GROWTH OF BACTERIA ASSOCIATED WITH FOOD POISONING EXPERIMENTALLY INOCULATED INTO DEHYDRATED MEAT¹

Abstract

The problems involved in the production and distribution of dehydrated meats have received attention recently under the Emergency Meat Dehydration Investigations, sponsored by the U. S. Department of Agriculture. The chemcial composition and nutritive value of dehydrated meat have been thoroughly investigated, Orent -Keiles, Hewston, and Butler (1946), Hoagland andSnider (1946), andHankins, Ernst, and Kauffman (1946). Rehydration problems were studied by Hankins and Hetzer (1947), and packaging research was reported by Whitmore, Seligson, Kraybill, and Webb (1948).Since dehydrated meat is not a sterile product, the possible danger of food poisoning following its consumption must be evaluated. The finished package of dehydrated meat may be subjected to various conditions altering the contents of the package either before or after the container is opened. The type of meat (beef, pork, etc.), concentration of salt, presence o r absence of nitrates o r nitrites, time and temperature of storage, changes in moisture content during storage, temperature during rehydration, length of rehydration period, and the possible effect of naturally occurring contaminants are all things to be considered. The food poisoning organisms of chief concern are Clostridium b o t d i n u m , staphylococci and possibly streptococci. The Salmonella group could play an important role if the finished product were subjected to contamination of rodents.The following experiments were done to determine ( a ) the conditions of moisture and length of storage necessary for C. botulinum to elaborate its toxin, and ( b ) the conditions which would allow growth of staphylococci, streptococci, and salmonellae. The organisms used in these studies were Clostridiurn botulinum, Type A, Staph ylococcus aureus, strain 161, alpha-type Streptococcus, and Xalnzonella enteritidis. The strains of staphylococci and streptococci used had been isolated from food poisoning outbreaks and had been shown repeatedly to cause food poisoning in appropriate laboratory animals and/or human volunteers during the course of previously conducted laboratory experiments. The strain of S. enteritidis used was isolated in 1914 from a patient who was caring for sick calves during an epizootic of enteritis.The meat samples obtained for study were supplied by the TJ. S. Department of Agriculture, Bureau of Animal Industry, and some of the meat packers.This paper is the tenth in a series which deals with the Emergency Meat Dehydration Investigations of the United States Department of Agriculture and cooperators.All samples of dehydrated meat with one exception were received in tin containers.The exception was a compressed sample wrapped in cellophane and received from a meat packer. Upon receipt, each sample was tested for original moisture and salt content and portions of the sample were adjusted to various moisture levels as required by the experiment? I n all cases the moisture was calculated on the total weight of the sample rather than on a fat-free basis.Suspensions of organisms t...

THE EFFECT OF EXPERIMENTBLLY INOCULATING CANNED BREAD WITH SPORES OF CLOSTRIDIUM BOTULINUM AND BACILLUS MESENTERICUSa,b

“…It has been previously observed in the case of dehydrated meat that growth and toxin production of C . botulinum occurred when the moisture content was 40% but not 30% (9). The bread had approximately 34% moisture when prepared b y the new formula as compared with 37% moisture in the old formula.…”

Water Relations of Staphylococcus Aureus At 30°C

“…The expectation that other strains will behave similarly is strengthened by considering the results obtained by Segalove and Dack (1951). These authors studied the growth of another enterotoxin-producing strain (No.…”

“…Observations on staphylococci have shown that they generally tolerate rather higher solute concentrations than most other bacte;ia, and this has formed the basis of media used for enrichment and isolation of staphylococci as proposed by Chapman (1946). Segalove and Dack (1951) reported the growth of various food-poisoning bacteria on dried meat at different water contents. They found that a food-poisoning strain of S. aureus grew at rather lower water contents than the other organisms tested.…”

Water Relations of Salmonellae At 30°C

“…The latter solution has an aw close to 0.95. Segalove and Dack (1951) inoculated S. enteritidis into dried meat with various water contents for which the approximate corresponding aw's have been deduced by Scott (1953). At 50 per cent.…”

“…NaCl. In experiments with dried meat adjusted to various water contents Segalove and Dack (1951) reported that a strain of S. enteritidis required greater amounts of water for growth than Staphylococcus aurem or an alphahaemolytic-type Streptococcus.…”