

Thesis - Open Access

Award Date

1985

Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

George S. Torrey

Abstract

Mold contamination of processed food and its raw ingredients is a major concern in agriculture. Although at one time mold contamination of cheese and other foods was considered to be of little conse9uence, discovery of carcinogenic and/or teratogenic toxins (73) produced by molds commonly associated with food has changed this innocuous and frequent inconvenience into a serious health consideration. The presence of mold on or in cheese is a common occurrence, indeed, many cheeses depend upon molds to provide characteristic cheese flavor and texture. Cheeses such as blue, Roquefort, Camembert, and Brie are ripened under controlled conditions by species of Penicillium. While certain molds are desirable, adventitious molds are undesirable contaminants in manufacture of most cheeses. Long ripening periods at controlled temperatures and humidity favor the growth of adventitious molds on Cheddar and other hard cheeses. Control of molds in ripening rooms and throughout cheese manufacture is important. One mold colony can give rise to thousands of airborne spores which can contaminate many kilograms of cheese. Some of the molds isolated from cheese produce mycotoxins in the cheese (10, 11, 48); therefore, control of mold growth is of paramount importance for the cheese industry. Surface-ripened cheeses are ripened by a smear of bacteria and yeasts growing on the surface of the cheese. Brevibacterium linens, the predominant microorganism in the smear of surface-ripened cheeses, is responsible for the typical aroma and flavor of Limburger, Trappist, Brick, and similar cheeses (1, 5, 8, 41, 42, 43, 60, 84). The aroma of these cheeses is a well-known characteristic and is due to the proteolytic metabolism of microorganisms in the surface smear (1, 2, 13, 21, 22, 23, 24, 26, 81, 84, 85). An interesting aspect of surface-ripened cheeses noted by Grecz et al. (29) is resistance to spoilage by bacteria or molds. These workers found that extracts of surface-ripened cheeses and of B.linens produced similar antimicrobial activity (30, 31). Grecz et al. did not examine the aroma of surface-ripened cheeses for antimicrobial activity. The aromas of surface-ripened cheeses contain a variety of compounds, several of these compounds are inhibitory to mold growth in environments other than cheese. The purpose of research presented in this thesis was to evaluate volatile compounds produced by B. linens for antimycotic activity. A method was developed to quantify inhibition of mold growth and spore germination in the presence of B. linens. The identity of the inhibitory compound was determined. Furthermore, the concentration of the inhibitory compound necessary to inhibit spore germination was determined. This thesis is arranged in an alternative style. The comprehensive literature review is followed by two journal articles which describe the majority of materials and methods. Results and discussion are also included in the journal articles. Materials and methods or results not presented in an article are placed in appendices as are statistical information and raw data. The conclusions derived from the project are included as a separate section.

Library of Congress Subject Headings

Cheese industry -- Quality control
Brevibacterium
Molds (Fungi) -- Control

Description

Includes bibliographies.

Format

application/pdf

Number of Pages

121

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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Included in

Dairy Science Commons

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