TEMPERATURE RELATIONSHIPS AND SOME OTHER CHARACTERISTICS OF THE MICROBIAL FLORA DEVELOPING ON REFRIGERATED BEEF ^a

Abstract

SUMMARY Growth curves were obtained for numbers of organisms surviving on beef stored at 0°, 5°, 10°, 15°, 20° and 25° C. These were related to the development of off‐odor and slime. It was shown that the initial load of organisms determined the time required for development of slime. The critical value for slime production was found to be 6 × 107 organisms or a log value of 7.8. There was a change in slope for the effect of temperature at 0° C when compared with that of 20° C. Comparison was made of the swab, rinse and cut‐section methods of sampling; swab samples were selected as being the most reproducible and most convenient to use. The effect of storage time and temperature on percentages of lipolytic, gelatin liquefying, oxidase producing, chromogenic and fluorescent bacteria was studied. Most of the bacteria on stored meats had lipolytic activity; from one‐third to two‐thirds of the organisms liquefied gelatin. Oxidase production could not be determined accurately. From 4‐20% of the initial population were found to be chromogens but colored colonies were rarely found beyond the fourth day of storage; also, plates stored at temperatures less than 15° C did not yield chromogens. Fluorescent bacteria comprised 10‐25% of the flora throughout storage. Microorganisms isolated from refrigerated beef were classified and it was found that at 10° C or lower the bacteria responsible for production of slime were almost without exception pseudomonads. Various species of Pseudomonas were identified. At 15° C or above, there was approximately an equal incidence of organisms of the genus Micrococcus and Pseudomonas. Other bacteria that were recovered from the sliced meat were Achromobacter, Flavobacterium, Microbacterium, Alcaligenes, Aeromonas, Bacillus, Clostridium and Streptococcus. Species of Penicillium were the most commonly encountered molds, more rarely, Cladosporium, Thamnidium, Mucor, Rhizopus, Aspergillus, Alternaria, and Sporotrichum were found.

Microbial growth and its control in meat, poultry and fish

“…Specific defects caused by aerobic bacteria include green, brown, gray or other discolorations, surface slime and odors, off-flavors and taints. The predominant microorganisms in refrigerated, aerobically stored fresh meat belong to the genus Pseudomonas, which cause putrefactive odors and slime when the number of cells exceeds 107.cm-2 (Ayres, 1960;Gill, 1983;Egan, 1984;Egan et aI., 1988). These organisms initially metabolize glucose, which is followed by degradation of amino acids and proteins.…”

“…Initial contamination, type, compoSItIon and processing of a muscle food, and storage conditions determine the predominating spoilage microflora and its effects on product quality. Several publications have reviewed the subject of microbial spoilage and loss of quality of muscle foods (Ayres, 1960;Cunningham, 1982;Gill, 1983;Dainty et al, 1983;Egan, 1984;Kraft, 1986;Venugopal, 1990). A muscle food is classified subjectively as spoiled when certain products of enzymatic (natural but mostly microbial) metabolism make it unacceptable, offensive and unpalatable to the human senses.…”

“…At subsequent stages of slaughter, processing and overall handling, muscle tissues are subject to additional contamination from various sources associated with the animal and its environment. In general, microorganisms found on fresh muscle foods originate from air, water, soil, manure, feed, hides, intestines, organs, lymph nodes, processing equipment and humans (Ayres, 1955(Ayres, , 1960Anon., 1980). Thus, the type and extent of contamination varies with individual animals, herds or flocks and seasons of the year.…”

Determination of Optimal Storage Condition for Pre-packed Hanwoo Loin

“…Physicochemical factors profile against storage temperature is difficult to describe on numerical formation for many variables affection. However, maintaining lowest temperature of chilling range in fixed temperature is the best storage method for quality preservation (Ayres, 2007;Dransfield et al, 1980;Jung et al, 1996).…”

Contagem total de bactérias e enumeração de coliformes em cortes de varejo de carne bovina e em equipamentos de supermercados

“…Uma vez recebida pelos supermercados, o tratamento a que é nestes submetida a carne pode modificar a composição da flora presente no alimento, bem como alterar o número total de bactérias. Fontes de contaminação do produto, bem como condições que afetam o crescimento bacteriano, foram estudadas e discutidas por AYRES (1955( , 1960( ), FRAZIER (1967, STRINGER et alii (1969), LECHOWICH (1971) e LAWRIE (1974, entre outros autores.…”