Résumé
Objective To determine the best method to detect thermo-acidophilic bacteria in apple juice concentrate. Methods L 16 (4 5) orthogonal test was applied to analyse the four factors, including culture medium, ways of heat shock, dilution degrees of AJC and pH value. The results were comprehensively scored according to the number of colonies. Results The isolated bacteria were polymorphous. A better method was as follows: after being diluted to 1∶10, the AJC was submitted to a heat shock at 80 ℃ for 10 min, and then spread on k agar with a pH value of 3.5. Samples were incubated at 45 ℃ for 3 days, and then enumerated. Conclusion This method can considerably improve the sensitivity of detecting thermo-acidophilic bacteria in apple juice concentrate.