Recovery of presumptive Alicyclobacillus strains from orange fruit surfacest.
Objectives of this research were to investigate the detection frequency of presumptive Alicyclobacillus strains, also known as thermoacidophilic or acidothermophilic bacteria, on oranges entering juice-processing facilities and to compare results from three common isolation agars (acidified potato dextrose agar, Ali agar, and K agar). A total of 1,575 fruits were sampled from three points (ungraded fruits, graded sound fruits, and graded defective fruits) at two juice-processing facilities during two harvest seasons. Buffer used to rinse individual fruits was assayed for the presence of thermoacidophilic bacteria using an enrichment procedure. Isolates were considered presumptive Alicyclobacillus if they were gram-positive, sporogenous, rod-shaped bacteria, with growth at 45 degrees C and no or slight growth at 25 degrees C on a low pH medium (pH 3.7) coupled with lack of growth on a neutral pH medium (pH 7.0) at both temperatures and a lack of growth in Sulfobacillus broth medium (pH 2.0). More than one third of all fruits sampled at the two facilities were contaminated with presumptive Alicyclobacillus strains. Therefore, incoming fruits are a substantial means by which these organisms gain entrance to the processing facility. Significantly (P < or = 0.05) more detection was observed with a mineral-containing medium (Ali agar) than with nonmineral containing media (K agar and acidified potato dextrose agar).
Parish
Mickey E
ME
Food Science and Human Nutrition, University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred, Florida 33850, USA. mparish@umd.edu
Goodrich
Renée M
RM
D001628:Beverages / Q000382:microbiology*; D032084:Citrus sinensis / Q000382:microbiology*; D015169:Colony Count, Microbial / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005525:Food-Processing Industry / Q000379:methods / Q000592:standards; D016937:Gram-Positive Endospore-Forming Rods / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D013696:Temperature
D003470:Culture Media