Comparison of conductimetric and traditional plating techniques for detecting yeasts in fruit juices

T. Deák, L. R. Beuchat

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Frozen fruit juice concentrates containing an average microbial population of log10 1.54 cfu ml-1 were examined by traditional plating techniques and direct and indirect conductimetry. The initial populations in diluted (1 : 4) concentrates increased to an average of log10 3.82 cfu ml-1 during incubation at 25°C for 24 h. Incubation before plating and subjecting to conductimetric tests also facilitated the resuscitation of cells that may have been freeze-injured. Yeasts were recovered in equal numbers on acidified (pH 3.5) potato dextrose agar and dichloran rose bengal chloramphenicol agar (pH 5.6). Yeasts and bacteria were recovered on orange serum agar. Detection times determined by indirect conductimetry correlated fairly well (r = - 0.73) with populations (cfu ml-1) detected on traditional plating media. Populations in diluted concentrates which were not incubated before examination were detected conductimetrically in an average of 48.9 h, whereas detection times for diluted concentrates incubated for 24 h at 25°C before testing were reduced to an average of 14.1 h. Examination by conventional (direct) conductimetry required an additional 10-20 h to reach changes in conductance of 5 μS h-1.

Original languageEnglish
Pages (from-to)546-550
Number of pages5
JournalJournal of Applied Bacteriology
Volume75
Issue number6
Publication statusPublished - 1993

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Yeasts
Agar
Population
Rose Bengal
Chloramphenicol
Solanum tuberosum
Resuscitation
Bacteria
Glucose
Fruit and Vegetable Juices
Serum

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Microbiology

Cite this

Comparison of conductimetric and traditional plating techniques for detecting yeasts in fruit juices. / Deák, T.; Beuchat, L. R.

In: Journal of Applied Bacteriology, Vol. 75, No. 6, 1993, p. 546-550.

Research output: Contribution to journalArticle

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