Deacidification by Debaryomyces hansenii of smear soft cheeses ripened under controlled conditions:: Relative humidity and temperature influences

Model smear soft cheeses were prepared from pasteurized milk inoculated with Debaryomyces hansenii ( 304, GMPA) and Brevibacterium aurantiacum ( ATCC 9175) under aseptic conditions. Debaryomyces hansenii growth and curd deacidification were studied in relation to ripening chamber temperature and relative humidity ( RH). A total of 9 descriptors, mainly based on kinetic data, were defined to represent D. hansenii growth ( 2 descriptors), cheese deacidification ( 5 descriptors), and cheese ripening ( 2 descriptors). Regardless of the temperature, when the RH was 85%, D. hansenii growth was inhibited due to limitation of carbon substrate diffusions; consequently, cheese deacidification did not take place. Debaryomyces hansenii growth was most prolific when the temperature was 16 degreesC, and the RH was 95%. Kinetic descriptors of lactate consumption and pH increase were maximal at 16 degreesC and 100% RH. Under these 2 ripening conditions, on d 14 ( packaging) the creamy underrind represented a third of the cheese; however, at the end of ripening ( d 42), cheese was too liquid to be sold. Statistical analysis showed that the best ripening conditions to achieve an optimum between deacidification and appearance of cheeses ( thickness of the creamy underrind) were 12 degreesC and 95 +/- 1% RH.