The rate of growth of salmonellas and other bacteria in some synthetic creams

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Abstract
The development of representative salmonellas [Salmonella enteritidis (Gaertner) and Salmonella paratyphi B] and of spore‐forming organisms which resist pasteurization has been studied in synthetic creams. The creams consisted of (a) a vegetable oil emulsified in an aqueous solution of cellulose ethers (‘cellulose ether cream’) and (b) the oil emulsified in a medium containing egg yolk and sodium alginate (‘egg cream’). Rapid growth of the salmonellas to populations of 30–40 × 106 cells/g. took place in the egg cream within three days at 18–20°, but practically no growth occurred in the cellulose ether cream. No change in the appearance or odour of the creams was evident. The presence of a heat‐resistant, mixed microflora did not significantly influence the growth of the salmonellas in egg or cellulose ether creams.Growth of the organisms which resisted pasteurization was more rapid in the egg cream than in the cellulose ether cream at 18–20°, and was accompanied by development of putrid odours in the egg cream. No detectable growth took place in either cream after incubation at 1–8° for 22 days.It is recommended that where refrigerated storage is not available, storage periods not exceeding 4–6 days and 3–4 days at 18–20° be adopted for cellulose ether and egg creams respectively.