Heat resistance of bacillus coagulants spores isolated from tomato juice

ABSTRACT

Seven species of Bacillus have been isolated from fresh juice of tomato [Ace cultivar]. B.licheniformis was the most prevalent followed by B.cereus, B.subtilis and B.coagulans, then B.polymyxa, B.pumilus and B.megaterium were found in an equal representation. Heat resistance of spores of B.coagulans was investigated in phosphate buffer, serum, serum + 1, 2 or 3% NaCl at 212, 221, 230 and 250 F. Then the heat resistance parameters as D- value, Z- value and food phosphate factor were measured. The use of different suspending media indicated that low pH in the serum decreased heat resistance of spores. Moreover, the combined effect of the acidic medium with different salt concentrations increased spores sensitivity to head as shown by D- and Z- values when compared with those of phosphate buffer treatments