Bacteriological Examination of Unbottled Soft Drinks

Abstract

Bacteriological examination of unbottled soft drinks. Appl. Microbiol. 10:311-320. 1962. A study of 300 samples, representing 14 different unbottled drinks, indicated that there are three vitally important criteria pertaining to their bacteriological examination. First, the total viable counts may be better accomplished by the pour-plate method, using enriched media, with incubation at either 30 or 37 C. Second, a comparative study of the coliaerogenes group and the enterococci as indices of pollution unquestionably favors the latter as the reliable indicator, owing to false interpretations of the presumptive test and to lack of accurate definition of fecal and nonfecal coliforms recovered from positive cases. The use of enterococci, however, did not provide as reliable an indicator as the pour-plate method. Third, the results with enterococci, in defining the probable source of pollution, are more precise. Experiments judiciously selected and simultaneously conducted revealed that the heat and heat-tellurite resistance tests, and the tetrazolium-reduction test, matched in relating 98.9 % of available enterococci to an animal source. Negligible but vital discrepancies were obtained with the two odd strains which qualified as human-derived according to the heat and heat-tellurite resistance tests. The differential criterion of Skadhauge and Barnes, based on the failure of animal-derived enterococci to grow in the presence of a low concentration of potassium tellurite, did not apply to the other two methods, since 99.5 %o of the recovered strains were found tolerant to the specified tellurite concentration. At the present time, the processing of Egyptian unbottled drinks is not controlled by designated standards or adequate specifications. Formulae employed in the making up of such drinks are quite varied and rest mainly on the so-called "individual art." Bacterial contamination reaching these feeds may be derived from the raw materials (usually of plant origin), water, sugar, ice, flavoring matter, coloring matter, utensils, hands of the producer, and surroundings (e.g., tables, flies, and dust). The main object of any bacteriological standards proposed for such foods is to secure three basic criteria, namely, their freedom from pathogens, toxinogenic bacteria, and high bacterial counts. Because the chief source of enteric pathogens of man is human fecal matter,

Studies on the Growth of Group D and other Streptococci in Different Media

“…The selectivity of a given medium depends on the kind of material examined (whether faeces of man, animal or contaminated feeds), and it has been shown that more than one fitreptococcus type may be recovered from a sample, again depending on the medium used (Cooper & Ramadan, 1955;Ramadan, 1960, Ramadan & Abd-Elnaby, 1962Ramadan & Sabir, 1963).…”

Survival of shigellae in food

“…Survival of shigellae in food 311 The shigellae survived for only brief periods in the carbonated beverages studied. Low pH was probably also a factor in limiting survival (Ramadan & Abd-Elnaby, 1962). Eagon & Green (1957) concluded that carbonation increased the bactericidal activity of acid environments.…”