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Ascospore Heat Resistance and Control Measures for Talaromyces flaws Isolated From Fruit Juice Concentrate
Author(s) -
DOUGLAS KING A.,
HALBROOK W.U.
Publication year - 1987
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1987.tb14055.x
Subject(s) - potassium sorbate , food spoilage , sodium benzoate , population , heat resistance , food science , chemistry , potassium , botany , biology , sugar , bacteria , materials science , demography , organic chemistry , sociology , composite material , genetics
Talarotnyces flavus were isolated from fruit juice concentrates in two unrelated spoilage incidences of packaged reconstituted fruit juice. The population of survivors in heated fruit concentrate was 0.6 colony forming units (CFU) per gram. The ellipsoidal ascospores diameters were 4.5 ± 6 μm. Potassium sorbate and sodium benzoate prevented outgrowth of T. flavus , the concentration required was lower when the pH of the growth medium was 3.5 instead of 5.4. Conidia were sensitive to 70% ethanol, but ascospores were resistant. Ascospores required heat activation before maximum outgrowth occurred, the time for activation was less with higher activation temperature. Thermal death rate curves were nonlogarithmic but approached logarithmic death rate at higher temperatures. A calculated thermal destruction rate, using the exponential formula, for 1 log 10 was 2–7 min at 90°C depending upon the strain; and the approximate z‐value was 10.3°C.