Incidence and Significance of Thermoduric Bacteria in Farm Milk Supplies: A Reappraisal and Review

Abstract

CONTENTS PAGE 26'i r i 1 hermoduric bacteria in farm milk supplies miportance of using a suitable brand of peptone in the plating medium, w liich should be at a pH of 7.5, while iiicubation should preferably be a t 28" for 96 h. The results of these findings should be incorporated in future revisions of standard techniques. Donovan & Vincent (1955) recommended the use of a double indicator (broniocresol purple and phenol red) agar medium for estimating the numbers and types of thermodurics, while Leali (1958) used a TTC medium which he claimed facilitated and reduced the error of counting colonies of thermoduric bacteria.

Thermoduric and Psychrotrophic Organisms on Poorly Cleansed Milking Plants and Farm Bulk Milk Tanks

“…Refrigerated farm bulk milk tanks do not provide a suitable environment for the multiplication of thermoduric bacteria, as most strains fail to grow a t temperatures < 10". Ten of the 12 tank rinses in the present survey contained < lo3 thermoduric organisms/ft2, compared with 84% of 104 tank rinses examined by Thomas et al (1967).…”

“…According to Egdell et al (1950) thermoduric counts > 104/ft2 indicate a build-up of these organisms on farm dairy equipment due to inadequate cleaning and sterilization. Later, Thomas et al (1967) and Parry & Egdell (1969) showed that pipeline milking plants can contribute appreciable numbers of thermoduric bacteria to the milk when the temperature of the cleansing solution is too low. Furthermore, the role of pipeline milking plants as a major source of large numbers of thermoduric organisms in bulk-collected milk has been emphasized by Leali (1960) in Italy, La Grange & Nelson (1961) in the USA and Thomas (1972) in the United Kingdom.…”

Effects of Pasteurization or Added Sulphite on the Microbiology of Stored Vacuum Packed Baconburgers

“…The thermoduric corynebacteria have been studied extensively in relation to pasteurized milk. Thomas, Egdell, Clegg & Cuthbert (1950) and Thomas, Druce, Peters & Griffiths (1967) reviewed the literature on their incidence and heat resistant character, and also Jayne-Williams & Skerman (1966) made comparative studies on coryneform bacteria from milk and dairy sources. Kraft, Apes, Torrey, Salzer & da Silva (1966) found that of 15 genera isolated from turkey giblets, Corynebacterium was the most commonly isolated, the majority of which were unable to grow a t 5"; no data were given on their heat resistance.…”