Lactobacillus fructivorans spoilage of tomato ketchup
1997
Björkroth, Johanna | Korkeala, Hannu | Department of Food and Environmental Hygiene | Elintarvike- ja ympäristöhygienian laitos | Livsmedels- och miljöhygien, Institutionen för
Spoilage characterized by bulging as a result of gas formation in bottled ketchup was studied and resulted in growth on MRS and Rogosa selective Lactobacillus agar. Seventy randomly selected isolates were typed using restriction endonuclease analysis (ClaI, EcoRI, HindIII) and were found to have identical patterns. The strain was identified as Lactobacillus fructivorans using morphological, physiological and biochemical characteristics, combined with information obtained from rRNA gene restriction patterns. Factors affecting growth and survival of this L. fructivorans strain in production circumstances were also studied. Lactobacillus count of 105 CFU/g resulted in spoilage of inoculated ketchup samples. Spoilage occurred only in samples incubated at 15 to 30°C. L. fructivorans implicated in causing spoilage demonstrated heat resistance with a D-value of 1.2 min at 65°C. The strain did not show resistance against alkaline, active chloride containing detergent sanitizer, and also alkyldimethylbenzyl ammonium chloride and alkyldimethylethylbenzyl ammonium chloride containing sanitizer was found to be effective against it.
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